Air to water system- New build

Mono2017

Hi Guys.
I was hoping for some assistance here.
We aim to build a 3200 sq ft house commencing in January.

The house will have floor to ceiling windows and doors in the main area (open plan)
House will be insulated to part L standard and be tested for air tightness.

My concern is that an air to water system consisting of under floor heating on both first and second floor along with a heat recovery system is costing circa 27-35k. And this may not be utilised based on heat generated and retained by Windows.

If you can offer any info around this that would be really appreciated.

Wearb

Are you concerned that it may not be utilized?

Mono2017

Wearb wrote: »

Are you concerned that it may not be utilized?

Hi. Yes this is my main concern while secondly looking at the expense versus a normal system

Wearb

My son is almost finished a similar build. We talked a lot about it. There is a very long payback time, but conventional heating sources will cost close to 30% less (very rough estimate) He has solar PV and hopes that it's surplus may produce credits in the future. It depends on power companies paying for such feed in in the future.

He also installed 2 wood burning dry stoves to act as an extra boost or standalone heat at the turn of the year, or just for aesthetics.

Tough decisions, but for what it's worth, that's what he's done.

Rabbo

The MHRV and the air-to-water heatpump are doing two completely different jobs.

Firstly, you have to generate a certain amount of renewables for the house to comply with Part L. If you don't go for a heatpump, you will probably have to install solar, either PV or hot water. You will find that there's not much difference between the oil/gas + solar setup VS heatpump. I'd opt for the heatpump every time- you don't have to deal with buying LPG/oil afterwards, its cleaner, easier to manage and you are not as susceptible to variations in fossil fuel costs.

In relation to the MHRV, your house has to reach a certain level of air-tightness to comply with building regs. You house also has to provide a certain amount of ventilation. You can achieve this by either punching 4" holes through your expensive air-tightness barrier or by installing a MHRV or DCV system. If you decide to install traditional ventilation, it will have a negative impact on your energy rating which will have to be counteracted elsewhere. In my mind it is madness to spend money on airtightness and then to punch big holes through your structure. MHRV/DCV is an absolute no brainer for a modern, efficient and comfortable house.

New houses are costing more money with all this new technology but you are getting an infinitely better product than you would have got 15-20 years ago

B-D-P--

Underfloor heating (UFH) is in my opinion far better than older methods such as rads, as your not loosing wall space and you have a nice even heat, not warm on one side of a room and cool the other.

For UFH to work, it needs a constant feed, eg oil for 20 mins doesnt work with UFH.
A2W is a constant low heat to the pipes, this makes the whole system work better.

In my opinion, If you going to the big expense of all them windows, and that size a house, dont skimp on the heating. Thats what makes your living area so comfortable to be in, to come home, strip down to 1 or 2 layers and still be warm.

As for heat recovery, I wont even comment, the more research you do there the more you'll see you cant logically build without it. Its a fools option to use holes in the walls for vents.

hero25

Mono2017 wrote: »

Hi Guys.
I was hoping for some assistance here.
We aim to build a 3200 sq ft house commencing in January.

The house will have floor to ceiling windows and doors in the main area (open plan)
House will be insulated to part L standard and be tested for air tightness.

My concern is that an air to water system consisting of under floor heating on both first and second floor along with a heat recovery system is costing circa 27-35k. And this may not be utilised based on heat generated and retained by Windows.

If you can offer any info around this that would be really appreciated.

we recently completed a 3200 sq ft house, so if i can help by giving my experience....
we have A2W with UFH on both first and 2nd floor.
we also have MHRV and an air tight stove.
I found the whole heating discussion/options to be the most confusing part of the build and as per many other comments, each person or "expert" had a different opinion. In the end we went with above ...maybe we could have picked something better ;-)
anyway.... re non-utilisation of the UFH: the UFH will only be called as required, so while you may not need it for a number of Summer months, you will need it.
the A2W also gives you constant hot water - a huge plus in our house.
we also have a lot of South facing glazing and while they can roast the place in the Summer, and heat the place even in winter sun, they also lose heat quicker than walls. they will not heat the house for you and those rooms are cooler in the Winter.
we've found the MVHR to be good, for clean air and even air temperatures around all the rooms...but i wouldn't be depending on an MVHR unit to heat the house. one thing we did find was huge variations in prices for MVHR ... seems to be down to the unit used, their weight etc ... e.g Audi vs Dacia. so I'd suggest some homework there.
our ESB costs for 12 months, i.e heating, lighting came to 2000euro. that's a family of 6 (3 ladies in there so a lot of hot water!). I'm sure it could be done a bit cheaper, but you have to live a bit also!

re costs, i'm in North Munster and the A2W with 11kw heat Pump is ~16k. MVHR was ~5k. Both excluding VAT.
hope this helps;)