Air source heat pump

[joegina]

Are they any good? The blurb always looks good, but has anyone used this type of system. If so, what are the pitfalls/benefits? I have an oil fired system now. Can I run both side by side, perhaps using the oil to back up/top up the heat pump? Questions for the salesman, I know, but I don't like talking to them without some knowledge!

[Clanad]

Your climate should provide an ideal situation for an air to air heat pump.

Here in the western U.S., where we live we've had heat pumps for a number of years. They preformwell down to about 20 degrees F, but temps lower than that require a back up heat. The newer technologies, especially the variable speed motors and scroll compressors make them an excellent choice.

We have an unusual situation here. If one elects to go with an all electric home, then a significant discount on all electricity consumption can be obtained if one also installs a back up heat source. We use propane. The electric company,through signals transmitted through the electric grid system has the ability to switch our system to the back-up heat source if high demands require it. Ours rarely runs. We also have an electric furnace to supply heat when the temperatures drop below 20 degrees F and the heat pump automatically cuts out.

Nice thing is, of course, it also provides centra l air conditioning in the summer.

It's considered an energy savings upgrade here and a significant tax rebate is supplied by the Federal Government on the purchase...

Best of luck!

[buildersmate]

I know very little about them but can recommend the Green Building Forum website as a good source of independent info and debate on these newer types of technology. As Clanad so adequately proves from the US, we are behind the curve on many of these technologies.
http://www.greenbuildingforum.co.uk/forum/inde x2.php?DATEIN=tpc_whqvqgitt_1149287153

[pug100]

Hi, having watched many programmes featuring these as well as ground source devices I came to the conclusion not for me. This was purely based on setup and running costs. For a 3 bed semi you're looking at around �15k - �20k install for ground source (compare to 1.5 to 3k for a gas boiler). Then you need electricity to run the system as it works in a similar fashion to a refigerator but in reverse. There is a coefficient of performance (how much power you need to put in to get useable heat out) most quote around 3 to 4 (to get 3kW of heat energy you use 1kW of electricity) . So you do get something for nothing but a lot also depends on location age of property and insulation levels.
I figured the system would take around 25 years to pay back the difference between it and a gas fired heating system, most of which was the initial setup cost rather than the running costs.In the UK these systems are still very new and imo still expensive to buy.
So in the end you will be saving the planet but it will cost you financially. These are some places I looked in my research.

http://www.ecoheatpumps.co.uk/ground_source_he at_pumps.htm

http://www.energysavingtrust.org.uk/generate_y our_own_energy/types_of_renewables/ground_sour ce_heat_pumps/

[buildersmate]

I think you are right, Pug, which is why I haven't bothered with them to date.
As the price of energy continues to rise (and it will) the cost-effectiveness and payback period of such systems will improve.
A few years ago we merely stuffed an old blanket in the loftspace to act as insulation.

[Clanad]

As a point of reference, our installation of a 5 ton capacity heat pump, which included a new air handler was about $6500 here in the U.S. It was a high efficiency (SEER and ASHP ratings) unit and, with the tax rebate for energy savings put the price, installed at about $5,800. Considering the exchange rate the price quoted in pounds in this thread seems awfully high, but perhaps it is what it is, no?
We're very happy with ours. Best of luck...

[pewe]

From my research so far, the figures quoted by pug100 seem very high - probably due to the high labour cost of digging out for the pipework.

I have had figures for the units only of between �1100 and �4000 for Air Source and �4000 and �6000 for Ground source - plus any installation costs. Installation of both can be done by a competent DIY'er with commissioning done by someone else to keep costs down.

The Air Source are slightly more expensive to run than Ground source, but the installation is not as involved (no digging) and can all be done by a competent DIY'er.

Cost, of course depends on the size of unit required (depending on house size and heating requirement), but for a 4 bedroom house we calculate we need a 10KW to 12KW unit to supply 40,000 btu, and have been quoted as little as �1200 to �3250 for that size unit.

Both systems can be connected to an existing radiator heating system (although underfloor heating is the most efficient solution) and run in parallel to other heat sources such as oil or gas fired boilers for use when needed.

Still investigating though, as I am also looking at ways to supply the power needed to drive it (eg Wind turbine).

[the-gas-man]

Re Air Source Heat Pumps - see www.icsheatpumps.co.uk
They offer free site surveys, technical information and advice. Also on Ground source Heat Pumps.