Basement Dehumidifiers for a Cold Basement

by Deb
( NH)

What dehumidifier would you recommend for an unheated basement that gets very cold in the winter ~40 degrees? The basement is ~1500 sq feet.



Hi Deb, thanks for your question.

You have already started on the right track as you are clearly aware that a basement as cool as yours needs a low temperature dehumidifier.

For the benefit of other visitors I will explain why this is so. Portable room dehumidifiers do not perform well in temperatures below 65F. The owner's manual for most models will point this out, despite the fact that portable dehumidifiers are usually able to operate at temperatures as low as 41F.

At these lower temperatures a portable spends more time defrosting than it does dehumidifying which means that little water is removed from the air and the dehumidifier becomes very energy inefficient. To make matters worse a portable will burn itself out in a matter of months trying to cope with its impossible task. This will be even more the case in a 1500 square foot basement which is at or a little beyond the size that even the most powerful (70 pint) portable dehumidifier can manage, even at 65F.

Low temperature dehumidifiers are built with much more robust components; larger fans, higher quality evaporator and condenser coils and a tougher compressor, all contained within a metal casing rather than the plastic of a portable. These units will work effectively at lower temperatures and are much more energy efficient than a portable in cooler conditions.

Low temperature dehumidifiers come with four "labels", "basement", "crawl space", "whole home" and "commercial" dehumidifiers. Inside they are all very similar and are all designed to work effectively in cool basements or, in the case of commercial dehumidifiers, in even more demanding environments.

Like all dehumidifiers the available models come in a range of capacities. The lowest capacity units are Oscar Air crawl space dehumidifiers with capacities of 35 and 50 pints per day. These are not powerful enough for your needs.

AT the next level are the 65 pints per day Compact model from Santa Fe, rated for 1600 square feet, and the 70 pints per day CMC100 from Dri-Eaz. Of the two I would recommend the Santa Fe which is US made and has high ratings in dehumidifier reviews written by consumers. The Dri-Eaz is not made in the USA and has rather less favorable reviews. Either unit is just big enough for your basement but my advice would be to go to the next level of capacity, around 90 pints per day.

The larger capacity units are more energy efficient; they remove more water per energy dollar spent. Being more powerful they run for fewer hours per day and will therefore last longer. These two savings will more than repay the extra $250 or so you would pay to buy the unit. In addition your basement is very cool in winter and having the additional capacity would be advisable.

At 90 pints per day your choices include the Santa Fe Advance Crawl Space Dehumidifier (Manufactured by Therma-Stor) and the Aprilaire 1710 Basement and Crawl Space Dehumidifier. Both are US made but only the Advance is Energy Star certified so, if it was my choice, I would pick the Santa Fe.

The Advance is suitable for areas of up to 2200 square feet and is rated for use in temperatures as low as 45F. This unit should be suitable for your needs, despite the apparent 5 degree "gap" between the 40F in your basement and the 45F minimum operating temperature I referred to. This is because the dehumidifier heats the air that passes through it by a few degrees which will close the gap.

You may also have heard of the SaniDry CSB. This unit looks very much like the Santa Fe Advance, which is not surprising as it is made by Therma-Stor and is mechanically identical. To purchase a SaniDry dehumidifier you have to have it installed by a contractor licensed by "Basement Systems" and pay their installation charges. It is easier to buy the Santa Fe in store or online and to make your own arrangements for installation.

On the subject of "installation" there is nothing to it if you are using the dehumidifier in stand-alone mode. Just set up the drainage hose, plug it in and switch it on! The dehumidifier may be ducted if you prefer. The main advantage in a basement of 1500 square feet would be to make it possible to site the dehumidifier in an enclosed area to reduce the noise nuisance.

The one issue remaining is the typical temperature in your basement. You describe it as around 40F in winter but if it falls more than a degree or two below 40F, and stays there for extended periods, the Santa Fe Advance may not be entirely effective at those times. Your options are to provide some background heating for use at such times or to use a commercial dehumidifier. Both of these options will involve additional cost.

