LG Therma V Monobloc CH14 flow error

[Tim Pearson]

Thx Kelvin, will keep it on the “to be followed up” list.

T

[ProDave]

  On 29/12/2022 at 14:20, Tim Pearson said:

Ok so partially drained, filter removed (little or no debris), cleaned and reinserted.

 

Flow switch is a Sika V3. Unclear which model at this stage, but label indicates 15l/min set point.

Not yet removed to check paddle operation. Also, it may have an adjusting screw, tbc.
 

Powered by cable back to control board - blue connector.

Attached info.

Any more suggestions before I remove FS, check paddle, any flow adjustment option?

On electrical connection, what is there to check and how?

thx again

T

 

Data sheet VK3 flow switch.pdf 355.39 kB · 1 download Ea3000_FlowSwitch operating instructions .pdf 1.7 MB · 1 download

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That's a different flow switch to mine.

 

If no obvious issue, i would be tempted to buy the same switch head but with a lower flow rate to make it less fussy.  Even if the flow rate is a bit on the low side it would trip on a different error if it was really an issue.

[Tim Pearson]

Help me out here Kelvin. Where would you expect the 2 way valve to be located? In the loft next to the buffer tank and DHW cylinder?

[ReedRichards]

Unless your plumber squandered copper pipes unnecessarily, there will be a single flow pipe from your ASHP to a two way valve that is close to (and probably about half way between) your buffer tank and your DHW cylinder. 

[Tim Pearson]

Ok so updates as follows.

 

1. Flow Switch

Flow switch removed and paddle appears ok. No debris. Connection and wiring checked, appears ok.

Option remains to replace with lower switch rate. (ProDave).

2. ASHP pump

Grundfoss 20-105 installed aligns to recommended spec. (Att 1). Document confirms runs at max. (per HughF I would assume that LG, like all good heatpump manufacturers, use a PWM controlled primary pump so they have control over the delta-T. So there should be no need to check what speed it is running at.)

 

However, comments (AKJOS) and engineering document (Att 2) suggest inadequate flow with this single 20-105 pump.

Option to add additional pump, or upgrade existing (15 to 25?).

 

3. Two way valve

Located two way valve, as per guidance.  Re valve response time (Kelvin, ProDave, ReedRichards) there is a manual switch on this valve. I’m unclear on how to check if there is an automatic by-pass.

 

“But most motorised valves take less than 10 seconds to open, and there should be some form of automatic bypass valve to give some flow even when all motorised valves are shut. If you suspect this is your issue, you can manually open most motorised valves, so do that to one of your valves and see if the CH14 error stops.”

Question - if it’s two way, then is the default (off/closed position) usually set on DHW or heating?

 

Option remains to

- refill the system.

- check for ASHP motor running.

- manually open two way valve and see if this has any impact.
(Any guidance on exactly when to do this? When ASHP is running?).

 

Again, thx all and HNY!

Tim

 

 

 

[dpmiller]

has the pump got 2 cables plugged in or just 1 mains supply? PWM pumps have a second signal wire to tell them what to do...

[ReedRichards]

  On 04/01/2023 at 13:23, Tim Pearson said:

3. Two way valve

Located two way valve, as per guidance.  Re valve response time (Kelvin, ProDave, ReedRichards) there is a manual switch on this valve. I’m unclear on how to check if there is an automatic by-pass.

 

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Locking the arm in the "manual" position should open the valve.  I don't know if there is a convention for whether this gives you heating or DHW but if the valve is the problem I think it should give you flow one way or the other.

[Tim Pearson]

There’s only one cable from the CH pump, to the Honeywell power unit. Att 1.

 

CH and HW both have their own two way valve, means I can manually open individually or together to test.

 

T

[ReedRichards]

The picture shows what is probably your central heating pump (too much in shadow to be certain).  I have an LG Therma V and AFAIK mine is completely unaware of the presence of the central heating pump.  I don't think there is even any option to take control of a central heating pump.  In my case I'm not using the Air + Water control option with Load Compensation so there wouldn't be any point anyway.

 

I can also see a pressure gauge which appears to indicate a disparity between the actual water pressure and the indicated pressure.  And what looks to be the top of a motorised valve actuator.     

[Tim Pearson]

You are correct.

I’ve shown the CH pump, also motorised valve actuator.

Pressure is 1.5 bar (ignore red arrow).

Reckon my Therma V ASHP is as yours - unaware (not connected/integrated) with the CH pump.

 

Don’t understand this point.

“In my case I'm not using the Air + Water control option with Load Compensation so there wouldn't be any point anyway”.

 

thx for FB.

T

[ReedRichards]

  On 04/01/2023 at 18:01, Tim Pearson said:

Don’t understand this point.

“In my case I'm not using the Air + Water control option with Load Compensation so there wouldn't be any point anyway”.

