Summer operation in a heat wave - is it advisable for ASHP to be off for long periods

Hardware Heatpump
1

In the UK, at least on the south coast we are experiencing exceptionally high solar.

I have an 8KW Samsung HTQuiet with 10kWh batteries and in this weather I regularly get 25kWh from my solar panels daily. This is more than enough to power the house, heat the water using a diverter and charge my EV. (No export tariff).

I have set the DHW so that the ASHP still runs for at least 30 minutes even though I do not need the energy efficiency saving (I limit the hot water immersion solar charge so that the ASHP will always run daily).

My question is should I allow the heat pump DHW to be completely off during the summer months. Could this risk long term damage to a two stage compressor.

What do others do? Do you let the compressor go idle for weeks on end. Some reading suggests this is a bad idea but maybe I am being over cautious.

PS there are no options to run my ASHP as an ACU in hot sunny weather unfortunately.

2

Best thing I did with our self install (no MCS) was to pay Octopus £250 to get export enabled. You could then use the ASHP to heat water as normal and export everything else and get 12p per kWh. If you have a battery sign up to Axle VPP and get £1 per kWh during events.

3

Can you actually get 12p/kWh under the non-MCS Octopus scheme? I was certain that this would only get you a basic SEG rate…

4

Yes as long as you have a working smart meter, they will give you 12p.

5

Our situation is similar with a Samsung R32 8kW ASHP. Both HW and heat are off at the moment but the pump seems to run about once a day for about 5 minutes, taking heat from the HW cylinder. I would guess that this is automatic in order to keep the compressor lubricated. That’s just a guess though.

6

Interesting question, @designerguy, so much so I just asked it of the Samsung UK Helpdesk, and they have replied:
“Keeping the units turned OFF from the remote controller, even for prolonged times, will not have any negative effect on the units as long as they still got power to them and the power not are turned OFF on isolators or in consumer units.”
My 8kW HTQ consumes about 15W in standby mode (according to NASA 0x8413), so in the scheme of things not something to lose sleep over…

7

Actually, @billt, I believe this is just circulating pump anti-seize (see Samsung Gen6, Joule Kodiak pre-plumbed DHW tank - pumps running every 24h - #3 by toadhall), rather than compressor lubrication.

8

Thanks Sarah. That is reassuring. I will just make sure the isolator is not turned off. I would like to see the compressor turning and distributing lubricant once a week though as part of an automatic maintenance cycle during the summer months or whenever the property is vacant. The longevity of a modern ASHP without costly maintenance is one of the key usp’s. I do not want to compromise that so I think I will make sure it runs occasionally and be ready for the heating season.

9

Hi Johnmo, Thanks for the reply. Good point . I could use the ASHP in place of resistance heating. It would free up say 5kWh on the sunniest day for export. In a normal summer there is not usually so many days of maximum solar so the export opportunities would not justify the expense in my case. Interesting to know you got your export enabled from Octopus I started the process but withdrew from it. I will start another thread to see what others experienced with Octopus self instal export meter.