Mechanical Heat Recovery Ventilation experiences

Has anyone installed one of these MHRV systems in their new build ?

If so, can you comment on your experiences in terms of
- cost
- complexity
- efficiency
- reliability
etc

We have HRV in our block-built house.

Installed by Proair of Galway. Very professional and thorough job, highly recommended.

Cost was c. 8k, but we have two units due to the size of the house.

Been in constant operation since October, no issues so far.

Complexity? Turn it on and leave it. When you have a shower/bath press boost. That's it.

In terms of efficiency, our gas bill for Nov/Dec was €111 for heating and hot water for a 450m2 house (with a recess woodbox fire for point heat on occasion). This is less than for the equivalent period last year in a poorly-detailed 3bed estate semi a quarter the size so that shows the benefit of good insulation and detailing and MHRV.

SSE

Hi Birroc,
I DIY installed a unit from MTD-Solutions back in November in our 70's bungalow so not a new build. But here are my thoughts to date.

- I went for this unit mainly because it only consumes about 20w in normal state (it ramps up when showering etc) and the company were very DIY friendly.
- House is much drier now, no condensation on inside of windows in the morning or in the bathroom when showering. The general dampness that we used to experience when we moved in a few years ago has (so far) gone.
- One feels much fresher in the morning when waking up
- Spiders are no longer in evidence around the house (in case that's important)
- Feels strange not opening the windows anymore
- very happy drying clothes in UT now as moisture is extracted.
- One might miss the hum from the old extractor fans in bathrooms (we don't)
- In our installation a very slight hum can be heard in bed late at night from the air coming out of the vent, but I need to follow up on this as it may be something to do with the way I ran the ducting.
- Total cost came to just over 5.5K and that included all the insulated ducting, vents, clips, tape etc. I believe I could have got it installed for another 500euro not including making the 2 x 6" holes in the wall.
It's very easy to operate, just plug it in and it also came with a remote which enables you to select low, medium or high speeds should you need it from time to time. We leave ours on Auto.
- There is a small maintenance job that must be done from time to time and that is to vacuum the filters
- Initially I thought it was chilling our bedroom but a check with a thermometer showed that this was not the case.

All in all I'm very pleased with the outcome so far.
I know some units allow you to add a little heat which seems like a good idea but I was determined to keep the power usage to a minimum.
That's all I can think of at the moment.

Rgds
Fran
ps I've no connection with this company

Thanks All. Sounds good.

Does all the internal ducting and piping make it difficult to install ?
I am building a 2 storey and I will have hollowcore ceilings so I am wondering where all pipes will go?

We have just built with hollowcore floor and the ducting is all in the ceiling - we put a suspended ceiling (100mm I think) the pipes are square-ish. We got ours from Proair too......not in the house yet but am preparing to be impressed!

Xsue said:

We have just built with hollowcore floor and the ducting is all in the ceiling - we put a suspended ceiling (100mm I think) the pipes are square-ish. We got ours from Proair too......not in the house yet but am preparing to be impressed!

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You put the pipes in the ceiling of the 1st floor ? Where did you put the pipes for the ground floor ?

Birroc said:

You put the pipes in the ceiling of the 1st floor ? Where did you put the pipes for the ground floor ?

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I think you miss understood the answer you got. You have to batten underneath the hollowcore in order to attach the groundfloor ceiling. You run the ducting in the cavity created. You of course have to leave enough of a cavity to suit the specific ducting size. Some companies use a box ducting which is about 2.5 inches deep i.e. a 3inch cavity would be plenty.

Hope this helps.

What is the return on putting in a MHRV system? 5 to 8 thousand is a lot of money, what is the saving per year and for how many years before you are looking at paying for maintenance/repair/replacement?

Hen

Difficult to say what the return is, you're right they are expensive.

However you must have ventilation and the only real alternatives are a) passive stack (no personal experience), b) trickle vents on the windows c) wall vents.

b) and c) are basically the same as having holes in your walls.

MHRV enables you to make your house airtight and very well insulated (as much as possible) and this is where you make savings - you only have to heat a house by the amount of heat you lose. They also provide vapour control for bathrooms etc. and, an unforeseen benefit we are very glad of now, mean that you're not plagued quite as much by flies!

