joe90

Help required wiring my ASHP/UFH

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2 minutes ago, PeterW said:

 

Reading this, is there any wonder why most installers just stick these units in with default values and walk away.??!

 

There is a real market opportunity here for tuning ASHP installations properly .....

 

I'm pretty sure you're spot on.  Our unit came with settings that just weren't anywhere optimum for our requirements, and resulted in the unit trying to deliver flow temperatures that were too high in heating mode, with consequent defrost cycling that sapped the efficiency.

 

I think the main problem is that the companies selling badge-engineered ASHPs just don't understand the products they are selling.  I would guess that the reason some of them just pulled out of the heat pump market was because they got their fingers burned by a number of installations that just didn't perform as they could have if set up properly.  A positive side effect of this has been a steady flow of bargain heat pumps on to the market, though.

 

Setting up a Carrier unit is a bit tedious, as the settings are far from being intuitive.  I had to spend several hours working through them by trial and error to determine exactly what changing each parameter really did.  To work out how the climatic curve set points worked I sketched little graphs in the blank pages of the manual.  I may have a go at sticking them into a spreadsheet later, as the graphs do help make sense of things, at least for me.

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2 hours ago, joe90 said:

 

Is the heating water temp one of these parameters?, is the DHW temp another or the same.?

 

my controller does have “touch and go” buttons, home, away, sleep, next. (Yet to programme them yet).

On my unit (I know it is different to yours) There is a parameter for hot (sanitary) water temperature. Mine has a temperature probe in the tank so heats the tank until that is satisfied.  I also have a parameter for "sanitary water leaving temperature" that is supposed to set the flow temperature from the heat pump when heating hot water. I have that set to 50 but whether by overshoot, or simply ignoring that parameter, I have seen the flow temperature as high as 55 on occasions.

 

What mine did not have was any external control ability for the hot water functions (i.e on and off times) so my solution was a bit of a fudge, already described on another thread.

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13 minutes ago, PeterW said:

 

Reading this, is there any wonder why most installers just stick these units in with default values and walk away.??!

 

There is a real market opportunity here for tuning ASHP installations properly .....

I agree

 

I have been tinkering with mine for weeks on and off, just a little adjustment here and there, then wait and see how it behaves.  And it has been a steep learning curve to get inside the head of the heat pump designer to really understand what each parameter really means.

 

Had I been paying someone to do all these tweaks, I feel it might have got expensive.  I am also aware that having learned how my unit works would not help me very much if I came to set up a different unit.

 

It is really easy to see how badly specified and badly set up heat pump systems can be dismissed as "useless" and removed by their owners after only a short period of time.

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I agree with all the above.... If I set the hot water point at 45’ this may well be sufficient for heating the UFH buffer and the DHW. Will have to “suck it and see”.

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6 minutes ago, joe90 said:

I agree with all the above.... If I set the hot water point at 45’ this may well be sufficient for heating the UFH buffer and the DHW. Will have to “suck it and see”.

 

If you just want the unit to deliver a constant flow at 45 deg C, accepting that it will start to run defrost cycles at this temperature, then don't bother with the DHW temperature setting or the dry contacts between 13 and 15 and just load these values into the command unit:

 

112 = 0

119 = 19

120 = 45

121 = 45

 

That will set the heat pump to deliver a constant 45 deg C flow whenever it turns on in heating mode.

 

If you want to use floor cooling, then setting these parameters will give you a constant 12 deg C, which I've found to be a good compromise between cooling effectiveness and the risk of floor condensation:

 

117 = 0

122 = 40

123 = 14

124 = 12

125 = 12

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Mine only heats DHW OR heating, never both at the same time, with a much lower supply temperature when space heating.

 

Mine also has a unique feature that it only heats DHW for 30 minutes at a go, then reverts so space heating for another 30 minutes. It will keep on doing these 30 minute bursts of DHW hearing until the tank temperature is satisfied.  There is no explanation of why it does this, but I speculate it is to minimse the time the HP is working hard, and reduce the risk of needing to defrost.

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29 minutes ago, ProDave said:

but I speculate it is to minimse the time the HP is working hard, and reduce the risk of needing to defrost.

 

That sounds like a very reasonable explanation. Shame this kind of information is not available it might make understanding how they work more usable (for those of us that don’t use just standard settings).

