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ASHP Standby Electricity Consumption


Kev M
(@kev-m)
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This was a discussion on another forum, with some reports of over 200W standby and some of near zero. The higher usage was attributed to compressor crankcase heaters or similar.  That can add up to a lot of money at today's prices.

What are others' experiences?  You'll have to have some sort of monitoring on your ASHP or electricity supply and and clamp on meters are not always reliable for this.

My ASHP uses about 24W, whether on stop mode (system running but ASHP not) or standby (system off at the controller).  I think that's due to standby power for the controller unit and the pumps.  I'm not unhappy with that although lower would be better.

Anyone else?


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Mars
 Mars
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I have certainly noticed something similar. A few months ago, when we were running HVO, our heat pump was in standby mode and when I’d go into the utility room, I would notice that one of our mandated RHI metres (because we’re running bivalently) would occasionally flash its red light indicating that the heat pump was using electricity, but not generating heat.

I raised this with Global Energy Systems and they assured me that the pump was not working and consuming electricity.

Our heating has been off completely since late April so our consumption is down. The heat pump is doing HW and is in standby 24/7.

I noticed something odd a few weeks ago on our SolarEdge app. We get hourly spikes in consumption. I couldn’t put my finger on it. Then last week, I turned our heat pump off completely to see if it was responsible. It was. With the heat pump off (not in standby) the spikes vanished.

86757653 673A 4141 A27D B2D7EC8F4013

Caernarfon 18kW ASHP from Global Energy System – 6.16kW solar PV array
Follow our sustainability journey at My Home Farm
Our heat pump installation: https://youtu.be/c3V0k_GeFOo


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ronin92
(@ronin92)
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Can an ASHP be turned off for a protracted period without damage?


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Kev M
(@kev-m)
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946 kWhs
Joined: 1 year ago
Posts: 759
Topic starter  
Posted by: @editor

I have certainly noticed something similar. A few months ago, when we were running HVO, our heat pump was in standby mode and when I’d go into the utility room, I would notice that one of our mandated RHI metres (because we’re running bivalently) would occasionally flash its red light indicating that the heat pump was using electricity, but not generating heat.

I raised this with Global Energy Systems and they assured me that the pump was not working and consuming electricity.

Our heating has been off completely since late April so our consumption is down. The heat pump is doing HW and is in standby 24/7.

I noticed something odd a few weeks ago on our SolarEdge app. We get hourly spikes in consumption. I couldn’t put my finger on it. Then last week, I turned our heat pump off completely to see if it was responsible. It was. With the heat pump off (not in standby) the spikes vanished.

86757653 673A 4141 A27D B2D7EC8F4013

@editor Mars,

see attached. This is how Mitsubishi explains how crankcase heating works.  It does manifest itself as spikes.  Not all compressors (and not even all Mitsubishi ones) do this. 

 

This post was modified 2 weeks ago by Kev M

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Kev M
(@kev-m)
Member Moderator
946 kWhs
Joined: 1 year ago
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Topic starter  

@ronin92 

I think yes within reason.  They will have a start up procedure before they start running properly.  Best ask your installer/manufacturerto be sure.

This post was modified 2 weeks ago by Mars

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Mars
 Mars
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@kev-m, very interesting. At least that's confirmed my suspicions. It's a shame our ASHP doesn't have a timer to just turn it on to do HW in the summer. It would save the spikes and wasted energy.

Caernarfon 18kW ASHP from Global Energy System – 6.16kW solar PV array
Follow our sustainability journey at My Home Farm
Our heat pump installation: https://youtu.be/c3V0k_GeFOo


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Mars
 Mars
(@editor)
Member Admin
2713 kWhs
Joined: 1 year ago
Posts: 1168
 
Posted by: @ronin92

Can an ASHP be turned off for a protracted period without damage?

Yes, I believe it can. Do you mean off off, like totally off doing nothing? We have switched our heat pump off for weeks at a time in the summer when we've had loads of sun around at the solar PV heated our HW. But as Kev suggests, speak to your manufacturer because different compressors behave differently. 

Caernarfon 18kW ASHP from Global Energy System – 6.16kW solar PV array
Follow our sustainability journey at My Home Farm
Our heat pump installation: https://youtu.be/c3V0k_GeFOo


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