Air source heat pump heating issue

marconi said:

What I would suggest if you feel able and safe - is to do a quick wire change. Before you touch any wiring you must isolate all electricity and check afterwards it is dead - do know how to do that? The easiest way to isolate is switch off the home main switch/switches which is what I recommend you do.

What we are going to check is the operation of the 2 port Motorised Valve(2PMV) for the CH circuit and check that the water pump starts.

To do this we are going to disconnect the white wire at terminal 13 at the ASHP and label with tape or a marker pen or note the number on it so its purpose is not lost. Put its end in a connector block or WAGO and then move it of harm's way.

Now, remove the wire from terminal 10 and insert it into terminal 13 and tighten up.

Re-connect power.

Set the programmer to 'Constant HW' (or advance the switch on or press override for HW).

Next we need to create a demand for HW (yes HW) by running off from the HW tank or turning up the HW set temperature. The latter is the easiest and quickest but up to you how. Now go to the water pump and observe the green lights on it. When a HW demand is created does the water pump start? If it does, go and see of the ASHP starts - it may take a little while. If the ASHP starts wait a while and feel the radiators to see of they become warm. If the pump does not start, it may be the HW demand has not been signalled so run off some hot water to much reduce the tank water temperature. Unless a demand for HW is generated the test will not begin.

Turn the HW tank stat to its lowest set temperature, when the demand for HW ends, the water pump and ASHP should shut down.

That's the end of the test. So isolate electricity and return the white wires you removed to their original terminals.

I look forward to hearing the results. We are checking the external logic ' demand 2PMV(CH) opens and when opened start water pump', and the ASHP internal logic 'if circulant water flow detected and there is an >?? Celsius temperature difference between out and return then start ASHP'

I won't give any more explanation to avoid confusing you.

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marconi said:

Re#76 - Ok. Don't do what I asked in #75 if you agree with this statement:

'When ONLY CH selected on the programmer (HW constant off) the 2pMV(CH) opens and the water pump starts when I increase the room stat to 30C and stops when I turn the room stat to 5C.'

If you agree with this statement then I would like you instead to link terminals 11 and 12 with a short piece of wire having first isolated electricity. Then see if the ASHP will come on (and rads warm up) with only CH selected on the programmer by turning room stat up to 30C.

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marconi said:

Very good question - at the heat pump. I should have been much clearer :-(

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marconi said:

Ok. Isolate again and remove the link you just put in. Then switch on.

Re#71 and the image of the ASHP control panel. There is a red light for the 'Programmer live'.

Could you observe and report its state (lit, not lit) when at the programmer you select HW constant and then select HW off at the programmer. I suspect the ASHP is in permanent HW priority mode irrespective of the state of the HW select button.

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marconi said:

I think we are close to the problem. Once again isolate electricity and now remove the white wire from terminal 14 at the ASHP and put a connector on its end to make safe. Turn power back on and check if CH demand starts ASHP.

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marconi said:

Ok. One last thing for now - maybe something else later.

Turn off electricity. Go to ASHP. Identify relays R2 and R3. Take a photo of where they are located.

Now see if they are plug-in relays. Perhaps try a more convenient relay first to see if when you gently pull it becomes unplugged.

TAke out R2 and take some photos of it including the pins, and observe the position of the contacts if you can see them; then give it a gentle tap to see if it is stuck and observe whether the contacts have moved. Replace the relay R2.

Then do same for R3.

Re-energise and check CH and ASHP starts.

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marconi said:

Ok, last for now as I go to think some more. I have been re-reading your posts and picked up in #1 you said (-sorry missed it before) you had disabled the defrost module - is it still disabled so that everything tried so far has been with it disabled?

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marconi said:

I recommend you take a break now. But before, how actually did you disable the DF module?

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