Whole House Ventilation with Heat Recovery

[terry]

Yes. Here called an air (and heat) exchanger. Becoming common and have been mandatory in highly insulated homes which are in accordance with R2000 for past ten or fifteen years or more.

For example a relative has just bought a 17 year old house that has an air exchanger but we have noted it is NOT a heat recovery type. It may only be an exhaust system but house also has bathroom and kitchen exhaust fans; so?

AIUI the heat recovery type has several ducts (presumably at least one on each floor?) to pick and exhaust stale air and that goes 'out' through one side of the 'Air exchanger' unit. Warming the incoming air on the other side of the unit Heat recoveries of up to 80% are claimed, but personally I doubt it and under what conditions? Also a set of ducts goes to each room or area to introduce the slightly warmed fresh air.

Will see if I can find some links (probably North American though) and post them here. Should be well established technology! The maintenance supervisor of a local school here was installing such items as a sideline business some ten-twenty years ago!

[Doctor Drivel]

AIUI the heat recovery type has several ducts (presumably at least one on each floor?) to pick and exhaust stale air and that goes 'out' through one side of the 'Air exchanger' unit. Warming the incoming air on the other side of the unit Heat recoveries of up to 80% are claimed, but personally I doubt it and under what conditions?

[<me9]

Running costs for an effective dehumidifier are *not* low, Suitable HRV would work out cheaper.

[chris French]

The typical computer fan is crap because they are cheap, it's got nothing to do with the voltage.

Decnet 12v can be quiet and last for a long time.

[terry]

[Owain]

No! Not plastic windows in a Victorian house! Please. You can have double glazed panels in timber sash windows, and existing timber sash windows can be renovated and draught-proofed.

You don't normally need ducts to every room - just suck from the kitchen and bathroom(s) and blow into lounge and hall. If you aren't using the fireplaces you could use the chimneys as ducts (with a liner)

Owain

[chris French]

My thoughts as well, it ruins the look of the house. (though if it's the usual vic terrace, the windows on the various houses will look a right mish mash by now anyway)

One of the other victorian houses near us has been ruined by the co that did it up.

They put in uPVC windows, the sandblasted (or somesuch )the brickwork, which now looks like new and stands out like a sore thumb against all the other houses around here built of the same brick. And the interior is very modern (ok I don't know what it was like , it may have been all ripped out previously). But it doesn't feel like it compliments the style of the house it just clashes.

But they haven't sold it, been on the market at least a year I guess.

[Jason]

I hear you, but there are costs to think about, plus matching the other houses in the street is probably more to the point.

Unfortunately the timber sash windows went several owners ago, and the sash boxes are now just hollow plasterboard. The windows at the moment are horizontal swing-around types, and rotten as anything. I have tried draught-proofing them (embedding fire-door strips into routed channels) and that does make a big difference to the draughts, but I think there is too much rot in the wood to recover them properly.

Looking down from the loft, the two main chimney breasts have channels running down each side, right down to the ground floor (below the floor actually). That means I have access to every room in the house from the attic, by at least two points (each side of the chimney breasts). I'm using it for network and TV cables at the moment, but they are about 9" square, so there is plenty of room to run further ducts.

-- JJ

[Jason]

Do you know our street then? ;-)

Just for you lot, I will enquire about wooden windows, but it really all comes down to price. The three large windows at the front of the house come in at around £500 for all three from a local supplier (fitted). The frames are a bit chunky, so I'm looking further afield for some low-profile frames. We'll see.

-- Jason

[Jason]

Well, thank you all for the help, hints and tips. It is clear from your responses that I absolutely need to fit the leaks first, which *is* going to be difficult in such an old house.

Leaks -> insulation -> airflow (in that order)

I've ordered a heat-recovering extractor fan for the bathroom (with built-in humidistat), so we'll see what difference that makes when it's fitted.

I have a loft-clearing task to do, so I can take advantage of some local (and nearly expired) grants available for loft insulation. I think Wickes are even in on the grants, offering their rock wool at half price until February.

Floors to be sealed and insulated. Yeah, not easy. I can get to the underside of all the floors quite easily, but the joists are not evenly distributed, so I cannot just cut all the foam or whatever to a single size and push it in.

The front windows to be replaced, and then we'll see whether whole-house ventilation is needed.

-- Jason

[Dave Liquorice]

I'm inclined to agree if just fitting stock jobbies. We've put plastic in here (17th C farmhouse) principly beacuse of the exposure and extremely short and unpredictable times that painting can be done. They are damn sight nicer looking and if better keeping than the old stock top horizontal vent '70's windows. Our plastic ones are designed to be similar in appearance to a sash window with 6 panels per sash.

[RW]

[Mike]

About 20 years ago you could head off down to Wickes and buy a system off the shelf. There was a Wickes leaflets telling you all you needed to know on sizing and system configuration.

[Owain]

I would disagree. Removing ventilation (albeit inadvertent and unwanted) in a poorly insulated house is quite likely to increase your condensation problems.

Insulation first if possible, then as you remove leaks make sure you have compensating airflow.

If you aren't set on heat recovery you might google passive stack ventilation. (a function currently performed rather crudely but effectively by your chimneys).

Owain

[Owain]

£500 for plastic windows plus £1000 knocked off the house value

vs

3 x £1000 each for replacement wooden sash windows less £1500 added to the house value

Alright, the figures will vary and can be skewed to show almost everything, but overall replacement wooden windows might be a better investment, or at least no worse.

If you are staying in the house then budget replacement costs every 20 years for plastic windows. Decent wood windows will outlast you and your children, if kept in good order.

You might be lucky and find some in a skip if a neighbour is getting plastic windows :-)

Owain

[Jason]

There's a thought - sash windows. There are a couple of local suppliers that do them. I'll check them out.

-- Jason

[Jason]

£1500, with £1000 deferred, or £3000 now, with £1500 cash-back deferred. I'll investigate.

-- JJ

[Jason]

Which brings us full circle to the original point of my enquiry: replacing uncontrolled leaks with a controlled heat-recovered forced air flow. The point is, unless I sort out the uncontrolled leaks, then the forced air is moot.

I am very keen on trying to save energy and money in the long run, without having to move house.

-- Jason

[Owain]

Somewhere like Jeld-Wen would probably be cheaper than 'specialist heritage window' companies.

bit more upmarket site has some useful information, eg British Woodworking Federation site has a find-a-supplier function

[Dave Liquorice]

You can get plastic sash windows but we decided against them as the sliding joints would be tricky to get suffciently storm proof(*). Probably alright in a less exposed position.

(*) It does regulary blow a real gale up here and sustained winds of 40mph gusting low 60's don't half drive the rain through the tiniest hole and when that rain is cominmg down like someone throwing buckets of water at the windows every couple of seconds you need good seals to keep it out.