Air source heat pump heating issue

[Themorganator4]

yes that was right. Ho hum. Let us call it a day. I will PM you about a possible visit next weekend with a fellow EF member. Remember to put covers and screws back.....

Good night to you.

Thank you very much. Are you sure you don't want anything more than fuel money?

 

[Deleted account]

Thank you very much. Are you sure you don't want anything more than fuel money?

Give him his fuel money and bung Him a bit more and a bottle of his favourite plonk if it makes you feel better.

Marconi top bloke.

 

[marconi]

Yes just diesel. I and my EF colleague Wilko plan to visit next Sat if that is convenient - but we need to confirm with our wives first which we have not been able to do yet. We are helping you because it is a fascinating problem to us. Wilko has all the state-of-the-art digital test kit and skill to use it and I will bring along my trusty AVO8 and Skytronics digital multimeter and voltage indicator stick. Wilko will sort out the snake's wedding inside the JB and I will pass him his tools The only thing we both look forward to from you is real coffee please. Between us with have the wiring accessories which are looking for a good home. Any spares for the ASHP though would be for you to buy.

 

[Themorganator4]

Yes just diesel. I and my EF colleague Wilko plan to visit next Sat if that is convenient - but we need to confirm with our wives first which we have not been able to do yet. We are helping you because it is a fascinating problem to us. Wilko has all the state-of-the-art digital test kit and skill to use it and I will bring along my trusty AVO8 and Skytronics digital multimeter and voltage indicator stick. Wilko will sort out the snake's wedding inside the JB and I will pass him his tools The only thing we both look forward to from you is real coffee please. Between us with have the wiring accessories which are looking for a good home. Any spares for the ASHP though would be for you to buy.

Thank you so much for your help, i am unable to do next Saturday as I'm visiting the in laws. I can do sunday?

I may not be able to buy any spares there and then (depending on cost) but it would be nice to know what the problem is and what needs replacing if needed. I also have an espresso machine so can provide decent coffee hah

 

[marconi]

Here is some 'out loud' thinking of mine on the problem with your installation.

How the CH sub-system is meant to work. If the programmer 'allows' CH to run (ie: ON, advance, timed on), then if the room stat is closed on under set-temp, a signal is sent to the ASHP to 'Go CH'. The ASHP responds by sending a signal out to the 2PMC(CH) which opens. When the 2PMV(CH) has opened, its internal auxiliary switch closes which sends energisation to the water pump. ALL THIS HAPPENS. Note no signal generated yet to run the ASHP.

To begin with the circulating water through the CH circuit is warmed by the Buffer Tank Direct(BTD). The temperature of the BTD is monitored its own tank stat. When its volume of water has cooled such that it no longer can warm the water for the CH circuit, the stat closes and sends a signal to the ASHP to run - THIS DOES NOT HAPPEN. Once the radiators have warmed the room the room stat opens. This does not immediately stop the ASHP because the ASHP has further work to do to reheat the BTD. So this means the 'Go CH' signal is latched in the ASHP and only unlatched once the BTD's stat opens. If Go CH was not latched then ASHP would stop immediately preventing BTD from being reheated. In the logic state of (no space heating required and BTD heating required) the ASHP sends a signal to divert water flow to the spring loaded 3 port valve - valve 3 on page 22 of manual reference. BTD heats up until its state opens: then ASHP shuts down. There is now a ASHP next start delay initiated circa 3 minutes.

If there has been a HW demand, I think it too is latched and only cleared after the HW tank has been heated to temp and the BTD reheated too. This might explain why radiators are being warmed after there has been a HW demand.

So why no operation of the CH sub-system independently of the HW sub-system? When I did a test which removed the priority to HW which is set in the ASHP, - 2PMV(CH) opened and the water pump ran. Nothing else. This indicates that the signal from the BTD is not being generated. Examining the wiring diagram on page 22 of manual reference the source of 230V for this signal is taken from the output of the HW stat (on page 22 upper terminal block - terminal 21 is linked to 18 and 12). This creates the logic that a BTD heat demand from its stat to the ASHP to run can only be generated if HW stat closed(HW GO to ASHP). I suppose during the test the HW tank was at temp so no HW GO which would explain why ASHP did not start.

So if I am on the right lines the installers have followed faithfully the wiring diagram with an error as described on page 22 it would explain why the installation has a problem.

I have a query into Ideal Boilers because I reckon the wiring diagram page 22 has an error. The BTD stat line input should be taken from terminal 14 the input to the room stat.

 

[Themorganator4]

Here is some 'out loud' thinking of mine on the problem with your installation.

