Heat Pump New Build

maysville

New Build Heat Pump
We're starting a new build next week
Originally we had planned on solar panels, condenser boiler, a back boiler stove, and rads throughout the house.
But are now looking into air to water heat pump with underfloor heating on the ground and first floor and rads in the converted attic space (2 bedrooms, a landing and a shower room)
The specs are, 405m2 (excluding converted attic).
The floors are insualted to 140mm.
The attic is insulated to 300mm
The external wall construction is as follows block 100mm with 150mm pumped bead cavity and block on flat on inside which is 225mm. There is no insulated board on the inside as we don't want to have plaster board walls.
There is thermal bridging around the windows and doors with insulated galvanised lentils.
The house will be air tight. Our windows are timber sliding sash, double glazed and argon filled with a U value of 1.0 W/m2K.

Our Engineer has given us a proposed BER of B1 based on the above specs.

In recent weeks we have been looking into air to water heat pumps and also GSHP. I would love any advice that anyone has on these. If we were to go down the heat pump route we would be doing UFH, no solar panels and no back boiler on the stove.

The main reason we want to go down the heat pump route is to reduce the cost of heating the house.

The more I read about them the more confused I get. It looks at the moment like the GSHP is too cost prohibitive for us the the only real option is the air to water heat pump.

The concerns I have are as follows
* The humidity in Ireland causing the pump to ice up and the energy cost of deicing the pump.
* High electricity costs
* Will the initial increased installation cost of the heat pump and UFH combined with the electricity bill actually make a real saving versus a condenser oil burner and oil.
* life span of the unit.
* Due to the size of the heat pump we need we have read that we would require 3 phase electricity. We are building in a very rural area, miles away from any town and are unsure if 3 phase electricity is even available to us. If it were available to us, the instillation cost to ESB is more at the time but how much would you save in running costs with 3 phase electricity?

Any advice is much appreciated

mvrce

hi i am looking into the same as i plan to build
i have been tokd geothermal is high on electricity slow to regulate and the most important factor if it breaks down not a huge choice of people to repair as its such a specialised system please keep me posted on what you decide also have you considered trille glazed windows?

nudedragon

how ya going with this?? would be interested to hear you thoughts now??

Duffman1

Hi I'm in a similar situation as yourself, I would be very interested in learning what options you went for in the end.

sky6

Hi Maysville, There's not enough insulation in the attic as the new regs are for a minimum of 400mm from March I believe.
You mentioned your looking to save money on heating. Have you looked at making sure the house is airtight first. Then the best way to save on heating is to insulate, insulate and insulate some more.
I would go with with 62 mm Insulated boards at least on all Ceilings.

Geothermal sounds like heating for nothing but in reality is to expensive and the payback is way too long. Added to that the repairs are also expensive.

Solar is a must install as it's cheap, virtually trouble free once installed and has a short payback time.

Open fires, Stoves and Back Boilers are nice but can be dirty, require a constant supply of fuels. They are not always practical for young couples either as there very often not home early enough to justify lighting it. Then you have the added problem of who cleans it in the morning, ready for the next evening.

That only leaves underfloor and Radiators. Underfloor heating although good is not everyone's cup of tea. For a start when it's on there's usually no escape when it's too hot, and you have to sit there melting until it cools.

Radiators have been around a long time and are well proven. Need I say more.
Relative to other heating methods there cheap to install and have a long lifespan.
I'd also recommend that you have two heat sources as there's nothing worse than sitting in a cold house when something doesn't work.
Even the electric goes off at times. Think of events with the weather in the last few Weeks.

Best of luck with your Build.