 

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You can set the Therma V to control based on the just the Leaving Water Temperature or on both the LWT and the room temperature read by the controller, "Air + Water".  In the Air + Water mode the controller will try to reach and then maintain whatever room temperature is set.  When trying to maintain a set room temperature then modulating the central heating pump could be used to increase or decrease the heat output from the heating so might be a useful control feature.    

[dpmiller]

^ not sure if anyone other than RED modulate heating flows in that manner?

 

Has the OP confirmed that this particular ASHP has an internal circulation pump, and that it is actually functioning correctly?

[Tim Pearson]

Ok so update below.

I did locate the two valves for the  DHW and CH valves, appeared fine. Having done the previous checks (filter, flow switch, bleed rads) and with the pressure at 1 bar, I decided to refill the system (partially drained).

 

Pressure remained at 1 bar. I then turned all the rads, UFH settings to freeze mode and fired up the AWHP, asking for DHW.

The CH 14 error did not reappear and the DHW heated to 45 deg.

Then adjusted the UFH settings and the heating came on.

That was a week ago - so far no issues. Pressure is still at 1 bar, which I know is on the low end.

 

3 points.

 

1. Is it feasible that the 1 bar pressure is “helping” to avoid pump capacity issues? (less pressure, less strain on the pump).

 

2. After 5 partial drains last year, the forthcoming “service” includes a glycol check. I expect more will need to be added and was told by the UK AWHP distributor that this is an expert job which requires pressure inserted G to dissolve the (very viscous liquid) and avoid blockages cause by G “blobs”. Pressure insertion process is very slow and installers are told to allow 1/2 day on a new install to fill the system with glycol. Not something I could do myself.

 

Does this make sense?

 

3. My installer service visit has still not been arranged (they still think my system isn’t working). The distributor told me most of the “industry” is focussed on solar installs (higher margins). So much for service and support. Owners of AWHP are going to be stretched to maintain annual service and protect warranty if this continues.

 

Best

Tim

 

 

 

[ReedRichards]

I'm pleased that you got your heating working again.  My heat pump installer tells me he is now busy with solar.  Since there is no plumbing involved in solar PVs and solar water panels are out of fashion I don't really know how he is being occupied but I did not question him further.

 

I don't think the water pressure will affect the pump and once you have got up to 1 bar I doubt that you would need to add much more water to increase the pressure.  If you have any leaks this would make them leak faster.  

Edited January 13, 2023 by ReedRichards

[PeterW]

  On 13/01/2023 at 09:33, Tim Pearson said:

Is it feasible that the 1 bar pressure is “helping” to avoid pump capacity issues? (less pressure, less strain on the pump).

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No because the “pump” in a system is actually an open impeller circulator so it doesn’t care as long as there is no air which causes them to cavitate

 

  On 13/01/2023 at 09:33, Tim Pearson said:

was told by the UK AWHP distributor that this is an expert job which requires pressure inserted G to dissolve the (very viscous liquid) and avoid blockages cause by G “blobs”

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That’s horse $h!t as the glycol you use is normally already diluted and is free flowing. Quickest way to add more (as it’s really antifreeze) is to drain the filter and add at that point 0.5 litres at a time. Easily done yourself.

 

 

[Michael_S]

Sorry for hijacking a thread.  We have a new to us 12kw Thema V (perhaps 6 years old) but on connection we are getting the dreaded CH14. I am wondering if the circulation pump (a wilo) is working at all.

 

Any suggestions for confirming it is actually running, I can't hear anything or feel any vibration, turning the speed/pressure selector makes no difference.  

 

It has been siting for awhile so might be seized/rusted.  I can not see the the end of the spindle to insert a screwdriver as the control unit is on the end not the side so I am not sure if this model has screwdriver access or whether it needs to be unbolted in half to manually try and loosen the impeller/spindle.

 

Thoughts?

[ProDave]

The only way I solved whether mine was getting enough flow rate or not was to fit an in line flow meter.  If you are not hearing any noise, it could be the pump is seized, but the Wilo pumps are one of the quietest pumps available.

[sharpener]

  On 06/10/2024 at 18:45, Michael_S said:

Any suggestions for confirming it is actually running, I can't hear anything or feel any vibration, turning the speed/pressure selector makes no difference.  

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Yes Wilo are quiet but I would be surprised if there was no detectable sensation when it was running. If changing the speed setting from I to III makes no perceptible difference I would guess it is probably seized, you might have to take it out (which is when you discover the valves do not shut off or the spindles leak).

[Michael_S]

Thanks for the comments so far.

 

OK - there is power going to the pump.  So we took the pump apart and it seemed to spin fairly easily by hand.

 

It did not seem to turn when connected to the heat pump, so then we tried connecting directly to a power supply and it did not turn either - except one time when it did, but we can't make it do so again.

 

So now we are not sure if the pump is working or not and they are hardly a cheap swap out part.  Can they be replaced by any random pump of the same power or does it need to be one with electronic control via pwm?

