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Weather compensation and air source heat pumps

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(@derek-m)
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Posted by: @sarah

I have also (last night) changed the comp curve to 45 (from 40) - it's not too warm outside today - so I will see if that makes a difference.  I've never been able to get this right in the 8 years I've had it - it either uses so much electricity when running that we are at the stage where we have to decide if we can afford to run it or when I make changes it doesn't heat up the area.  I really want to like the ASHP but I never have.

I'm assuming that you are not too technical, is that correct?

Could you please post photo's of all the equipment within your system so that we can get some idea about how it has been installed.

When you mention '3 boxes', are these thermostats?

 


   
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 SKD
(@skd)
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Joined: 3 years ago
Posts: 54
 

@sarah Hi, the highlighted "-30" your compensation curve is fine.  The two highlighted parameters on the graph are just indicating the curve at the marker point, which is the black spot at the bottom left hand corner. You can move this point along the axis using arrow keys, and the highlighted readings will update accordingly.  Hope this helps.

Mitsubishi Ecodan 11.2kW R32 ASHP; Ecodan DHW cylinder; UFH+rads
20x430W Jinko TOPCON Tiger Neo solar; Luxpower 6+4kW hybrid inverter; 20kWh LFP battery storage


   
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 SKD
(@skd)
Estimable Member Member
800 kWhs
Joined: 3 years ago
Posts: 54
 

Posted by: @sarah

@gary picture of flow rate

-- Attachment is not available --

When our Ecodan system was first commissioned we had a low flow rate, very similar to this.  The engineer simply cleaned the in-line strainer, and since then our flow rate has been over 20l/min.  The strainer gets checked on each annual service and it's remained clean.

I just thought it worth mentioning in case you have something similar going on, especially if your strainer hasn't been checked for some time.

 

Mitsubishi Ecodan 11.2kW R32 ASHP; Ecodan DHW cylinder; UFH+rads
20x430W Jinko TOPCON Tiger Neo solar; Luxpower 6+4kW hybrid inverter; 20kWh LFP battery storage


   
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(@sarah)
Estimable Member Member
421 kWhs
Joined: 2 years ago
Posts: 79
 

@skd Hi - yes that does!  I put on the compensation curve in March and hadn't looked since and when I saw yesterday thought I had not done it properly - thanks!


   
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(@sarah)
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421 kWhs
Joined: 2 years ago
Posts: 79
 

@derek-m yes not too technical - at least for heating systems!!!  I'm having to learn about it though.  Yes three thermostats in each room (they are all on same level) - the "slab" (about 70/80 sqmetres) is one level separated with three manifolds for each space (living area/bedroom and bathroom) - there are doors separating the room but they are not always closed.


   
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(@sarah)
Estimable Member Member
421 kWhs
Joined: 2 years ago
Posts: 79
 

I will post some photos later - I've got to go to work now - thanks.


   
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 Gary
(@gary)
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Posts: 305
 

In the Eng menu there is a pump speed setting from 1 to 5.  What is yours set to. If you increase it and go back to the running info what does the flow rate number change to.

How are you running the system hest pumps needs to be on for hours all day especially with ufh if yours is deep in the concrete you will never get the concrete up to temp if you don’t run it for long periods 


   
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(@sarah)
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Posts: 79
 

@gary its set to 5


   
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 Gary
(@gary)
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Joined: 2 years ago
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@sarah With the pump set to 5 the flow rate you are achieving is too low for the heat pump to be working correctly, it won't be transferring enough heat to the UFH circuit. 

When the heat pump is running if you go back to eng menu and into thermistor readings this will show us what the flow and return temps of the heat pump are and the outside temp at the time that will help clarify, but at the moment it looks like the heat pump flow rate is too low.


   
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(@sarah)
Estimable Member Member
421 kWhs
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Posts: 79
 

@gary hi - attached picture of thermistor readings...am I right i

IMG 8206

 n saying that TH1A is the room temp reading - not sure where that is set?  THW1 and THW2 are flow and return?


   
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 Gary
(@gary)
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Yes you are correct but room temp is the temp of the location where that controller is.

Is it currently heating hot water as flow and return aren’t in line with your WC curve.

If so check again when it’s doing heating

THW5 is your HW tank temp and TH7 is the outside temp by the heat pump 


   
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(@sarah)
Estimable Member Member
421 kWhs
Joined: 2 years ago
Posts: 79
 

@gary OK - so the actual controller which is next to the tank in a separate room - 15 degrees would be about right.  Attached a reading from just now

IMG 8207

   
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