Heat Pumps - post here.

@fitzparker Can you adjust the flow temperature of you oil boiler ? If so, simulate a heatpump by reducing the flow temperature

A heatpump should be able to be clipped onto the oil flow and return, but with even the grant, I think you will rarely escape with under €10k net 😮 - which is completely nuts.

I hope someone proves me wrong on this

Here is the load from my house this morning, charging 2am to 5am with washing machine and dryer running.
Heat pump rated 3kw using between 300w and 600w. The rest of the house using about 200w. So my heat pump is probably pushing 1.2 to 2.4 kw out.


Regarding your heat pump short cycling when you lowered the flow temp.
Did you put the room thermostat back to 20c?
What power is the heat pump rated at?

Heat pumps have minimum outputs based on their size, you mentioned having an 8kw Heat Pump, your minimum output could be 2 to 3kw which will cause the heat pump to short cycle at low flow temps if the system only needed a 4/5kw Heat pump.
Weather compensation may not help an oversized system if the minimum power output is too high.
You could look to see if the heat pump has a silent mode which may lower the minimum output.

Thanks for sharing this.

I think my heat pump might be a 6kw but that’s based on asking ChatGPT. The model written in the machine is:

• ERLQ006CAV3

I left the thermostats at 30deg although have now turned them off. Not sure if they are really off or just have displays off? The quick spikes look to have stopped, not sure what I will see though. Too early.

Your graph doesn’t have any real spikes does it just run smooth?

It does have a silent mode I can see from there display although I don’t want to change multiple things at once.

is 6kw pump more in size?

The kitchen is now 23 degrees! A record! My wife will love me but only sustainable today as solar is paying for it.

Edit: thinking of this now has burning off the thermostat has that turned off any signal to heat?

Thanks. I finally found the menu so will drop my flow to 38 @ -5 and 27 at +15.

For anyones (or my) future reference the how to is here:

https://www.youtube.com/shorts/uDBTc5r0-og

I will see how that runs for a day and go from there.

Thank you. Will try now for a day.

By temperature limit do you mean the temperature on the thermostat? And how do they not call but take it?

I am actually very confused by all this!

So I changed my weather compensation settings last night. Is this cycling? Bad for the pump?

House temperature seemed decent this morning, not sure if it’s too early to tell

Your thermostats are set to the max, so they are calling for heat.
Your flow temp was at 40c, you have dropped it to 38?
So the temperature of the water in your system is higher than the flow rate you have set it too.
So it looks like the heat pump responds to the call for heat, turns on, the water is hotter that the temp set for flow temp so it turns off. This then repeats.

You could turn the heating off for a while, allow the water in systems temperature to drop, so that when you turn it back on the heat pump heats the water in the system up to to the flow temp you have set. Or you can wait till it drops, which may take a while as your house is just 15c cooler than than the water in your system.

I do think you should turn your heating off, set your 1st point to 25c @ 15c outdoors and your second point to 33c @ -5c outdoors. Your display should show you your current flow temp somewhere, when it gets down to 33c turn the heating on and let it run for a while. Use a thermometer to measure the temp in your room and adjust the 2nd point up if required.

Might be worth noting that not all heat pumps operate in the same manner to measure against the heat curve setpoint, my unit a Bosch/IVT, uses a sensor called "radiator forward" (GT4) which is the reference point for measuring against the heat curve setpoint. This is somewhere between the flow and return temperatures, there is a specific sensor on a pipe external to the unit. My understanding is that some units also use return temp as means of controlling, including a Daikan unit my neighbour has.

Where can people see their HLI? I dont see it on my Part L report.

Is it this?

Should be on the advisory report you got along with the BER assuming it was carried out using DEAP 4.0.

Search with your MPRN here and if it is recent it should list both for download

LWT is the temp of the water returning after heating the rads?
I am not familiar with your heatpump but a quick google says
Delta T / dT: This is the temperature drop across your heating system (Flow Temp - Return Temp). A standard, efficient delta-T for Daikin heat pumps is often considered to be around 5°C (dT5), though some systems, particularly with radiators, may be set higher (e.g., 10°C).

So a delta of 6c looks about right.
What's the room temp and power usage looking like?