If you do wish to consider a commercial dehumidifier my recommendation would be the Hi-E Dry 100. This dehumidifier is also made by Therma-Stor, in the USA, and is attractive because it has the required water extraction capacity, 106 pints per day, is rated for use at temperatures as low as 33F, is not excessively priced for its power (by commercial dehumidifier standards) and will run from a standard 115v power supply. Many commercial dehumidifiers of this power require a 220v supply. The Hi-E Dry 100 will cost around $1900 so you will have to judge your needs and your options with care.

I hope I have covered all the necessary ground and that my explanations are clear but, if not, please don't hesitate to come back to me about any point.

Tom (Webmaster)

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Basement Dehumidifiers - Hanging Installation

by Mike
(Portsmouth, VA)

I have a 1600 foot basement/crawl - approx. 50/50. I am very close to water and am in a flood zone - recently had five feet in my basement. When not flooding (rare), I have only have moisture, some visible wetness on the floor, sometimes on the wood following days of heavy rain. I have two sunken sumps and a back-up - flood occurred when electricity was out.

I am working with a reputable local basement company and they are recommending sealing the windows and doors, etc. additional french drain-waterguard system along perimeter and adding a dehumidifier - SaniDry Upright (I believe it is the XP).

My question is, I would like to hang the dehumidifier from the rafters (in case of future flood). Have you ever heard of this (hanging a dehumidifier)? Would you recommend against this? And, if you are in favor, is there a product your would specifically recommend or any guidance you can offer?

Based upon your comprehensive website info, the recommended dehumidifier appears to be adequate. If I can get the Santa Fe Max Dry Dual XT Crawl Space Dehumidifier for a similar price, would you recommend it (even with my mere 1600 foot space)? And, can it be hung?


Hi Mike, thank your for your question.

I have indeed heard of hanging a dehumidifier before but not one so large as the Santa Fe Max Dry Dual XT Crawl Space Dehumidifier. The much smaller capacity (65 pints per day) Santa Fe Compact Crawl Space dehumidifier, for example, is recommended by the manufacturer for a hanging installation and an optional Hang Kit is available for this model. This unit is recommended for areas of up to 1600 square feet so would be just large enough for your needs.

I am inclined to agree with your implied preference for a dehumidifier with a higher capacity. "Just enough" is never ideal, you have two spaces to cover and the threat of further flooding. Additional capacity would be particularly valuable in the unfortunate event of a future flood. Obviously, with the possibility of future flooding, standing a dehumidifier on the floor would be impractical.

If you are unhappy with the idea of a Santa Fe Compact the alternative is to locate your dehumidifier outside the basement/crawl space entirely. This can be achieved by a ducted installation for which most basement and crawl space dehumidifiers are pre-configured. Clearly this depends on your being able to identify a site on the ground floor of the house that would be suitable for locating the dehumidifier. Your choice between an upright configuration and the "low, squat" profile crawl space dehumidifier would depend entirely on the shape of the space in which you would wish to site the dehumidifier. A ducted installation would require the use of a remote humidistat located in the basement/crawl space.

Apart from the possible difficulty you may have in identifying a site for the dehumidifier the other disadvantage is that the noise generated by the unit would be more of a nuisance in the living areas of your home. With a ducted installation, however, the dehumidifier could be placed in a closet or within a purpose built cabinet. The use of sound deadening material on the interior surfaces of the closet/cabinet would reduce this nuisance and the dehumidifier would also be out of sight. It is worth saying also that a hanging installation will result in more noise being transferred into the house than a floor location.

As far as models are concerned you cannot go far wrong with Therma-Stor's Santa Fe range. This recommendation also extends to SaniDry models which are manufactured by Therma-Stor and are virtually identical to their Santa Fe equivalents. Indeed if you have reason to seek repairs under warranty it will be Therma-Stor that you will be dealing with.

SaniDry dehumidifiers are only available through installers licensed by Basement Systems Inc. Prices for these units are only available on application to your local installer and include the costs of installation so you will have to make your own judgement about which offers best value for money.

The SaniDry XP, or the Santa Fe Classic (equivalent model) will certainly be powerful enough for your needs. If you prefer the lower, squatter profile of a crawl space dehumidifier the SaniDry CSB/Santa Fe Advance (90 pint/2200 square feet) units should be more than adequate.

