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Author Topic: ASHP on BBC You and Yours  (Read 12511 times)
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« Reply #45 on: December 03, 2013, 12:06:08 PM »

I downloaded the part in question from You and Yours - try and keep things complete for future reference:


My advice is based on me spending my money doing this and my job spending others money doing this.
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« Reply #46 on: December 03, 2013, 12:28:45 PM »

She seems like a lady who would order something in a restaurant and when it comes  wish she had ordered something else.

DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
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« Reply #47 on: December 03, 2013, 04:03:06 PM »

I have installed/had installed an ASHP this summer and my experiences may help answer some points which have arisen. The design service supplied by the bidders was variable and generally not very good. Basically I did the design myself and then asked for bids to install the pump.

I chose to install the ASHP to supply my radiators instead of the existing oil boiler. I chose not to heat domestic hot water as the higher delta t means the COP is less good and I am already pretty well served for domestic hot water by solar thermal and a log burning stove back boiler.

The existing radiators were over sized because the house is now well insulated but when I calculated the temperature needed it was still too high for good efficiency so I changed nearly all the radiators for ones with a larger surface.

I wanted a monoblock heat pump for space reasons and, as I understand it, this has to meet the heat demand of the house at the design temperature (-3.1C in our area) to qualify for RHI without using the back up immersion. I chose the Panasonic TCAP 9kW unit as this met the duty and is inverter driven. I installed a low loss header and rerouted the pipework to outside the walls. The certified installer installed the ASHP, local piping and electrics. Cost for my materials about 1000, the ASHP 5000. (awaiting 1300 grant).

The results so far are really good, the ASHP is controlled so that the water recirculates at 30C when the outside temperature is between 15 and 10C and rises to to 50C as the outside temperature falls to -10C. This maintains the house at our desired temperature of 17C and we have a log fire most evenings.

Subjectively, it is great because the low water temperature means that you don't get hot areas near the radiators and don't get wide swings of temperature as the radiators heat and cool. The boss thinks I've painted the temperature on the thermostat because it almost never changes except when the log burner pushes it up.

Our electricity consumption so far this winter is 309 kWh although this is not covering the full heating load because of the log burner.

It was never expected to make massive savings in term of CO2 emissions (with the current generating mix and grid losses) or save massively financially; but I believe it is a good and competitive option for the well insulated house if properly designed and operated.


Schuco solar hot water - 3300kWh/annum, 16 BP 4175N PV panels - 2.8kWp, log burner and back boiler and 18 Ying Li 235 PV panels - 4.2kWp, 42kW ground mount PV, 9kW Panasonic ASHP, 40kWh Nissan Leaf
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« Reply #48 on: December 03, 2013, 04:16:25 PM »

OK i guess i was wrong   genuflect

She probably missed out on the other insulation grants and hoping if she makes enough noise..

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