How the CH sub-system is meant to work. If the programmer 'allows' CH to run (ie: ON, advance, timed on), then if the room stat is closed on under set-temp, a signal is sent to the ASHP to 'Go CH'. The ASHP responds by sending a signal out to the 2PMC(CH) which opens. When the 2PMV(CH) has opened, its internal auxiliary switch closes which sends energisation to the water pump. ALL THIS HAPPENS. Note no signal generated yet to run the ASHP.

To begin with the circulating water through the CH circuit is warmed by the Buffer Tank Direct(BTD). The temperature of the BTD is monitored its own tank stat. When its volume of water has cooled such that it no longer can warm the water for the CH circuit, the stat closes and sends a signal to the ASHP to run - THIS DOES NOT HAPPEN. Once the radiators have warmed the room the room stat opens. This does not immediately stop the ASHP because the ASHP has further work to do to reheat the BTD. So this means the 'Go CH' signal is latched in the ASHP and only unlatched once the BTD's stat opens. If Go CH was not latched then ASHP would stop immediately preventing BTD from being reheated. In the logic state of (no space heating required and BTD heating required) the ASHP sends a signal to divert water flow to the spring loaded 3 port valve - valve 3 on page 22 of manual reference. BTD heats up until its state opens: then ASHP shuts down. There is now a ASHP next start delay initiated circa 3 minutes.

If there has been a HW demand, I think it too is latched and only cleared after the HW tank has been heated to temp and the BTD reheated too. This might explain why radiators are being warmed after there has been a HW demand.

So why no operation of the CH sub-system independently of the HW sub-system? When I did a test which removed the priority to HW which is set in the ASHP, - 2PMV(CH) opened and the water pump ran. Nothing else. This indicates that the signal from the BTD is not being generated. Examining the wiring diagram on page 22 of manual reference the source of 230V for this signal is taken from the output of the HW stat (on page 22 upper terminal block - terminal 21 is linked to 18 and 12). This creates the logic that a BTD heat demand from its stat to the ASHP to run can only be generated if HW stat closed(HW GO to ASHP). I suppose during the test the HW tank was at temp so no HW GO which would explain why ASHP did not start.

So if I am on the right lines the installers have followed faithfully the wiring diagram with an error as described on page 22 it would explain why the installation has a problem.

I have a query into Ideal Boilers because I reckon the wiring diagram page 22 has an error. The BTD stat line input should be taken from terminal 14 the input to the room stat.

That makes sense (as much as it can with my layman brain)

The HW works fine, rads only heat up if HW is on, ASHP is on and CH is on (on the programmer)

 

[DPG]

Full marks to Marconi for the work he's doing on this one. Especially if the wiring diagram does indeed have that error!

 

[Themorganator4]

Full marks to Marconi for the work he's doing on this one. Especially if the wiring diagram does indeed have that error!

It's much appreciated

 

[marconi]

I have technical queries in with Ideal and Dantherm(Calorex) the makers of the ASHP in which I question the correctness of the wiring diagram on page 22 - but I am 95% certain I am right that there is an error.

What I would like you to try before Wilko and I visit on Sunday (toa tbc) is to do a further test run if you have the time and inclination. Not a problem though if you cannot - I will do it when I visit on Sun.

First switch off power and check dead. Go to ASHP and gain access to the terminal block. Remove the white wire from TB15 and make safe in a connector.

Using a short length of wire make a link between TB15 and TB9.

Turn Room stat down to lowest setting.

At programmer select HW off and CH constant.

Switch on electricity. Wait 5 minutes. Nothing should have run up including the water pump.

Now turn Room stat up to full. Wait at least 6 minutes. Does the water pump start? Does the ASHP start? Do the rads get warm?

End of test. Switch off electricity.

Remove link wire and reconnect white wire to TB15. Replace covers and screws and reset room stat and programmer.

 

[Themorganator4]

I have technical queries in with Ideal and Dantherm(Calorex) the makers of the ASHP in which I question the correctness of the wiring diagram on page 22 - but I am 95% certain I am right that there is an error.

What I would like you to try before Wilko and I visit on Sunday (toa tbc) is to do a further test run if you have the time and inclination. Not a problem though if you cannot - I will do it when I visit on Sun.

First switch off power and check dead. Go to ASHP and gain access to the terminal block. Remove the white wire from TB15 and make safe in a connector.

Using a short length of wire make a link between TB15 and TB9.

Turn Room stat down to lowest setting.

At programmer select HW off and CH constant.

Switch on electricity. Wait 5 minutes. Nothing should have run up including the water pump.

