Basement/Crawl Space Dehumidifier

by Shem Uzele
(Wilmington DE)

What size dehumidifier do I need for a 480sq ft basement that has a 350 sq ft crawl space connected on one side of it?




Answer

Hi Shem, thanks for your question.


There are three issues to consider:

  1. The area to be dehumidified


  2. The typical temperature of your basement/crawl space


  3. The exchange of air between your crawl space and your basement



Area

The combined area of your basement/crawl space is well within the capacity of a standard portable home dehumidifier of at least 50 pint or, preferably, 70 pint capacity.

If a home dehumidifier suits your purpose I would recommend a 70 pint unit for three reasons:

  1. It will give you a greater margin of dehumidifying capacity which may be helpful in a high humidity area like Wilmington


  2. A 70 pint dehumidifier, of almost any brand, will be more energy efficient than a 50 pint model, removing about 12% more water for every energy dollar you spend


  3. A 70 pint dehumidifier will operate for fewer hours per day to maintain your chosen humidity setting (I recommend 45-50%) so will last longer than a 50 pint unit.



Temperature

If your problem is summer humidity a portable room dehumidifier should be fine from May through September. In a cooler summer you will notice a reduction in performance (amount of water removed) but generally speaking the temperature should remain above 60°F, and will often be considerably higher, so a portable unit will be ok.

If your problem is year round a home dehumidifier may struggle from October/November to February/March when outdoor temperatures can fall below freezing and will, at best, reach the 40s, occasionally the 50s. In these conditions a purpose built basement or crawl space dehumidifier would be a better investment, despite its higher purchase price.

If you opt for a basement or crawl space dehumidifier a 65 pint model, such as the Santa Fe Compact will have all the power you need although a larger capacity model, the Santa Fe Advance or Santa Fe Classic will be more energy efficient.

Air Exchange

Since one dehumidifier will be enough it will have to be located in either the basement or the crawl space. For full effectiveness you will need to ensure that the exchange of air between the two areas is sufficient or the efficiency of the dehumidifier will be significantly reduced.

I have no information about the size of the aperture between the crawl space and the basement but if it is fairly small, and you opt for a portable home dehumidifier, you will find it helpful to locate a fan in one or both of the basement and the crawl space.

If you decide on a basement or crawl space dehumidifier you have the option of ducting air to and from the two spaces which will be even more effective.

Final points

  • It would be wise to invest in a separate hygrometer and to monitor the relative humidity in whichever of the two areas does not contain the dehumidifier. This should not be necessary if you choose a ducted solution.


  • The vents in the crawl space must be sealed for the dehumidifier to work effectively. Without this precaution the humid air from outside will transfer its moisture to the crawl space, defeating your efforts to keep it dry.


I hope I have covered all the points that may be helpful in selecting the right dehumidifier to meet your needs. If I am telling you stuff you already know, please bear with me. Many other visitors will also see this answer and may be less well informed :).

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Basement Dehumidifier - Danby DDR7009REE

by Dan Doroga
(Terrebonne, Quebec, Canada)

Basement area 1400 square feet.

I have a Danby DDR6011R dehumidifier but I would like to buy a Danby DDR7009REE. Which is the best and what is the difference?

Merci !

Dan D




Answer


Hi Dan, thank you for your question.

The main difference between the Danby DDR6011R and the Danby DDR7009REE Dehumidifiers is the amount of water each will remove over a 24 hour period.

The Danby DDR6011R is a 60 pint dehumidifier and in the right conditions will remove 60 pints of water per day. The Danby DDR7009REE is a 70 pint dehumidifier and will remove 70 pints of water per day in the same conditions.

The amount of water removed by a dehumidifier varies. When it is warmer and more humid the dehumidifier removes more water and when it is cooler and/or less humid the dehumidifier removes less water.

The DDR7009REE is the more powerful of the two dehumidifiers and, although the absolute amount of water it removes will vary it will always remove 1/6 more water than the less powerful DDR6011R.

In all important ways the two dehumidifiers are very similar. These similarities include the "Energy Factor", the measure of energy efficiency used by Energy Star. Both dehumidifiers have an Energy Factor of 1.8. This means that each dehumidifier will remove 1.8 litres of water for every kilowatt hour of energy consumed. In other word their energy efficiencies are the same.

The other part of your question asked "which is the best?"

I am in no doubt that for your basement the Danby DDR7009REE Dehumidifier is the better of the two. If you had asked me to recommend a dehumidifier for your 1400 square foot basement I would have suggested several brands but the models I would have suggested would be the largest available, around the 70 pint mark.

A 70 pint model is almost the same weight and makes a similar amount of noise to a 60 pint unit and, as I have said, is equally energy efficient. The additional water removal power is an advantage because it means that a 70 pint dehumidifier runs for fewer hours per day to maintain the level of relative humidity in the 45-50% range that we recommend. Working for fewer hours per day extends the working life time of the dehumidifier and, although it is no quieter than a 60 pint dehumidifier, the noise from the compressor is heard for a shorter time each day.

If you are looking for alternatives to the Danby brand you may like to visit this page where you will find more information about the Danby DDR7009REE and the other four brands we recommend.

Tom (Webmaster)

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Basement dehumidifier sizing

by Peter
(St, Clair Shores, MI)

QUESTION:
Need to know what size, pints per 24 hrs, to purchase.

BACKGROUND:
Basement area is approx 800-900 sq. ft.
Has a damp / musty odor...particulary in summer.

RECOMMENDATION:
Mfg / Model
Desire Energy Star unit

Thank you for your assistance




Answer

Hi Peter, thank you for your question.

The information you provided is pretty comprehensive. You mentioned that your problem is greatest during the summer so I assume that this is the season when you will rely on the dehumidifier the most.

