9Kw LG Heat Pump

[Potatoman]

Can anybody tell me why my flow rate oscillates so frequently, the image is over 24 hrs. The Heat pump is controlled by a Homely, but that does not control flow rate.

[SteamyTea]

I have no idea what is going on.

But when sampling (in statistics) you have to make sure that the sample rate is high enough to capture enough data (Shannon sorted this all out and it is why we have MP3s and reliable internet).

To me it looks like it is only sampling every few minutes, and they are not coinciding with reality.

 

https://en.wikipedia.org/wiki/Nyquist–Shannon_sampling_theorem

[JohnMo]

Something like this?

There are several ways to setup how the circulation pump runs, yours looks to run based on compressor running. Your heat pump will have a temperature controller which regulates flow temp. The circulation pump looks to be going off with the compressor.

 

The drops in flow rated other than on off is the circulation pump being modulated to maintain flow return differential temperature.

[ReedRichards]

There is a setting which gives you various control options for the circulation pump.  Not all of these (e.g. the option to aim for a particular delta T) are likely to give you a fixed flow rate.  Which option have you chosen?

[Potatoman]

 Hi, thanks for that, do you think it is more or less efficient set up like this and is there anything I can do about it.

[Potatoman]

Hi, I have recently changed that setting to optimal,it has helped a little

[sharpener]

Looks like the compressor is cycling on and off bc the heat demand is less than the min it can modulate to, and the circulation pump flow rate is following that.

Not a problem in the absence of other indications or error messages IMO.

[Potatoman]

Hi, that's interesting,I do believe the heat pump is oversized. Is there any way to encourage a heat pump to modulate, low noise mode perhaps

[JohnMo]

Low noise mode will reduce output across the board doesn't make it want to modulate more.

 

If you have Homely it's sorting out the running modes.

 

What are trying to fix?

[sharpener]

9 minutes ago, JohnMo said:

Low noise mode will reduce output across the board doesn't make it want to modulate more.

 

Many ppl would think cycling less than 3 times per hour is fine, my 12kW Vaillant cycles like this in mild weather but I am not angsting about it.

 

10 minutes ago, JohnMo said:

What are trying to fix?

 

+1

[JohnMo]

4 minutes ago, sharpener said:

Many ppl would think cycling less than 3 times per hour is fine,

If you look at the best performing (CoP and SCoP) on the heat pump monitor, they all cycle quite a lot. It's a normal behaviour.

[Potatoman]

Hi, that's interesting, I am just trying to get the heat pump to run as efficiently as possible and looking at the flow rate/heat pump on ,off and wondering if it was excessive

[Potatoman]

With what has been said about low noise mode, would that help efficiency, as my Heat pump is well oversized.

Edited 15 hours ago by Potatoman

[sharpener]

14 hours ago, Potatoman said:

With what has been said about low noise mode, would that help efficiency, as my Heat pump is well oversized.

 

Depends. It will not improve the modulation range of the compressor, just restrict the use of the top part of the range. It might reduce any temp overshoot if you are seeing that at any point.

 

You might find there is a mains current limit setting which will have a similar effect. In addition to NR I have this turned down to the min of 20A, as some of the time it runs off my battery storage system which can only provide 4.4kW for everything in the house.

 

NR mode might improve CoP for DHW production, the restricted power means less of a delta T between the flow in the coil and the body of the cylinder. So higher CoP as the HP runs at a lower flow temp. Vaillants have a DHW Eco mode which does this as well.

[JohnMo]

14 hours ago, Potatoman said:

With what has been said about low noise mode, would that help efficiency, as my Heat pump is well oversized.

Homely is running the heat pump changing the demand flow temp etc. to get lowest running costs.  I would be careful trying to hard, Homely may just throw a wobbly or just overwrite your settings anyway.  If it's mild outside any heat pump will only run a short while because the radiators or UFH cannot shift the heat quickly enough. The only way to make it run a long time, is to use an elevated flow temp.

 

If want Homely to run your heat pump then let it do so, or remove it and set it up yourself, not sure there is a middle ground. Homely is set to manipulate any or all heat pump settings to get the best energy usage/cost.