ASHP Differential Temperature Settings

[Marvin]

HI

 

I noticed that our ASHP cycling is a bit too short on our Coolenergy inverTech Monoblock.  To extend the cycling period I have been looking at the Differential Temperature Settings.

 

Can anyone please explain what these two mean:

 

Hotwater setpoint.

Temp. diff. = (Default 5c) (Temperature differential before restart)

Stop temp diff. = (Default 0c) (Buffer range to optimise compressor frequency)

 

I guess that Temp diff  means the distance between the set point and where the ASHP reacts: (Set at 5 degrees on heating means 5 degrees below turn on and 5 degrees above turn off?)

 

 But I'm not sure I understand this one at all: Stop temp diff.

 

Thanks

[Marvin]

17 minutes ago, Marvin said:

HI

 

I noticed that our ASHP cycling is a bit too short on our Coolenergy inverTech Monoblock.  To extend the cycling period I have been looking at the Differential Temperature Settings.

 

Can anyone please explain what these two mean:

 

Hotwater setpoint.

Temp. diff. = (Default 5c) (Temperature differential before restart)

Stop temp diff. = (Default 0c) (Buffer range to optimise compressor frequency)

 

I guess that Temp diff  means the distance between the set point and where the ASHP reacts: (Set at 5 degrees on heating means 5 degrees below turn on and 5 degrees above turn off?)

 

 But I'm not sure I understand this one at all: Stop temp diff.

 

Thanks

I now know that the Temp. diff. is only the difference before restart

 

So I assume that the Stop temp diff. is how much the Temperature differential before stop?

 

Related to heating: Why not just set the temperature a little higher instead of extending the stop temp???

 

Edited December 6, 2022 by Marvin
further thoughts

[dpmiller]

Stop difference allows the inverter to wind down more progressively, lessening the chance of / ignoring an overshoot (lack of buffer capacity eg) and reduces short-cycling in my experience.

[HughF]

@MarvinI see from the ecodan thread that you were able to reduce cycling by adjusting the differential stop temp, which way did you adjust it?

 

Could you post up your most recent settings for us running the same ashp, it would be helpful.

[Marvin]

Hi @HughF

 

I think that all technical adjustments require trial and error and will be specifically related to the properties individual installation and location.

 

That said, we are running like this:  

 

5. Differential Temperature settings:

 

Hotwater set up:

Temp diff. set at 4°

Stop temp diff. set at 3°

 

Also the Weather Compensation has been bespoked.

 

 

However, our set up is:

 

Bungalow with 104m2 floor with AIM and APE(search on buildhub the word APE if your not familar)

ASHP: Coolenergy CE-iVT9r.

60 litre buffer tank. 15 litres used as expansion vessel.

 

Total system liquid volume 132 litres. 27% antifreeze. All pipes, ASHP, buffer and radiators volume.

 

205 litre hot water tank.

Radiators.

No UFH 

 

All external pipes (28mm) super insulated. (Total length less than 2 meters)

All primary pipework (28mm) highly insulated. (Total length less than 10 meters)

 

Buffer tank additionally insulated.

 

Hot water tank additionally insulated.

 

All the above means we are running like this: 

 

Inside temp 22°C

Heating temp set at 40.5°C by weather compensation.

Outside temp now 3.4°C was down to -1°C.

Last 24hrs 14.03kWh used for heating and hot water.

 

Reasonable is possible. 

 

Good luck

 

M