Geothermal- The way to go or not?

Condenser

Carlow52 wrote: »

How did you arrive at this conclusion.
You say the geo would cost u 800 pa to heat a 2900 sq foot house.
whats the capital cost, and expected life of ALL the gear?

I would guess 25 k and 5 years

If the Heatpump equipment is quality it will last 25yrs or longer. The UFH anywhere between 50 and 100yrs. The cheap air to water units available at the moment will last 7-10.

Condenser

The Lone Ranger wrote: »

Builder has just finished his own house, similar spec to ours but with oil condenser boiler. gone through 2 tanks already. He sayes oil is not a runner.

geo pump salesman said it would cost E800 pa to heat,(not me).

quote from that guy : 12k (pump and 300l water tank)

hope it would last longer than 5 years!

With the right system you'll heat it for less than €800

The Lone Ranger

Condenser wrote: »

Can you give me the dimensions of the garden because it sounds perfect for a horizontal loop. A DX system will give you the best COP. As long as the collector bed is sized properly and you're not drawing too much energy from the area, putting it under the veg patch wouldn't be a problem.

dont know exactly, the site is .33 hcts, with the house and garage set in the middle, front garden being bigger than the rear. also a 64sqm percolation area in the rear.

Condenser

The Lone Ranger wrote: »

dont know exactly, the site is .33 hcts, with the house and garage set in the middle, front garden being bigger than the rear. also a 64sqm percolation area in the rear.

Thats a pretty decent size site. Why not put the collector in the front garden?

The Lone Ranger

Condenser wrote: »

Thats a pretty decent size site. Why not put the collector in the front garden?

Firstly, thanks for all the info. I thought (I could be wrong) that the pump would have to be very close to the collection area. I had planned to have it in the garage and pipe it into the house in a (no loss) insulated pipe. How would i get around that, if indeed it is a problem.

Condenser

Once they are not ridiculously far away it doesn't have a huge impact on performance. I would however consider siting the unit in the house as the unit will be quiet and even the highly insulated pipes lose heat.

nulabert

Its illegal for a start. You must recharge any groundwater withdrawn, back into the ground via a dumpwell

I wouldn't entirely agree with that statement. Its more that you would probably need a discharge licence under the Water Pollution Act 1977 as amended. You would probably have to apply to your local Authority for the licence. These licences have an annual charge so more expense.

bruschi

The Lone Ranger wrote: »

Yes, we are, but not sure which system yet. A heat pump seems to be our only option as oil would cost too much run and who knows how high the price of it will go.
Lots of conflicting info out there about geo, wish i could find someone it works ok for, then I would be more sure.

I have a geothermal system. also have MHRV installed. heating of the house is perfect, and house is pretty much air tight and well insulated. those were the first 2 priorities, and wanted to get away from oil based system. UFH is great balance of heat throughout a house, much prefer it to rads. needed an area of roughly 30m x 10m for the geo pipework, its about 10m away from the house, but had the area for it so there was no issues there. average costs seem to be around the mark quoted by someone there earlier in the thread, around 1600 or so per year.

fclauson

the price for running any of these systems must be based on how much heat is leaking out of the house - regardless of the systems used - if insulated right it will use very little heat input to maintain the right temp

• with oil - its cheap to install but then you are open to oil price changes
• with GSHP - its expensive to install but the argument is that its cheaper over the life of the system to run (althought electricicty is not cheap nor green)

look at http://www.seai.ie/Publications/Statistics_Publications/Fuel_Cost_Comparison/

if you can get your heat demand low - then the above becomes a bit academic - happy to help with a simple PHPP type calculation - this will give you the demand which if you insulate right should be about 10W/M2/Annum (most heat engineers work on a figure of 20 or 30)

In order of importance
a) design the house you want
b) get good wall/floor/roof make up to get a reasonable U value
c) eliminate as much cold bridging as possible
d) put in good windows - balance price vs value - tripe glaze would be my recommendation
e) make the whole house as airtight as possible (more heat can be lost due to poor air tightness than to a slightly worse off U value)
f) finally work out how you want to heat it

Francis

fclauson

The Lone Ranger wrote: »

Builder has just finished his own house, similar spec to ours but with oil condenser boiler. gone through 2 tanks already. He sayes oil is not a runner.

Just see the above - may I hazard a guess that its either not insulated right or its not airtight right :mad: read my note above - a house heat demand is simple to work out - but the house has to be built right to perform right