Hello after 3 years I can finally see the energy my LG Thermobloc V 14kw heatpump is using. Now I want to know if it is set up optimally. I run on Heat mode at 22C overnight, on AI/weather compensation mode during the day, apart from 4pm to 7pm when it’s off because we are on Octopus Agile tarrif. The house is at a steady 18/19 which is good. I’m concerned about the spikes though. Apologies if this is the wrong thread for this question!
Hi Helen, and welcome to the forum. I’ve moved this topic to the Heatpump section.
These do indeed look odd. Are you still seeing these spikes? Can you share a picture of the chart zoomed in on, say, a 1 hour period?
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Hi Tim thank you for getting back to me. I was advised on the Facebook Group for LG Themabloc owners to try turning on silent mode, which I did yesterday at 1.30pm. This is the first picture, it dud seem to reduce the frequency of the spikes. The second picture is zoomed in. I have set my feeds to public but I haven’t looked into how to share them yet.
Looking at your first charts, some of the spike seem so coincide with the peak power draw when the heat pump is running…
…though not always:
Turning on silent mode does look to have changed the behaviour when running:
Can you zoom in on one of these spikes?
How is the electrical power being measured?
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Hi Tim it is measured by a CT clamp on the power cable to the heatpump, the same one the little metre is on in the consumer board. This goes to the Emonpi2 port P1. I don’t know if it could be affected by other cables nearby.
I have zoomed in on one if the spikes that occurred while in Heat mode.
Thank you, Helen
Hmm… that is quite a chunk of power, which doesn’t look like noise. It also doesn’t look like a backup heater, which the manual suggests would be 3kW.
Would be interesting to know what the flow temperature is doing during that period, if you’re able to find out.
What is the layout of the central heating? Radiators? Underfloor? How is your heating controlled?
Hi Tim the flow temp overnight is set to 22, plus or minus 4 degrees. During the day it’s on AI mode so varies. We have radiators only. The control is now just the heatpump. All the radiator TVR valves are fully open and the thermostat in the hall is effectively not in control because it is set much higher than the temperature we want, so never suppress the heatpump. I’m not using the heatpump for hot water at the moment because I want to understand if it is set up optimally for heating.
I hope that helps!
Well that’s a good start 
Ooof, that is very low, possibly too low for your model of heatpump and size of radiators. I can now see that the night time behaviour is very spiky as it tries to get the flow temp up to 22°, overshoots within 10 minutes and turns off again. This is what we would call “cycling”.
I would suggest either a higher flow temperature of, like 35°, or keep it on AI mode all the time. The daytime behaviour on silent mode looks much more sensible.
Do you have anyway way to see what the actual flow temperature the heat pump is producing? Perhaps in the LG controller or app somewhere?
Edit: I found this in the LG brochure:
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Hi Tim if I turn the heatpump off overnight it maintains a temperature of between 14 and 18 anyway so I thought it would be ok to set a low temperature and make use of that heat. The silent mode turned itself off at some point but I will keep experimenting.
The house will be too hot if I leave it on AI all night, plus it will be too expensive.
We are at 20C at the moment which is above the 19C I’m aiming for with - 4 adjustment on the AI, but it will drop between 4pm and 7pm when it turns off.
I might use the woodburner tonight because it warms the brick chimney that runs up the centre of the house and it is predicted to be - 5 tonight!
I have seen that data displayed so I could photograph it, but it would be much more useful if it could be downloaded?
Here is the current position. I’m about to take the dog out, it is such a lovely day.
I’d say the consumption looks to be right, and the spikes are just normal cycling operation; not too frequent to be of any concern. Silent mode may help with this, have seen similar advice for other heatpumps.
The heatpump looks to be targeting a flow temperature of 32° during the day, which is pretty good for a radiator only system. Is there a setting in LG for what room temperature it’s aiming for? Is there a mode where it’ll turn off when the house is warm enough?