You have pretty warm summers in the Detroit area so a portable home dehumidifier should work satisfactorily in your basement. Winters can be cold, with occasional sub-freezing temperatures. There may be times during the winter when the effectiveness of your dehumidifier will be less at these colder times unless your basement is heated to 65F or above. It's probably not enough to justify the extra expense of a basement dehumidifier, especially for around 900 square feet, so we'll stick with the portables in my answer.

In general terms you need a minimum of 50 pints per day water extraction power. A dehumidifier of this capacity will almost certainly keep your basement dry. My advice would be, however, to choose a higher capacity unit, in the 65-75 pint range.

My reasoning is set out in detail on this page but in essence it boils down to two points. First, a larger capacity dehumidifier is more energy efficient. It will pull about 12.5% more water from the air for every energy dollar you spend. Second, a larger unit will operate for fewer hours each day to maintain the relative humidity you program into the unit; 45-50% will be fine, any lower and you are spending extra money for little or no benefit. Fewer hours work per day = a longer working life. That means fewer replacement dehumidifiers will have to be bought in a given period.

The energy saving, plus the longer replacement intervals will save you more than the difference in ticket price between the two models. As a bonus fewer operating hours means less noise nuisance and even the best dehumidifiers make some noise!

As far as brands and models go we have identified five brands that we consider to be the best currently available. These are listed and briefly described on this page, with links to individual reviews of each unit we describe. The five brands are Alen, Danby, Frigidaire, GE and Winix.

I can confidently recommend Alen, Danby and GE. The Frigidaire range has just been replaced and the jury is still out on the new models - FAD704DUD etc. It is still possible to obtain the FAD704TDP and FAD504TDD from the preceding range however and these are tried and proven models. The Winix is almost unique in so far as it includes an internal condensate pump but I would not currently steer you toward that brand. Recently received information may lead us to revise our view of the Winix. If you need a condensate pump it would be more prudent to obtain a separate one for use with one of the other four brands.

On your final point all of the five brands I have mentioned are Energy Star certified.

I hope this provides you with most if not all of the information you need to make the best choice.

Tom (Webmaster)




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Dehumidifier for a 600 square foot basement

by Sam
(Hurley ,Wi)

What size of dehumidifier is needed for a 600sq ft basement?




Answer

Hi Sam, thank you for your question.

I am assuming that you are considering a portable home dehumidifier. These units are not suitable for low temperature operation but if your problem is summer humidity this will not be an issue in Wisconsin. In the winter months your basement would need to be heated to around 65F in colder weather for a portable dehumidifier to be fully effective.

The simple answer to your question is that almost any dehumidifier will be powerful enough for your needs, say from 30 pint capacity upward. I would recommend, however, that you choose a unit with at least a 40 pint and, ideally, 50 pint, capacity.

The larger the capacity of the unit the greater its energy efficiency. A 40 pint dehumidifier will have a typical Energy Factor (EF) of 1.5L/Kwh while a 50 pint unit will have an EF of 1.6L/Kwh. That means that a 50 pint unit will extract around 7% more water for every energy dollar you spend. As the energy cost over the life time of a dehumidifier is always greater than the purchase price of the unit this saving will more than compensate you for the difference in ticket price.

A 50 pint dehumidifier will also run for fewer hours per day to maintain your chosen level of relative humidity; we recommend 45-50% RH. Running fewer hours should mean a longer working life, a further saving.

A 70 pint dehumidifier has an even higher energy factor, of 1.8, but would really be over-kill for a 600 square foot basement. A 50 pint dehumidifier is the best balance between energy efficiency, length of working life and purchase price and would be my first choice for your basement.

Hope this is helpful.

Tom (Webmaster - Best Dehumidifier Choice)

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Basement dehumidifier 30 or 70 pint?

by Tony
(Erie, PA, USA)

I am looking to replace my current dehumidifier. I have approximately 1000- 1500 square foot basement area.

90% is used as living quarters (TV Room) it is carpeted and well insulated with proper insulation.

The other 10% is storage area and a small office.

Would the Danby DDR3010E or the Frigidaire FAD704TDP be a better unit to purchase? Would both work for this area?




Answer

Hi Tony, thank you for your question.

The answer to your question is very simple; if you are choosing between the Danby DDR3010E and the Frigidaire FAD704TDP you should choose the Frigidaire, no ifs or buts, it must be the Frigidaire.

Let me explain why my answer is so definite. The DDR3010E is a 30 pint dehumidifier which means it will remove up to 30 pints of water per day. The FAD704TDP is a 70 pint dehumidifier so will remove over twice that amount per day. For an area of 1000 to 1500 square feet you will need a larger capacity home dehumidifier, of at least 50 pint capacity and preferably 70. A 30 pint unit will not be sufficiently powerful and will most likely run 24/7 trying to cope.

Larger dehumidifiers are more energy efficient than smaller models. Energy Star ratings are based on the "Energy Factor" (EF) which is a measure of the volume of water removed by the dehumidifier (in litres) for every unit of energy consumed (kilowatt hour). The FAD704TDP has an EF of 1.8, the DDR3010E an EF of 1.4. In other words the FAD704TDP removes an additional 0.4 litres of water for every energy dollar spent, nearly 29% more than the DDR3010E. Since the life time cost of energy consumed by a dehumidifier will almost always be greater than its ticket price this is a significant saving.

This difference in energy efficiency between larger and smaller dehumidifiers is recognised by Energy Star who require a lower EF in a small unit to qualify than for a larger model. Even if your basement was considerably smaller you would almost certainly spend less money, over its lifetime, using a larger dehumidifier in preference to a smaller unit.

The other factor to consider is the number of hours per day your dehumidifier will run. The 30 pint unit, as I said earlier, will probably run 24 hours per day. A 70 pint model will reduce humidity more quickly and cycle on an off to maintain that level, running for much less than 24 hours per day. The more hours a dehumidifier runs the more quickly it wears out. A 30 pint unit will almost certainly have to be replaced more often than a 70 pint model, further increasing the life time costs of operating the dehumidifier.

