Heating System for new build (HP, UFH, Sealed Gas fire and HRV)

murphy31ie

Hi,
I am at just about to put the slabs down on the first floor of a new build (2500 sq foot), the decision on the heating system needs to be made. I am thinking/ have got a quote for, heat pump (Waterkotte 16kw), UFH throughout, a sealed glass three sided gas fire (balance flue, no vent needed) and HRV. The gas fire is the misses request, wants a focal point in the room, wants a flame etc. I am insulating the house well 150mm pumped cavity etc and trying to keep as airtight as possible, taping windows, eliminating cold bridges and will get airtightness test before plastering. Anyone any thoughts, all advise is welcome.
Thanks
Brendan

Tommyboy08

murphy31ie wrote: »

Hi,
I am at just about to put the slabs down on the first floor of a new build (2500 sq foot), the decision on the heating system needs to be made. I am thinking/ have got a quote for, heat pump (Waterkotte 16kw), UFH throughout, a sealed glass three sided gas fire (balance flue, no vent needed) and HRV. The gas fire is the misses request, wants a focal point in the room, wants a flame etc. I am insulating the house well 150mm pumped cavity etc and trying to keep as airtight as possible, taping windows, eliminating cold bridges and will get airtightness test before plastering. Anyone any thoughts, all advise is welcome.
Thanks
Brendan

In the honour of god who quoted you for a 16kw heat pump??????????!!!!!!!!!!!!!!
Again installers who haven't got a clue
My advise, get a quote from a reputable heat pump installation company, your looking at a unit closer to 6 kw than 16

Condenser

Tommyboy08 wrote: »

In the honour of god who quoted you for a 16kw heat pump??????????!!!!!!!!!!!!!!
Again installers who haven't got a clue
My advise, get a quote from a reputable heat pump installation company, your looking at a unit closer to 6 kw than 16

Exactly, unless the house is being built to 2002 regs I'd go get a quote from someone who knows what they're talking about

murphy31ie

Cheers for the reply's

Looks like I need to go back to the company regarding the pump size. The company I am using are going a long time. The house is being well insulated and airtight as possible.

Condenser

murphy31ie wrote: »

Cheers for the reply's

Looks like I need to go back to the company regarding the pump size. The company I am using are going a long time. The house is being well insulated and airtight as possible.

Doesn't matter how long they're going, if they can't size the heat pump correctly I'd fear for the rest of the installation. I'd spread my search if I were you.

Condenser

murphy31ie wrote: »

Cheers for the reply's

Looks like I need to go back to the company regarding the pump size. The company I am using are going a long time. The house is being well insulated and airtight as possible.

Doesn't matter how long they're going, if they can't size the heat pump correctly I'd fear for the rest of the installation. I'd spread my search if I were you.

gooseygander

My build is 2700sq with good degree of insulation and airtightness and I have been sized a 14kw heat pump, first I have heard of this been excessive, I presume it is better to be a tad bit oversized rather than undersized, I mean the running costs are the same no matter the size of the pump and the only cost difference in in the outlay to purchase pump at the start, am i right ????????

Condenser

gooseygander wrote: »

My build is 2700sq with good degree of insulation and airtightness and I have been sized a 14kw heat pump, first I have heard of this been excessive, I presume it is better to be a tad bit oversized rather than undersized, I mean the running costs are the same no matter the size of the pump and the only cost difference in in the outlay to purchase pump at the start, am i right ????????

No unless its an air to water which needs to be 30% oversized to account for efficiency losses in cold weather then your heat pump should be sized to meet the needs of the house. Not only will the heat pump be more expensive, it will short cycle frequently which isn't ideal for the longevity of the unit, it will be louder, need larger circulating pumps, larger collector beds, deeper bores, need more expensive parts in the case of a breakdown etc. The list goes on. Imo if an installer can't be bothered to size a system correctly on day one what makes you think that attitude would change throughout the course of the install or the back up required later. The warning signs are usually there from early on, its up to people to heed them or don't complain when the system ends up a dud. Being a couple of kw out is acceptable, being probably double as in the case above is alarm bells time. I'd wager yours is oversized too if working to the new regs.

gooseygander

hi Condenser you are correct, my system is an air to water heat pump, a diakin altherma 14kw heat pump, in view of this do you still think I am oversized ??

Condenser

gooseygander wrote: »

hi Condenser you are correct, my system is an air to water heat pump, a diakin altherma 14kw heat pump, in view of this do you still think I am oversized ??

Thats an invertor so it doesn't matter as much but its also not really 14kw. Its 14kw at air 7 when if you wanted to test it at the equivalent of the ground source you would need the air 2c figure (A2/W35). That probably makes it an 11kw/12kw unit in reality so its probably about right but without exact u-values I couldn't tell you with certainty. I would always err on the side of caution with air to water due to the efficiency losses they are prone to.