Mechanical Ventilation Heat Recovery Unit

safename

Hi folks

We are currently planning on building a ne house and I was just wondering if anyone has any experience with MVHR units?

I really just want to know if people think the benefits out weigh the cost (projected to be £4.5k for our build).

Just by way of background our house is around 2200 sq ft and will have underfloor heating on both floors.

Nay advice would be welcome

Peter:beer:

GlynD

I've no experience of using one of these systems myself but I've seen them on TV and before I decided to respond to your posts I read this article which explains how it all works. http://en.wikipedia.org/wiki/Heat_recovery_ventilation

If the architect has recommended the use of such a system I would say go for it because it's well proven and it will recover at least part of its costs, possibly all of them, over a 20 year period. Comfort, good air quality in an almost airtight house and efficiency seem to be the prime benefits of using MVHR and if I were going to build a new house and could afford this feature I think I'd want it included.

safename

Thanks for the response Glyn!

Yeah to me it makes sense to install it, I think my only problem is that I think the architect may be affiliated with the company that he got a sample price from and if he is, he has not advised me of it.

I think I will just go ahead and get SAP calculations prepared based on having a MVHR unit and I can always go ahead and get alternative quotes!

I'm probably being over sceptical but when its your first self build its a bit daunting!

Peter

GlynD

safename wrote: »

Thanks for the response Glyn!

Yeah to me it makes sense to install it, I think my only problem is that I think the architect may be affiliated with the company that he got a sample price from and if he is, he has not advised me of it.

I think I will just go ahead and get SAP calculations prepared based on having a MVHR unit and I can always go ahead and get alternative quotes!

I'm probably being over sceptical but when its your first self build its a bit daunting!

Peter

The way you're talking indicates you know a helluva lot more than I do. Alternative quotes is always a good idea. I'm not sure if an architect would be allowed to be affiliated with a specific company but I'm always prepared to be educated.

Daunting is one way of describing your first self build but I'm sure you're excited too? I know I'd be dancing from foot to foot. I've never done a self build and I don't think I ever will. The way I am now I'd prefer to buy something which was up for a while with mature surroundings, even if I had to do a lot of renovation.

That's what I've done in my current bungalow and my previous one. As we speak I have tradesmen in the house putting the finishing touches to a new bathroom which completes the major renovations in this property which is about 40 years old and hadn't been touch for the last 30. It's been a long haul but with just the addition of a few interior doors to go we've completed a full renovation now and can enjoy it this Christmas.

We'll take the good out of what we've done for a few more years before, hopefully, selling this one on and moving into that final, retirement property in the middle of nowhere, well away from any neighbours.

warmhands.coldheart

safename wrote: »

..................... I think my only problem is that I think the architect may be affiliated with the company that he got a sample price from and if he is, he has not advised me of it. .............

You always get this with Architects and Designers of anything.... They all have "Favourite" suppliers of certain items be it Kitchens, Bathrooms, Paving, even the building work.
Not a bad thing if it is based on good quality and/or workmanship. I've seen this pay dividends with a few friends who have built houses. Architect and Builder/Supplier are on the same "wavelength" and have a good working relationship. It can make things work well. It IS a problem though if it's just purely based on kick-backs.......

motorguy

We looked at heat recover systems, but because of the size / shape of our house we'd have needed two units.

We opted instead for the Nuaire Drimaster system and have two of those in the house. Doesnt do heat recovery, but it allows us to have an otherwise relatively air tight house without having to worry about stale air / condensation

Not sure what the ROI is on it, but its certainly better than 20 years. Anything we put into the house we tried to ensure the ROI was 7-10 years max.

GlynD

motorguy wrote: »

We looked at heat recover systems, but because of the size / shape of our house we'd have needed two units.

We opted instead for the Nuaire Drimaster system and have two of those in the house. Doesnt do heat recovery, but it allows us to have an otherwise relatively air tight house without having to worry about stale air / condensation

Not sure what the ROI is on it, but its certainly better than 20 years. Anything we put into the house we tried to ensure the ROI was 7-10 years max.

I was only guestimating the ROI. What age is your house? I'm asking because I'm wondering how I might fit something like that to this 40 year old bungalow. I can't achieve anything like a good air tightness at the moment because I've still got a hardwood front door with a (badly sealed) frame, which I'm just about to address. I have looked at composite doors and think they're excellent with great sealing capacity. If I had one of those fitted then I'd be getting as good a seal as I think is possible in the house, bearing in mind the amount of insulation I've put in the loft.

