70 Pint Kenmore Dehumidifier
Cycles on and off Continually

by Ann
(Scranton)

We just purchased one of your dehumidifiers, have had one in the past also. It's difficult to get this one started though as it seems to keep turning off and on, off and on immediately, one time after another and we want it to run all the time, not in 3, 6 or 12 hr increments. We can't seem to adjust that either?

Can you help? We have it in our basement.




Answer


Hello Ann, thank you for your question.

Before I start I should say that the Sears Kenmore 70 pint Dehumidifier is one of the models reviewed on our site. It is not supplied by us; indeed we do not supply dehumidifiers directly although they may be purchased by following a link to one of our affiliate partners. We only include links to our affiliate partners leading to products we recommend. As the Kenmore 70 Pint Dehumidifier is not among the models we feel confident to recommend you will not find a link to the product on this site.

I assume you have followed the instructions in the manual. Sears source their dehumidifiers from different suppliers at different times and this model may not operate in the same way as your previous Kenmore Dehumidifier.

If this is the case it may be that the unit you have purchased has a fault. I can think of no reason why the dehumidifier should switch on and off immediately, straight out of the box, which is how I interpret the situation from your question.

If the dehumidifier ran continuously for several hours immediately after setting up and has since begun to cycle on and off at short intervals, every ten minutes or so, this may simply reflect the way in which the dehumidifier functions. Many dehumidifier users complain that their recently purchased dehumidifiers cycle on and off far more frequently than models they purchased a few years earlier.

To check whether this may be the case set the humidistat to the lowest relative humidity setting and try again. If the dehumidifier still behaves in a similar way it is almost certainly faulty.

It would also be helpful to check relative humidity in your basement using a separate hygrometer. If you have not used one of these humidity measuring devices before please note that it must be left in the basement for several hours before an accurate reading is possible. If the relative humidity in the basement is close to the level you have programmed into the dehumidifier, and is maintained at this level, the dehumidifier is functioning normally.

If, in the light of these tests, the dehumidifier appears to have a fault you should refer back to the supplier, either a Sears or Kmart store or web site. The appliance is presumably under warranty and you should be able to return it, have it repaired or receive a replacement.

Should you return the Kenmore and are looking at alternative brands you make like to visit this page to see our recommendations.

Tom (Webmaster)

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Dehumidifier - Sunpentown SD 65E

by Dell
(Charlottesville, VA)

I've had this unit for about a month. It dehumidifies fine BUT cycles are so short. It usually runs for around 10 min, then shuts off about 2-3 min, then back on again--all day and night. I've read before that many new units have this cycling issue. Why?

I followed a recommendation I read and put the unit on a timer (like lamp timer) and have it run an hour, then off 2 hours. This keeps the humidity at the level I want and doesn't run so frequently. I would think this constant cycling would use a lot of electricity and wear out the unit quickly.

I note they now make a 70 pint unit. Specs show it uses more electricity but does not explain why. Is the fan bigger, faster? Or condenser.

Thanks for information and providing this service.




Answer

Hi Dell, thank your for your question.

As you say the constant cycling on and off of dehumidifiers seems to be a characteristic common to current models of most if not all brands. If your "fix" using a timer is maintaining the level of relative humidity you require then there is no obvious explanation specific to the unit you have purchased or the conditions in which it is operating. The dehumidifier does not appear to be faulty, it is large enough for the room and the ambient temperature is high enough for the appliance to function effectively.

From the frequency with which this "complaint" is made, and the wide range of brands it applies to, it appears to ne the result of deliberate choices made by most dehumidifier manufacturers about how their dehumidifiers should operate. I have not yet seen a convincing justification of this policy and I share your concern about the wear on the unit.

With regard to the new 70 pint model from Sunpentown an increase in energy consumption is inevitable if the unit is to have a greater water removal capacity. In an area of given size a 70 pint unit should operate for a shorter time each day to maintain the same level of relative humidity, cancelling out the additional energy used while it is operating. Given your first point this may be doubtful if the machine cycles on and off as frequently as your 65 pint model.

As to the precise cause of the increased power consumption I have been unable to find definitive evidence but my assumption would be that the air flow volume has been increased and that the size and/or speed of the fan is greater in the larger model.

Tom (Webmaster)

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Dehumidifier used in basement

by Alan Schroeder
(Fairfax, VA)

I have an open, unfinished 930 sq ft basement with painted cinder block walls and a concrete floor. No water leakage, but it gets damp. I've used an LG 45-pint and a White Westinghouse, but a after a year or two, they both began icing up. When new, they worked great, but I noticed they cycled on and off every few minutes when they got the humidity down to the set point, 55%. I think all the cycling caused unnecessary thermal expansion and contraction of tubing joints and components, leading to a refrigerant loss somewhere.

So I'm thinking for puposes of compressor longevity and prevention of fatigue due to thermal expansion and contraction cycles, a smaller size that ran more continuously might last longer. I was thinking of the Frigidaire 30-pint even though you recommend the larger 70-pint. Does this reasoning make sense to you, or am I way off?




Answer

Hi Alan, thank you for your question.

Your idea is interesting and, yes, your reasoning makes sense. The tendency among almost all dehumidifiers currently on sale to cycle on and off very frequently must, inevitably, place a strain on the refrigeration system. Indeed it provides a plausible explanation for the relatively short working lives of most current models compared with units produced some years ago.

While I cannot say with confidence that a 30 pint unit, running more or less continuously, will have a working life significantly longer than a 70 pint dehumidifier there is an intuitive validity to your hypothesis that suggests that it might. If we assume that the 30 pint model can be bought for $140 and the 70 pint for $190, and that the 30 pint lasts three years while the 70 pint last for two, the annualized cost of the 30 pint unit is 140/3 = $47 and the of the 70 pint model 190/2 = $95 (figures rounded to nearest whole dollar).