 

Thoughts?

[sharpener]

  On 08/10/2024 at 22:35, Michael_S said:

It did not seem to turn when connected to the heat pump, so then we tried connecting directly to a power supply and it did not turn either - except one time when it did, but we can't make it do so again.

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Sounds like a failed capacitor, it's typical that you might get a motor to run without it but not reliably so (had this problem with the heat exchanger motor in our MVHR plant).

 

If you can find one of the right capacitance and voltage rating you could solder in a new one for a few quid.

 

If OTOH the control board has failed you might not be so lucky.

 

Sorry but no idea how essential a fancy pwm pump might be in yr circs.

[ProDave]

Almost any pump of that size will work, the Wilo are good because they are very quiet.

[Michael_S]

Again, thanks both.

 

I think the heatpump board is ok as it is definitely sending power to the pump live.  I was wondering if the heatpump got clever with the pump speed/power as part of regulating the output and flow/return temp difference but hopefully it might still cope with a standard fixed speed pump.  It being a second hand heat pump I don't want to throw huge sums of money at it.

[sharpener]

I meant the control board inside the circulating pump.

 

If the HP only provides a standard LNE connection to the circulating pump then I don't think it can do anything clever.

 

Pumps with inbuilt electronic control will modulate according to demand so esp if only a few rads are open (a) will reduce their power consumption compared with a fixed speed pump and (b) may be less noisy either in themselves or for flow noise in the pipework. So I have one of these Wilo pumps for my thermal store, but largely bc it was left over from a previous installation (and luckily wasn't damaged when the garage got flooded), advantage is it does not mind if there is zero flow.

 

Personally I would try and fix the existing pump myself and if unsuccessful replace it like-for-like. But you could elect to try a cheapo own-brand replacement from yr local builders merchant and might well get away with it.

[Michael_S]

OK.. I have got past CH14 using a second pump, currently running about 12.5l/m

 

System runs and heats the house nicely but then after about an hour seems to turn itself off in that the operate light goes off and the it just sits.  Seems to happen whether I use the weather comp 'AI' or a set flow temp.

 

Not sure exactly how the programming works with simple sleep, holiday etc 'Reservations'.  Ideally I would want it to run 24/27 in the weather comp 'AI' mode with an offset during the night hours but no idea if this is an option.  I am using it with no thermostat and with the auxiliary heater turned off (dip switches set accordingly) and heating only no hot water.  I have printed the user and install manuals but they are not entirely clear and some of the programmer functionality seems to be slightly different.  I purchaser the programmer separately from the heat pump and do wonder if it is 100% compatible?

 

Any suggestions welcome.  Thanks

[majlb]

Long time lurker, first time poster. Also a bit of a hijack, but I have a similar issue. 

Happy to repost as a new thread if deemed appropriate. 

 

I have a 12 kW LG unit, fitted spring 2022. Turns out it's probably slightly oversized for my house, I think I would have been fine with the 9kW, which may have also helped my short cycling and occasional low-flow warning issues. But anyway, I've noticed some CH14 errors which don't seem to be of much consequence to the operation of my unit, but this forum seemed like a good place to discuss and try to resolve. See below. 

i was checking the control unit box looking at energy use and on-off records, to try and understand short cycling behaviour of the unit, and noticed I had some CH14 fault codes from that day. I generally have no operational issues with the unit, so this was a surprise. Knowing this is linked to low flow, and having read around, was monitoring the flow rate by looking at the display, and saw the flow rate drop from around 30 to 15 L/min, and then threw a CH14 error in front of me. So it seems like it was triggered by the system reducing the flow rate to provide the heat requirement, below a min acceptable level. 

 

Playing around trying to understand this, I realized that you can specify the water flow control method, which was set to either optimal or fixed delta T. But I experimented and changed this to pump capacity mode and set 80% and 100%. No additional CH14 errors have since been thrown. I presume the flow rate was being reduced to an optimal level for the heat requirement, but gets to a certain level which is too low and then throws the error. So it seems like the control software allows too low a flow rate. 

 

I'm not sure of the effect on the unit's behaviour if I specify the water flow by the pump capacity. I presume if I set it to 100% it will short-cyle more when there is a low heat requirement. And in cooler weather, I'd be artificially limiting the heat delivered. I'm unsure what else can be modulated in the unit to produce less heat .

I'm also not sure of if throwing CH14 errors is of much consequence in my case, if the system seems to reinitialise and continue operating successfully. I did notice very occasionally the hot water hadn't operated and tank was cold, but unsure if that's related. If throwing a CH14 error isn't of much consequence if the system continues to operate, I may as well leave it and have optimal flow behaviour with some CH14 errors, rather than a manually applied x% flow capacity defined and inefficient operation. 

Michael_S, I presume this is all not relevant for you as you have a different control box?