Air to Water Heat Pumps

[ringi]

In most case they are not worth it if the building is connected to mains gas, or can cheaply be connected to mains gas.   

They come into their own compared to a oil boiler (oil prices change often).  Heap pumps hate being used as “on/off” heating, so need the thermostat to be set, and the heating to be left running all day to get best results.    They also don’t like outputing hot water, and would much rather be outputting warm water – this required UFH or very large radiators and a well insulated building.

[corium]

I can't talk about but note the following from the Energy Saving Trust website:

"Air source heat pumps are usually easier to install than ground source as they don't need any trenches or drilling, but they are often less efficient than ground source heat pumps. Water source heat pumps can be used to provide heating in homes near to rivers, streams and lakes"

I do know someone who installed a ground source heat pump  (in Kent not up here) as part of a new build attached to a huge plot of land so lots of space for the requisite pipework & they were v disappointed with the results. Though as advised they had factored in some additional heating for use at the coldest times they found the heat pump alone never got the house warm enough when needed, even in early autumn, and the suggested additional back ups were as a result, inadequate and they then had to install additional heat sources. They were not looking for tropical conditions just a moderately warm house. I know they would never take this approach again as it will end up costing them money, not saving it as they had hoped.

[Howard]

I guess you mean an Air Source Heat Pump. I have a friend in Scotland who installed one and he believes it has saved him about 30% off his heating bill. Here's a clip of a message he sent me when I asked him when I was thinking about installing one. Some things to consider:

• Do you have somewhere to put it? You need a place outside the property where a unit can be fitted to a wall or placed on the ground. It will need plenty of space around it to get a good flow of air. A sunny wall is ideal.
• Is the building well insulated? Since air source heat pumps work best when producing heat at a lower temperature than traditional boilers, it's essential that your property is insulated and draught-proofed well for the heating system to be effective.
• What fuel will you be replacing? The system will pay for itself much more quickly if it's replacing an electricity or coal heating system. Heat pumps may not be the best option for homes already using mains gas.
• What type of heating system will you use? Air source heat pumps generally perform better with underfloor heating systems or warm air heating than with radiator-based systems because of the lower water temperatures required.

Hope this helps. In the end I didn't go for it for several reasons; I live in a a drafty old brick-built Victorian terrace with high ceilings, heated by gas and not much space to put the unit. It just wouldn't have worked for me.

[wheels]

I wonder has anyone had one of the above installed or if anyone has any knowledge of them?

Many thanks