Hi, I have 14 Kwh, PUHZ-SHW140, EHSC-VM6D installation and I started to monitor recently. Could you guys take a look and express an oppinion about how it is performing? I am running a single zone, only heating, no DHW. The first thing I am surprised by is the fact that is running almost continuously. Do you see something that can be improved?
Looks to be running well with no cycling, though with relatively high flow temperature which will result in lower COP.
I guess you’re heating with radiators? How many do you have? Are they all open?
Which heating controls are you using: Mitsubishi’s own controls, or some 3rd-party?
How is the heat being measured? The feed looks to be quantized to whole kWs and doesn’t have any values in between.
What is the heat loss at design temperature?
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Thank you @Timbones for reply. I am at the begining of understanding heatpumps behaviour and monitoring.
I am heating with radiators. 15 radiators always open. I have some areas in my house I am not using and heating.
I am using Mitsubishi “room temperature control”
I am polling melcloud using mjr script I found on this forum. For the electricity I use shelly device and for room temperature a smart device.Both of them are not seen by FTC6 but external.
I would like to measure better but don’t know how yet. I am discovering here
"heat loss at design temperature” - how should I measure this? is it relevant for understanding how to optimize the house heat loss or the heat pump efficiency? I would like to learn more, sorry for the stupid question.
I think my differences of temperatures are too low especially at lower flow temperatures. Is this indeed a problem for efficiency? I attach a graph with difference of temperatures at heatpump (provided by melcloud) and difference of temperatures I collect separately from the radiators water circuit (after the buffer tank). I added also the flow temperature for the context of observed dt’s
I’m not familiar split models, so not sure what to advise. Here are some more questions:
- Can you describe how the buffer is plumbed into the system?
- How many circulation pumps are there?
- What type of refrigerant does it use? R410a?
- Is your heatpump app available to see publicly?
The datasheet for this model suggests that at an air temperature of 2C and flow temperature of 40C would achieve a COP of 2.7 at nominal power, which is the same as what you’re seeing. Performance is slightly better at lower power bands “Mid” and “Min”.
The main way to improve COP is to reduce the flow temperature, and the way to drop the temperature is to increase emitter (radiator) surface area.
Having a buffer does add complication though, and if that’s misconfigured then it might be losing you performance. For instance, the discrepancy you’re seeing in dT could be caused by different pump speeds.
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This is actually the ideal operation of a heat pump, generating just enough heat to keep the house warm.
This would normally be worked out by the engineers who installed the heat pump, along with the flow temperature it was designed to run at. However, it’s quite common for the heat loss to be estimated much more that it really is.
What was the total kWh for the period you showed in the top chart? (Click on “Show detail” to get the stats)
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- Can you describe how the buffer is plumbed into the system?
The boiler is indeed there as a backup source for very cold days. It did not do anything yet.
(3) and (4) are the heat sensors I used to calculate “radiators DT” in the earlier graph
- How many circulation pumps are there?
Heatpump circulation pump + 1 circulation pump after the buffer (number 5) in the figure
- What type of refrigerant does it use? R410a?
R410a
- Is your heatpump app available to see publicly?
I realise now that this would be very useful when asking for advices here. I will look into how to publish data from my internal server
I tried different values of circulation speeds but did not observed anything meaningful. No surprise as I do not know what I am doing. My intuition said that lowering the pumps speed will increase the DT … but there are 2 of them so I am lost.
Thank you!
This is actually the ideal operation of a heat pump, generating just enough heat to keep the house warm.
Great! Thank you! This is different than how boilers operate and I am used with.
What was the total kWh for the period you showed in the top chart? (Click on “Show detail” to get the stats)
135 Kwh with a consumption of 49 Kwh