To make a complete comparison we need to compare energy costs. This is more difficult because the tarriffs vary between energy suppliers and are often tiered according to usage levels. To illustrate how the calculation may be made I have used fairly conservative figures so as not to overstate the point.

For the cost of energy I have taken the average cost across the USA in 2009 of 12c per kilowatt hour. I have based my calculations on the assumption that a 70 pint dehumidifier might operate for an average of six hours in every 24. My comparison is between the current 70 pint and 30 pint Frigidaire models.

70 Pint: 6 hours @ 765 watts = (6x765/1000) 4.59 kwh
4.59 kwh @ 12c = 55c per day = (365x55c) $201 per year

30 Pint: 6 x 70/30 = 14 hours @ 420 watts = (14x420/1000) 5.88 kwh
5.88 kwh @ 12c = 71c per day = (365x71c) $259 per year

70 Pint Annualized cost = (190 + (2x201)/2) = $296

30 Pint Annualized cost = (140 + (3x259)/3) = $306

I have rounded some of the figures in these calculations.

Let me stress that these figures are illustrative only; they do not constitute an "argument" for or against your proposition. What they do show is the simple calculations you might make, based on the energy costs specific to your home and your own estimates of usage times and the potential extra life time of a smaller unit running continuously.

What I believe the figures do show is that the financial advantage of either solution may be fairly modest, even marginal.

If you are looking for an alternative solution you may like to consider one suggested by another visitor to this site. That is to use the dehumidifier timer, or a separate timer, to run a larger capacity model for specific periods during the day. His concern was also the wear and tear occasioned by frequent cycling on and off and he found that, when he monitored the humidity, this solution was maintaining a relatively steady level of around 50%.

I cannot say with certainty which is the right way forward for you as this will depend on your individual circumstances. I hope I have provided you with some food for thought and a means to attempt some calculations of your own.

Thank you again for a most interesting and provocative question which will, I am sure, generate further comment from other visitors.

Tom (Webmaster)

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Short Cycles - Dehumidifier cycles on and off too frequently

by Anon.

I have a Frigidaire 50 pint dehumidifier (model # FAD504DUD). It seems like it cycles on and off far too often. It will kick on, run about 10 minutes, max, then the compressor shuts down, the fan continues to run for 5 minutes and then it too shuts down. In less than 2 minutes, the whole cycle starts over again. Seems like this short cycling would kill the compressor in no time.

I've seen many comments on short cycles regarding Kenmore, Frigidaire, GE, etc. Is this common with the new dehumidifiers? Is there any way to increase the cycle time? The old 50 pint Kenmore I replaced would run for an hour or so then shut down for an hour or two. The humidity would fluctuate a couple of percent. With the Frigidaire, the three humidity gauges I have never vary - not even 1 percent. Thanks!




Answer

Thank you for your question

First you are quite right, frequent cycling on and off is a common complaint from dehumidifier users and applies to all popular brands and models. Second, this problem has not been experienced with older Kenmore models.

Unfortunately, as you mention in your question, this does not mean that current Kenmore models behave any differently from your Frigidaire FAD504DUD. Kenmore is a label applied by Sears to the dehumidifiers sold as their "house" brand. Sears source their dehumidifiers from various manufacturers so a current model may have little or nothing in common with one bought several years ago, except the Kenmore label.

One possible explanation could be that the dehumidifier is being used in an area that is very small in relation to its capacity. This might explain why a dehumidifier will operate for a very short time to lower humidity but does not satisfactorily explain why it should resume operation so quickly. The chances are you are using this unit in a basement, and almost any basement would justify a 50 pint dehumidifier, so I think it highly unlikely that this is the answer.

A second hypothesis is that the dehumidifier's behaviour is related to the temperature of the area in which it is operating. As you will know ice forms on the evaporator coils at temperatures below 65F and when this happens the dehumidifier enters de-frost mode. In defrost mode the compressor stops and the fan keeps running. The fan stops when the ice has melted and the compressor restarts. A delay between the stopping of the fan and restarting the compressor is built into some dehumidifiers to protect them from damage. This fits the pattern you describe so is a more plausible explanation.

To produce the behaviour you describe the temperature would have to be at a level just a few degrees below 65F. If it was significantly lower the defrosting cycles would be longer. If this seems to be a possible explanation (and only you know the temperature of your home) it may be enough to raise the dehumidifier a few feet above the floor. The air is warmer in the upper part of the room than in the lower so this solution, however unlikely it may sound, can be effective and has worked for some dehumidifier users. To be honest I would not bet more than a few cents on this as an explanation either. As a savvy dehumidifier user my guess is that you would have considered and discounted this possibility by now.

The third possible answer is the rather depressing idea that this is a design fault common to most, if not all, portable home dehumidifiers. The humidity sensor is located inside the dehumidifier casing and is, in effect, monitoring the level of relative humidity inside the dehumidifier rather than in the room. I am aware that some dehumidifier users have located the sensor and rigged it so that it is outside the dehumidifier casing while still connected. This has been found to be effective in solving the problem you describe. I cannot, of course, recommend this as a course of action. There are safety issues involved and you would certainly invalidate your warranty. I include it simply as evidence that the location of the sensor may be the source of the problem.

My final suggestion is that the dehumidifier may be faulty. The humidistats installed in portable home dehumidifiers are not always entirely reliable and if yours is not functioning correctly that could be the cause of your problem. If you decide that the unit is not working properly and wish to return it you may find it helpful to have considered the ideas of room size and temperature when responding to the inevitable questions from the sales person you are dealing with.

Tom (Webmaster - Best Dehumidifier Choice)

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