Obviously you could consider any other large capacity dehumidifier but the Frigidaire is one of the five brands of portable home dehumidifiers which we recommend. The others are Alen, Danby, GE and Winix and there is little to choose between them.

I hope this is helpful and that my explanation makes it clear why my answer is so clearly in favor of the Frigidaire FAD704TDP.

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Dehumidifiers

by Mike
(Mason,Ohio)

I have a 65 pt. GE dehumidifier and it is not cooling down to a setting of 50%. It is in a 1200 square foot unfinished basement. There has been a mildew odor in the basement. GE is saying that the Dehumidifier is too big and that I need to step down to a 30 pint dehumdifier for that size of room.





Answer

Hi Mike, thanks for your question.

I assume from your question that you have programmed a relative humidity setting of 50% into the dehumidifier and that it is running constantly or that the dehumidifier is cycling off before the 50% level is achieved and that you are monitoring this with a separate hygrometer.

My first comment has to be that the advice you have been given by GE is nonsense. A dehumidifier is controlled by a humidistat and should continue to operate until the relative humidity in your basement is at the level you have programmed into the humidistat. Many people use larger capacity (65-75pint) portable home dehumidifiers, including GE models, in basements of exactly the same area as yours and most report that their dehumidifier does the job, even if they complain about other issues. If your dehumidifier is running constantly and is functioning correctly it would suggest that its capacity is too low, not too high.

If you had asked me whether a 30 pint dehumidifier was suitable for your basement I would have encouraged you to buy a 65-75 pint unit as I consider 30 pint capacity insufficient for a basement of 1200 square feet! I would be interested to know how GE explains that your dehumidifier is prevented from doing its job by the "small" size of your basement. If their explanation makes any sense, which I doubt, the thousands of people who have had excellent results with dehumidifiers of this capacity in similarly sized basements must have been extremely lucky :).

I do not take manufacturers' recommendations of room sizes for dehumidifiers at face value. If you would like to see another example of an opinion about this visit sylvane.com, a web site which I admire for its refreshing honesty. Although they do not sell GE dehumidifiers there are two examples you may like to check out.

If you look on the page for the Alen MDF3-74 (74 pint) dehumidifier and scroll down to the table marked "Product Specifications" you will see, near the top of the table, that the Manufacturer recommends this unit for areas of up to 800 square feet but that Sylvane has recommended a "Practical Room Size" of 1200 square feet.

In contrast if you move to the Danby DDR7009REE (70 pint) Dehumidifier page you will see, in the equivalent table, a manufacturer's recommendation of 3800 square feet but a recommendation from Sylvane of, once again, 1200 square feet. Whose word would you take on this issue?

Having ruled out the ridiculous let's consider the possibilities.

You have not said how long you have been using this dehumidifier. If you have only had it a couple of days you may need to leave it for a few more days to get humidity down to 50%. Once the level is achieved the unit should simply cycle on and off the keep the level constant. If this does not cover your situation the other possibilities are as follows.


  1. The temperature in your basement is too low for the dehumidifier to work properly.

    I rule this one out given that you are, presumably, using this appliance now, in the middle of a record heat wave. Even without the exceptional weather average summer temperatures in Mason are more than warm enough for a home dehumidifier to function effectively.


  2. The dehumidifier is not removing moisture at the proper rate; it has a fault.

    If the bucket is filling once or twice per day, or an equivalent amount of water is being drained through a hose, the dehumidifier is working as it should. If it is not it is almost certainly faulty and needs attention, under warranty if is still current.


  3. The humidistat is faulty.

    If you are not already using a separate hygrometer to monitor relative humidity you will need one to check out this theory. If the dehumidifier is running continuously the humidistat may be wrongly calibrated and the dehumidifier "thinks" it is still trying to reach 50% when it is already way below that level. If the humidistat is wrongly calibrated in the other direction the dehumidifier will cut out way before 50% is achieved. If the humidistat is not working at all the dehumidifier may be operating in continuous mode. A fault in the calibration could be corrected for by changing the setting on the humidistat to compensate for the error. A complete failure can only be solved by replacing the humidistat.


  4. You have a source of water entering your basement and the rate at which it is coming in is greater than the dehumidifier can cope with.

    If this is so the amount of water being removed by the dehumidifier would be very large, 40 to 70 pints per day depending on the temperature. In that case a suitable repair is obviously the solution.


I can't think of any other possible reasons why your dehumidifier should not be doing the job you bought it for. GE's explanation does not hold water (excuse the pun:) ). I believe a fault in the unit is the most likely cause. Under no circumstances would I advise you to switch to a smaller capacity dehumidifier.

I hope this is helpful.

Tom (Webmaster)

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GE 50 Pint Dehumidifier

by Anon.

What is the square footage the unit is rated for?




Answer


Thank you for your question.

Q. What is the size of the area which a dehumidifier can cover?

A. It depends on who answers the question!

Let me give you an example. Alen states that its 74 pint MDF3-74 Dehumidifier is good for 800 square feet. Danby states that its 70 pint DDR7009REE Dehumidifier is good for 3800 square feet!

GE explicitly states very little but informed one of our visitors that a 65 pint dehumidifier was too big for his 1200 square foot basement and recommended a 30 pint unit.

A tad confused? I would be.

So, I am not going to answer your question with a manufacturer's recommendation. I will tell you what I would recommend.

A 50 pint dehumidifier, of whatever brand should be able to control the humidity in a area of about 700 to 1000 square feet, depending on the conditions. Having said that, if the area of your space is approaching 800 square feet I would recommend that you go for a larger model, in the 65-74 pint range. In an area larger than 1200 to 1500 square feet even a large portable home dehumidifier may struggle, particularly if the basement is very wet and/or cool (below 65F/18C).

