joe90 Posted December 15, 2022 Share Posted December 15, 2022 Recently noticed the ASHP goes off (outside unit) but the internal pump still runs. DHW calling fir heat to drive the ASHP but after a short while the unit just stops. There is some frost on it but why would the unit turn off rather than go into defrost mode. As I and others have said before the command controller is horribly complicated but I believe it’s set up properly. So with the internal pump going the DHW is loosing heat via the ASHP being “off”. Our ASHP has no internal pump just the internal one driven by the comments unit. HELP Link to comment Share on other sites More sharing options...
SteamyTea Posted December 15, 2022 Share Posted December 15, 2022 What happened last winter when you had a similar problem, did you change some pipework about? Has a sensor fallen off somewhere, are all connections good? Mild weather coming in on the weekend. Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 (edited) Hi Nick, last years problem was UFH problem and buffer tank plumbed wrongly 🙄. It’s started again after a while turned off (to stop draining the DHW tank of hot water) this small 4KW model has no led,s to show error codes, they exist only on the 12KW model apparently (busy reading info on the net). However, the pipe running out of the compressor does seem very hot, and has a temp sensor on it, could the compressor be overheating ? Edited December 15, 2022 by joe90 Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 Right, sit rep…..,I removed the temp sensor to see if that would start it, NO. After a couple on minutes the compressor tries to start but only for about 5 seconds then stops again 🤯. Link to comment Share on other sites More sharing options...
ProDave Posted December 15, 2022 Share Posted December 15, 2022 Hot pipe out of the compressor usually means the water is not removing the heat from the heat exchanger fast enough. I would look at your plumbing to ensure water is really flowing to the outside unit. It could be the pump is running but no flow due to ice or an air lock for example? Is the pressure high enough? 1 Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 (edited) 6 minutes ago, ProDave said: Is the pressure high enough? Yes, first think I checked. I don’t have flow meters 🤷♂️ Edited December 15, 2022 by joe90 Link to comment Share on other sites More sharing options...
JohnMo Posted December 15, 2022 Share Posted December 15, 2022 Are you diverter valve(s) opening correctly. Not sure if you 2x 2 way or a 3 way? Sounds like there is a blocked flow path? Is it ok in heating mode? Link to comment Share on other sites More sharing options...
ProDave Posted December 15, 2022 Share Posted December 15, 2022 So find the heat exchange in the outside unit. It will have 2 thin refrigerant pipes probably soldered, and 2 larger water pipes. If the refrigerant pipes are hot, and possibly both the same temperature, but the water pipes are cold, this suggests little or no flow through the water pipes to take the heat away. In normal operation you would expect one refrigerant pipe to be hot and the other to be less hot as the water will have removed some heat as it passes through the heat exchanger, and you would expect the water pipes to be warm. I had lots of low flow issues with mine when I first ran it and the best thing I did was bought a flow meter and connected that in line with the pipes to the outside unit so I could see what flow I was getting. 1 Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 My ASHP is built like a modern car, very difficult to work on and cramned in, so difficult to see let alone feel pipes. Link to comment Share on other sites More sharing options...
ProDave Posted December 15, 2022 Share Posted December 15, 2022 Can you post a picture? Do you have an IR thermometer so you can do a non contact temperature reading of a hard to reach part? Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 Ooh that’s interesting, turned off DHW (turned down stat and switched on immersion) and running the UFH it appears to run, will give it more time ……… Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 (edited) I pulled some insulation off….. but spooky it’s running the UFH with no problem 🤷♂️, makes me think it’s not the ASHP (phew). You can’t see it but there is a smaller “cylinder” behind which has some frost on it. Edited December 15, 2022 by joe90 Link to comment Share on other sites More sharing options...
ProDave Posted December 15, 2022 Share Posted December 15, 2022 How is yours plumbed to switch between hot water and heating? two 2 port valves ore one 3 port valve? Try turning the hot water back on again and see if the fault comes back? I am not seeing anything in that photo that looks like a heat exchanger to me (does not mean it is not) Link to comment Share on other sites More sharing options...
joe90 Posted December 15, 2022 Author Share Posted December 15, 2022 2 minutes ago, ProDave said: two 2 port valves ore one 3 port valve? A change over 3 port (I know you don’t like them,!,!) 2 minutes ago, ProDave said: Try turning the hot water back on again and see if the fault comes back? Yes I will do this after I get some heat into the floor and prove it will run fir a few hours at least 3 minutes ago, ProDave said: I am not seeing anything in that photo that looks like a heat exchanger to me That was my thought, without dismantling loads of stuff I can’t get to where a heat exchanger “might” be. However if the UFH continues to work ok I have proved the fault in the DHW cct (and not the ASHP thankfully) 👍 Link to comment Share on other sites More sharing options...