I've got a problem though. We have cats and they need access night and day. I know some people would say forget the cats but they're our children, if you know what I mean, so provision has to be made for them. I have one or two ideas in my head but with the house crawling with tradesmen for the last 9 out of 10 days, fitting a new bathroom, I want to take a wee break for a week or two. The next project is replacing all interior doors, including a set of sliding doors and to be honest I think that'll see us up to Christmas. I'd like to have that done by then at any rate but I won't be screaming if it isn't.

motorguy

GlynD wrote: »

I was only guestimating the ROI. What age is your house? I'm asking because I'm wondering how I might fit something like that to this 40 year old bungalow. I can't achieve anything like a good air tightness at the moment because I've still got a hardwood front door with a (badly sealed) frame, which I'm just about to address. I have looked at composite doors and think they're excellent with great sealing capacity. If I had one of those fitted then I'd be getting as good a seal as I think is possible in the house, bearing in mind the amount of insulation I've put in the loft.

I've got a problem though. We have cats and they need access night and day. I know some people would say forget the cats but they're our children, if you know what I mean, so provision has to be made for them. I have one or two ideas in my head but with the house crawling with tradesmen for the last 9 out of 10 days, fitting a new bathroom, I want to take a wee break for a week or two. The next project is replacing all interior doors, including a set of sliding doors and to be honest I think that'll see us up to Christmas. I'd like to have that done by then at any rate but I won't be screaming if it isn't.

Its been up four years now and the system was fitted when we built it. With regards to air tightness we did the composite doors, no letter boxes, no trickle vents in the windows, the chimney blocked off (but removable) and some other things i cant remember now, and the the two drimasters.

We've two cats, but they're house cats so no issues with cat flaps.

GlynD

motorguy wrote: »

Its been up four years now and the system was fitted when we built it. With regards to air tightness we did the composite doors, no letter boxes, no trickle vents in the windows, the chimney blocked off (but removable) and some other things i cant remember now, and the the two drimasters.

We've two cats, but they're house cats so no issues with cat flaps.

We don't have a letter box but we do have trickle vents in the windows. We also have an open chimney - very much in use as we love an open fire.

Looks like I'll have to settle myself here with a job reasonably well done and save my best efforts for my next (and last) purchase. If I live that long.

A.L.D.A

safename wrote: »

I think my only problem is that I think the architect may be affiliated with the company that he got a sample price from and if he is, he has not advised me of it. Peter

The way that reads is a serious accusation. Do you mean financial or just knows them by reputation? I assume the latter. Is he an Architect? If he is not listed on this site http://www.arb.org.uk/ then he is not, and should not be described as such, (It is an offense!). If he is then he should disclose any financial affiliations.

To clarify in my mind, your house was designed and you have Planning Approval and have yet to apply for Building Control Approval. Ventilation control will need to be specified and included in the design and in your SAP calculations along with any wood burning stoves, heat pumps etc.

A controlled ventilation system needs to be designed and balanced. It needs to be maintained, be accessible and filters changed. Some systems need to be located on the warm side of the insulation or you will have condensation in the unit, others do not. You have to accommodate the ducts, By the way use rigid ducts, not the expanding type! Consider noise transmission from room to room along the ducts, and fire compartmentalisation.

If your are building this yourself, and coordinating, know exactly what is going in, its size and where. The common mistakes are routes through steel beams or other services. So you need to check thoroughly any proposed layout. Make sure someone reputable installs it.

Oh just one more point if you are installing a wood burning stove make sure it can get ventilation directly from the outside for obvious reasons.

HappilyRetired_2

Yes, an HRV system is worth the cost. Dry fresh air even if you're out all day (or on holiday), smells and moisture removed from kitchen and toilets, annual running costs low (I'm still monitoring, but reckon on less than £30 for the electricity). The heat loss through air chucked out is less than any other ventilation system, eg trickle vents on windows or opening windows as and when you can. I reckon, after a lot of calculation, on about another £25. It's impossible to calculate heat loss on random window opening, but I believe it to be much more for similar air quality, mainly because there is no heat recovery on random window opening.
Best of all - you can specify windows without horrible little vents.
A few thoughts, though:
1 The machine itself makes more noise than the installers would like to admit, so put it away in a utility room, attic, etc.
2 The noise from the ceiling vents should be negligible at daytime running speeds but you might need to have a slower nighttime setting if you live in a very quiet area.
3 The ceiling vents are visible.
4 The main disadvantage of an HRV system, in my opinion, is that smells from your neighbours' new wood burner or the local farmer spreading manure might be sucked into the inlet and sent round the house. Check if the system has a temporary shut down control to deal with that.