ground source vs air souce for new build

[Exfarmer]

have a chat with @Chris F on this - he has done loads of research for a new build he's planning

I think he reckons air source

I have an ASHP and would never recomend it if there is any alternative. It is fine all summer but a block of ice as soon as autumn comes. Mine does not have an immersion heater that most have to cope with winter weather . but that is not the idea as I understand it.
i have been challenged on this many times here, but nobody has taken up my challenge to replace my ASHP with their product , I will pay for it provided they give me a cast iron guarantee that their product will perform!

 

[Hfd Cattle]

What was the cost and the time of projected payback on this system??

I've been looking at a similar setup here for 2-3 years, but have not been able to get it to stack up yet...

Cost was about £30,000 but we get payback of about £1650 a year on the heating and the solar but we have no water bill , virtually no electric bill no heating bill but we have a lovely warm house and very hot water . Pay back is measured more in what you don't spend than what you get back .

 

[steveR]

Cost was about £30,000 but we get payback of about £1650 a year on the heating and the solar but we have no water bill , virtually no electric bill no heating bill but we have a lovely warm house and very hot water . Pay back is measured more in what you don't spend than what you get back .

Sorry, I was meaning more on the cost and the projected payback of the Battery storage aspect?

I have a large GSHP and PV here in a refurb build, so understand totally the lure of ample warmth and hot water Still paying leccy bills though... :-(

 

[Hfd Cattle]

Sorry, I was meaning more on the cost and the projected payback of the Battery storage aspect?

I have a large GSHP and PV here in a refurb build, so understand totally the lure of ample warmth and hot water Still paying leccy bills though... :-(

It's a job to quantify it as it was an all in package

 

[steveR]

It's a job to quantify it as it was an all in package

Aha. It is difficult to separate out such costing as I know here...

 

[Donaldgray1112]

I think ground source is more important for plants rather than air.

 

[steveR]

I think ground source is more important for plants rather than air.

?

 

[Hfd Cattle]

I think ground source is more important for plants rather than air.

Explain please !

 

[Hfd Cattle]

Aha. It is difficult to separate out such costing as I know here...

What I would say is the battery back up means we only use mains electric in the depth of winter when the nights are long and dark .... we never know when the system changes from battery power to mains it just happens !

 

[steveR]

What I would say is the battery back up means we only use mains electric in the depth of winter when the nights are long and dark .... we never know when the system changes from battery power to mains it just happens !

Bit like the diverter we are using on the PV. It all just works... As good tech should do

 

[steveR]

Explain please !

 

[The Stig]

We are considering a gshp on a barn conversion. Does the paperwork andHeat exchanger etc take up much room internally?

 

[Mur Huwcun]

We are considering a gshp on a barn conversion. Does the paperwork andHeat exchanger etc take up much room internally?

Your heat pump will be the size of a tall larder fridge plus a buffer tank somewhere and you will need wall space for pipes and two or three pressure vessel. You will also need a thermal store for your hot water somewhere in the house, ideally as close as possible to bathroom and kitchen sink.

Our heat pump, pipework, connections from outside loops etc are all in a small lean-to about 8x5 foot built on the gable end of the house. We also have our water treatment and booster pump there aswell as were on a private supply. Lean-to is insulated with 150mm kingspan all around and all pipes are lagged. The buffer tank is in a cupboard in the utility room though as you’re bound to get sone heat loss and the thermal store is in a fitted wardrobe in a bedroom directly above kitchen sink and 12” away from main bathroom. Hot water then does not need to travel.

Only photo I could find of the ‘boiler house’!!!

EDIT, found some more
here’s the lean to in the snow!! No issues with beast from the east or -8 degree apart from the 32 hours power cut!!

some of the trenches and manifold chamber

the manifold when they were welding the pipes on, two pair of loops fitted in photo with the 20m insulated pair running back to the house. The first three to four meters of the pipes were then insulated as they are close together before they split to their own trenches. The water actually helps as water maintains a steady temperature. We have actually had to dig a drain from the manifold down the side of the yard afterwards as that patch started to develop into a bog with all the water that was finding its way down from the field in the disturbed soil in the trenches.

 

[steveR]

We are considering a gshp on a barn conversion. Does the paperwork andHeat exchanger etc take up much room internally?

Paperwork is no room at really

Pipework on the other hand will take up the room required and will be sized to suit the calculated requirments of your conversion. I think experience has shown that squeezing ground loops is not a good thing, but again a good engineer will advise you of this.

The heat exchanger and associated gubbins needs room with thing like buffer tank and DHW tank*, and based on my personal experience and of a couple of other local installs, if you can put the plant room outside of the house itself, that is a sensible option. That way, you can allow a bit more room for access and maintenance. And it WILL need maintenance and repairs!!

*Oversize the DHW tank as it allows it to be used as an energy store for solar heating from solar thermal or a PV system usin an immersion coil, some installs dont use a buffer tank, but my understanding (limited!!) is that they are a useful inclusion for many setups.

 

[steveR]

Your heat pump will be the size of a tall larder fridge plus a buffer tank somewhere and you will need wall space for pipes and two or three pressure vessel. You will also need a thermal store for your hot water somewhere in the house, ideally as close as possible to bathroom and kitchen sink.

On advice, I kept my 300l (too small) thermal store in the plant room 3-4m from the house and I have used a pumped system to provide instant hot water to the taps as found in hotels and the like. As we had 2, yes TWO storage tanks leak after a bad batch left the factory, that was a good call.

Just measured the space in the plant room actually taken up across one wall, and it is approx 2.5m x 1.5m with the pipework all mounted on a wall behind the big plant. I can gain access to most everything which is IMO a positive thing for service and maintenance. Also got a small electrical control panel in the plant room for the PV system.

Insulated pipework comes underground into the house and goes into the main control manifolds. Needs a "cupboard" 1m x 2m, again, some room about it is very useful, If your plant room is essentially in the house, then the manifolds can be housed next to the HP and gubbins

 

[Speedstar]

That sounds very far fetched!, our ground source heating has only really kicked in this month, and usually is running very lightly by April again so is only drawing heat for 8 hrs a day for 6 months of the year at the most. I thought ground source actually drew most of its heat requirements from the moisture in the ground and as this is constantly moving thru the ground and as such doesn't really hav an effect on the long term ground temps.
In the summertime our pump can actually run reverse and draw heat out of the house and disapates in back into the ground!

What have you had to do to make it cool the house in summer time ?

 

[Dave645]

What have you had to do to make it cool the house in summer time ?

The heat pump it’s self, has to have that function from the factory, as far as I know.

 

[steveR]

@Mur Huwcun some grand pics there.

Looks some reasoanble soil there, I had to put some sand around my ground loop pipework which was a PITA as it is really heavy clay

 

[MikeNeaverson]

We are currently on second fix in our new house. We inherited a prepayment meter which has been fine for the build but now need to change it for when the air source starts up properly.

Is there a cleverer way to run airsource? We are underfloor heating downstars and radiators upstairs. The house is built to modern building regs standards, at least 150mm insulation in the floor, cavity and roof. Would it be more efficient to have an economy 7 tarriff for example, and run the heat pump with generally cheaper electric? What have others found?

 

[Exfarmer]

Remember the heat pump will be less efficient at night, due to lower temperatures and the humidity higher so far more frosting and recycling.