LG Therma V mono block Air Source Heat Pump

[joe90]

43 minutes ago, ProDave said:

it simply does not wait the 10 seconds it should to give time for the motorised valves to open and the pump to get up to speed. Instead it decides in a very much shorter time that the required flow rate has not been met and hence it trips with the CH14 error.

surely that is a fault that you can demonstrate to LG and ask them to fix?

[ProDave]

1 minute ago, joe90 said:

surely that is a fault that you can demonstrate to LG and ask them to fix?

How can you demonstrate a fault that happens once in a blue moon?  It can go months without tripping, then one day, like today it will trip.  Do you expect them to take up residence on a camp bed in the plant room?

 

But I know I am not the only one to have this issue so you would have thought they would have fixed it with perhaps updated software or a new control board?

 

[joe90]

23 minutes ago, ProDave said:

How can you demonstrate a fault that happens once in a blue moon? 

Trying to think “out of the box” set up a dash cam ?. How often is “once in a blue moon?”. I would have thought a company like LG would take this seriously!, very annoying I am sure.

[ProDave]

If I had been in charge of a product that was showing an infrequent glitch but in a very well defined way, I would recognise that actually finding the issue was going to be difficult.  Therefore I would simply re design that part of the unit so it attempts to do the same logic, but make some changes to the hardware and in particular re write that bit of software from scratch. Then put the modified version out to customers machines who have had problems.

 

I also take issue with this being one of the few faults that needs a power cycle to reset it.  Perhaps just reset and try again after an hour is all the fix that is needed?  If there is a genuine flow issue it would trip again with no harm done, but if it had tripped due to a glitch, resetting after a time delay to allow it to restart automatically would solve the issue for most users.

 

I keep hoping I can find a way to detect this fault condition, in which case I could use that to instigate a power off reset.

 

LG just denied there was ever an issue and simply said my pipework is too long and there is not enough flow and it's an installation issue.

[joe90]

On 09/07/2018 at 17:15, ProDave said:

Before I did anything else, I went and bought a flow meter and installed that so I had a measure of the water flow rate that I was achieving, and that came back with a figure of 14 litres per minute.

 

It then took an email exchange with LG technical to be told the flow switch is "Set to 10 litres per minute plus or minus 3"  So I guess my 14 l/m was just failing to trigger the flow switch.

 

In my case I solved this by adding a second circulating pump external to the heat pump, and that boosted my flow rate to 20 litres per minute and the unit then sprang into life.

just re read from start (not all of it yet!), So is your flow meter still reading 20?, dash cam pointed at flow meter? To re wind and see if it falls below threshold? (Clutching at straws now!!!).

[ProDave]

I haven't checked my own flow meter for a while but it is not something you can check quickly when you get one of these short bursts followed by a trip.

 

If I was serious about debugging LG's creation, I would have something data logging recording the output of the invuilt flow switch, together with demand inputs and other outputs like pump on and motorised valve commands.

 

It looks like sometimes it does not allow the 10 second window to achieve the correct flow rate and for some reason decides there is a flow rate error and trips in very much under 10 seconds.

[joe90]

Not easy!!!

[1not24get]

Hi ProDave,

I'm looking at a LG or Hitachi ASHP.  Can I ask what size pipe you are using in your system?  What length are the pipe runs?

 

Thanks 

[ProDave]

8 minutes ago, 1not24get said:

Hi ProDave,

I'm looking at a LG or Hitachi ASHP.  Can I ask what size pipe you are using in your system?  What length are the pipe runs?

 

Thanks 

22mm copper pipe probably 20m long in total.

 

I don't think the length of the pipe is contributing to my spurious CH14 errors, but the length of pipe did force me to fit a second pump to achieve enough flow rate to get the thing working in the first place.

[philphluter]

On 13/11/2020 at 14:58, ProDave said:

Yes a buffer tank would make it easier / more dependable to achieve the flow rates.  I don't have one.

