Air to Water

rodge68

Hi Folks, this is my first time using I have only lately "found" boards.ie. I have just started building a 2500 sq foot house and was going to use an Air to Water system (a work colleague has one and is very happy) but after reading up on the subject here i am sceptical and thinking of going back to a condensor boiler and solar panels ?? I have 100mm insulation in the floors and the rear of the house is south facing. Any advice is most welcome

rodge68

Hi, I meant to call this post " Air to Water"
Going to the Self Build Expo in Galway at the Weekend so I should get some advice or else become more confused !!!!!!!!

muffler

rodge68 wrote: »

Hi, I meant to call this post " Air to Water"
Going to the Self Build Expo in Galway at the Weekend so I should get some advice or else become more confused !!!!!!!!

Do you want me to change the title of the thread to "Air to Water"?

rodge68

Hi, that would be great if you could do that !!:D

muffler

There you go. All done

mr_edge_to_you

Hi Rodge, welcome to boards! There is so much opinions here that you will constantly find yourself questioning every decision you think you've mad. We've been to hell and back in our decision to use ground source geothermal heating, eventually decided to go that route. We made a list ourselves as to why we felt it was the best choice for us. There comes a time when you've got to make the hard decision and run with it!! I've been dealing with a company in the midlands and they have been very helpful. Two friends have gotten their heating systems off them. In relation to your question the only downside is oil is a diminishing resource. Zoned heating with an oil condensing boiler are very common now. We've visited a load of houses in the last few weeks with the builders who quoted us, they've all gone with oil and solar panels and have really pushed the boat on insulation, along with stoves as backup.

sinnerboy

See if you can find your proposed heat pump as it performed in this series of lab tests

http://www.ntb.ch/3896.html

I don't speak German and so can't interpret the report to the full extent I would like to .

But a distinct relationship between COP and Delta T ( the temp difference between water before heated and after heated ) be clearly seen in seen these tables

COP - co efficient of performance COP 3 means - for every unit of power consumed by the heat pump you get 3 back

Heat pumps cope well with raising water to about 40 degrees max . Fine for underfloor heating , but not rads ( 70 degrees ) and not for your kitchen and bathroom hot water (60 degrees ) . When required to do this the COP drops - fast . This reality is most pronounced with air to water

Read some of those Swiss reports and see for yourself

.

yop

Thats it with regards to COP, the higher this is the better return on your system.

Air Sourced HeatPumps (ASHP) is the "worst" performer with regards this form of heating, Geothermal or Ground Sourced HeatPumps(GSHP) and the best is the bore hole. The option is also there to heat the water from a lake if you were near them.

Its a maze out there with regards to whats best, I went with GSHP and underfloor heating as what I have read is that GSHP and rads are not ideal!

Good luck with it.

Borzoi

sinnerboy wrote: »

http://www.ntb.ch/3896.html

Nice link, useful

sinnerboy wrote: »

Heat pumps cope well with raising water to about 40 degrees max . Fine for underfloor heating , but not rads ( 70 degrees ) and not for your kitchen and bathroom hot water (60 degrees ) . When required to do this the COP drops - fast . .

Very true

sinnerboy wrote: »

This reality is most pronounced with air to water

Absolutely untrue. The efficiency (and hence COP) of both ASHP and GSHP is determined (in the main) by 2 temperatures - the output water temp and the heat dump temp. If the output water temp is the same, then the only difference between the efficiency of the two types of heat pump will be the heat dump temperature - ie the ground temp for geothermal or the air temp for aerothermal.

For an Irish climate ASHP will work out to be about 20-30% more expensive to run than GSHP ( calculated using Copeland software) measure this against the extra cost of the ground works associated with Geo. It will take a looong time for GSHP to pay back the extra investment.

rodge68

Hi and thanks to you all for your replies. After visiting the Self Build show in Galway most of the exhibitors seem to say that a bore hole with the GSHP would be the best option, we are waiting on 3-4 quotes, but it does seem very expensive, one ball park figure was 30,000 euro !! The one thing they all did say was Insulate, Insulate Insulate !!

yop

If the quote is heading towards 30k then I would reconsider then and look at a passive house with some sort of venting system (this is an area I have not a clue about! sorry) but putting 30k into insulation and sealing the house & solar panels might have a better return