Tagging in @miles who also has an LG Therma V and may have some useful insights.
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I’ve never seen similar spikes on my LG Therma V system. But mine’s more recent - installed last April, so almost certainly slightly different inside. I can’t say I’m impressed with it yet though. I don’t see great COP figures.
I don’t know of a way of downloading that internal logged data either (and its only 50 data points according to the manual), but I’m certainly able to log everything live via Modbus → TCP → Computer. (After a bit of trial and error). That’s what feeds my emoncms installation - the only independent sensor I have is a Shelly Energy clamp on the feed to the heat pump.
I’m interested that you use the “AI” feature - I’ve tried it a couple of times and it’s just wizzed the flow temp up to 45 degrees, making things much worse. I’ve got the installer coming back soon, so they can look at it.
My installer didn’t know anything about how to set up the weather compensation (AI) but I had some fabulous help from a chap I connected with on bluesky. Now I understand it much better and have changed the parameters to suit me. Other makes have heat curves that you pick from. Mine you have to set discreet points that create a straight line. There is an LG Thermobloc group on Facebook that have documents about the process too. This is my plot of my heat curve. Effectively the target flow temp is varied based on outside temp.
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While it’s desirable to have it slightly cooler at nighttime for sleeping, if the house gets too cold then it will take a lot of energy to get back up to day time temperature. It’s generally recommended to have a “setback” of just 2 or 3 degrees, so that the heating keeps ticking over through the night. This is counter-intuitive, especially after generations of gas heating that outputs way more heat. The name for this is “low and slow”, and usually results in much more efficient operation of the heatpump.
Given that you’re on Agile, the overnight rates are usually lower than in the morning, so keeping the heating on would probably save more than turning it off would.
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Hi Helen,
I’d really love to read that weather compensation doc, but I’m not on FB. Is there any way you could post it here, please? Or a link that I could retrieve it from?
My “AI” weather compensation clearly isn’t set up right at all, so anything you can share would be very helpful.
Thanks
Miles
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I have this LG on heatpumpmonitor.org.
Similar to what Helen sees, mine cycles a lot in warmer temperatures if I don’t switch silent mode on and allow a +4C overshoot which gives it space to find a balance. I think this comes from the pump being a bit oversized.
@Peter_WA is the expert on LG spikes though. If I were to butcher his summary, I’d say that the LG starts each cycle very heavily - it consumes a lot of power for the first 20-30mins before settling down. If the pump is oversized to begin with, this means it will often overshoot and stop. Allowing the +4C overshoot helps it get over this bumpy start.
Peter has also been looking at some spikes that occur during normal operation but not in silent mode. He was speculating if they may be for an “oil recharge cycle where lubricant is injected into the refrigerant circuit”.
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Hi @sambeaton - I’m actually under @dyllysdad 
Attached is a doc I created regarding observed short spikes which I think is what Helen is seeing, together with possibly the usual LG aggressive startup. I only see the spikes when running in normal (vs silent) mode and the system is humming along continuously. I expect that when a compressor cycle starts that some housekeeping is performed, and that could involve some lubricant operation - but a complete guess on my part (I have seen others mention it, but never had LG confirm it). If the system is cycling then there will be that housekeeping - but if its continuous then my suggestion is that it enforces this action. In silent mode I don’t see this. As the spike is high power then it escapes silent mode temporarily so I guess silent mode supresses it.
The doc. contains an appendix with some captured refrigerant cycle data from the LG. Samples every 1 minute so not super detail but does show the behaviour I think.
LG silent mode operation - v2.pdf (924.7 KB)
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Hello as requested by Miles here is the document on Weather Compensation by Ian Skeet on the Facebook UK LG Therma V Heat Pump Owners Group.
LG Therma V Weather compensation v2.docx (5.1 MB)
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Adding the latest version: LG Therma V Weather compensation v5.pdf (1.3 MB)
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