The reason I would recommend a larger dehumidifier, even if your space is a little short of 800 feet, is that it will save you money. A larger dehumidifier is more energy efficient; you get more moisture out of the air for every energy dollar you spend. A larger dehumidifier will run fewer hours in any given space than a 50 pint unit. This means it will last longer and need replacement less frequently; another saving for you.

For a fuller explanation of why this is so take a look at this page. You may also find another page about basement humidity control helpful.


Tom (Webmaster)

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How big a dehumidifier for my basement?

by James
(Kenora, Ontario )

How do you know what size of a dehumidifier to purchase?

My situation is that my house is built on bedrock and my basement is only half developed. The back half of my basement is all bed rock and I get water weeping under or through the bottom of my footings. It is more wet than just humid, I have a fan and a small dehumidifier running 24hrs. a day. If it is actually humid outside than its like nothing is going to help and the two of them working together can't keep up, they barely keep it under control at the best of times. Would it be wise to purchase a commercial sized dehumidifier?

Thanks,

James.




Answer

Hi James, thanks for your question.

I guess you will have explored the options for waterproofing your basement to prevent the water seepage. Obviously the less liquid water entering the area the less severe the humidity. I appreciate that bedrock is a special problem although it is not entirely uncommon in parts of Ontario. A competent basement waterproofing contractor in your area should be able to offer a solution if you choose to consider this option.

I don't know the area of your basement and I can only guess at what you mean by a "small dehumidifier". I am assuming that your dehumidifier is a portable unit. If by a small dehumidifier you mean a unit with a water extraction capacity of less than 50 US pints (23-24 litres) per day then it sounds like your humidity problem is manageable. If a portable unit is just managing to keep control in less humid weather a larger capacity dehumidifier should be able to cope with the area of your basement. If you are using a portable dehumidifier of the largest capacity, around 70 US pints (33 litres) per day, you may indeed need a more powerful unit.

Apart from the area of your basement the other issue is temperature. You live in an area where summer is temperate and winter is darned cold, with sub-zero temperatures for five to six months of the year. Portable home dehumidifiers are not designed for use in areas where the temperature is below 18 degrees C (65F) for extended periods. Unless your basement is heated to or above that level a portable dehumidifier will always struggle to keep pace and will burn itself out trying in a relatively short time.

As I see it your options are as follows:

1) If you are currently using a sub-50 pint unit and your basement is typically at or above 18C a 70 pint portable dehumidifier will almost certainly do the trick. If you are already using a 70 pint dehumidifier you need more capacity, regardless of temperature.

2) If you need more capacity, and the temperature of your basement is above 18C, you could consider a second dehumidifier to supplement the first.

3) Alternatively you may wish to consider a purpose built basement dehumidifier such as the Santa Fe Classic. This unit is built to commercial standards and has a water extraction capacity of 100 pints per day. It is considerably more energy efficient than a portable and will last longer. The purchase price of a Santa Fe Classic is much higher than for a portable but it should last at least twice as long as a portable. This means that during the lifetime of a basement dehumidifier you may buy at least four portables (on the assumption that you need two at any one time). Combined with its greater energy efficiency a basement dehumidifier will almost certainly have a lower life time cost than four portables, even in a basement at 18C or above.

4) If your basement temperature is lower than 18C for long periods a portable dehumidifier, let alone two, is a poor investment. In cooler temperatures portable dehumidifiers will be relatively ineffective and will burn themselves out even more quickly. A basement dehumidifier is designed for these conditions and its relative energy efficiency is even greater in such conditions.

5) Even basement dehumidifiers have their limitations and the Santa Fe Classic is not recommended for use in temperatures typically below 12-13C for extended periods. If your basement is only a little above freezing in winter then you will have no alternative but to invest in a commercial dehumidifier. The dehumidifier you select in this case must be a unit with an active defrost system, called "hot gas defrost" by some manufacturers. This feature allows the dehumidifier to operate at temperatures as low as 1C.

I hope I have covered all the angles here and that you now have enough information to assess your needs and select the best solution to meet them.

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How to determine the power required for a wholehouse dehumidifier?

by Marc

Is there a method or formula to determine the power of the dehumidifier in order to select the most appropriate whole-house dehumidifier model?

I'd think that with size of the basement (~1,500sq ft), the current humidity level (64%), the humidity level targeted (50-55%) it could be possible to determine if a 65 pint, 90, 100 or 150 pints per day model is best.




Answer

Hi Marc, thank you for your question.

I am not entirely clear whether the dehumidifier you are seeking is for your basement or for the whole house but the best guidance I can give you is to quote the maximum areas recommended by the manufacturers for examples of each of the four dehumidifier capacities you have quoted.

65 Pint - 1800 sq ft (Honeywell DR65)

90 Pint - 2800 sq ft (Honeywell DR90)

100 Pint - 2500 sq ft (Santa Fe Classic)

150 Pint - 3600 sq ft (Honeywell DH150)

The apparent anomaly in the figures quoted above (a 100 pint unit being suitable for a smaller area than a 90 pint model) arises because the Santa Fe Classic is a stand-alone unit, specifically for basement use, whereas the other three are whole home dehumidifiers designed for integration with the existing HVAC ducting in the home. The greater air circulation achieved by a ducted system means that a dehumidifier can control humidity in a larger area if ducted than a stand-alone unit. All three of the Honeywell models can be operated in stand-alone mode but the area for which each would be suitable will be correspondingly smaller.

In a typical home the existing level of relative humidity is not relevant to calculating the capacity of the dehumidifier required. If the area is within its capabilities, and there is no major source of incoming liquid water, the existing level of RH is only relevant during the first few days of operation; the wetter the air the longer it will take the dehumidifier to achieve the programmed level of relative humidity. The type of calculation which is implied by your question is complex and is usually only appropriate in water damage restoration and other specialist applications. Any one of the four dehumidifiers listed above will be more than capable of controlling relative humidity to 45%, well beyond your requirements.

