dehumidifier versus panel heaters

koolkat66

I live in an Housing Association old ground floor flat in a Listed Building, all electric, no gas. Heating is storage heater in living room/ kitchen (open plan), and wall panel heaters in the two small bedrooms and entrance. I am on economy 9 tariff. Last year the storage heater did a fairly good job in the kitchen and living room, and absolutely nothing in the rest of the house. I had the panels heaters on but only when needed, yet the electricity bill was big and the flat not particularly warm. The heating from the panel heaters seemed to disappear the moment they were switched off. The flat was also very humid, with large condensations pools at the windows.
The windows are double glazed (actually, more like another single layer glass window in front of the old window), bricks are not vented , there are no fans or extractors installed anywhere (and cannot be as it is a Listed Building). I am dreading this winter coming...

There is now an HRVS (Heat Recovery Ventilation System) installed. I have been running a dehumidifier for a few days in one of the room and I realised that as well as making the room nice and dry it actually warm it up. I am now wandering if it is actually more cost effective to have dehumidifiers instead of the panel heaters, as they have cheaper running costs, and do two jobs instead of one! The dehumidifier I have is a large industrial Ebac which runs on 400 w (the panel heaters range from 1500 to 3000w!!!), it has been lend to me, but I have seen others much cheaper to buy and to run...what do you think?

HappyMJ

The 400W of power does go into the room as heat as well as removing the water from the air. The Ebac website does say it should increase the room temperature by 3 deg C. If that's enough for you then stay with it.

grahamc2003

Where you have a mvhr, you shouldn't need a dehumidifier in any of the rooms the mvhr can ventilate. So I assume you have the system in your bathroom(?), and the dehumidifier in your lounge(?).

You gain in several ways by having a dehumidifier (when needed). Firstly, you get more heat output than electricity you put in - so say yours is 400w, then you'll get something like 405w heat output, so a little gain there. Then there's a gain because to warm up dry air, you need less energy than warming moist air, so for the same heating, the room temperature will be higher. Ime, breathing drier air (but not too dry) is much more preferable in a house than moist air - hard to describe why, ime it's a subtle but definite difference. You can usually buy different filters for dehumidifiers which claim to do all sorts of life enhancing things to the air. Condensation will definitely be cut down, but may not be eliminated - that depends on many factors. Many benefits for something costing about 5p per hour to run.

You'll still need some form of heating - if the temperature drops to around 10C say, the dehumidifier will/may ice up and stop working (and stop warming the room).

As a general rule, pure electric heating should be a last resort, since you only get the one benefit (heating). All other uses of electricity give you a couple of benefits - in your case, dehumidification, as well as the heating. Same goes for stereos (but you need a powerful one to generate much heat!). There's really not much point in turning off TVs and PCs (to be environmental/save some cash) if you are heating the room with panel heaters.

koolkat66

The HRVS is in every room but it has only been fixed in the last two weeks, so I still have to see what the effect will be in winter. I know that pure electric heating is the last resort, but this is what is installed in the flat, and I have been looking at other forms of heating, oil filled radiator etc. Just haven't found the solution yet!

Swipe

I swear by using my dehumidifier in the winter to raise the temperature in the hallway.

mandycrawford71

Yes, my home similars yours. You to get an ecoair ECODD122FW dehumidifier which can increase the room temperature around 7 degree! I bought 1 which only cost me £159. You can check the product information at ecoair.org

Mister_A

mandycrawford71 wrote: »

Yes, my home similars yours. You to get an ecoair ECODD122FW dehumidifier which can increase the room temperature around 7 degree! I bought 1 which only cost me £159. You can check the product information at ecoair.org

There is a very interesting article at iwilltry.org (sorry, I am not allowed to post a direct hyperlink) that delves in to the benefits of using a dehumidifier as a heater. As already mentioned, because a dehumidifier removes water vapor and then condenses it to a liquid, energy in the form of heat gets released back into the room. This makes it more efficient at heating a home than say an electric fan or panel heater.

Hooking my dehumidifier (Eco Air DD322FW Simple) up to a plugin-in power meter and measuring the amount of water extracted over several hours I calculated, using the formula in the iwilltry.org blog post, that the units COP was 130%. In other words, for every 1KW of of electricity the unit consumes, 1.3KW of heat is released in to the room - bonus !

grahamc2003

Mister_A wrote: »

There is a very interesting article at iwilltry.org (sorry, I am not allowed to post a direct hyperlink) that delves in to the benefits of using a dehumidifier as a heater. As already mentioned, because a dehumidifier removes water vapor and then condenses it to a liquid, energy in the form of heat gets released back into the room. This makes it more efficient at heating a home than say an electric fan or panel heater.

Hooking my dehumidifier (Eco Air DD322FW Simple) up to a plugin-in power meter and measuring the amount of water extracted over several hours I calculated, using the formula in the iwilltry.org blog post, that the units COP was 130%. In other words, for every 1KW of of electricity the unit consumes, 1.3KW of heat is released in to the room - bonus !

Hmmm, I think you've made a bit of an error there!

Unfortunately, a dessicant dehimidifier such as yours doesn't produce the extra heat (from the latent heat of evaporation) which a more usual compressor type dehumidifier does.

The reason is that a dessicant one works by blowing warmed air over the dessicant material to evaporate the water (i.e. you put in the latent heat of evaporation to evaporate it!), then the warm moist air is cooled over a heat exchanger where the water condenses out (releasing the latent heat you've just put in).

The more normal compressor type simply blow the room air over a cold heat exchanger to condense the water out - hence the latent heat is released then without first putting it in.

The interesting blog you linked to calculate a cop of 1.5ish (i.e. you put 1kw into the compressor dehumidifier, and get 1.5kw of heating). At first that seemed pretty unlikely to me, but the maths looks correct. The blogger is getting an amazing 3 litres of water from his dehumidifier over 8 hours - I get one litre over 7 hours. The difference is his area in the States is more or less 100% humidity and 17C, so can condense much more water than us in the UK.

edit btw - I'd really recommend using a dehumidifier rather than a panel heater (unless your house is already too dry, which is unlikely). If the temperature in your home is above say 14C when running the dehumidifier, I'd recommend a compressor type, but if it drops to less than that, I'd use a dessicant type, like the ecoair one mentioned, which work down to 0C

highrisklowreturn

Do not assume you can adequately heat a room with a dehumidifier....

grahamc2003

highrisklowreturn wrote: »

Do not assume you can adequately heat a room with a dehumidifier....

What a very well argued post. You've really convinced me.

ariba10

The heat you get from a dehumidifier is the same as you would get from a small refrigerator with its door open.