ProDave Posted December 15, 2022 Share Posted December 15, 2022 1 minute ago, joe90 said: A change over 3 port (I know you don’t like them,!,!) A 3 port 2 position changeover valve is okay, they feed one or the other, never both. It is the 3 port mid position valve that by some trickery / bodgery can be made to stop half way and feed both together that I think is the work of the devil. 1 1 Link to comment Share on other sites More sharing options...
joe90 Posted December 20, 2022 Author Share Posted December 20, 2022 It appears now that it does not matter if the ASHP is feeding the DHW or the UFH, the ASHP fan starts, the compressor starts but within a few minutes it all switches off again. The command unit indoors has a symbol that shows if the compressor is working, this never comes on. I have tried lowering and raising the pump speed to see if it makes a difference but no. Can anyone recommend the next course of action before I have to get an ASHP engineer to visit 😞 Link to comment Share on other sites More sharing options...
ProDave Posted December 20, 2022 Share Posted December 20, 2022 Take the cover off the ASHP, instruct it to start, then go and listen / observe, can you even hear the compressor starting or trying to start? Link to comment Share on other sites More sharing options...
joe90 Posted December 20, 2022 Author Share Posted December 20, 2022 3 minutes ago, ProDave said: Take the cover off the ASHP, instruct it to start, then go and listen / observe, can you even hear the compressor starting or trying to start? Yes, it wobbles, starts but turns off after about 3 minutes (as if something is instructing it to abort!) the symbol on the command unit never comes on which I take as “it’s not reached it’s operating criteria” 🤯 Link to comment Share on other sites More sharing options...
dpmiller Posted December 20, 2022 Share Posted December 20, 2022 there's generally a stabilising period before they ramp up to full power, are you *sure*there's enough water and flow in the circuit? Can you read the signal from the flowmeter/ is there a visual flowsetter? Link to comment Share on other sites More sharing options...
joe90 Posted December 20, 2022 Author Share Posted December 20, 2022 38 minutes ago, dpmiller said: Can you read the signal from the flowmeter/ is there a visual flowsetter? No flow meter 🙄, pump sounds normal tho! I have just ramped the pump up to max and it appears to be running!!,!, compressor symbol now on 🤞 I will let it run fir a bit and report back. Link to comment Share on other sites More sharing options...
dpmiller Posted December 20, 2022 Share Posted December 20, 2022 worth having a flowsetter inline, just for visual confirmation. So restriction or airlock? Link to comment Share on other sites More sharing options...
joe90 Posted December 20, 2022 Author Share Posted December 20, 2022 With the pump ramped up a bit it appears to be fine now, time will tell. Link to comment Share on other sites More sharing options...
ProDave Posted December 20, 2022 Share Posted December 20, 2022 So it sounds like it was tripping on insufficient water flow. Perhaps there is a filter of some sort that is partly blocked and increasing the pump speed has get the flow back to acceptable limits. This is one area heat pump manufacturers could improve. My unit tripped with a low flow error (at least it had the grace to tell you why it had tripped) when I first installed it. Water flow was measured with a flow switch. Now the stupid bit, the installation manual did not even state what the minimum flow was. It took a call to the manufacturer to find that out. I then had to buy a flow meter to find out how far short I was, and the answer was not a lot. I added a second pump to boost the flow. Link to comment Share on other sites More sharing options...
ReedRichards Posted December 21, 2022 Share Posted December 21, 2022 In the case of our LG Therma V's, @ProDave, a flow rate error shortly after installation seems to be a "known bug". Quote First two weeks: Blocked filters and/or air pockets Flow rate alarms are likely to occur during the first two weeks after commissioning; this is due to the formation of air-pockets which may occur and temporarily affect the flow-rate. In most cases, the air will migrate to the auto-air vents (AAV) and release without any requirement for intervention. Equally, if any sediments are in the hydronic pipework, they will be caught by the internal strainer. Blockages in the strainer can cause CH14 alarms. In this case, the strainers will need to be cleaned Recommendation: once the unit has been installed, advise the customers that it is quite likely and normal for a CH14 alarm to occur in the first two weeks. This will give the customer reassurance if and when the fault does arise! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now