There is a form of "ready reckoner" for estimating the capacity of dehumidifier required for areas of different sizes and with varying degrees of dampness. This is in the form of a table produced by AHAM (Association of Home Appliance Manufacturers) and reproduced at the Energy Star site. This table can be used to get a "feel" for the size of unit you need but may not be the ideal tool for the job.

For what it's worth my view is that, for a basement of 1500 sq ft, your best choice would be a 90 pint whole home dehumidifier or a 100 pint basement dehumidifier. Let me explain my reasons.

The larger the capacity of a dehumidifier the more energy efficient it is. Energy efficiency is best expressed using Energy Star's "Energy Factor" (EF). The EF is the volume of water (litres) removed for every unit of energy (kilowatt hour) consumed. The higher the EF the more energy efficient the dehumidifier or, put more simply, the more water is removed for every energy dollar spent.

The cost of a dehumidifier over its working life time is made up of two major costs, its ticket price when you buy it and the cost of the energy it uses over its lifetime. The energy cost is almost always the higher of the two. It is therefore important to have the most energy efficient unit for the job.

A typical 65-75 pint portable home dehumidifier has an energy factor of 1.8. A 65 pint whole home dehumidifier, such as the DR65, is a little more efficient with a factor of 1.9. The DR90, however, has an EF of 2.67 and the Santa Fe Classic an EF of 2.65. The energy savings from the larger models are very significant and will certainly be greater than the difference in ticket price in a basement of 1500 square feet. A larger unit will also run for fewer hours per day, producing less noise nuisance and lasting longer before needing replacement.

If you are looking for a dehumidifier for the whole home simply apply the same principle and select one that has a capacity somewhat greater than the total floor area of your house, not one that is "just big enough".

I hope this information will help you to make the right choice for your home.

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Large Basement Dehumidifier

by Neil
(Beachwood, OH)

What dehumidifier would you recommend for a relatively open, large 6,000 square foot basement?




Answer

Hi Neil, thank you for your question.

Boy, you have one big basement! Most basements are less than half this size and domestic dehumidifiers are designed to work effectively in the more typically sized basements, around 1000 to 2500 square feet. You will need more dehumidifying capacity than any single domestic unit can provide or you will have to consider a
higher capacity unit designed for industrial use.

Dehumidifiers labelled as "basement dehumidifiers", such as the Santa Fe Classic, have a water removal capacity of around 100 pints per day. A pair of these units may manage your problem, depending on how humid your basement is. The only alternative to the Santa Fe Classic is the SaniDry XP. Both dehumidifiers are manufactured by Therma-Stor and are virtually identical. The main difference between them is that you can buy a Santa Fe in a store or online whereas a SaniDry has to be supplied and installed by an approved installer, licensed by Basement Systems who own the SaniDry brand name. As installation in stand-alone mode (i.e. without ducting) requires setting up the drainage hose and plugging the machine into a power socket I would opt for the Santa Fe.

If you are in any doubt about the capacity of two Santa Fe Classic dehumidifiers your second option would be to consider two larger capacity units. Both crawl space and whole house dehumidifiers may be used in stand-alone mode in a basement and are configured to be lower in height and longer in length to fit into spaces where a taller basement dehumidifier may not be suitable. There are three 150 pint units you may consider, the Santa Fe Max Dry, the Honeywell DH150 (manufactured by Therma-Stor) and the Aprilaire 1770. A pair of 150 pint dehumidifiers, rated at over 3000 square feet apiece, will be more than enough for your large basement.

Although all the dehumidifiers I have mentioned may be operated in stand-alone mode all can also be ducted. In a large basement such as yours, even though relatively open, the additional air flow will improve the effectiveness of the dehumidifiers. In addition ducting will permit you to locate the dehumidifiers in enclosed areas which will remove them from view and, more importantly, muffle the sound they make.

If you are committed to using a single dehumidifier you will, as I said earlier, need a commercial unit. The one I would suggest is the HI-E Dry 195. Once again this is a Therma-Stor product and has a water extraction capacity of 183 pints. I recommend it for several reasons; it is a Therma-Stor product, although targeted at the pool/spa market it has good low temperature effectiveness, although expensive its cost is around the same as two of the 150 pint units I mentioned, and much lower than many other commercial units and, finally, it is the only commercial unit of this capacity of which I am aware that will operate from a standard 115v
electric circuit.

On the down side this unit is large, comparable to a chest freezer. You would be well advised to install ducting with this unit as, despite its size, it is not as powerful as two 150 pint units. Whenever it fails you will have to replace it which means a major outlay whereas, with two smaller units it is roughly half the expense at any one time. Also, with two units, you have some dehumidification for your basement while awaiting a replacement for the other dehumidifier.

I have outlined the options I feel you might consider but, when considering an outlay of this size, you may want a second opinion. I suggest you contact Sylvane, a highly reputable supplier, for a telephone consultation. Their number is 1 (800) 934-9194 and consultations about the products they sell are dealt with Monday -
Friday from 8:30 a.m. to 6:00 p.m. EST. Their web site can be found at http://www.sylvane.com/. This company has a good reputation with its customers for the quality of its advice.

To reassure you let me state clearly that we have no direct affiliations with this company. Affiliate links are placed on this site to merchants of dehumidifiers and associated products but our link with Sylvane is restricted to affiliate links to Amazon.com who advertise their products as one of their approved suppliers. The only occasion on which we would benefit financially from a purchase made from
Sylvane would be if our visitor clicked on the link from this site to Amazon and subsequently purchased from Sylvane through Amazon.

I hope I have covered all the options thoroughly and that you have the information you need to make your choice.

