Running Costs for a Dessicant Dehumidifier

bogatyr

These are the results of a controlled experiment to measure the actual electrical costs of a desiccant and condenser dehumidifier in ordinary winter domestic conditions.

Measurements were taken over a period of two winter weeks in an unheated interior domestic space of something over 300 square feet, with an internal temperature range of 40 to 55F, and with exterior day-night humidity averaging over 80%. In this case, two dehumidifiers (desiccant and compressor) were checked to see actual electricity average usage over a period of one week for each. The room humidity level for both was set (and maintained successfully) at a measured 60%. Each dehumidifier was run singly and continuously for an entire one week period.

The desiccant dehumidifier delivered measured electrical usage of almost exactly 6kw per day.
The compressor dehumidifier delivered measured electrical usage of just under 3kw per day.

It should also be noted that the compressor dehumidifier was working at full capacity (including a defrost cycle of 10 minutes per hour) during the period, while the desiccant dehumidifier remained capable of delivering still lower measured humidity, but at a significantly greater electrical cost.

SuperAllyB

bogatyr wrote: »

These are the results of a controlled experiment to measure the actual electrical costs of a desiccant and condenser dehumidifier in ordinary winter domestic conditions.

Measurements were taken over a period of two winter weeks in an unheated interior domestic space of something over 300 square feet, with an internal temperature range of 40 to 55F, and with exterior day-night humidity averaging over 80%. In this case, two dehumidifiers (desiccant and compressor) were checked to see actual electricity average usage over a period of one week for each. The room humidity level for both was set (and maintained successfully) at a measured 60%. Each dehumidifier was run singly and continuously for an entire one week period.

The desiccant dehumidifier delivered measured electrical usage of almost exactly 6kw per day.
The compressor dehumidifier delivered measured electrical usage of just under 3kw per day.

It should also be noted that the compressor dehumidifier was working at full capacity (including a defrost cycle of 10 minutes per hour) during the period, while the desiccant dehumidifier remained capable of delivering still lower measured humidity, but at a significantly greater electrical cost.

On the slight off chance that you are not a spammer, and come back to this thread, are there any records of the amount of water removed?

bogatyr

In answer to your question (above) about water removal, we did not keep exact records. However the APPROXIMATE water removal was on the order of about three liters per day. Both dehumidifiers removed roughly the same amount of water. We started the test when the room humidity had already been stabilized at 60% so that neither dehumidifier would have to do the extra work of bringing down excess humidity to begin with. The room background humidity at this time of year would ordinarily mirror the outside humidity -- in other words, the ordinary interior humidity is usually something over 80%.

sk240

bogatyr wrote: »

In answer to your question (above) about water removal, we did not keep exact records. However the APPROXIMATE water removal was on the order of about three liters per day. Both dehumidifiers removed roughly the same amount of water. We started the test when the room humidity had already been stabilized at 60% so that neither dehumidifier would have to do the extra work of bringing down excess humidity to begin with. The room background humidity at this time of year would ordinarily mirror the outside humidity -- in other words, the ordinary interior humidity is usually something over 80%.

Where abouts do you live? 80% humidity is well above what I get in my house, infact levels that high can have serious consequences to your health. a health level is no higher than 60, anything higher and your house will go mouldy!

I'm not disputing your results though as I really have no idea, but I have been happy with my desiccant dehumidifier, compressor ones are too noisy.

bogatyr

As regards your question as to where I live, this test was done in the current New Zealand winter. The AVERAGE humidity levels in the four main New Zealand cities are just over 80% throughout the year. The country has one of the highest incidences of respiratory disease in the world, and yet most New Zealanders are completely unaware of the really very high level of their day-to-day humidity.

We did the test to check the longer-term electrical usage of the two types of dehumidifier, and so we did not note how effective either type would be in INITIALLY bringing down excess humidity. I think most people would agree that desiccant dehumidifiers will lower cool-climate humidity much quicker than compressor versions. But as I say, that was not the purpose of our small test.

alanwarwic

It is the norm to expect double running costs for the less efficient desiccant type.

The only place that would not be so is a cold garage in winter time, but even there it would be best to use compressor one in summer.

Consider desiccant if you really want to also use your electricity for heating the room, though obviously at a cold 5C (minimum temp for decent compressor type) both will likely heat the room the same.

alanwarwic

kevlar22 wrote: »

Are the dessicant type much quieter than the compressor type as we had a Delonghi DEM10 which worked really well but although reasonably quiet, it was on a landing and was just a bit too annoying for the wife

The desiccant type is quieter when in low power mode but at a guess, that likely makes it more inefficient, maybe typically 4 times that of the compressor type.


Maybe check the maximum decibel rating before you buy one.

Mister_A

I'd like to bump this post once more with some data i've been sitting on for a couple of years that others might find of use

I own two dehumidifiers:

• Ecoair DD322FW (Desiccant)
• Mitsubishi MJ-E16VX (Compressor)

The Ecoair was my first purchase in 2011. After several months it developed a couple of faults which although fixed under warranty prompted me to buy the Mitsubishi which is the machine I have been using since on a daily basis for the past two and a half years with the ecoair used occasionally when there is an abnormal amount of wet washing to dry quickly..

I was interested in the running costs I faced when I purchased the Mitsubishi, so I hooked up an inline power monitor and measured the daily kWh consumption and water extraction quantities. From the data I was able to figure out the running costs for my 5 occupant, 3 bedroom semi-detached house in the Middlesex area of England.

The figures below are based on a total run-time of 117 days between mid November 2012 through to mid March 2013. The machine was set to either maintain a constant 50% relative humidity level or switched to laundry mode to help dry roughly 2 loads of washing per day. The machine was left switched on 24 hours a day.The room temperature typically varied somewhere between 20-23 degrees C in the daytime with the central heating switching off of a night.

I recorded the data each each time I emptied the tank, using a database app from which I was able to populate a spreadsheet. I'm blocked from posting links to the spreadsheet but here is a summary of the data for the totals accumulated:

Runtime (switched on though not necessarily dehumidifying) 2827 Hours (118 days)
Water collected 164 Litres
kWh consumed 291
Calculated latent heat released in kWh 102

At the time of testing my electricity was about 12 pence per kWh which worked out to £9 per month running cost. I was more than happy with this. However, I'm of the view that the 291kWh energy consumed by the dehumidifier and 102kWh equivalent latent heat released, both contributed towards the heating of my home reducing the work that my gas boiler had to do.. At a gas unit price of approx 4 pence / kWh this amounted to a saving of £4 a month resulting in a grand total dehumidifier running cost of roughly £5 per month.

I don’t have a tumble dryer so all our wet washing during this period was dried out with the dehumidifier. If we had been using a tumble dryer I would have expected considerably lower running costs.

Note: The gas and electric unit prices are approximately what I was paying in 2012/2013