@s-watson, the initial issue that you'll experience with a central thermostat is that when the hallway gets to 19C, it'll switch the heat pump off. So if the living room, for example, is at 17C, it doesn't have the option to call for heat. This is something we tried to explain in our ASHP controls video:

It's all about experimenting and tweaking things as you go along. This is admittedly a tricky time to do this because the temperature changes can be quite drastic. 

But you're spot on - ASHPs are slow burners and it's better for them to generate heat slowly, all day, as opposed to 'spiking' on and off. 

As I said, it's all about experimentation so please share questions and your findings.

Hi George,

I now see why you are using a large amount of hot water.

Solar thermal would probably still be beneficial in your case, in that it would help reduce the load on your ASHP and hence reduce your electricity bills.

To heat 500L of water from 20C to 50C requires 17.5kW of energy (excluding any losses).

Because solar thermal panels are much more efficient than solar PV in capturing the free energy from the Sun, then you don't need as many them.

If a suitable site is available they can be mounted at ground level rather than on a roof, which has the added advantage that they can be on a frame allowing them to be tilted for the optimum angle to the Sun. On the shortest day in Winter the Sun only rises above the horizon by 13 degrees, whereas on the longest day it is at an inclination of 60 degrees.

Hi S. Watson,

A good analogy to heating your home would be driving a car. When you first set off the fuel usage will be quite high whilst you accelerate, but then once up to speed you would ease off the accelerator to the point were you are just maintaining the desired speed.

In Winter you are going up a hill, so using more fuel to maintain your speed.

In Summer you are going down hill, so ease off the accelerator.

If my memory serves me well, I believe the Ecodan has a climate setting, which automatically varies the water flow temperature to suit the weather condition. When the outside air temperature is lower the controller will increase the desired flow temperature and when the air temperature is warmer it will reduce the flow temperature. This should provide the most efficient way for your ASHP to operate.

Leaving your ASHP switched on does not mean it is operating continuously, it will only produce heat energy when it is requested by the heat demand in your home.

In terms of "tweaking" your system I've found that it's necessary to look at each individual room (we have underfloor heating upstairs and on the ground floor).

Our house is well insulated but part of the new build when we did the renovation, was the entrance hall. It is outside the main envelope of the building and because it's small has a high surface area to volume ratio. Like all the rooms in the house it has its own thermostat connected to the ASHP controller.

During the really cold weather in January it would never reach the 19 deg set on the thermostat. When the rest of the house was up to temperature it was still calling for heat and the ASHP was running. In the end I gave up and lowered the thermostat to 12 deg - not really warm enough but at least the ASHP then switched off.

Now its warmer I've set it back to 19 deg which it reaches easily. Although every room can have its own heating schedule I have all of them set to 19 deg 24/7. Typically the temperature settles at 1 deg above ie 20 deg, which we find comfortable.

@derek-m

I will look into this Derek. Appreciate the advice.

Scott 

@mike-patrick, that’s a sensible way to approach it. It’s inefficient heating the buffer and running the pump to get just one room to temperature. 

@derek-m

Hi Derek,

On a day when the outside temp read 22° on a thermometer I then did a temp reading by the pump. I didn't do it directly in front as it obviously blows out cold air and there's only 80cm before it hits the fence.

 I stood to the side in the courtyard area. The thermometer read 10°. Do you think this could be another reason the pump is working so hard/ noisily? Would it be worth changing the fencing panel to one with gaps to allow the air to escape?

When/if the legal battle regarding pump size is over and a larger unit is fitted I'm concerned this problem won't be sorted as the pump has nowhere to be easily resited.

@sam pretty sure I've been told that ASHP's need a lot of space to ensure they get a good flow of air around them. If its intaking air at 10 degrees you are losing a load of heat potential energy. Having the fence means the cold air is being reflected back and then into the side intakes on the pump. Its a "cold well"

@batalto

Would changing the fence panel to one with gaps in help?

I cannot see how it would hurt. I am surprised an installed recommended that space given how tight it is. Ours discounted the side of our house for that exact reason (a close fence panel). We've put it on the drive with several meters all round for air to flow

@sam, I'm with @batalto on this one. We have a fence around our pump (about 1m to the sides and behind, but the area where the fan is pointed is completely open to allow the cold air to be pushed out as far away from the pump as possible. If you  put gaps into the fence, that would allow more of the cold area to be pushed away. With a solid fence, there will be some cold air that "bounces" back towards the pump leading to cooler air around the evaporator which is what you want to avoid. So that may be a worthwhile exercise. Air flow is paramount.

@editor

 Frustratingly, these walls were the other options!!! The fitter admitted he didn't know what he was doing and so adhered to the irrelevant facing south rule regardless.

Does anyone know if it's possible to simply move the pump round the corner to the wall to the right of the bi-folds?