Heat Pump background /idle power consumption

[Countrypaul]

We have an 11.2kW Ecodan ASHP, in recent weeks this has not been required for either hot water or space heating yet it is still consuming a significant amount of electricity, around 1/2kWh per day which I assume is its background usage. I have tried searching online but not found anything concrete, however I have found some heat Pump owners that appear to have background loads as high as 275W (24/7) which seems absolutely crazy.

Has anyone on here got any figures for what their HP uses?

At ths time of year I could probably turn it off, but as soon as I do and we get a couple of poor sunshine days, my life will be made miserable 

1/2 kWh per day at present is probably <8p /day so not worth me taking the risk of having insufficient hot water.

[Philip R]

I went looking on the internet. Seems that several brands of HP have high quiescent power consumption that adds up to quite a chunk of energy that has to be paid for.
Seems to be heaters used to keep the compressor warm.


Have a read of these comments :  http://johncantorheatpumps.blogspot.com/2013/08/stand-by-power-and-air-source-heat-pumps.html

[marshman]

I know it is not Air Source, but my 10kW GSHP has consumed 0, (zero), kWh since 16th May 2020 when it last was used for DHW.  It does fire up the circulation pumps once every so often, but only for a few minutes,  not sure what protocol it is using, I only know this because I have heard them on occasion.

Can't think why an ASHP would consume anything if there is no heat demand - unless there are circulation pumps running on the wet side - assuming an Air to Water - in which case maybe a simple thermostat to shut the power off over a certain room temp would suffice.

Roger

[Philip R]

Running the pumps few a minute every day is to help prevent them from jamming.

[benseb]

Aparently there’s something to do with the way the ASHP uses a reactive load that shows up as high standby consumption but doesn’t actually use that much

When I’ve Monitored our Ecodan the power sits about 200w but the flow switches between “usage” and “generation” so probably nets close to zero


Looking at the app we’re using approx 400-500w per day on standby for heating.

[Countrypaul]

Having checked with Mitsubishi, the Ecodan does keep the crankcase warm with a heater which accounts for the 1/2kHw per day we are seeing as a standby load - this doesn't appear to be mentioned in any of the literature that came with it. They have advised that it we turn the entire Ho off, we should turn the outside unit on for 2-3 hours first then switch it off turn the indoor person on followed by the outdoor unit in order that the crankcase is warm before the control system is started.

having read more around the sbject we are lucky some ASHP appear to use upto 275W on standby 

[knighty]

the crank case heater is to stop the refrigerant gas dissolving into the oil...

if you check what kind of gas your system has in (should be on a sticker somewhere)

you could check the temperature needed to keep it out of the oil, and then fit a thermostat to keep the compressor above that temperature?


you might even be able to put it on a timer? - it'll need googling to check but I wouldn't be surprised in an hour a day to get the gas out of the oil would do?

[DonL]

I have been logging my Panasonic ASHP consumption and it does no heating all summer as I do not use it for hot water. In the summer months it uses between 10 and 14 kWh per month (or about 14 to 20w if it is drawing power constantly).