Air source heat pump heating issue

[marconi]

Yes, that's right wait over 3 minutes - say 6 minutes each time. Tedious I know but it is protection electronics preserving the life of the motor-compressor in the event of a brief power outage. The most stressful time is when it starts - electrically and mechanically speaking.

 

[Themorganator4]

Yes, that's right wait over 3 minutes - say 6 minutes each time. Tedious I know but it is protection electronics preserving the life of the motor-compressor in the event of a brief power outage. The most stressful time is when it starts - electrically and mechanically speaking.

Ok I'll do that shortly and post back the results
[automerge]1570376455[/automerge]
Interesting, it seems that the water pump now doesn't work, I'll have a fiddle in the junction box to make sure everything is connected

 

[marconi]

It is best to isolate and then slowly, slowly move connectors and wires to discover the fault(s) and not create any new ones in the process. I already have a volunteer to sort out that JB for you.

 

[Themorganator4]

It is best to isolate and then slowly, slowly move connectors and wires to discover the fault(s) and not create any new ones in the process. I already have a volunteer to sort out that JB for you.

By chance whilst I was moving connectors around, another wire slipped out with ease. I assumed that the connection wouldn't be that loose unless another wire was connected there. I was right.

Just waiting to complete test 1 of 2 now
[automerge]1570378816[/automerge]
Ok both tests failed as before. On test 2 just to double check, i am removing the white wire from the bottom not the red and white striped one at the top

 

[marconi]

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.

 

[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.