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No heat in radiators since heat pump failure

 
Air Source Heat Pumps (ASHPs)
Last Post by AllyFish 4 years ago
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 tony clarke
(@tony-clarke)
New Member Member
Joined: 4 years ago
Posts: 2
Topic starter 10/01/2023 2:56 pm   [#738]

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
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 4763
10/01/2023 6:18 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)
New Member Member
Joined: 4 years ago
Posts: 2
Topic starter 10/01/2023 6:22 pm  

Yep pressure within range as that's been checked



   
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 Benseb
(@benseb)
Estimable Member Member
Joined: 4 years ago
Posts: 109
10/01/2023 6:29 pm  

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


250sqm house. 30kWh Sunsynk/Pylontech battery system. 14kWp solar. Ecodan 14kW. BMW iX.


   
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 Derek M
(@derek-m)
Illustrious Member Member
Joined: 5 years ago
Posts: 4425
10/01/2023 7:06 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
 Mars
(@editor)
Illustrious Member Admin
Joined: 5 years ago
Posts: 4763
10/01/2023 11:32 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.


New to heat pumps? Take the Heat Pump Fundamentals course and use INTRO50 at checkout for 50% off.
Rewritten and updated for 2027
📘 From Zero to Heat Pump Hero
🛠️ Bodge Buster
🎧 Prefer to listen? Heat Pumps Explained


   
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 AllyFish
(@allyfish)
Prominent Member Contributor
Joined: 4 years ago
Posts: 520
11/01/2023 6:16 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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