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Shore house dehumitifier

by John
(Seaside, NJ)

I have a house on the water which I installed a 3 zone mini split heat pump which works great. Since I only go there on weekends I wanted to install a whole house dehumidifier. Since I am limited with space I was going to intall the unit in the Attic and pipe the air from the main room into the unit then exaust it into the 2 closets in the bedrooms. I am able to get the Lennox HCWHD 65 pint whole house dehumidifier. I would like your opinion if this will work and if you had another solution.




Answer

Hi John, thank you for your question.

From you description it sounds as if your house is within the capacity of the Lennox HCWHD 65 pint whole house dehumidifier. Whole house dehumidifiers are designed for installation in locations which are convenient for the householder and while attic installations are not the most frequently chosen they are not uncommon. On the basis of the information you have provided I can see no reason in principle why this arrangement should not be effective.

Lennox Dehumidifiers are invariably installed by approved installers so, unless this is a pre-owned unit which you have purchased from a private owner, I assume that you have a contractor lined up to undertake installation.

For the sake of completeness I will mention that you have the option to purchase a dehumidifier of another brand, Aprilaire or Honeywell for example, and select a HVAC contractor of your own choosing to undertake the work. All three brands are of equivalent quality and looking at other options may enable to have the work done at a better price.

I hope this is helpful.

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Unfinished Basement Dehumidifiers

by Val
(New York State)

How do you compare the Sante Fe Classic to the Aprilaire 1710?

I have about 2500 sq ft of basement space that is damp and the Frigidaire 70 pint I bought from Lowes ran constantly and never got it below 70% (briefly got it to 65% but only after a week of low humidity, sunny, high temp days)

Thanks for your great site!




Answer

Hi Val, thanks for your question and the comment on the site :).

The first thing to say is that you are, in my opinion, thinking of the right move. A 70 pint portable home dehumidifier is not large enough to cover 2500 square feet, despite some manufacturers' claims that a large portable is suitable for areas of this size and more.

You live in New York State and, depending on what part of the State you are based, your dehumidifier may have to work in cool (below 65F) or cold conditions at some times in the year. This makes conditions even more unsuitable for using portable home dehumidifiers as they become less effective as the temperature falls.

The two models you have short-listed are both fine dehumidifiers but there are some important differences which will need to be weighed in the balance according to your particular needs.

The first is one I touched on a moment ago; the temperature of your basement at the times you want to use the dehumidifier. The Aprilaire 1710 is rated for use in temperatures as low as 40F whereas the Santa Fe Classic is only fully effective down to 55F.

The second is the difference in water removal capacity. The Santa Fe Classic is capable of removing 110 pints per day at the AHAM (Association of Home Appliance Manufacturers) standard testing conditions and is suitable for areas of up to 2500 square feet. The Aprilaire 1710 is a 90 pint dehumidifier at AHAM standards and rated for 2000 square feet.

A third difference is energy efficiency. The Aprilaire 1710 is not Energy Star qualified whereas the Santa Fe Classic is so qualified. The Aprilaire 1710 will, therefore, cost more to run but only if your basement temperature is at or above the Santa Fe's minimum operating level of 55F. Below this level the Santa Fe Classic will be less effective and the Aprilaire 1710 will come into its own.

In my view these three differences are the critical ones but there are two more which may have some bearing on your decision.

The Santa Fe Classic is considerably louder than the Aprilaire 1710, at 68dB to the Aprilaire's 54dB. The dB scale is, as you most probably know, a logarithmic rather than a linear measure which means that 68db is not simply 14/54 louder and you will certainly notice the difference. In an unfinished basement this may not be critical to your decision.

The Santa Fe Classic has a very different external configuration, tall and thin, compared with the Aprilaire 1710 which is much shorter and cube-like. This may be relevant only if you want to site the dehumidifier in a restricted space in which only one of the two will fit comfortably.

There are other differences but they are of less concern and it is the five I have mentioned, particularly the first three, which critically affect the decision.

If the temperature of your basement is typically at or above the 55F mark I think the answer is clear. The capacity of the Santa Fe Classic is more appropriate for your basement's area and it will cost less to run.

On the other hand, if your basement is cooler the Aprilaire 1710 is the only option of the two. It will be more effective and equally energy efficient if not more energy efficient.

There is a problem however. The Aprilaire 1710 is not quite as powerful a unit as your basement really needs. I am confident that the 1710 would cope but it will need to run for more hours per day in order to keep your basement humidity at the 45-50% level generally recommended. This will not help with your energy bills and will shorten the working life of the dehumidifier.

As an alternative may I suggest the Santa Fe Max Dry Dual XT. This is labelled as a "crawl space dehumidifier" but is equally suitable for use in a basement. The bad news is that this unit will cost over $400 more than the Santa Fe Classic but, when you pick yourself up off the floor, let me explain my thinking.

The Santa May Dry is a 150 pint dehumidifier rated for areas up to 3600 square feet. It is obviously going to deal effectively with your basement. The lowest effective operating temperature of the Santa Fe Max Dry is 45F so it should cope with your basement in cooler conditions as well as the Aprilaire if this is your need. The biggest point in the Max Dry's favor is its energy efficiency. It is Energy Star qualified and has an Energy Factor of 3.56 compared with the Santa Fe Classic's 2.65 and your Frigidaire's 1.8.

What this means is that the Santa Fe Max Dry will remove one third more water per energy dollar spent than the Santa Fe Classic and that the Max Dry uses no more energy to remove 150 pints than your Frigidaire consumes to remove 70! Over the life time of your dehumidifier the energy saving will more than pay back the difference in purchase price.

The Santa Fe Max Dry will be operating well within its limits so you are not only assured of a dry basement but the unit will operate for fewer hours per day than the Santa Fe Classic and should have a longer working life time. The noise level is still higher than the Aprilaire 1710 but at 68dB is identical to the Santa Fe Classic.

One final point I would like to make is that both Santa Fe dehumidifiers may be operated in stand-alone mode but are also configured for ducted operation. In a basement of 2500 square feet a ducted installation will be beneficial by improving air circulation and distributing humidity more evenly.

