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Mitsubishi Ecodan return flow temperature same as weather curve temperature

Air Source Heat Pumps (ASHPs)

Last Post by borkov 10 months ago

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borkov

(@borkov)

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Joined: 1 year ago

Posts: 4

Topic starter 04/11/2024 8:17 am

Hi,

I have an Ecodan heat pump configured with a weather compensation curve for underfloor heating. From my understanding, the flow temperature (THW1) should align with the set temperature on the curve that corresponds to the outdoor temperature. However, when I check the thermistor temperature or the commissioning wizard, it appears that the set temerature is the same as the return flow temperature (THW2) instead of the expected flow temperature (THW1). Is this OK or should the flow THW1 temperature be the same as set temperature in the curve?

This topic was modified 10 months ago by borkov

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curve flow temerature

Lucia

(@lucia)

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Posts: 313

04/11/2024 11:10 pm

I'm not really sure how it works temperature-wise with UFH so someone else will maybe be able to answer this but is UFH your only heat emitter or do you have radiators or fan coils as well?

With radiators it should be your flow temperature that produces your set temperature but they are not the same. UFH usually runs at lower temps.

My current system flow temperature is 32º producing my set temperature (room temperature) of 22.5º. The return temperature is 27º - my system uses radiators as emitters. The difference between flow and return temperatures is usually less for UFH.

It may help if you share the details of your system.

This post was modified 10 months ago by Mars

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Mars

(@editor)

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04/11/2024 11:49 pm

@borkov, I’ve reached out to Mitsubishi about your issue, and they recommend contacting their Homeowner Helpline at 0161 866 606.

If you’re connected via MelCloud, they can also review your system remotely, looking at the Delta T over recent heating and hot water cycles to give more specific advice. They may ask for details to help identify if it’s related to a defrost cycle, whether heat transfer into the UFH circuit is an issue, or if the thermistors might be incorrectly positioned (e.g., THW2 on the flow pipe).

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borkov

(@borkov)

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Topic starter 05/11/2024 7:41 am

I only have UFH. The system is now running for the third season, and both the heating and DHW are functioning well, with no complaints. I don't think the sensors are switched, as THW1 temperature is higher than THW2.

However, I still want to resolve the issue or find the setting (if it exists) where I can select which sensor (THW1 or THW2) follows the WC temperature. Or perhaps there is something not right with my heat pump.

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Mars

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