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Radiators don't receive hot water

Air Source Heat Pumps (ASHPs)

Last Post by Derek M 2 years ago

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sobo

(@sobo)

Eminent Member Member

Joined: 2 years ago

Posts: 11

Topic starter 12/10/2023 2:19 pm

I have a Daikin Altherma monobloc 9Kw. Turned space heating on for the first time a few days ago. Most of my radiators don't get hot water at all, their flow pipe is cold. The flow pipe of the two radiators in the loop is warmish. I bled all radiators, there was a tiny bit of air in one, and re-pressurised to 1.5 bar.

In the pump's user interface, the leaving water temp is 45 and the flow rate is 43.2 although it sometimes jumps. I left the heating on for over 24 hours (cheated the thermostat to make it work continuously). Still the rad pipes are cold.

Suggestions anyone?

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iancalderbank

(@iancalderbank)

Noble Member Contributor

Joined: 3 years ago

Posts: 643

12/10/2023 2:45 pm

so there is hot water in the system being generated by the ASHP and its going somewhere, but not to your radiators.. this is a normal plumbing and heating problem, doesn't sound ASHP specific. Either work out where the hot water from the ASHP does go (follow the pipes , draw a diagram) and report back... or call in a heating engineer? as I said it doesn't sounds like an ASHP specific problem so any local PHE person will do.

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Derek M

(@derek-m)

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Joined: 5 years ago

Posts: 4425

12/10/2023 3:20 pm

Posted by: @sobo

↑

I have a Daikin Altherma monobloc 9Kw. Turned space heating on for the first time a few days ago. Most of my radiators don't get hot water at all, their flow pipe is cold. The flow pipe of the two radiators in the loop is warmish. I bled all radiators, there was a tiny bit of air in one, and re-pressurised to 1.5 bar.

In the pump's user interface, the leaving water temp is 45 and the flow rate is 43.2 although it sometimes jumps. I left the heating on for over 24 hours (cheated the thermostat to make it work continuously). Still the rad pipes are cold.

Suggestions anyone?

If you have a 3-way valve or two 2-way valves in your system then check that they are operating correctly.

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sobo

(@sobo)

Eminent Member Member

Joined: 2 years ago

Posts: 11

Topic starter 15/10/2023 8:43 pm

@derek-m thanks, not sure which valves to look at and how are they supposed to operate?

Two of my radiators do work (I guess they’re the first in the loop) but their flow pipe is below tepid. My leaving water temp is 45. is this supposed to be the temp of the water flowing into the rads?

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Derek M

(@derek-m)

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Joined: 5 years ago

Posts: 4425

15/10/2023 8:59 pm

Posted by: @sobo

↑

@derek-m thanks, not sure which valves to look at and how are they supposed to operate?

Two of my radiators do work (I guess they’re the first in the loop) but their flow pipe is below tepid. My leaving water temp is 45. is this supposed to be the temp of the water flowing into the rads?

If you are not getting sufficient warm water to your radiators, then the flow is being reduced by a valve, your pump is not working correctly, your filter is blocked, or the flow is being diverted.

Check that the water pump is running.

Check that any filters are not blocked.

Look for an automatic bypass valve and check its setting. Just Google 'automatic bypass valve' if you are not certain what to look for.

Check the operation of any electrically operated valves. Just Google 'electrically operated valves' if you are certain what to look for.

Post photo's if you require help.

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