The Running Cost of a Dehumidifier can depend largely on two crucial factors, namely the actual energy rating of the Dehumidifier and the number of hours in which the Dehumidifier is actually operating.
Suffice to say that Dehumidifiers have become more popular in households over the years, probably as a result of the increase in rental properties, which usually tend to be poorly heated, and ventilated and the widespread use of double glazing which limits natural room ventilation, causing moist air to get trapped in rooms, increasing humidity to a level which causes condensation to form on cold surfaces such as outside walls.
Dehumidifiers will not, by themselves, completely substitute the requirement for a heating system, however they can be a perfect partner to any existing heating system, as damp and levels of high humidity can often cause even a warm room to feel much colder than it is, and also require more energy input from any domestic heating system in order to combat the effects of damp, humid air and so the use of a dehumidifier can effectively reduce heating costs. The energy rating of most Dehumidifiers is measured in watts, and often the wattage figure is far less than an average sized electric heater, however Dehumidifiers are designed to be left running for much longer periods in order to maximise their effect.
Many people believe that they should leave their Dehumidifiers running 24 hours a day, which can work out quite expensive. Unless your room and household has extremely high levels of damp and humidity, then this is really a waste of Electricity. Most good quality modern Dehumidifiers are very efficient and can often collect the same amount of moisture from out of the air during a 6 hour running period, as an older system would collect in a 12 hour period.
Its a good practice to use a plug in timer to control the running of your Dehumidifier, and three timed bursts of five to six hours in duration spread out over the day with at least one overnight period (Humidity levels generally reach their peak during times when people are asleep and breathing out moisture) this will usually be just as effective at curing damp or reducing humidity issues, as would leaving the Dehumidifier running 24 hours. If you have Economy 7 Electricity then it would also be cheaper to leave your Dehumidifier running overnight, to take advantage of the cheaper off peak period.
There are two types of De-humidifier available. The most common type uses a rotary compressor, to cool metal coils which then draw the trapped moisture out of the air, these tend to be very noisy in operation and are slower at starting to remove moisture, however they do have the lowest electricity consumption of the two types. The newer type of dehumidifier is called a Desiccant De-humidifier these are virtually silent and also much more effective in removing moisture compared to conventional dehumidifiers, however they also consume more power, around two to three more times Electricity than compressor types, but using a Desiccant De-humidifier for a few hours can also raise the room temperature by as much as 7c to 12c in a well insulated room which is often enough to reduce the requirement to use any background heating in the room, thus effectively paying for its own use through a commensurate reduction in heating bills.
Desiccant Dehumidifiers are also more effective than compressor types when working at lower ambient temperatures, and so are more suitable for use in porches, conservatories, outhouses, cellars and conservatories or poorly insulated homes and flats. Older buildings especially, will benefit from the use of a desiccant based appliance.
I have listed below the hourly running cost of the most popular models of Dehumidifiers. All running cost have been calculated using an example figure of 12p per KW/H as an Electricity cost (Which is the average UK electricity kw/h cost – updated as of Feb 2016)
Ecoair DD122FW – 390 watts (low) 4.7p per hour / 640 Watts (High) 7.8p per hour
Delonghi DEM10 – 190 watts – 2.3p per hour
Delonghi DES12 Dehumidifier – 180 watts – 2.2p per hour
Delonghi DES14 – 230 watts – 2.8p per hour
Meaco 10L Dehumidifier – 220 watts – 2.7p per hour
Ebac 2650e Dehumidifier – 360 watts – 4.3p per hour
Prem-I-Air PGD10L – 250 watts – 3p per hour
Meaco DD8L Junior – Low (330 watts) – 4p per hour / High (650 watts) – 7.8p per hour
Ecoair DC12 Home Dehumidifier – 230 watts – 2.8p per hour
Blyss 10L Dehumidifier – 205 watts – 2.5p per hour
Meaco DD8L Dehumidifier – Low (330 watts) – 4p per hour / High (650 watts) 7.8p per hour
330 Watt Desiccant Dehumidifer – 330 Watts – 3.9p per hour
650 Watt Desiccant Dehumidifier – 650 Watts – 7.8p per hour
If you model or wattage of dehumidifier is not in the list above, you can work out the cost of running it yourself by using the following formula.
(1000 watts = 1kw and so 250 watts would equal 0.25kw)
So you would work out your dehumidifier running cost by using the following equation:-
KW X Electricity cost in pence X number of hours run
So a 150 watt dehumidifier running for 12 hours with an Electricity cost of 14p per unit can be worked out as:-
0.15(kw) x 12 x 0.14 = £0.252 = 25.2 pence
a factor that is normally missed in these cost calculations is that every litre of water that is condensed releases 0.6kWh of heat energy ( latent heat of vaporisation).
If the air is very damp this will be easier for the dehumidifier to extract (i.e. cheaper) and the use of a dehumidifier is very cost effective.
In addition to this it appears that damp plaster is a much better conductor of heat than when it is dry further improving the efficiency of using dehumidifiers.