Hi Sam,

It would appear, that as I feared, your ASHP is poorly sited and is creating as batalto stated a 'cold well'.

Because the cold air coming out of your ASHP is more dense (heavier) than the warmer air above, it cannot escape and is pulled back into your ASHP and cooled even further. Hence the 12C difference in temperature around your ASHP with the ambient air temperature.

As a quick way to check the effect on your ASHP of having warm air going in rather than cold air, it may be possible to make a simple duct from strong cardboard, or similar, to funnel warm air from above your ASHP into the intake. Basically, you need to put cardboard on each side of your ASHP, from the ground to about 2 metres high. Tape it to the wall and the sides of your ASHP and tape over any leaks. Then put a third piece of cardboard above your ASHP up to the same height as the side pieces and tape the joints. Then put an old blanket or similar to stop air being sucked underneath your ASHP. If you are not certain what to do I can provide a sketch.

Obviously switch off your ASHP whilst you put the cardboard etc. in place.

If you now run your ASHP you should find that it is not working as hard as previously and the air temperature around your ASHP does not fall as low.

The optimum solution would be to re-site your ASHP to a more appropriate location.

I have recently installed an Air to Air ASHP at my home, and extended the pipework and electrics to position the outdoor unit at the desired location. Whether it is refrigerant pipework or water pipework it should be quite easy to extend within the maximum limit, which I believe is approximately 20 metres. You could even consider moving your ASHP some distance down your garden, though obviously this would require more work and hence be more expensive.

An alternative would be to mount your ASHP on a wall bracket so that it is above the fence height, though this would probably infringe on planning permission requirements.

I hope that this helps.

Regards,

Derek.

@derek-m

Thanks Derek,

Once we have sorted the sizing issue, I think the best thing to do would be to move it around the corner (did you see the images I uploaded?). This would only need a few metres of extension to the pipes. 

Kindest regards,

Sam.

Hi Sam - I don’t think “moving it round the corner” is a simple task. Because of the power cables (the easy bit) but mainly the insulated water pipes (the difficult bit) that allow the heat water to flow into your home with directly to radiators/UFH or via a hydro box or buffer tank. You’d need to get a competent ASHP engineer in to discuss. 
the chap who will be fitting my ASHP said south facing units can overheat in the summer and cut out. They need a north sited thermometer connected to know the real temperature. 
lovely property by the way

Hi JulianC/Sam,

I did not mean a DIY move around the corner, it would have to be carried out by a competent Engineer.

Since the installation of Sam's ASHP does not meet the specified requirements of at least 1 metre from the boundary fence, then it should be the builders responsibility to have it re-sited to an appropriate location.

Regards,

Derek.

@derek-m

Crikey! Don't worry about me attempting a DIY solution - changing a light bulb is about my limit. Good to hear you think it could be possible to do it though.

@derek-m, the rules for permitted development say that the ASHP needs to be 1m from the boundary. If Sam's house is a new build it would have had full planning permission, which could have included the ASHP being nearer the boundary.  The builder definitely has a case to answer for the poor siting but it might not be a planning one.  Is distance from boundary also specified as part of buildings regulations or MCS? 

Hi Kev,

If I am understanding you correctly, to use permitted development to avoid the need for planning permission, you cannot install the ASHP closer than 1 metre from the boundary, but if you get planning permission you can stick it wherever you like!!!

I suppose that sounds about right for the modern world in which we now live.

@derek-m, planning departments, processes and decisions make my head ache.

@derek-m, theoretically yes, but I don't know if planning permission for an ASHP closer than 1m would be given or if there is anything else (building regs, MCS guidance) that might influence ASHP placement.  

Hi all,

I just checked my current boiler (Ideal Vogue Max 32kW) and I checked the efficiency level which is an option in the menu. Its down at 58%! which is a real kicker considering its quite new. However this has totally changed my ASHP calculations as currently I am wasting 42% of my gas costs.

My gas use for the last 12 months was 34,600kW but with the efficiency calculations I actually only needed to use 20,000kW if the boiler was being efficient. I imagine it wasn't set up well when it was installed and I didn't really play with the settings. If I can get a COP of 2.7-3.0 in the winter I should reduce my current gas bill even without changing my electricity tariff.

I'd advise anyone looking at an ASHP to first consider how efficient their current boiler actually is!!!

@batalto, that's super interesting. I didn't realise that gas boilers were able to monitor this. 

58% is crazy, which certainly paints a far more favourable picture for things like heat pumps.

I totally forgot the boiler had the feature. I was told when it was put in that it should be 90% efficient. But I can just tap a button to see. To be honest it makes sense as the figure after efficiency matches up with the heat pump calculation I was given when they went room by room to work out my heating and loss demands. 

Clearly the boiler is configured wrong or just isn't as good as stated. I imagine it's the former. I'm keeping it anyway as a backup heating system in case something ever goes wrong. But worth considering when your ASHP calculations