Dehumidifier energy usage, is it worth the extra upront cost?

dealyboy

witty...

Really appreciated your contribution.

sammyjammy

ChaunceyGardiner said:

dealyboy said:

I don't know that that's true. My humidifier (condenser Electriq CD12LE) alternates between warm and cold air outflow according to the ambient temperature. User manual states heating effect neutral. 

That machine uses up to 180W, all of which ends up as heat, mostly waste heat from the compressor. Plus, it recovers some latent heat from the room's humidity.

Mine definitely warms up the room, we had one in a house 30 odd years ago that had no heating, was kept on the landing and really took the chill out of the air as well as the dampness.

Ally_E.

I prefer dessicating dehumidifier, it's less noisy, less bulky and work in lower temperatures.

This is the one I have, had it for 10 years now and works perfectly fine.

https://amzn.eu/d/64dCVSj

I also have compressor dehumidifier and don't use it much at all as I prefer the dessicating one. 

rothesy

Maybe also have a quick look at Ebac dehumidifiers.  They are made in Britain for the British climate.

Apodemus

Qyburn said:

EssexHebridean said:

For those of us regularly needing the use of dehumidifiers, 80% may not be too far off a familiar number... 

Indeed, but presumably not 30 deg C.

I'd guess that the vast majority of the dehumidifiers in the world are used in the humid tropics and subtropics so, from the perspective of the manufacturers and the majority of users, quoting figures for 30C and 80% may make a lot of sense. Of course, this perhaps also highlights just how much of an anomaly we are in UK of having cold, damp houses!

wittynamegoeshere

The compressor (and peltier) ones work by passing the air over a chiller that's a number of degrees below room temperature, which makes the moisture in the air condense onto it, then it drips down into the tank.  My experience is that if the room is below about 10-15C then this chiller will be below freezing, so it ends up as a block of ice.

Most decent dehumidifiers sense this happening and go into a defrost mode, usually the compressor switches off and the fan remains on until the block of ice gets blown away.  This can take up a fair percentage of its time in a cold room, during which it's not dehumidifying very much.

Following this, the now dry air gets passed over the heating part of the heat pump, heating it back to or just beyond the temperature it was to start with.

My cheap little peltier one doesn't have an automatic defrost, and I've seen it end up literally full of a giant block of ice in the past when in an unheated room.  I now have it plugged into a plug-in timer that is set to 6 hours on, 2 hours off all day.  This seems to be enough to keep it clear, plus that bit of a rest is probably good for it.

Definitely check if a compressor one has such an automatic defrost function before buying - if not then it shouldn't be used anywhere that's not pretty warm.  If regularly using in a cold room then a dessicant one may make more sense.  I don't have experience of using them but others say they're pretty good.  If they're theoretically less efficient then they may make up for this by spending less time full of ice.

Qyburn

wittynamegoeshere said:

Most decent dehumidifiers sense this happening and go into a defrost mode, usually the compressor switches off and the fan remains on until the block of ice gets blown away.  This can take up a fair percentage of its time in a cold room, during which it's not dehumidifying very much.

The best ones have what I've seen called "Hot gas defrost" which does something like reverse the flow of refrigerant to warm up what is normally the cold evaporator. This is done with the fan off, presumably so as not to evaporate water back into the air. But as you say while it's doing that it's not dehumidifying.

Irratus_Rusticus

No expert on dehumidifiers but have owned one just over a year - a Meaco "Meacodry" 10L. 160 Watts rated, presumably that at higher fan speed. Rarely need that setting. Sits in hall and dehumidifies two bed flat - target < 55-60% RH. First expected to have to run most of time, but for long periods merely need on after shower/bathing or cooking. This time of year RH needs much more on time. Quiet enough when on lower fan setting. Faster fan noiser if drying clothes or want faster results. Tend not to dry clothes indoors. No mould no more. Not cheapest. 

wittynamegoeshere

Meaco and Ebac both seem to be "reassuringly expensive", for those who like to pay more.

This may or may not mean they're better.  I have a pretty deep-rooted cynicism of these premium sort of things, but plenty of people drive around in BMWs and Audis so everyone definitely doesn't think the same way.

[Deleted User]

wittynamegoeshere said:

Meaco and Ebac both seem to be "reassuringly expensive", for those who like to pay more.

This may or may not mean they're better.  I have a pretty deep-rooted cynicism of these premium sort of things, but plenty of people drive around in BMWs and Audis so everyone definitely doesn't think the same way.

By the time I get to see them, the failure rate of many appliance categories is independent of brand - it's just that there is less volume sold of the 'premium' unit so the absolute number of failures is smaller.