Had a good visit to site today and met up with an installer there. He usefully had temperature pipe clips and was quickly able to ascertain that the rads were getting about 32C water to them and 31C back. I stupidly hadnt picked up on the fact that all the rads pipework is in the concrete floor slab which might not even have insulation under it. The floor certainly doesnt feel warm.
He also measured the temps to and from the heat pump at 45C/40C although this might not be that accurate as the flow temps were oscillating again.
I positioned the temperature probes I bought around the LLH. Here is whats happening. The pictures are taken minutes apart and you can see the oscillation in flow temps
Best to wait until they steady down, can you confirm that (from the top) the first probe is the primary flow, the second is the primary return, the third is the secondary return and the fourth is the secondary flow?
A question that’s not been asked yet: where and how is the room temperature being measured?
Is this with Mitsubishi’s own “remote room controller”, or something else?
Is there a 3rd-party thermostat somewhere that is also connected?
Also, is the property managing to maintain the desired temperature, or is it struggling?
OK, so the order of sensors is the same as the pipes coming off the vertical LLH. Top sensor - Top pipe, bottom sensor bottom pipe. With all the insulation it was hard to see. I was just looking for a schematic but no joy yet.
They are all stuffed under the insulation.
The room temperature is measured in the hallway by the remote mitsubishi sensor/controller, no third party thermostat.
The property cant reach the the set 23C but seems to be able to hold 20.5C more or less.
Its probably safe to assume that the top probe is the primary flow, what’s a bit surprising is that neither of the secondary probes is reading some where close to 40C, except that there is a huge imbalance with the secondary flow far in excess of the primary.
Also worth checking that the two circ pumps are installed on the correct pipes and orientated correctly.
The “LLH” in the schematic looks more like a Low Loss manifold, a conventional LLH looks like the one below, the primary pump is the (gas) boiler’s own circulating pump
Yes, this schematic gives a good view. As long as the probes are securely positioned in their proper locations then should get a bit more info with system running steadily.
The primary pump,16, should be pumping/arrow pointing, to the HP and the heating pump, 23,should be pumping/arrow pointing away from the secondary side of the LLH.
According to the charts on Melpump, flow rate is 11 l/min when heating water, with a dT of 11° and estimated power of 5 kW in / 8 kW out. Flow temperature reaches 60°+ bringing tank temperature up to 50°. Profile is fairly consist each time, and similar to other Ecodans.
Very good, a flowrate of 40.1LPM for the 14kW unit is required to give the recommended 5C dT (on CH) but 13LPM is only being achieved despite the very powerful circ pump running almost flat out, on fixed/full speed, 13LPM will only achieve a 5C dT at a tiny 4.54kW output, the dT would be 15.45C at full output.