The Santa Fe Max Dry Dual XT Crawl Space Dehumidifier is probably more dehumidifier than you need and will be considerably more expensive. Hang Kits are not supplied by Therma-Stor for this model or for the Advance and for further advice on the possibility of a hanging installation for either model I would recommend that you contact Therma-Stor (1-800-533-7533 between the hours of 7:30 a.m. and 4:30 p.m. Central Time). A one-off installation of this type may be possible but I would advise that it receive the blessing of the manufacturer so as not to invalidate your warranty.

I hope this is helpful.

Tom (Webmaster)

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Kitchen Dehumidifiers

by Chris
(New York City)

We live on the top (5th) floor of a 100 year old brownstone in New York City.

We moved in a year and a half ago. This summer, as the weather got warmer, we started noticing a strong mildew smell coming from under our sink. Also, after Irene passed through, we noticed the kitchen tile floor (foot by foot-size tiles) under our stove (under a sealed window) was damp.

This may be a huge project, but in the mean time, is there a type of dehumidifier that could help us?

When we run a small Vornado fan on high under the sunk with the cabinet doors open, it definitely helps, but it needs to be on 24/7… a quieter way, with the doors closed, would be preferable. The kitchen is about 20’ x 20’, and opens out into the living room (no doors). During the winter, the heat in the apartment is almost oppressive and dry, so maybe that’s why we only noticed it this summer.


Chris, NYC


Hi Chris, thank you for your question.

There are small dehumidifiers that are effective in enclosed spaces and they come in three distinct types.

The first I will only mention to explain why it is unsuitable for use in your situation. This type is the heated rod dehumidifier of which one of the best known brands is Goldenrod. This type of "dehumidifier" simply warms the air. Because warm air holds more water than cooler air this lowers relative humidity and prevents condensation. In other words it raises the dew point. This type works well in gun safes which are often located in cool basements. What you need, however, is a dehumidifier which physically removes moisture from the air to dry out your cabinet.

The second type is a small desiccant dehumidifier. This type contains water absorbing crystals, usually silica gel. The water absorbed by the crystals can be removed by the application of heat.

There are two sub-types of desiccant dehumidifier. The simplest consists of a tub containing silica gel. When the crystals are saturated they can be heated in the oven for 20 minutes or so and dried out for reuse. This type is quite easy to make for yourself from a suitable container and loose silica gel crystals which can be bought from many hardware stores.

The other type is the so called rechargeable dehumidifier, typified by the Eva-Dry models. This type encloses the crystals in a sealed container and when saturation is reached a panel on the unit changes color. The unit may then be "recharged" by attaching it to the electricity supply for about 12 hours every few weeks.

The disadvantage of the desiccant dehumidifier is the small volume of water it removes. Depending on the size of your cabinet and the amount of water to be removed one or more dehumidifiers may be effective. This type of dehumidifier is silent when in operation because it has no moving parts.

The third type of dehumidifier, often called a mini dehumidifier or a thermo-electric dehumidifier, looks like a small version of the type of portable home dehumdifier widely used in a basements. The dehumidification process is different, however, because it does not use the conventional refrigeration system employed in a portable home dehumidifier and does not, therefore, have a compressor.

It relies on the "Peltier Process" which passes an electric current through a panel consisting of two different materials which transfers heat from one side of the panel to the other, the so called "Peltier Effect". The water condenses on the cooled side and is collected in a small pan which needs to be emptied periodically.

The panel has no moving parts so is silent but the dehumidifier includes a fan to draw in and expel the air and the fan will make some noise, despite the somewhat exaggerated claims that this type is "whisper quiet".

The advantage of this type is that it removes more water, between about one half pint and one and one half pints per day, depending on the model. The disadvantages are that mini dehumidifiers are relatively expensive to buy in relation to their water removing power and are less energy efficient than a conventional refrigerant dehumidifier.

A mini dehumidifier may control humidity in your cabinet but, once again, this depends on the size of the cabinet and the amount of water which needs to be removed. If more water is making its way into the cabinet the amount of water ingress may be too much for even this relatively more effective type of dehumidifier. A point to consider also is that this type of dehumidifier needs to be attached to an electric socket so provision has to be made to run a power cable
into your cabinet to the dehumidifier.

