heat revovery ventilation

proteus

I am currently renovating my 1950's era house. I'm getting the whole house insulated, dry-lined and new double-glazed windows throughout.

I was thinking of installing a heat recovery ventilation (HRV) system but have read that the house needs to be super air-tight to achieve any advantage.

Has anyone installed this equipment in an old house, did you have to make any major changes to achieve air-tightness?
I have heard the cost can be from €2000-€6000. Is there a cheaper (around €2000) provider in the Dublin area?

mylesmcd

Hi Proteus,
I've no advice to offer but I'm just about to sit down with an architect to spec out our renovation of a 1950's built semi-d that we plan to treat the same as you describe. Was wondering about HRV - any luck with your queries?

zippy 99

Try a heat exchanger maybe.

Be The Holy

Does anyone know if anywhere in Ireland provides individual heat recovery/ventialtion units for a typical cylindrical air vent? Theres an almighty gale blowin through it as well as the roar of boy racers, motorbikes, forty foots etc..

Capt'n Midnight

I've thought about having the air intake in the kitchen directed to the bottom of the back of the fridge. Would the cold air there make the fridge more efficient ?
It would heat the incoming air a bit anyway.

Anyone know how much heat a fridge gives off , compared to HRV reuse ?

carveone

Be The Holy wrote: »

Does anyone know if anywhere in Ireland provides individual heat recovery/ventialtion units for a typical cylindrical air vent? Theres an almighty gale blowin through it as well as the roar of boy racers, motorbikes, forty foots etc..

I think the problem here is the word "typical". Those things aren't typical in the other countries I lived (primarily Canada). I guess I don't get it. Still, if you imagine an air conditioning unit as an example of a heat exchanger, they aren't very small things and I'd guess the efficiency would go to hell as the size drops.

Anyway - the only thing I could think of was a damped shutter, driven by a fan (the fan blade part anyway). When the wind blows, the fan turns and closes the vent. The fan isn't spinning, you understand, the wind produces a turning moment which holds the (sprung) shutter closed. When the wind stops, the shutter slowly opens. This would provide ventilation without blowing papers around the room...

My product idea for the day

Conor.

PS: Most people are just shuttering the vents off, which isn't the best idea either. But people would rather be warm and have the option to open a window vent, rather than freezing and well-aired..

carveone

Capt'n Midnight wrote: »

I've thought about having the air intake in the kitchen directed to the bottom of the back of the fridge. Would the cold air there make the fridge more efficient ?
It would heat the incoming air a bit anyway.

Stop being sensible! This is Ireland, you're supposed to huddle in front of a SuperServ gas heater in your uninsulated, single glazed house!

Anyone know how much heat a fridge gives off , compared to HRV reuse ?

Newer fridges use about 300kWh/year so that's the amount of heat given off. That's not much help I guess but it works out to 24 W continuous. Not a lot but I guess it would heat the incoming air a small amount. If houses weren't designed by muppets you could use every scrap of spare heat in recovery units. Showers, driers, hell that's a lot of warm pee going to waste. I wonder about all the gas boilers too - all that hot, moist air being hurled out into the atmosphere. Great...

Capt'n Midnight

carveone wrote:

I wonder about all the gas boilers too - all that hot, moist air being hurled out into the atmosphere. Great...

condensing boilers have been mandatory in England for a while, so much of the heat could be recovered by them.

dhaslam

proteus wrote: »

I have heard the cost can be from €2000-€6000. Is there a cheaper (around €2000) provider in the Dublin area?

I am installing a system in a new house and the cost is about €7000. However the same unit can be purchased in the UK for about £1300. The fittings will cost about the same.

www.dealec.co.uk/acatalog/intervent_heat_recovery_systems.html

It is obviously going to be difficult to install in downstairs rooms in a two storey house., you need to be able to access the ceilings which might involve lifting floorboards. If you could skip rooms which are used less or are hard to reach, you would still get the benefit of better air flow. I wouldn't worry too much about air tightness in the main building structure but obviously outside air vents and gaps around doors and windows need to be sealed.

dhaslam

carveone wrote: »

Newer fridges use about 300kWh/year so that's the amount of heat given off. .

A fridge is a heat pump, just transferring heat from inside the fridge to outside. The heat produced is up to four times the power used. It should heat 1-2 sq metres of floor space in a well insulated house.

carveone

Capt'n Midnight wrote: »

condensing boilers have been mandatory in England for a while, so much of the heat could be recovered by them.

ah thanks. I wasn't aware they were mandatory in the UK. Since 2005 according to wikipedia. I guess they're bigger than the tiny boilers you see in apartments these days and maybe that's why they're not used (expense aside - the government could easily whack a tax rebate on them and that would solve that objection).

dhaslam wrote:

The heat produced is up to four times the power used.

Um.. 1st law of thermodynamics anyone?

On a humorous note - one hot hot summer in canada I saw a guy who'd bought an airconditioner and just plonked it in the centre of his living room. Good job dude. Yeah, it was cooler in front of the thing but... He didn't get it either - presumably it was just magic to him...

Conor.

holdfast

hello

if the house is not well sealed to a rate of less than 4 air changes dont bother. i dont think it would work in an old house. get the house air tightness tested and then see what works are required to imporve the air tightness. it may cost you a few pennies to get where you want to be. best of luck

Capt'n Midnight

carveone wrote:

Um.. 1st law of thermodynamics anyone?

The heat transfered by the heat pump between inside and outside is four times the electricty input to the pump.

Though for HRV it's usually a lot closer to two times or break even maybe. But like a dehumidifier you get more heat per unit of electricity than if it was a straight forward heater.

KMSL

proteus wrote: »

I am currently renovating my 1950's era house. I'm getting the whole house insulated, dry-lined and new double-glazed windows throughout.

I was thinking of installing a heat recovery ventilation (HRV) system but have read that the house needs to be super air-tight to achieve any advantage.

Has anyone installed this equipment in an old house, did you have to make any major changes to achieve air-tightness?
I have heard the cost can be from €2000-€6000. Is there a cheaper (around €2000) provider in the Dublin area?

Try getting info from a company in Galway called ProAir Systems Ltd

KMSL

KMSL wrote: »

Try getting info from a company in Galway called ProAir Systems Ltd

I have one of their systems, it works well.
I would suggest that you get one with a summer bypass otherwise the house could get too warm in the summer.