Many high-spec. houses now are including HRV so there are also resale benefits to consider. I'd say these units will be fairly ubiquitous before long.

In terms of maintenance the units themselves aren't too stressed so they should be longlasting and you need to replace/clean filters but I'm not sure there's much else to do.

SSE

Was thinking of putting in the ducting now when i'm building and later on put in the unit itself when i can afford it or when it becomes more economical.

Can you buy the ducting from building providers or must you get it off the companies that supply these units and is it expensive ie euro/meter?

johhnnyg,

the option of putting in the ducting and when you can afford it - 2/3 years ?? is a postively bad one. under the building regulations houses ate required to be permantly ventilated. we've all see duncan stuart in the adverts on tv - regarding blocked vents etc. lets say you install the ducting with no hrv unit, then you light the fire, say for instance a closed gas fire, if there is a leak in the flue you and your family could be enhaling deadly toxic fumes and not even realise it.

my advice, put it in now. its far more effectve than any other forms of ventialtion. but don t do half now and half later

I will have ventilation in the form of trickle vents, unfortunatey our budget is stretched as we have gone with geo/UFH.

weigh up the cost of adding trickle vents to your windows, versus installing the hrv, one company i've dealt wth [not involved in company]] are mtd-solutions.com, they have a hrv with 97% heat recovery. fair enough money is tight but you and your partner/wife will hopefullly only build a family home once. so perhaps cut back on the quality of the wallpaper items of the house, and put the money into the bones of the house now. perhaps don't finish out one of your bedrooms for a couple of years

johnnyg said:

I will have ventilation in the form of trickle vents, unfortunatey our budget is stretched as we have gone with geo/UFH.

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How would you intend sealing those trickle vents down the line when you are ready to install the HRV unit? I've never seen a trickle vent that was anything close to airtight when closed.

the ones i have seen are airtight when closed, its only a thought as we hadn't planned to go with geo/ufh, we are taking the hit on that over HRV, so was thinking of putting in the ductwotk downstairs only just in case we ever go for it down the line...

We also got ours from Pro-air and are very happy with it. We were strapped for extra cash, but our geo-therm. guys recommended the MHRV as a way of making the whole system more efficient. No condensation is a great thing. Your house will be healthier overall. If anyone in your house suffers from hay-fever, special filters can be fitted to prevent irritants coming in from outside. And Franm is right about the spiders. They're just not there. Does anyone know why this is??

We also got ours from Pro-air and are very happy with it. We were strapped for extra cash, but our geo-therm. guys recommended the MHRV as a way of making the whole system more efficient. No condensation is a great thing. Your house will be healthier overall. If anyone in your house suffers from hay-fever, special filters can be fitted to prevent irritants coming in from outside. And Franm is right about the spiders. They're just not there. Does anyone know why this is??

For a house in the country that is only occupied at night during the week and at the weekends, is a MHRV system worth it? Spiders or slatters are not a concern, and the house is healthy even before damp proofing the floors.

pops said:

We also got ours from Pro-air and are very happy with it. We were strapped for extra cash, but our geo-therm. guys recommended the MHRV as a way of making the whole system more efficient. No condensation is a great thing. Your house will be healthier overall. If anyone in your house suffers from hay-fever, special filters can be fitted to prevent irritants coming in from outside. And Franm is right about the spiders. They're just not there. Does anyone know why this is??

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2 questions;

Is it noisy in any way?

Did anyone hear of this air tight membrane that should also be fitted on all outside walls to ensure air tightness and thus increase MHRV efficiency ?

Birroc said:

Did anyone hear of this air tight membrane that should also be fitted on all outside walls to ensure air tightness and thus increase MHRV efficiency ?

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It's mostly only used in timberframe houses to make them airtight. A plastered block wall is airtight as long as you plaster right down to the floor. You will need specialist airtightness tapes around the windows\doors etc.

www.ecologicalbuildingsystems.com supply the Proclima Intello system.

They also give very good (and free) advice on how to make any build type airtight.