If you decide on a ducted installation and are concerned about the noise level from these units you can, of course, site the dehumidifier in an enclosed area where the noise is less intrusive or build a small "box" around it, lined with sound deadening material, to muffle the noise.

This answer is a little longer than most of those I give on this site but you are deciding on a major purchase and the level of detail I have provided reflects that. I hope this will be of help.

Tom (Webmaster)

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Whole house dehumidifier sizing/energy efficiency

by Ann Causey
(Auburn, Alabama)

My house is about 2400 ft and in very hot and humid Alabama. I have a heat pump for A/C but find if it keeps the humidity in check, the temp is uncomfortably cool. I want to add a whole house dehumid unit, and have narrowed it down to he UltraAire and Honeywell systems, which are both made by Thermastor. I want the most energy efficient unit I can get, but that leads me to the largest models these companies sell, ones that are rated for houses up to 3500 ft. Wouldn't buying that large a unit but running it in a smaller house waste energy, or would I just be wasting money on the initial investment?



Answer

Thank you for your question. Your problem is not uncommon and I would guess that your A/C system has excess capacity, by which I mean it could handle a house significantly larger than your 2400 square feet. Because A/C systems are governed by a thermostat they switch off when your programmed temperature is reached which, if the system is very powerful, may be before an acceptable level of relative humidity is achieved. To reach the desired, lower humidity level you have to run the A/C for longer which, as you describe, can result in uncomfortably low temperatures. This wastes energy.

A whole house dehumidifier is controlled by a humidistat, which responds to levels of moisture in the air rather than to temperature. It operates independently of your A/C system although it is integrated with the existing HVAC ducting.

The energy efficiency of dehumidifiers, as defined by Energy Star, is expressed as the "Energy Factor" (EF). The EF is an expression for the amount of water (litres) removed from the air for every kilowatt hour (energy unit) consumed. The higher the EF the higher the energy efficiency.

Taking the three Honeywell models; the 65 pint unit has an EF of 1.9, the 90 pint an EF of 2.67 and the 150 pint an EF of 3.56. The 65 pint unit is rated for 2600 square feet so is just enough for your needs but its EF is barely higher than that of a portable home dehumidifier of comparable capacity. I would discount this model entirely.

The 90 pint unit is rated for 3100 square feet and the 150 pint for 3600 square feet and I would choose one or other of these two. The greater purchase cost of a larger dehumidifier will be offset by its lower operating costs. To calculate the energy cost per hour the math is unit wattage/1000 x rate (cents) per kilowatt hour charged by your energy supplier. The key point is that a larger unit will remove more water per hour at that hourly cost and will operate for fewer hours per day to maintain your chosen level of relative humidity, a double saving. Also an "over-sized" unit, suitable for a home bigger than yours, will run for fewer hours still.

For comparative purposes the purchase cost of the unit must be annualized. So, a unit which cost $1000 to buy and lasts for five years has an annual cost of $200. Think of this as the amount you would need to put in a cookie jar each year to pay for a replacement. A larger unit will run for fewer hours per day and should last longer so the annual cost may be lower than the difference in initial purchase price might suggest. Your point that you could be wasting money on the initial investment is not, therefore, as straightforward as it might seem at first glance.

Returning to your A/C system, with a dehumidifier installed you will only need to run it to maintain the temperature you prefer. You will also find that you can adjust the thermostat upwards by a couple of degrees without noticing any difference in the temperature you perceive. This is because the lower humidity makes the body's cooling system, sweating, more effective as the water evaporates more quickly from the skin into the less saturated air.

My final point concerns the two brands you are considering. UltraAire and Honeywell whole house dehumidifiers are technically identical, as you might expect. The UltraAire models, however, can only be obtained through approved installers whereas the Honeywell units may be bought "off the shelf" and either installed by the purchaser or by a HVAC installer of her or his own choosing. My resident oracle tells me you may be familiar with local installers, or have contacts who are, so you may want to compare prices for installation before making a final decision.

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50 or 70 pint dehumidifier??

by Alan

I ordered a 50 pint Frigidaire (FAD504DUD). This model is now back ordered and will not ship until the end of April. I don't mind that, but I got an interesting e-mail today about it not being available until the end of April.

They offered a no cost upgrade to the Frigidaire 70 pint dehumidifier (FAD704DUD). My basement is about 650-700 sq ft. Very tempting. But is the 70 pint too much? Is the 50 sufficient? I want to make the right choice, not just upgrade because its no extra charge. Some insight would help.

Thanks.




Answer

Hi Alan and thank you for your question.

The first thing to say is that the 50 pint model is entirely adequate for a basement of around 700 square feet. Nevertheless there is an argument for choosing a 70 pint model even for a basement of this size.

As it happens I wrote a brief article on this very subject some time ago. At the time the current range of Frigidaire models had not been introduced and the comparison I made was between the FAD704TDP (70 pint) and FAD504TDD (50 pint) units. The argument still applies with equal force to the current range or to any brand.

You will find the article by following this link:

70 vs 50 Pint



In my view the logic of my argument applies in your case but take a look and see what you think.

Tom (Webmaster)

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Large crawlspace question

by Gary
(Western NC mountains)

Hello, I just found your website. Great site! I have a question about sizing a dehumidifier for a very large crawl space.

The space is under a single story home that sits on an inclined mountain. The house is 2300 square ft. Due to the incline, the space underneath is approx. 3000 square ft., and has a height that varies from about 6ft min. to about 25 ft max. I estimate the average height as 15ft. so, needless to say, a very large cubic area.

The space is fully enclosed with 20 mil, all vents closed. Currently, two Danby 70s are operating basically full time and keeping the level in the low 60% range. Temp in the space is currently 61. It varies year round from high 60s in the summer to lower 40s in the winter.