 

If you are paying for a system to be supplied and installed, then any issues you have land firmly back with the installer to sort out.  Not a luxury you have when you buy a cheap end of line old model and self install it.

Two or three hundred pounds for a small buffer tank might be worth it?

[ProDave]

9 minutes ago, philphluter said:

Two or three hundred pounds for a small buffer tank might be worth it?

It is certainly an upgrade I might consider.  But if I do, it would only be to enable the water pump between the HP and buffer to run flat out to satisfy the HP's flow rate appetite, while then allowing the circulation pump from the buffer to the heating to run slower to make the whole system quieter inside the house.

[philphluter]

Sounds good.  Also depending on the size of the buffer tank it will reduce cycling of the HP which will make it more efficient and save you money.

[Gav_P]

Is it possible to temporarily configure your system to be as short as possible to see if it continues to run without an error? Or even swap out the pump with a spare to make sure you don’t have a prematurely worn pump? 
 

When I first installed my HP, the pump was energised at the same time as the HP so it didn’t quite get up to the required flow rate in 10 seconds, so the HP timed out. I added in a 3 second delay and it was then fine. I wonder if your pump has always been on the cusp of the 10 second limit in getting up to acceptable flow rate? 
 

Also is you pump on flow or return? I assume if you move it to the return side it would definitely get up to flow rate in time. 

[Hogboon]

I have aproblem with a similar setup to thast installed by ProDave

The PROPERTY: detached bungalow TA21 0BZ built c. 1975 rendered conc. blocks, tile roof. Insulated loft and walls. Solid floor probably uninsulated. Double glazed throughout. Ground floor: 9 rooms [incl. bath room] plus hall and corridor with 11 rads in all. First floor: 3 rooms [incl. bath room] with 1 rad in each.  

Apr 2016 EPC total floor area = 169 sq m and the EER = 56.                      

“Current primary energy use per square metre of floor area = 180 kWh/sq m p.a.”

“Space heating [kWh per year] = 14,873”

“Water heating [kWh per year] = 3,534”

 

May 2020 EPC total floor area = 176 sq m and the EER = 59. 

"Current primary energy use per square metre of floor area = 165 kWh/sq m p.a.”

“Space heating [kWh per year] = 16,184”

“Water heating [kWh per year] = 3,537”

 

HEAT PUMP INSTALLATION AUG 2020.

          LG Therma V 9 kw HM091M.U43 [Flow: 50 SCOP: 3.17]

          200 litre Worldheat unvented WH + 18 litre expansion tank

          12 x Perlight 320W Mono 60 PV cells

          Solis 4kw inverter

 

The original quotation, based on the above May 2020 EPC was for a 7 kw LG Therma V but as increasing the heatpump to 9 kw did not significantly add to the cost I asked for the 9kw heatpump, thinking that would guarantee delivery of more than sufficient heat. This has not been the case to date.

The then existing oil-fired radiators were connected to 10mm microbore. It was suggested that the pipework be replaced with 15mm to improve flow. This was done. The spec on the quotation states:

          22mm flow and return. 15 mm drops to each radiator.

All the rads have thermostatic valves.

There is one other significant heat source. The sitting-room has a small woodburner with door. I don’t know the ‘output’ but the fire-box measures about 13” wide 10” high and 8” deep. 

For the moment, all I am concerned with is the central heating, not hot water. I am now able to control the heatpump’s wayward behaviour of turning itself on in the middle of the night by a programmable thermostat. The regime is as follows.  

Starting at 08:00 the required temperature in the house is 18ºC.

From 10:00 till 15:00 it is increased to 20ºC.

From 15:00 till 22:00 is reduced to 18ºC

From 22:00 till 08:00 it is 12ºC

In cold spells I start it ‘manually’ at 07:00 [set to 18ºC] as I did on 2 Jan 2021. I do not intend to alter the above schedule. If the machine can’t cope then the machine has to go. Below is how the heatpump performed on 2 Jan 2021 with no additional internal heating [i.e. no fire lit in the sitting-room] until after 15:00. The outdoor temperatures are only approximate as taken from a cheap stick-on thermometer of dubious accuracy.