If none of these measures is sufficient and you still wish to use a dehumidifier the only alternative I can suggest is to site a standard portable model in either the kitchen or the living room and to leave the cabinet doors open. This unit would need to be powerful enough to control humidity across the combined area of the kitchen and the living room which, as a total area, would need to be sealed from the other rooms of your apartment and from the outside air. The size of dehumidifier needed would depend on the size of your living room plus the 400 square feet of your kitchen. A total area of 1000 square feet would require a dehumidifier of at least 50 pints daily capacity.

I realise this last suggestion does not meet any of your criteria, except the need to dry out the cabinet, and I suggest it only for the sake of completeness.

Tom (Webmaster)

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Where should I put a dehumidifier?

by Barbara Keene
(Mashpee, Ma Cape Cod)

Where should I place a dehumidifier?

Our Cape Cod home has a dirt cellar, and no windows, our living quarters is subject to mildew but the source of the moisture is coming from the cellar. Where should I place a dehumdifier?

Thank You in advance.


Hello Barbara, thank you for your question.

You should put the dehumidifier in the cellar. The cellar is the source of the moisture and it will also be the coolest part of your home. As warm air escapes from the upper part of your home the air from your cellar is drawn up into the living quarters. Controlling the humidity of the air in your cellar will, therefore, reduce the relative humidity in the rest of your home.

To prevent mold and mildew you need to maintain relative humidity at no higher than 50%. I would suggest that you use a separate hygrometer to monitor relative humidity in both the cellar and the living quarters. It is unwise to rely on the humidistat on a dehumidifier as these are seldom accurate to less than +/-5%.

You may have no obvious signs of water ingress to the cellar but it is highly probable that water vapor is entering the cellar through the dirt floor. To reduce or eliminate this a vapor barrier may be helpful. Prevention is better than cure but I must emphasise that advice should be sought from a competent, qualified professional who has surveyed your cellar before any radical water proofing work is considered.

When choosing a dehumidifier there are several factors to consider:

  1. The size of the area in which humidity is to be controlled

  2. The condition of that area (how wet is it?)

  3. The ambient temperature in which the dehumidifier has to operate

The larger the area the larger the capacity of the dehumidifier you require. An area of, say 400 square feet would be comfortably managed by a dehumidifier with a capacity of around 35-40 pints per day but, if it is very wet, a higher capacity unit would be preferable.

Portable home dehumidifiers are only fully effective at temperatures of 65F and above. If you need a dehumidifier to run effectively at temperatures significantly below 65F for extended periods a low temperature dehumidifier will be more effective and more energy efficient.

You have not provided information about the environment in your cellar or its size so I am simply flagging issues about which you may wish to seek further advice.

Whichever dehumidifier you are using the simple answer to your question is to locate the appliance in your cellar. I hope the additional thoughts I have shared will be helpful is assessing your needs and finding the right dehumidifier model to meet them.

Tom (Webmaster)

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Whole House Dehumidifier for House Without Duct Work

by Anon.

Hi, I have an old house, about 6,000 square feet, with radiators and no duct work. Could I use one or two free standing dehumidifiers (say one in the basement and one on the third floor) to dehumidify the whole house? Thank you!


Hello, thank you for your question.

From your question I am assuming that you have a basement and three storeys above the basement. In that case I also assume that your basement is about one quarter of the total floor area of around 6000 square feet. 6000 square feet is quite a lot of house. The highest capacity whole house dehumidifiers typically extract about 150 pints per day and are recommended for homes with a total area of around 3500 square feet.

The first thing to say is that a whole house dehumidifier will be more effective than multiple free standing units. It is possible to have ducting installed for such a unit and this may be your most cost effective option. The economic and technical benefits of this option will depend on conditions in your house which I cannot evaluate. My advice would be to consult a professional HVAC installer in whom you have confidence.

If you wish to proceed with one or more free standing units my suggestion would be to start in the basement. This is typically the coolest part of the house and the most prone to condensation. If you want to have some effect on the rest of the house you will need the highest capacity unit you can find. This will be a whole house or crawl space dehumidifier capable of stand alone operation, such as the 150 pint Santa Fe Max Dry Dual XT.

Although it may seem that a pair of 70 pints per day portable units would perform as well this is, in my opinion, an unsuitable alternative. Portables are much less energy efficient with an Energy Factor, for a 70 pint unit, of 1.8. The Max Dry has an Energy Factor of 3.56 so will use approximately half the energy of two 70 pint portable dehumidifiers to remove a similar amount of water. The Max Dry will also last longer than a portable unit so, although the initial purchase price is much higher, should be cheaper in the long run.

