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No heat in radiators since heat pump failure

Air Source Heat Pumps (ASHPs)

Last Post by AllyFish 3 years ago

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tony clarke

(@tony-clarke)

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Topic starter 10/01/2023 1:56 pm

I have an Ecodan system that was working fine for the last 4 years until it failed in the cold spell back in December and promptly froze. After defrosting I had a company come out and repair which seemed to go fine and it heats water no problem but only get heat in about the bottom 2 inch's of all the radiators. They have been out and checked the system and say it is working fine !! All statistics and traces from Mitsubishi say it is working fine. Last recommendation from them was to replace the pump which I have done with the one they recommended and still no improvements. Getting to the end of my tether with them. Does anybody have any suggestions on what the problem could be and how to resolve? All rads have been bleed and all full

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Mars

(@editor)

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10/01/2023 5:18 pm

Weird that the pump is working (as per the latest team to visit) but you're not getting heat to the rads @tony-clarke. My first thought was distribution pump, but that's been replaced. Have you checked your expansion vessel? Is that pressurised and maintaining pressure?

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tony clarke

(@tony-clarke)

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Topic starter 10/01/2023 5:22 pm

Yep pressure within range as that's been checked

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Benseb

(@benseb)

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10/01/2023 5:29 pm

Presume you've bled the radiators? Air might have got into the system during the service?

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Derek M

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10/01/2023 6:06 pm

@tony-clarke

If the heat pump is producing warm water, then I would suggest tracing along the pipework from where it enters your home, measuring the pipework temperature to see where the warm water is going. Ensure any manual valves located on the way are fully open and any actuated valves are functioning correctly.

Has the system been drained down and refilled? If so you may possibly have an airlock somewhere, try opening the filling valve to increase the heating system pressure slightly then bleed the radiators again.

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Mars

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10/01/2023 10:32 pm

@tony-clarke , Derek’s reply prompted me to remember something that occurred to us a couple of years ago. Our heat pump was working fine, rads were hot, but the UFH stopped working.

We followed the pipework out of the heat pump to the UFH circuit and when we hit the Honeywell valve the water getting to it was hot, but the pipes after the valve were cold. As it turned out, the motor in the valve has died - we replaced it, and everything worked again.

So follow the pipes and see where that leads. Hopefully it’s something simple like a faulty valve.

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AllyFish

(@allyfish)

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11/01/2023 5:16 pm

Radiators that are only getting warm at the bottom only sounds like they are full of air. Easy to check that one. Has the Ecodan got either a manual flow gauge or automatic flow measurement? With all manual valves open, radiator TRVs open and zones calling for heat, easy to check if you have correct flow.

Pumps can cavitate if they are working against closed valves, when that happens their flow drastically reduces and air bubbles will be generated in the system as the pump suction tries to pull water that simply isn't there because something is stopping the flow, but the cause is usually quite obvious. Check all circuit isolation and service valves are open.

Hope it gets resolved soon!

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