Time	INSIDE Temp ºC	IN required ºC	OUT ºC
0700	15.5	18	2
0800	15.5	18	5
0900	16.0	18	5
1000	16.5	20	5
1100	17	20	6
1200	17	20	7
1300	17.5	20	8
1400	17.5	20	8
1500	<18.0	18	9
1600	17.5	18	8
1700	18	18	7
1800	>18	18	7
1900	>18	18	7
2000	>18	18	6
2100	>18	18	5
2200	>18	12	5

 

At 15:00 we lit the fire in the sitting-room. The weather outside was sunny till about noon then increasingly overcast. At no stage did the house achieve the required temperature until after 17:00 by which time, of course, the fire had been alight for 2 hrs.

It seems absurd that a very modest temperature [18ºC] should be attainable only with the help of ‘technology’ that would have been familiar in the stone-age. 

There is a paucity of hard data from LG concerning their pumps. It is hard enough even getting hold of a manual. [LG’s telephone customer help line has limited options about TVs and washing machines etc but absolutely no mention of heat pumps. The same goes for their website.]

As things stand at present LG claims the Therma V “operates reliably at external temperatures of -25ºC” and they claim their heatpumps are “powerful heaters with leaving water temperature up to 65ºC.” See https://www.lg.com/uk/monobloc My experience so far suggests that both these claims are at best misleading exaggerations, at worst mendacious deception.

On the same page are images of LG’s ‘Remote Controller’. One shows an ‘Energy Monitoring’ screen; another shows a ‘Data Logging’ screen. I can find neither. Does anyone know how to access these? The software on mine seems to be v.3.05.5a [Master].

I have of course contacted both LG and the installer about the poor performance as exemplified on 2 January and have yet to hear back. I wonder if anyone here might have any bright ideas. In particular;

1. is the 15mm pipework likely to restrict delivery of sufficient heat? Should I have bigger [e.g. 22mm] tails to each rad?

ProDave makes frequent reference to ‘CH14’ errors. I have no idea what these are and have seen none.

2. Where might they appear?

3. Could a larger or additional pump improve flow and performance? If so, any recommendations? [I think ProDave inserted a Grundfos somewhere…]

 

 

 

[ProDave]

What temperature are you running the heating water (you set the heating water temperature as a setup parameter, and there is a separate parameter for hot water temperature)

 

It will almost certainly be running the radiators at a lower temperature than the old boiler did. So lower temperature and they will give less heat output.  It may well be that just the lower temperature means those radiators will simply not put enough heat into the house regardless of the capacity of the heat pump.

 

Think yourself lucky you don't live here.  It was -9C this morning and it has not been above 0 all day.  In fact it has barely been above 0 for nearly 2 weeks now.  This is a normal winter cold spell up here, we get a period like this every year.

[Hogboon]

Thanks for the reply ProDave. The short answer is "I have no idea" but one picture etc please see attached images which are of my LG 'Remote Controller' which, as you have remarked is less than user-friendly. E.g. I have absolutely no idea what is 'Off'. The central heating is controlled by another gizmo - a Nest [over-rated] Thermostat but I see nothing in its equally convoluted menu that might regulate temperature. 

 

Do I infer correctly from your reply that you don't think it is a flow issue? and adding a pump would not cure? and where are these CH14 errors reported?

 

My family is from Orkney. That's why I live in Somerset!

[ProDave]

First picture, symbol with a thermometer and and arrow pointing out means that is showing the FLOW temperature, currently 50 degrees and shows the DHW  target temperature as 52 degrees.

 

Third picture shows the flow temperature is 45 degrees and the return temperature is 38 degrees.

 

So if your radiators are running at 45 or 50 degrees they won't give as much heat as typically running at 60 degrees from a boiler.

