Julian S Posted July 22 Share Posted July 22 Has anyone ever come across the compressor in a Samsung ASHP turning itself off during cold weather? This happened to me last winter when our 12kW Samsung (model AE120RXYDEG/EU) system ended up pushing ice-cold glycol around the house during a cold frosty night (-10C outside). There were no errors on the controller, the heat pump fan was running (couldn't hear the compressor though), all the valves and pumps were working, and the regular freeze-prevention cycle operated during the night as normal prior to programmed heating start from 4am to 7am (Cosy Octopus tariff) – so it seemed to me that the compressor had stopped for some reason. Following a suggestion from someone locally, I got the system going again by diverting the glycol through the hot water cylinder (heated using the immersion) and using that to heat up the ASHP again (and it has been fine since). Although my assumption was that the compressor had stopped working, I have not been able to find any information to suggest that cold temperatures can cause that to happen. Can Samsung ASHP compressors really turn themselves off when it's particularly cold outside without causing any error messages on the Samsung controller? If so, under what conditions can this happen? I hope to get a better understanding to that I can take steps to stop it happening again. Many thanks for any help and insights you might have. Link to comment Share on other sites More sharing options...
JohnMo Posted July 22 Share Posted July 22 (edited) The cost tariff but confuses me are you saying at -10 you only run the heat pump for a couple of hours? If you are only running on a set tariff period I would check your programmes to check what's occurring. If your system has cooled to sub zero temperature it will take hours to recover. That's why it's pump cold water around. Things to check crankcase heaters, if the crankcase isn't warm no start. In sub zero temps don't switch it to standby or off. Cosy isn't really designed for heat pumps (heat pumps and battery yes) running for short bursts is no use . Edited July 22 by JohnMo 1 Link to comment Share on other sites More sharing options...
Julian S Posted July 22 Author Share Posted July 22 38 minutes ago, JohnMo said: The cost tariff but confuses me are you saying at -10 you only run the heat pump for a couple of hours? If you are only running on a set tariff period I would check your programmes to check what's occurring. If your system has cooled to sub zero temperature it will take hours to recover. That's why it's pump cold water around. Things to check crankcase heaters, if the crankcase isn't warm no start. In sub zero temps don't switch it to standby or off. Cosy isn't really designed for heat pumps (heat pumps and battery yes) running for short bursts is no use . Thanks for your reply, JohnMo. Yes, we were running the heating for 3 hrs 4am to 7am to warm the UFH to take advantage of the cheap Cosy tariff (very well insulated house), but I agree that probably not best practice for the HP when it's very cold. It's weird that there wasn't an error on the controller though. Are you saying that the heatpump should have a crankcase heater and it might not be working, or that I should consider fitting one? Thanks again. Link to comment Share on other sites More sharing options...
JohnMo Posted July 22 Share Posted July 22 11 minutes ago, Julian S said: Are you saying that the heatpump should have a crankcase heater and it might not be working, or that I should consider fitting one? They all have them, but some also look at crankcase temperature as a permission to start the compressor. It may not have an error code for it. We are also well insulated and ran the heat pump mostly in the E7 cheap period, but even then used a lot more than expected although very cheap energy. This year I am doing straight WC and compare. Our WC curve is something like 26 @ 10 OAT and 31 @ -5 to see how it goes. With Cosy I would just reduce target temp a couple of degrees during expensive period. And maybe uplift target during really cheap periods. Get your WC curve right it will modulate itself well. Link to comment Share on other sites More sharing options...
Julian S Posted July 22 Author Share Posted July 22 1 hour ago, JohnMo said: They all have them, but some also look at crankcase temperature as a permission to start the compressor. It may not have an error code for it. We are also well insulated and ran the heat pump mostly in the E7 cheap period, but even then used a lot more than expected although very cheap energy. This year I am doing straight WC and compare. Our WC curve is something like 26 @ 10 OAT and 31 @ -5 to see how it goes. With Cosy I would just reduce target temp a couple of degrees during expensive period. And maybe uplift target during really cheap periods. Get your WC curve right it will modulate itself well. Good advice - thank you. Link to comment Share on other sites More sharing options...
sharpener Posted July 22 Share Posted July 22 6 hours ago, Julian S said: Are you saying that the heatpump should have a crankcase heater and it might not be working Sounds plausible, IIRC Daikin HPs have a similar restriction, there is a minimum temp at which they will start, below that they do not in order to protect the compressor(!). Link to comment Share on other sites More sharing options...
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