This unit is not very efficient (70% claimed) and uses a significant amount of power 18W low, 30W high, but it has two advantages for me:
1. its quite small so may well fit above my bathroom ceiling
2. its cheap (<£200), and as I need a decent extractor fan anyway the extra for HR is quite small

It would be used for extracting stale damp air from a small shower room, and would vent fresh into the adjacent (huge) living room.

Would the efficiency and power consumption tip the balance into energy consumption, rather than energy saving?

I think the general idea is that they run constantly, although we wouldn't do that as the building would not be used every day, so would probably have the trickle on a timer of some sort.

I've now got one and although its not properly installed yet, its ducted in and working well. It could be quieter, though I think it will be fine once boxed in. Just need to sort out where the ducts will go.

I'm not sure which units to go for, the HR100 or 2 x HR25. The HR25 are more efficient, only use 2 W on trickle but still shift 20m3/h extract and 8m3/h intake. It will be for an off-grid house so every W of electricity is more valuable than a W of heat. The only problem with the HR25 is that it's unbalanced, almost 3x as much extract as supply, but I need balanced as this will be for whole house application. Do you think it would be possible to boost the supply by sticking an external fan in front of it? A cheap computer fan should do the trick.

<blockquote><cite>Posted By: stephendv</cite>I'm not sure which units to go for, the HR100 or 2 x HR25. The HR25 are more efficient, only use 2 W on trickle but still shift 20m3/h extract and 8m3/h intake. It will be for an off-grid house so every W of electricity is more valuable than a W of heat. The only problem with the HR25 is that it's unbalanced, almost 3x as much extract as supply, but I need balanced as this will be for whole house application. Do you think it would be possible to boost the supply by sticking an external fan in front of it? A cheap computer fan should do the trick.</blockquote>
We couldn't consider the HR25 as our walls are too thick and difficult to penetrate so the HR100 was the only option. We may not run it constantly long term, but for now, with the building still potentially damp from plastering etc, its running full time and the place is amazingly warm. Our dehumidifier is running 24/7 too and RH is now down to about 50 on average which is plenty dry enough.

I do like the idea of humidity control, we have this on the bathroom fan in the main house and it works well, though can run all day some days!

Most of these single room units seem limited to very thin walls such as 315mm. My new build will have 400mm walls.

The idea of decentralised system appeals to me. A low power unit responding to humidity in wet rooms and CO2 in others would be much easier to install. They only need wires instead of fat ducting. Can such a decentralised system meet AD F 2010 without the need for trickle vents?

Posted By: evanProvided they are used mainly as an extractor, and only runs for an hour or two a day, I don't see the problem with it using a few Watts.

Posted By: RoburHi jemhayward,

We are just about to install 3 x HR100's in a new build house project (bathroom extract) - rather than having them run all the time we are going to control them with a humidistat to reduce the energy consumption, noise and wear to a minimum - they only need to be on when the humidity is above say 70%.

Posted By: jemhaywardI do like the idea of humidity control, we have this on the bathroom fan in the main house and it works well, though can run all day some days!

These units are meant to run continuously. Otherwise what's supplying fresh air to the room it's meant to be supplying? The humidity switch switches between high/low rather than on/off.

Heh, that's why I love forums over mailing lists. Threads never have to die.

So we have this HR100 up and running now but it seems too powerful. It cools the loft conversion down considerably when on continuously. Is there any way to adjust the fan speed down? I don't have terminal covers on the room extract and inlets yet, will this make a big difference?

Yes two speeds, but not stuck on boost.

Posted By: jamesingramyou could try a varible fan speed controller maybe , you need to reduce the power going in prior to boost etc.

In addition to the normal/boost humidistat?