 

You would know if you have a CH14 error, the thing would stop and you would be aware of it.  You have a different controller to me, yours looks more modern.  This confirms my suspicion that what I have is an older model and hopefully all the issues I have suffered have been fixed in the newer versions.

 

Assuming you have the full manual, you can edit some of the setup parameters and you could try increasing the water flow temperature in heating mode to perhaps 55 degrees but the more you increase it the less efficient a heat pump becomes and the more likely is that it will have to defrost.

[Hogboon]

I haver increased the reading of 50º [above] to 55º - which seems to be the max - and left everything else the same. The image, which remains incomrehensible to me, was take some 3 hours after the one above. 

[ProDave]

I am not familliar with your controller so can't help much more, a good read of the manual should make it a bit clearer.

 

You only have water flow of 24 degrees in that picture, I wonder if you have turned up the DHW temperature?

[Hogboon]

I posted my second image before seeing your reply - for which many thanks. I'll tinker. As it happens I am waiting for a visit from a bloke from the installation company later this afternoon. As for defrosting, I noticed this morning it was doing that about once an hour and that was before I altered anything.

 

About the first images I posted you say  "...the FLOW temperature, currently 50 degrees and shows the DHW  target temperature as 52 degrees. Third picture shows the flow temperature is 45 degrees and the return temperature is 38 degrees." These images were taken within seconds of eachother. How come the first one shows flow temp = 50º and the third one 45º ?

 

I don't know how old your Remote Controller is but presumably 2018ish. Mine was installed August 2020. The RMC software version in mine is 3.05.5a (Master). It seems to be Open Source but how to hack it or update it remain mysteries at present. Whoever wrote it needs horse-whipping i.m.h.o. as they/he/she seem not to realise that the Gregorian calendar has been in use since about 1582 whereas the software seems to expect manual entry of leap years and summer time etc. What would be a considerable improvement from my point of view [and I imagine yours] would be the addition of a simple sine function with editable parameter of latitude and longitude to take account of optimal generation from PV panels during daylight hours, but that would appear to be an ask too far.   

[ProDave]

I completely ignore all date and time functions in mine, I have not even bothered to set the clock to the right time.  I have wired a standard central heating programmer to control the heating on and off times, and the LG display is just a thing to go and look at if something has gone wrong, or a means to tinker with system parameters, like flow temperatures.

 

My unit dates from I think about 2016 but the way it came to me was "complicated" and although it was described as new, I was not entirely convinced that really was the case but in any event I think it was an old version being offloaded.

 

When you get your visit, ask him to show you how to adjust the heating water temperature, and the hot water temperature, and make notes or take photographs so you can repeat what he shows you.

 

[Gav_P]

1 hour ago, Hogboon said:

As for defrosting, I noticed this morning it was doing that about once an hour and that was before I altered anything

If it helps, I have seen my ASHP frost up for the first time today, it’s defrosted 3 times that I have noticed.

[Arvyd]

Hi guys, here are some files

 about Lg therma installation I found in the internet, maybe this info will be useful for someone.

Link to wetransfer:

https://we.tl/t-Ly2XDsiW3m

Edited January 7, 2021 by Arvyd

[Hogboon]

Morning all - thanks for the suggested line of interrogation with the company rep ProDave but I only saw it this morning! But things have moved on a bit and the details will appear on my introductory page - Heat Pumps, Lock Down and Darkest Somerset - rather than pollute your thread. But in a word they are going to install a new pump. Hoooray - possibly.

 

 

[Arvyd]

After 1,5 year of my experience with this monoblock when I thought that AI function is unusable at all, seems that I was wrong.

Guys I suggest You try AI function with seasonal settings in PPT file I added, and try set pump pre/ower run to another settings (my 2/2). Sensors air+ water. Seems heatpump working continuesly, I newer seen it before, without shuttdowns. The electricity consuption is wery interesting too.

Its just another way ?. Its short expierence, but maybe its right way.

Waiting for yours expierence if you try it.