Retrofit heat recovery ventilation - experienced advice needed

Bathsheba309

Bendy_House said:

I understand where you're coming from, 'Sheba. But still...

That is a hell of a lot of outlay, in order to treat symptoms and not the cause. It just seems 'wrong' to me, when natural ventilation should be the obvious way to tackle it - and there MUST be ways of doing this; trickle vents should be able to be retro-fitted to windows.

And whatever is causing this excessive humidity should be tackled. If this is simply lack of ventilation, this really should be sorted - naturally. Crazy to go 'forced', when passive should do the trick. Cost = zero.

But we particularly want heat recovery in order to reduce our carbon footprint. Given the astronomical rises in fuel costs this will increasingly make economic sense as well as environmental, and anyway, compared with most jobs these days 300 quid per room plus fitting is pretty cheap to start with.

ComicGeek

Are you in NI, I can only find that company in NI? If so, you are probably subject to higher costs. I also can't find anything on their website about MVHR - perhaps they really don't want to do it, or make more profit on PV installs.

250m2 at 0.3 l/s/m2 = 75 l/s 

That's a good size MVHR unit, but still only £1500 for the unit https://www.i-sells.co.uk/mob/prod_detail.php?cPath=1599_171&products_id=47891&gclid=EAIaIQobChMIvaubvOL_9gIVkoBQBh2ffQ7gEAQYASABEgK-RvD_BwE

Pre insulated 100mm diameter rigid ducting costs about £3.5/m length - even if you allowed for really long lengths per room it would still be less than £1000. Grilles, electrics, condensate - say another £1000 max. 

Really easy fitting in the loft - not many bends, or vertical drops or joists to navigate. 

Bathsheba309

Sorry, was green building store, not green energy store as I said previously. I think they probably go above and beyond, with everything done to passivhaus standards, so we probably could find someone cheaper than that. The other company I spoke to were solarcrest in Macclesfield and they said similar. If you know what you're doing (and it sounds like you do) then fitting a central system sounds like a good option. Our problem is that we don't, we would have to have someone in to design and fit it for us, and at the moment there's hardly anyone out there that know what they're doing, so the ones that do can charge a premium :-(

ComicGeek

Passivhaus accredited units are really expensive, and completely over the top for most properties. They may have additional heaters and specialist ducting etc which pushes the prices up even more.

The design can be done free by the manufacturer - that can be Nuaire, Vent Axia, Titon, Rega to name a few.

Most installs are done by plumbing/electrical contractors rather than specialist contractors. Just give a few larger local companies a call to see if they do it. Local builders merchants may even know a couple of companies who buy the units through them.

Mutton_Geoff

Fans4Less sell a range of units. No connection with them, just a happy customer.

https://fans4less.co.uk/collections/heat-recovery-units-1

Mardle

If you don't already have a trickle extractor fitted in the bathroom or kitchen maybe install one. We have a Vent Axia which has been running for the last 7 years in an end terrace built in 1908. The humidity right through the house is less than 40% (but we do tend to leave interior doors open)