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Ecodan standby power consumption


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Not really paid much attention until now but it appears that my Ecodan ASHP is consuming around 200W in power 24/7 when not in use. Seems a tad bit high for my liking, is this normal? Interested to hear from others to see if this is standard or an issue at my gaff!

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My heat pump is not in use overnight (unless it gets very cold) and consumes no power that I can perceive (the inverter on my solar panels logs power consumption).  Occasionally there is a little blip which could be the heat pump but on most nights that does not happen. 

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Is it really 200W continuous?  or 200W averaged over a period?

 

I think we determined on another thread, the Ecodan when it does it's automatic frost protection circulation turns on either the resistance heater or the heat pump itself so will briefly consume a lot more power.

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15 minutes ago, ProDave said:

Is it really 200W continuous?  or 200W averaged over a period?

 

200W average over 24H is 4.8kWh so like, 2 hours of 2.4kW resistance heating? I'd hope not!

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Does seem high.

Can you find any parts of it that are constantly warm. Or noisy.

Just to put that 200W into perspective, about what I used, on average, yesterday, for everything.

Edited by SteamyTea
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To be honest I haven't scrutinised the system too much. Got a few panels on the roof now so paying a bit more attention to what is consumed and where. Seems to be a constant 200W according to the emporia energy meter I have installed. We seem to be using approx 11kWh per 24hr at the minute, that 200W is a big chunk I'd like to eliminate so will need to dig deeper into this.

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7 minutes ago, LA3222 said:

To be honest I haven't scrutinised the system too much. Got a few panels on the roof now so paying a bit more attention to what is consumed and where. Seems to be a constant 200W according to the emporia energy meter I have installed. We seem to be using approx 11kWh per 24hr at the minute, that 200W is a big chunk I'd like to eliminate so will need to dig deeper into this.

I bought a cheap energy monitor and found it to be totally useless with PV and an immersion heater diverter.  It seemed to be summing the generated power and the imported power and coming up with a big number when in fact it was at equiulibrium with nothing being exported.

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Posted (edited)

I think this monitor is not too bad. I have 18 individual CT clamps for seperate circuits as well as for the total power used. Helps to drill down into what's going on.

 

So far after a crude bit of 'process of elimination' it appears that something on the outside unit is the culprit. System turned off I.e. standby or whatever and the drain is still there. Turn the breaker off and consumption dropped to zero.

 

Turned breaker back on and powered it all up, the 200W comes back. Turned the isolator off at the outside unit and the consumption dropped to zero again. Turned back on and reappeared.

 

So. What the hell within the outside unit is using 200W all the time when it's doing feck all. Just sitting. A big lump draining my electricity😒

Edited by LA3222
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6 minutes ago, SteamyTea said:

Band heater on the compressor maybe?

I did read somewhere about talk of resistance heaters to keep oil etc warm so it's ready to go. But 200W. That makes my eyes water just thinking of when my fixed tariff ends in June🧐

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7 minutes ago, LA3222 said:

But 200W

Only 3 old lightbulbs, or 2 if you are blind.

Open the case and see if you can touch the compressor when it has not been running.  Could be a fault if it is warm (stuck relay, broken thermostat).

If you cannot get your hand in safely, point an IR thermometer at it.

Edited by SteamyTea
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If I remember rightly the Ecodan units don't have a dedicated crankcase heater - they energise the (stationary) compressor windings to heat it up internally. It shouldn't be necessary at all when the unit is actually running (e.g. 24/7 in a cold climate) and shouldn't be necessary when it's warm out but I wager the UK climate will fit neither of those requirements for much of the year.

 

Stupid design in my view but that's what you get by bodging warm-climate rotary compressors meant for air conditioning into heat pumps. The better units will use scroll compressors purpose designed for heating that don't need crankcase heaters.

 

Do verify the draw using a real meter though (do you have a smart electricity meter that does instantaneous load?) as it could be an artefact of a noisy power supply etc.

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My understanding of compressor heaters is that they’re needed under fast cold-> hot temperature transitions.  That is, after it’s been cold and warmed up, the compressor being a big heavy lump remains cold for a while, and so is likely to have liquid phase A/C fluid inside it while there is gas phase everywhere else.  My understanding is that most compressors could be partially damaged starting up like this, so it’s safer to prevent it from happening by warming them up before turning them on.  This generally translates to keeping them forever warm (gah), so a vampire load.  It must be possible to heat only when needed though, even if this means a slow startup.  Is there a scroll/reciprocating compressor difference to this though?

As far as I know Ashp don’t generally state standby consumption, which could be quite high.

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Scrolls aren't damaged by liquid slugging the same way that reciprocating compressors are.

 

They also are less bothered about the refrigerant being mixed with the oil at initial cold start. Buildings that need cooling in a cool climate might still need heaters though.

 

CTC, Nibe, Thermia/Danfoss etc all use scrolls. It's the eastern AC manufacturers who use recip units.

 

Compressors won't be cold during the heating season if they're running 24/7. Intermittent use is another matter. You could get clever and only preheat when required. But if it isn't captured by official tests you can be they'll err on the side of maximum electricity use / minimum warranty claims unless making an explicit thing about performance of that element.

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You learn something every day.  Like for minimum "off" power demand, you want to choose an ASHP with a scroll compressor.  If that is a genuine advantage, I am surprised those that use scroll compressors don't make a big thing of it?

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The installation instructions specifically say to turn on the power at least 12 hrs before starting it up. I turned on for 24 hrs and it used about 300W in 24hrs. I can't remember where I read it but it is to pre heat the compressor as in cold weather the oil can get mixed in with the refridgerant (I think!) and it seperates again when warmed slightly. I dont think it's an issue when it is operating full time

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Well, as an update - I had emailed Mitsubishi technical about the issue and just recieved a response (fairly quick tbf). 

 

The ASHP requires constant electrical heat to the compressor, so it does not run cold after being idle for a while.

 

This is what the additional power is – and is totally normal.

 

So, it is apparently normal. Jeez, £500 a year energy consumption for an idle white box. I have followed up with 'how long before a call for heat kicks in does the compressor need to start warming up' - might get the thing on a timer of some description to cut down in this idling.

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For reference I had a Shelly EM monitoring my Nibe F2040. 

When not in use the standby power required is 39W. This includes running the internal control unit, & display etc (Can't normally hear any circulation pumps running).

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