I have a 5kW Ecodan. This is slightly oversized as the heat loss calculation was closer to 3kW but 5kW is the smallest they do (and my installer goes with Ecodans).
(Data coming from Shelly for power and from modbus on ecodan for flow / return)
As can be seen my COP isn’t great. Wondering if anyone has any tips to help it? Any settings I can adjust? I have radiators over two floors. All are fully open on lock valves and TRVs.
I’m running auto-adjust. The remote used for sensing room temperature is in my kitchen which is the coldest room in the house so other rooms are warmer as intended.
Last night I turned on quiet mode in an attempt to avoid the heat pump ramping up too hard / quickly given its a bit over sized.
can you do a brief drawing of the setup - flow return cylinder etc what size pipe work you have
you say you have a buffer so can you put that on your drawing , wonder if the buffer and its setup is causing the issues (extra pump etc )
have you got a way of measuring the radiator circuit flow and return and pump speeds
looks like you HP is defrosting even in these warmer conditions so maybe their is a clue there
also is your heat pump reacting to the spikes of the outside temps
I’m assuming one is for the hot water and one is for the radiators but I’m not sure. If one is the radiator one I assume thats the flow rate of the buffer ↔ radiator system.
Is the defrosting unusual? With 6 degrees it seems to be one defrost cycle an hour? Yeah the outside temperature sensor is behind the pump so it does have a bit of a jump in temperature when it defrosts.
I have the Mitsubishi remote and the system is running auto adapt so it’ll alter flow temp as it decides. Flow rate appears fixed.
The flow rate of the heat pump seems fixed as is the two that I took pictures of. In settings it’s set to ‘5’ whatever that means which seems to be the maximum. The flow rate seems to stick at 10l/min. I can lower the setting from 5 if it might help?
I think the grundfos is heating circuit fixed curve and the other is just the main loop. I think water relies on mains pressure.
i would say its more likely the heating circuit is not pulling enough heat out of the buffer , but if your house is not huge the circuit is not big enough to pull more heat out
are you sure the TRVs on rads and the lock shields are fully open
maybe someone else on here could help who has more experience with buffer tanks and the extra pumps , most pumps nowadays dont have buffers unless there is a good reason and just use the heat pump to flow the water around the house.
is your house warm enough for you
Yeah it’s warm enough and can get well above what I consider warm enough so I’m generally happy with it. Due to batteries and time of use rates I’m also making a slight saving over gas boiler but was expecting better than 2.3 level COP for heating.
I’ve figured it out a bit. The wilo pump is controlling the flow rate. The heat pump isn’t. It appears ecodan might need this external pump. I can adjust the speed of it fairly easily. I might reduce it a little to see if it helps.
i would try playing with the speeds on this to see if it improves things , but if you home is warm enough it looks like it might be better to reduce what the heat pump circuit feeding the buffer is doing (ie lower the flow temps of the heat pump )
So from what I gather from google and trying to follow the pipes Ecodans require an external circulation pump. This appears to be what the wilo is doing. The wilo has PWM settings which I think can be controlled with the heat pump but this isn’t being done on mine and is instead fixed directly - This seems fine. I can directly turn the wilo dial and see the pump speed increase / decrease on the ASHP settings unit.
The grundfos I believe is the heating circuit which pumps between the buffer and the circuit.
The tank says its mains pressured so I assume that doesn’t have a pump for hot water.
The temperature of the heat pump is controlled by the ecodan ‘auto adapt’ which should appearently learn the best way to heat rooms and others have had better success with that rather than a pure WC curve.
Wondering if @Timbones has any advice. Looks like he has an ecodan too.
im sure most of your low Cop is because the heating circuit is not pulling enough energy from the buffer
the heat going in to the buffer should be be matched with what’s going out
and because of the low difference between the flow and return of the buffer tank from the heat pump (dT) is so close the heat pump if not making good use of the energy its producing
because you happy with home temps that only leaves reducing what your putting in to the buffer from the heat pump
just make notes of what your changing so you can always go back
Two pumps is quite common, one for the primary circuit to the outside unit and a second from the buffer to the radiators.
The behaviour of the system looks okay, though I’d expect COP to be higher. How is electricity and heat being measured? How well attached are the temperature sensors?
The water tank sensor is fine - I kinda expect the COP of that to be low. I have it on quite hot as I like hot long showers and I’m okay paying a penalty for that.
This is usually under insulation, I just took it off to photo it. I think this is probably the return? Not sure where the other is. Perhaps thats built into the HP?
The electricity usage is coming from a Shelly Pro CT clamp so that should be fairly close to accurate.
