Following the various threads on ASHP tweaking and I’m conscious that I’m very near the bottom of the rankings at https://heatpumpmonitor.org/ . One issue I suspect I have is the flow rate between my HP and the buffer tank. The pump is running flat out / maximum speed setting and I’m getting 1.25m3…

Using Trystan’s Carnot COP facility, the carnot cop when the dt is around 3.5 is about right at 49% (at 20:00), but where flow temp is edging up to 45, and the compressor slow, the Carnot efficiency seems to be down at 38%… it should be around 49%. The dt is close. Could this actually be in-part be…

Why is the return temperature on the graph wobbly (the green from 20:30 inwards) Generally, the return from the buffer or rads should be steady. I have seen a wobbly flow temp when the COP is lower than expected, and I think this is a bit of a refrigerant issue… liquid refrigerant entering the c…

The system is essentially plumbed with the CH on one side of the buffer tank - one pump and two zone valves for which I monitor the temperatures (using a tx3) of each zone flow and the return into the tank. The other side is the ASHP with a circulation pump, filter, heat meter and valve to control …

Re flow rate out of buffer tank… given the average kW in must equal average kW out to rads, you should be able estimate the flowrate to radiators using simple proportion of dt. I was looking again at a recent section. After stopping, the pump keeps running, and the dt decays over the 5min ‘off’ pe…

I’ve uploaded below two graphs showing the same thing but one also has the ASHP current on to indicate how hard it is working (or not). The date/times match the graph posted above. Note that all my data is also publicly available on emoncms.org I think. The HP is just outside the wall where the …

How large is that buffer in litres and how far apart are the tappings for flow and return, there is a possibility that your buffer is having a negative effect on your system with your heatpump pump just circulating around the flow and return and the same effect on the circuit side. i will draw and u…

[image] Satwelsh: How large is that buffer in litres and how far apart are the tappings for flow and return, there is a possibility that your buffer is having a negative effect on your system with your heatpump pump just circulating around the flow and return and the same effect on the circuit s…

[image] johncantor: Re flow rate out of buffer tank… given the average kW in must equal average kW out to rads, you should be able estimate the flowrate to radiators using simple proportion of dt. At a rough estimate I’m getting about 20 l/m on the CH side. Difficult to be exact because of t…

I think Mike is right about recirc in the buffer. Looking at your graph temperatures, its surprising how bad it is. It is also the only way of explaining how the return to HP rises very soon after start. Its got 1" bsp fittings, so it might be possible to fit a 28mm copper extension to go insi…

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