Hi all - first post so be gentle.

Had some issues with condensation and really need to fit some extraction (no extractor in kitchen and like to steam veg!)

Clearly, heat recovery makes pure sense, so would like to install some. No room for ducting associated with normal loft positioned ones. 1920's semi, Pretty well insulated now considering the type of house.

Saw a couple neat looking units at EcoBuild. One by Vent-axia (Tempra) and Xpelaire do one too (HXR150).

Essentially a replacement for a standard through the wall extractor, but claiming 75 or 80% recovery, Draws slightly less air in to maintain a negative pressure in the room.
Would like to fit one to my bathroom, and one in my kitchen. (Will have to be vigilant with using our cooker hood which is just a recycling one, but clearly don't want to cack up an expensive MVHR with grease etc)

Has anyone out there had any real world experience with these rather neat looking units.
Wondered if they can live up to their claims.

Hi Sam,

See

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=1248

The HR25 is unlikely to be 'grunty' enough for a kitchen, I think, and beware of simply decanting the (moisture) problem into another 'room' - your washing will not dry so quickly!

Be aware that they can be noisy when operating at top wack even in good conditions, but when it's below freezing outside if ice forms from the condensate, they can sound like you've got a small plane taking off.

The model I noticed this on IIRC was a vent axia, with the other problem being that it only had trickle mode or fully on mode, no medium setting. In even a moderate breeze, trickle mode didn't work because it was so underpowered, resulting in cold air blowing straight in from outside with no heat recovery, and that to actually get it sucking the moist air out of the room rather than effectively blowing it through into the rest of the house it had to operate in full noisy mode.

I think some sort of a wind protective external hood might have partially solved the problems, but haven't yet had chance to test this theory out.

This was in stirling with the outside air temperatures dropping to -15, so I suppose it's less of an issue if you're in the south. Something to be aware of anyway.

very droll - and the kettle ????

I have HR25s in our bathrooms and also in the utility room: this is their first winter of operation (we are in SE England). They seem to work fine. Yes they are noisy in boost mode, but that's generally only for about 5 minutes after someone's had a shower. Otherwise they've v quiet and only consume 2W. I haven't noticed any problems on windy days, but I couldn't say for sure that the problem Gavin mentions doesn't happen. Following the coldest night of the year the one downstairs did rattle badly presumably because of icing, but I just turned it off until the afternoon and the problem went, and otherwise it's been fine (remember that on really cold frosty nights outside temps will be several degrees lower at ground level than at first floor level, so upstairs the risk is much less).

One thing about HRV is that the colder the outside temp, the drier the air which is drawn into the house, so ironically they may have been more effective this year than they would be in a mild damp winter.

Final point- the big downside of the HR25 is the price: £200 plus.

Arthur
Mine is on 24/7, and 99% of the time it's in trickle mode. As I said previously, the only time it goes into boost mode is when someone's having a shower, and then it's rarely for more than 5 mins.

Since I turned them on in October not a single window has been opened in the house at any time. For me the objective was not to open windows in the winter and also not to have to worry about making the house as airtight as possible. The HR25s are my alternative ventilation. Since the house is 100 years old and large, it's unlikely ever to be airtight enough to need proper MHRV.

Once the heating goes off I shall turn them off and allow people to open windows...

Quote from jules
"As I said previously, the only time it goes into boost mode is when someone's having a shower, and then it's rarely for more than 5 mins."

Is your's operated on a Humidistat then

Sam, my units have a humidistat - they are the HR25H. As you probably know, you can get different versions that are manually switched from one mode to the other, or are linked to the bathroom light etc.

Peter - all my remarks are about these units, as they are the only ones I have. I'm not sure what Arthur was referring to.

As I said they've only been installed for 6 months, so my experience is limited, but so far I'm have no complaints. Although you do need to drill a 150mm diameter hole in your wall for them!

Should just add that in a post above I meant to say, in case it was confusing, that an objective of installing these fans was to be able to make the house as airtight as possible without worrying about the consequences. The only other thing I should add is that we have a large and quite open house (~240sqm), so there is less of a problem with "stuffiness" anyway. But I haven't had any problems with dampness/condensation, despite never opening the windows in the bathrooms all winter.

Arthur
In our kitchen we just have a cooker hood extractor. The kitchen is in a large open plan area so steaming up is actually not much of a problem, and in fact we don't actually use it a lot. I had wondered about having an HR25 in the kitchen, but I suspect that there are issues with grease etc getting in the works.

Final point - we only bought the house 2 years ago and then had it gutted, so I cannot make a "before and after" comparison for these fans. Smaller and less open houses with different levels of leakiness might have different experiences. Would be nice to hear from anyone else who has single room units.

when you say 'does exactly what this fan does, but without HR, what exactly do you mean?

a HR unit effectively blows and sucks at the same time, so doesn't really draw air through the house at all in the way you describe regardless of whether there's heat recovery or not.

to draw air through the house in the way you describe without heat recovery, you just need a standard extractor fan, or an extractor fan with humidity sensor if that's the function you want.

As an aside, the HR25 draws in about half the volume of air that it sucks out in both trickle and boost mode, so you would get a slight negative pressure in the room relative to the rest of the house, resulting in a slight flow from the rest of the house.

HR25 figures: Trickle mode - 15.7m3/h out, 7.8 in
Boost mode - 54.8m3/h out, 35.8 in

Thanks for that info Jules, I suppose there was a strong wind blowing through the unit at the time I tested it (aka taped a plastic bag over it) to see if it was blowing/sucking/both equally, so I should really have worked out that it was supposed to have been more sucking than blowing.

Gotanewlife - if it was clear then I'd not have been asking. Anyway, something like this is probably what you're after

vent axia Lo-Carbon Solo Plus SELV Fan + H/Stat & Timer - £134.67 + vat etc from here
http://gil-lec.co.uk/products/Extractor+Fans/Centrifugal+Fans/Lo-Carbon+Solo+Plus+SELV+Fan+%2B+H/Stat+%26+Timer/1274882248

it's not quite as low wattage on trickle mode as the HR25 at 5.7watts, but it extracts 25% more air in trickle mode than it, and has a low boost function that extracts double the air at only 6.5 watts, and even it's peak mode draws less power than the HR25's peak. It also has both timer and humidistat functions, so I'd think that overall it's energy consumption would be pretty much the same as or lower than the HR25.

The house in question was in outside Inverness, at the peak of the winter freeze (-15 night time temperatures and sub-zero daytime), with 2 of those HR25 units on north facing walls, with a howling gale blowing from the north, so pretty extreme conditions.

In a more sheltered location probably not on a north facing wall, or in areas not so prone to such extreme low temperatures I'm sure they work really well, just something to bear in mind for anyone who is in a more exposed location really.