Now turn Room stat up to full. Wait at least 6 minutes. Does the water pump start? Does the ASHP start? Do the rads get warm?

End of test. Switch off electricity.

Remove link wire and reconnect white wire to TB15. Replace covers and screws and reset room stat and programmer.

I cannot do the test until Thursday evening or Friday as I am away in exmouth for a work event. As soon as i am back on thursday i will do the test, possibly Friday if I don't get back until late.

I appreciate all your help

 

[Themorganator4]

I have technical queries in with Ideal and Dantherm(Calorex) the makers of the ASHP in which I question the correctness of the wiring diagram on page 22 - but I am 95% certain I am right that there is an error.

What I would like you to try before Wilko and I visit on Sunday (toa tbc) is to do a further test run if you have the time and inclination. Not a problem though if you cannot - I will do it when I visit on Sun.

First switch off power and check dead. Go to ASHP and gain access to the terminal block. Remove the white wire from TB15 and make safe in a connector.

Using a short length of wire make a link between TB15 and TB9.

Turn Room stat down to lowest setting.

At programmer select HW off and CH constant.

Switch on electricity. Wait 5 minutes. Nothing should have run up including the water pump.

Now turn Room stat up to full. Wait at least 6 minutes. Does the water pump start? Does the ASHP start? Do the rads get warm?

End of test. Switch off electricity.

Remove link wire and reconnect white wire to TB15. Replace covers and screws and reset room stat and programmer.

Tried the above, rads got very slightly warm but this could be from water in buffer tank, water pump worked when turning room stat to max. Nothing worked when turned to min. ASHP did not come on at all during test

 

[marconi]

Thank you. I have just spoken with Wilko and we are planning our journey down to you. Will be in touch.

 

[marconi]

And just to confirm - you did all this with the defrost sensor and a wire from the defro module disconnected? I suspect this has changed the ASHP logic because I was expecting the ASHP to run up. I will do the same test when I visit and with defro in service.

 

[Themorganator4]

And just to confirm - you did all this with the defrost sensor and a wire from the defro module disconnected? I suspect this has changed the ASHP logic because I was expecting the ASHP to run up. I will do the same test when I visit and with defro in service.

That's correct however defrost mode is faulty:

When defrost mode is connected then the pump will go into defrost when there is little or no ice on the coil and if temps are below approx 10.c. when it goes on the fan stops and the pump goes in reverse (like its meant to) for approx 5 mins, the fan then turns back on but the refrigerant gets stuck in reverse meaning that the ASHP is actually extracting heat from the house. I disconnected it as a quick fix and it seems to work (fan still stops for 5 mins but refrigerant is not reversed)

 

[marconi]

My study of the ASHP wiring diagram (difficult because it is so small) indicates that the NO output of the DEFROST module, the one you have disconnected, is required to energise two relays R6 and R9. The CH signal to R5, which controls the start of the compressor, passes through the normally open contacts of R6 and R9; which means for a CH signal demand path to R5 these relays need to be energised by the NO output of the DEFROST module going live to 230V; at the moment this cannot happen because you have disconnected the NO output to R6 and R9.

The ASHP DEFROST mode is is actually the CH mode but with the radiators bypassed by the 3 port diverter valve - see page 21. What is meant to happen is that on entering DEF mode, the 2PMV(CH) opens, the water pumps starts, the diverter valve is energised and water circulates through the Buffer Tank and ASHP heat exchanger. At this stage there is no demand from the Buffer Tank stat to start the ASHP. When the water in the Buffer Tank has cooled below the set temp of its stat because it has been circulating as just described, the BT stat closes generating a start demand to run the compressor to produce hot air which warms the circulating water going through the heat exchanger which at the same time defrosts the ASHP because there is no cooling from the fan which is off in DEF mode- you will see steam being produced from the ASHP for about 5 minutes.

The problem I believe you have is that the CH mode at the moment derives its 230V live from the output of the HW stat and the ASHP is set to give priority to the HW sub-system. What this means is that once the HW demand (ie: HW stat closed) is satisfied 'cos water is above its set point (60C), the HW stat opens removing 230V from the relay logic of the CH sub-system which needs it to generate an ASHP start demand via the Buffer Tank stat. So the ASHP in DEFRO mode remains stuck 'waiting' for the Buffer Tank tank stat to produce a 230V live output to create a start demand which it cannot do even though its contacts have closed because the HW stat is open.

This is the wiring fault I believe exists on page 22 which my test was a simulation of correcting. But I had forgotton ( :-( ) that you had disconnected the DEFRO NO output.

I am almost dead certain (98% now) if you reconnected the DEFRO module and did the last test again the ASHP would start.