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Still waiting for my new processor card for my ASHP but I was wondering how I could wire the immersions to top up the DHW after the ASHP got it to 40’. I notice that the DHW tank stat has a change over contact so if I set the ASHP to deliver 40’ water and the stat on the tank  is set to 40’ (or 39’) and wire this via the make contact not the break contact the immersion it will only come on when the DHW tank has been heated by the ASHP. The stat within the immersion could be set to the temp required for DHW (50?). An over ride switch could be used if the immersion is needed from cold. If I do use E7 or E10 things will be different. Is there a flaw in my plan?.

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Does your heat pump have any provision to control the thermostat?

 

My LG one has control of the thermostat via a contactor. That is either for periodic "stertilisation" cycles, or to do just what you want and heat the water the last bit up to full temperature.

 

I foresee a problem with the logic though.  If the HP heats the tank to 40, then the immersion heats it to say 55. Then as soon as you draw water and the temperature drops, the immersion will come on and heat the water.  So unless you run a full bath and use the whole lot up in one go, the HP will never get a go at heating and it will all be done with the immersion.

 

That is why I am heating my HW to full temperature with the HP.  Mine is now set to 49 degrees (minor adjustment from previous setting) and so far no ill effects and no sign of the HP defrosting.

 

P.S if you are thinking of using the cylinder stat, that won't handle the immersion heater load, you will need to use a contactor or SSR to switch the immersion.

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According to the command unit I can only set one water temp (unless DHW is separate but it’s not clear). I am trying very hard to stop the ASHP from going into defrost mode (although I still recon it can be set to heat till it’s “about” to defrost then stop, but that’s a different story). 

 

The tank stat (using the break contact not the make contact) switches the immersion on (via a relay) only when the temp is up to 40’ and the immersion itself turns it off at say 50’. If the tank is say 30’ then the ASHP will heat till 40’ is reached then the tank stat will switch on the immersion.(I hope 🤔).

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You can set two different flow temperatures, one set by the heating curve parameters and another set by the DHW temperature parameter.  To switch between the two needs a connection to the DHW dry contact in the ASHP; when that is connected to 0 V the DHW setting over-rides the heating temperature that is set and the ASHP delivers hotter water for DHW.  There's also a switched 230 VAC output available from the ASHP to operate a three port valve, so that the flow can be redirected to a hot water tank when the unit goes into DHW mode.

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As you may have seen from the other thread about GMC board problems I have got my ASHP working 👍.  @JSHarris what climatic curve would you suggest as a starting point for me?

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6 minutes ago, joe90 said:

As you may have seen from the other thread about GMC board problems I have got my ASHP working 👍.  @JSHarris what climatic curve would you suggest as a starting point for me?

 

 

If you just want to heat the buffer to a constant temperature, say 45 deg C, then these settings will do that:

 

112 = 0

119 = 19

120 = 45

121 = 45

 

That will set the heat pump to deliver a constant 45 deg C flow whenever it turns on in heating mode.

 

 

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Great, but I think your idea of a different DHW temp to heating temp (which I believe I can do with using the heating curves ) might be better, you pointed out that constant 45’ would lead to defrosting cycles which I would like to avoid for obvious reasons.

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1 minute ago, joe90 said:

Great, but I think your idea of a different DHW temp to heating temp (which I believe I can do with using the heating curves ) might be better, you pointed out that constant 45’ would lead to defrosting cycles which I would like to avoid for obvious reasons.

 

 

For a constant 40 deg C in heating mode then change the settings to these:

 

112 = 0

119 = 19

120 = 40

121 = 40

 

The DHW mode is turned on and off by linking dry contacts 13 and 15, and the temperature of that defaults to 50 deg C IIRC.  You can change this by changing parameter 113 (I think!) to the hot water temperature you want, say 55 deg C.

 

The above assumes that the unit is set to operate from dry contact controls (default I believe) and that sanitary hot water (parameter 153) is set to always on (1).  DHW will over-ride heating and take priority when dry contacts 13 and 15 are linked, so when there is a call for DHW as well as linking these two dry contacts you also have to switch the diverter valve so that the flow goes to the DHW tank coil.

 

Hope this makes sense!