For this to affect the rest of the house the basement must remain open to the ground floor to allow air flow between the two. The doors of rooms throughout the house should remain open at all practical times and the process will be assisted by fans to increase air flow around the house.

You may find this is sufficient, dependent on the typical level of relative humidity in you house but I can give you no assurances. You may, of course, supplement the basement unit with one or more additional dehumidifiers.

I offer this information as "food for thought" and would not suggest that you act upon it before taking the professional advice I have suggested. The information I have about your house is very limited and I cannot make any sort of definite recommendation upon which you should rely.

I am sorry that I am unable to be of more practical assistance but I hope that the information I am able to provide will be helpful in moving toward an effective and economical solution to your problem.

Tom (Webmaster)

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Gun Safe Dehumidifier - Where to drill the hole for the power cable.

by Cecil
(Huntington, WV, USA)

Where is the best place to drill a hole in my safe to allow an electric cord?


Hi Cecil, thanks for your question.

Some gun safe manufacturers pre-drill a hole for this purpose. This is usually on the lower part of the back of the safe. If your safe has a pre-drilled hole it will almost certainly have a plastic plug in it.

If you do not have a pre-drilled hole I would recommend you drill in the same place, the lower rear of the safe.

If you are using a heated rod dehumidifier this should be mounted on the floor of the safe on the brackets provided with the dehumidifier, hence the low site for the drill hole.

Hope this is helpful.

Tom (Webmaster)

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Sani Dry CSB Dehumidifier Noise Level

by Joe Macaluso
(Wilton, CT)

What is the expected noise level if the unit is located in the crawl space under the kitchen area? would there be a constant hum heard in the kitchen area?


The simple answer is yes, probably, but I have included some additional information you may find helpful.

The Sanidry CSB has a noise output of 64dB. By comparison a normal conversation would generate about 60dB while a vacuum cleaner 10 feet away would produce about 70dB.

The decibel scale is logarithmic so 70dB is twice as loud as 60dB, not one sixth louder. Most human ears can only detect that one noise is louder than another if the louder noise is at least 3dB greater than the quieter noise.

This information provides a few clues to the measurable level of noise the unit will produce.

That level will be reduced by the floor above the crawl space. It is impossible to estimate the sound dampening effect as it will be affected by the construction of the floor and other parts of the fabric of your home.

Although the noise level may be measurable the subjective experience of noise depends on the individual and on the quality of the noise. Finger nails being scraped across a blackboard for example (think of Robert Shaw in "Jaws" if you have seen that movie) would be more uncomfortable for most of us than a comparably loud but steady, lower frequency humming, such as a fan might produce.

For a sense of the subjective experience we can only look at what users say; in reviews of the product for example. The majority find this unit relatively quiet if it is in a crawl space and they are in the house. Some certainly report, however, that it can be heard in the house.

If it is used in a finished basement a larger number of people find the noise intrusive when they are also in the basement.

The probability is that a hum will be audible in the kitchen of your home.

If such a hum was to prove irritating the most effective way to reduce the noise would be to enclose the unit in a "box" with sound-deadening material applied to the interior of that box. The unit would then need to be ducted, for which it is configured.

If a ducted installation was chosen the unit could still be located in the crawl space, or at another site inside the house, with an aperture created in the floor for ducting to the crawl space, or outside the house proper, in a garage attached to the side of the house for example, and the aperture created in the exterior wall of the house.

Tom (Webmaster)

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Sanidry dehumifier leveling feet

by jay kern

Just had a SaniDry dehumidifier installed in my crawl space. Does it no longer come with balancing feet? Mine is supported on wooden blocks.


I assume the model installed in your crawl space is the SaniDry CX. I have not reviewed this model thus far, only its predecessor, the SaniDry CSB.
Illustrations of the CX currently on suppliers' sites clearly show leveling/balancing feet.

I cannot rule out the possibility that such feet have been discontinued very recently but I think the more probable explanation is that the surface on which the appliance is located varies in height by too great a degree for leveling feet, with their limited range of adjustment, to cope adequately.

If this matter is of continuing concern I suggest you approach the installer for comment.


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