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Air Source Heat Pumps (ASHPs)
Last Post by Derek M 4 years ago
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 Derek M
(@derek-m)
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Joined: 5 years ago
Posts: 4425
06/12/2021 3:47 pm  
Posted by: @adaml

@derek-m Thank you! This manual did not match my controller, however, this one does;

 

DAIKIN.EU "https://www.daikin.eu/content/dam/document-library/installation-manuals/heat/air-to-water-heat-pump-low-temperature/eblq-cv3/EDLQ_EBLQ-CAV3_EKC(2)B-CAV3_EKMBUHCA3V3-CA3V3_CA9W1_4PEN405544-1_IM_Installation+Manuals_English.pdf"

 

https://www.daikin.eu/content/dam/document-library/installation-manuals/heat/air-to-water-heat-pump-low-temperature/eblq-cv3/EDLQ_EBLQ-CAV3_EKC(2)B-CAV3_EKMBUHCA3V3-CA3V3_CA9W1_4PEN405544-1_IM_Installation%20Manuals_English.pdf

 

The link doesn't seem to work, sorry - if you Google this you should find it though.

Bivalent activation temp is currently set at the default of 0°C and bivalent hysteresis temp is currently set at the default of 3°C.

 

Please let me know if you have any suggestions?

Hi Adam,

You need to look at pages 68 and 69.



   
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 adaml
(@adaml)
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Joined: 4 years ago
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Topic starter 06/12/2021 4:09 pm  

@derek-m Got it - thank you! I think me reading it, understanding and knowing what is sensible are all different things. I can see though that @editor advice earlier is down to this setting to prevent the ASHP activating when it is not beneficial to do so.

Do I understand correctly that as set the ASHP will not activate below 0° and will not activate until the ambient temp is above 3°C?

Screenshot 2021 12 06 at 16.05.06


   
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 Derek M
(@derek-m)
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Joined: 5 years ago
Posts: 4425
06/12/2021 4:29 pm  

@adaml 

Hi Adam,

The way I interpret the instructions, is that as the ambient air temperature falls to 0C, the ASHP will be switched off, and the controller will send a permission signal to the gas boiler to switch on. The reverse happens when the ambient air temperature rises to 3C.

A more economical option would be to input the tariff values for both gas and electricity into your controller, and let the controller decide when to change from ASHP to gas. Based on your present tariffs, your ASHP would require a COP of 5.11 or higher, to make it economically viable to run your ASHP in preference to your gas boiler.



   
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 adaml
(@adaml)
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Topic starter 06/12/2021 4:50 pm  

@derek-m 

Hi Derek,

 

That makes complete sense, sorry I think I had become too focussed on Possibility 1 and negated to spot the other option. I have my current tariffs setup already.

I have noted it states;

To have an optimal operation when choosing possibility 2, it is for [C‐04] recommended to choose a higher value than the default value.

[C-04] is Range: 2°C~10°C (default: 3°C) (step: 1°C). I have increased this to 6°C - a guesstimate, so if any input please let me know?

Depending on the used boiler, the boiler efficiency should be chosen as follows:

#

Code

Description

[A.6.A]

[7‐05]

  • ▪  0: Very high

  • ▪  1: High

  • ▪  2: Medium

  • ▪  3:Low

  • ▪  4: Very low

The option of 0: Very high is already selected.



   
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 Derek M
(@derek-m)
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Joined: 5 years ago
Posts: 4425
06/12/2021 5:50 pm  

@adaml 

Hi Adam,

Do you know what COP you are getting from your ASHP at the moment?

I suspect it will be less than 5.11, in which case your gas boiler should be running.

You should be able to get operational data from the controller.



   
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 adaml
(@adaml)
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Topic starter 06/12/2021 6:03 pm  

@derek-m 

Hi Derek, yes definitely less than 5.11. November was 3.96 and December to date is 1.6.



   
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 Derek M
(@derek-m)
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Joined: 5 years ago
Posts: 4425
06/12/2021 6:08 pm  

@adaml 

1.6 seems quite low, have you made any changes?



   
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 adaml
(@adaml)
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Topic starter 06/12/2021 6:15 pm  

@derek-m 

 

I've been playing around with the weather dependent curve;

 

45°C flow at -1°C and 30°C flow at 15°C

then

50°C flow at -5°C and 30°C flow at 20°C

then

50°C flow at -7°C and 31°C flow at 14°C

 

I am also running the system for longer, so unfortuntely lots has changed and I wonder if I'd be better reverting it all with the exception of lowering the DHW temp.

The trouble being I am not sure what impact this will be having on my COP as I cannot get granular data from the controller. 



   
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 Derek M
(@derek-m)
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Joined: 5 years ago
Posts: 4425
06/12/2021 7:10 pm  

@adaml 

Hi Adam,

Given the difference in the tariff rates for electricity and gas, I would expect your ASHP to only be operating when the ambient air temperature is in the range of possibly 15C and above.

The other thing that I discovered, is that when used with radiators, the ASHP is set for a delta T of 8C between flow and return temperatures. This is probably why you cannot set the weather compensation curve below 30C.

I am still trying to get my head around how the system will work on weather compensation, when for most of the time the gas boiler will be on and the ASHP will be off. You can correct me if I am wrong, but I suspect the controller will be acting more like a thermostat, and just switching the gas boiler on and off to control the temperature.

Could you monitor and report back on the system operation, whilst I have a read through the correct manual.



   
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 Derek M
(@derek-m)
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Joined: 5 years ago
Posts: 4425
06/12/2021 7:34 pm  

Hi Adam,

One thing that I forgot to ask, did you have any optional equipment installed?

 



   
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 adaml
(@adaml)
Trusted Member Member
Joined: 4 years ago
Posts: 42
Topic starter 06/12/2021 7:37 pm  

@derek-m 

Hi Derek,

Yes I would say you are correct, the ASHP was operating more in November when the outside temps were around 11-15°C and we could bring the house up to 21°C without the gas boiler.

The outdoor temp tonight is 2.5°C and the desired water temp is showing as 42°C - which is based on the weather comp curve. The gas boiler is firing and on the LED for the boiler it is showing as 48, if I raise the DHW temp to 49 and run the hot tap this display shows 49 so would appear to be degrees Celsius. I wonder where the 48°C is coming from for the gas boiler water temp for the radiators?

That is also correct, it's acting more like a thermostat at the moment switching the gas boiler on and off to maintain the house temp of 21°C. I suppose that is in part what triggered my curiosity to explore what was going on with the ASHP side of things. The ASHP was last active a couple of days ago early one evening for perhaps an hour and then the gas boiler took over.

Thanks for all your help so far, really do appreciate it!

Adam

 

 



   
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 adaml
(@adaml)
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Joined: 4 years ago
Posts: 42
Topic starter 06/12/2021 7:40 pm  

@derek-m 

No extras. The gas boiler is EHYKOMB33AA, the ASHP unit EVLQ05CAV3 and the controller EKRUCBL2.

 



   
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