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1 minute ago, JSHarris said:

 

 

For a constant 40 deg C in heating mode then change the settings to these:

 

112 = 0

119 = 19

120 = 40

121 = 40

 

The DHW mode is turned on and off by linking dry contacts 13 and 15, and the temperature of that defaults to 50 deg C IIRC.  You can change this by changing parameter 113 (I think!) to the hot water temperature you want, say 55 deg C.

 

The above assumes that the unit is set to operate from dry contact controls (default I believe) and that sanitary hot water (parameter 153) is set to always on (1).  DHW will over-ride heating and take priority when dry contacts 13 and 15 are linked, so when there is a call for DHW as well as linking these two dry contacts you also have to switch the diverter valve so that the flow goes to the DHW tank coil.

 

Hope this makes sense!

Yup, got that, thanks a lot. I am just trying the ASHP (after changing the GMC board) to make sure it works as it was an EBay special with no guarantee 😱. I will pick your brains again about heating curves once I establish it works.

 

ALL HAIL THE KNOWLEDGEBLE ONE. ! @JSHarris

 

This is yet another example of the good will of members, sharing invaluable knowledge .

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It's worth scrolling through all the parameters from 1 to 301 (they are in groups, so there aren't 302 of them - check pages 95 to 99 in the Carrier 30AWH004HB Service Manual) and noting down all the values that are set by default, to make sure they are correct.  If you don't have this manual, I've attached a copy below.

 

30awh004hb - Carrier ASHP Service Manual.pdf

 

Running through all these settings will be useful in terms of checking that the communications are OK with the board, too.  It's a heck of a complex bit of kit to programme, given the number of programmable variables and some of the unusual terminology, so running through the settings and checking them against those in the tables on the pages listed above will give a good feel for things.

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Brill, will do. programming is not my thing, it’s sunny and I want to be digging with my JCB. but needs must.

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It may help to just print out pages 95 to 99 and then pencil in the margin what your default settings are.  Also worth noting that many of the parameters can't be changed, they are just status indications, so only of use in terms of checking what the unit is or isn't doing.

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I knew it was too easy! Just changed command unit to act as room stat,( 100 changed to 4) that worked ok but scrolled to 113 to check heating temp for UFH and it’s not there!!!, nor is 146 (not that I need to change this). Will double check everything.

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I suspect the unit will need programming from scratch, check to see what parameter 100 is set to.  It should be set to the right mode for the type of controls you wish to use.

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10 minutes ago, JSHarris said:

I suspect the unit will need programming from scratch, check to see what parameter 100 is set to.  It should be set to the right mode for the type of controls you wish to use.

 

Yes the default for 100 is 1, but I changed it to 4 (with nui as thermostat). Them went to 113 to set water temp and it’s not there. Just changed 100 back to 1 and 113 is there and I can change the temp????.

 

as an aside, the command unit now shows an alarm, the GMC board shows alarm 9, flow switch/ pump, checked for air and non there?, didn’t @ProDave have a similar problem and ended up with a scrap ASHP. 

 

ITS SUNNY AND MY JCB IS CALLING ME 🤔

 

i need to get get my head around this, I will read up everything tonight and start with a clear head tomorrow, immersions back on!

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The command unit needs to programme the GMC with all the set values, I believe, so what's probably happened is that the values were stored in the Command Unit, but weren't transferred to the GMC until you changed a value.  My guess is that at that time the Command Unit may well have transmitted all the parameters that were stored in it to the GMC, which has now stored them.

 

Still worth cycling through all the settable parameters, I think, just to be sure that everything looks right.  The chances are that the alarm may relate to a setting not having transferred, with a bit of luck.

 

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Right, new day, start again. I started running through the installer configuration on the command unit and 104 is the output test (enables various functions to be tested), 1 was pump test, yes that worked ok. 6 is the three way valve test, nothing happened!. I have noticed that the three way valve is permenantly on (power applied to it) even when the DHW is switched off.?

 

question. Is the three way valve normally sitting to provide Heating then “on” (powered up) when wanting DHW. (This is what I would have thought). If so mine is not working correctly.

 

just draining the DHW tank and turning off the immersion to test.

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does the valve's microswitch report back to the ASHP? Any chance NC and NO are reversed?

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