I want replace these with a Santa Fe ASAP. I can get a lightly used Classic for $1000 from the contractor that encapsulated the space. He will warranty it for that $1000 for 5 years. He is very reliable, and has already freely replaced one failed Danby free of charge.

I have estimated the Classic as basically equivalent to 3 Danbys in terms of moisture removal. The humidity with no Danby operating was high 70s. Adding one dropped the level 70. Adding the second dropped the level to the current lower-mid 60s.

Based on all this data, I'm guessing adding a third Danby (not considering actually doing this), or alternatively, a single Classic will the level into the mid 50s.

Do you think a single Classic can handle this large a cubic area?




Answer

Making a rough estimate, your crawl space has a cubic area roughly equivalent to a typical space of 6,000 square feet. I have made this rough estimate simply by regarding the average height of your crawl space (15 feet) as being twice that of the floor to ceiling height of a basement. If this rough figure is inaccurate it probably errs towards a modest under estimate but it is close enough for our purpose.

In addition to the area of the crawl space the ambient temperature has also to be considered. The Danbys you have will work effectively in temperatures down to 60 or so but will lose effectiveness when it is cooler. The Classic will work well in temperatures down to the mid or lower 50's.

Danby rate their 70 pint models for 3,800 square feet. If this was correct you would have no problem controlling the humidity in your crawl space at 50% (2 x 3,800 = 7,600 square feet), especially in the warmer months. A more realistic rating is around 1,200 square feet which, even with two units, is less than half your "effective" crawl space area of 6,000 square feet. It is not surprising, in my view, that the two Danby's are only capable of maintaining a humidity level of 60-65%.

The Classic is rated realistically, by the manufacturer (Therma-Stor), for 2,500 square feet. This is twice the area of one Danby and, given the greater effectiveness of the Classic in cooler temperatures, your estimate that it is equivalent to three Danby's is in the right ball park.

You don't need me to do the math :). It's clear that the three units in combination should have just about enough juice to control humidity in your crawl space to a level in the mid 50's, which should be enough to avoid any humidity related problems.

I am a little doubtful as to whether the Classic alone will be able to do this but I don't want to be dogmatic about it. Controlling humidity depends on a combination of various factors and cannot simply be predicted from the volume of the area and the specs of the appliances alone.

The best advice I can offer you is to experiment. If you purchase the Classic try all three together. If the humidity does not drop below 55% you certainly need all three units. If it falls to 50% or a little lower try it with one of the Danby's switched off. There are several permutations, including using the Classic and one Danby full time and switching on the second Danby for a number of hours per day. You will need to experiment twice; summer results may be very different from those during winter. I hope you enjoyed lab work at school :).

I guess you may feel that I'm pushing a lot onto you in my answer. I suppose I am but the alternative would be to recommend that you buy a couple of large crawl space units, each with a capacity of around 3,000 square feet, such as the Santa Fe Force. These babies retail at just under $1,600 each so I thought you'd rather have a cheaper option even if it gives you some extra work.

Gary, I hope this helps and wish you all the best. Thanks for your interesting question.

Tom.

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Square footage related to brand and size of Dehumidifiers

by Richard Stahl
(Ludington, MI)

In searching for what we would like to believe is the right dehumidifier for our basement, we are finding that some 70 pint units of some brands cover up to 1,400 square feet while some other brands that would remove 50 pints cover up to 3,000 plus square feet. How do we determine what unit is the best for our needs.

Our basement is 1,400 square feet with poured concrete walls and floor. There are two vents for heat and air but no return air. Moisture level is not at the wet level but we did experience some mold on wood furniture that was stored in the basement so there is a need for a unit during the warmer months. Current level of humidity during the winter months is in the 45-48% range. Temperature is currently in the low 60's.

Am hopeful that we can find the right size unit within the next month.

Thank you

Richard Stahl




Answer

You are not the only one who is confused. I get similar questions all the time.

The simple answer is that the higher estimates should be treated with caution. In my view, and that of suppliers I trust, is that 1400 square feet is the maximum area that can be adequately covered by the largest capacity portable models (70 pints per day).

If you would like to see one of these suppliers for yourself go to sylvane.com. Click in the individual pages for each large capacity model and then on the specification page for that model. You will see exactly what I mean.

I hope this helps.

Tom

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One or two dehumidifiers for my basement?

by Eileen
(Caledonia, WI)

I currently have a Danby Premier 70A2GP dehumidifier in my basement. It is 6 months old. The basement is sectioned off to a degree with paneled walls and a dropped ceiling in half of it. Square footage is about 2000 sq. ft. It does get damp starting in spring and throughout summer.

I previously had two 70 pint Danby dehumidifiers running. One on each end of the basement. One has been recalled so now have only one which is fairly new (6 months old).

In order to keep the basement from smelling, do I need to purchase another to replace the recalled one or do you think the remaining Danby will suffice for the entire basement. I am more concerned about the cost of running the units rather than the purchase price of another.

Is it more economical to run just one unit if it removes the moisture sufficiently or two units for less time?

Thanks.




Answer

Despite any claims that may be made by some manufacturers a 70 pint model is only good for areas of between 1200 and 1400 square feet (depending on ceiling height). To be on the safe side you would need a second unit to keep your basement dry.

I understand your concern about energy bills. These appliances do use a lot of power. You could try to manage with one unit and keep a close eye on your basement to detect any damp formation. One might be enough and, if it is, you could carry on with just the sole appliance.

On the down side your solitary Danby will almost certainly run 24/7 in such a large space. This itself will be costly in energy use and will almost certainly shorten the life of your dehumidifier.

It is almost impossible to estimate the relative costs of the two options without an intimate knowledge of the conditions in your basement which would require an on-site inspection which is, of course, not an option for me.

I hope at least I have been able to give you a few additional thoughts to weigh in your decision.

Tom.

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