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Vaillant water pressure gauge vs Analogue gauge

jeegnesh · 2025-03-19T15:19:49Z

So this has been the story since install but via the controller the water pressure always shows lower than the analogue gauge at the filler loop, Example ASHP is saying 1.4 bar, the analogue gauge is saying 2.2 bar How do I know which is correct?

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Air Source Heat Pumps (ASHPs)

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jeegnesh

(@jeegnesh)

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Topic starter 08/04/2025 1:04 pm

@adamk - Yes they get very close when HP is off within 0.1 or 0.2 once the HP goes on there a difference of 0.4-0.6

13.6kw Solar, 40kw Battery, 10kw Heat Pump and EV Cars

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AdamK

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08/04/2025 1:50 pm

yeah sounds like its pumping against something. is the whole circuit UFH?

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jeegnesh

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Topic starter 08/04/2025 1:58 pm

@adamk - Its a huge system, ground floor is predominantly UFH around 100sqm, rest is rads I think 13 of them

13.6kw Solar, 40kw Battery, 10kw Heat Pump and EV Cars

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AdamK

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09/04/2025 9:33 am

Posted by: @jeegnesh

↑

@adamk - Its a huge system, ground floor is predominantly UFH around 100sqm, rest is rads I think 13 of them

just wondering if the UFH is creating some back pressure and the rad locksheilds are closed down too much so when the pump kicks in its pumping against too much resistance.

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jeegnesh

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Topic starter 09/04/2025 10:04 am

@adamk not sure I want to mess with the lockshields I assume that would mess with the balancing.

have someone coming next Wednesday to take a look at all the issues.

13.6kw Solar, 40kw Battery, 10kw Heat Pump and EV Cars

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jeegnesh

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Topic starter 17/11/2025 4:51 pm

@adamk yes they equalise once off

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jeegnesh

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Topic starter 17/11/2025 5:02 pm

As winter is coming back, I can give an update -- so the new installer came months ago and flushed the system and removed the small strainer and instead a regular Y strainer 28mm has been added -- after this the weather was good and so no real testing. My heating has been running lightly for a month or so and guessing this week it is ramping up.

The good news is after the clean and new bigger strainer my flow rate was touching 2,000 and many months after I just took a look and it still exactly the same figure which suggests the blockage issues are no more.

The pressure gauge still has the same behaviour 1.7bar when off and 1.3 when running this is consistent behaviour, which I still don't know is right or wrong.

Winter 2 - let the games begin again (oh my annual service is due too 🙂 (first one)

13.6kw Solar, 40kw Battery, 10kw Heat Pump and EV Cars

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JamesPa

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17/11/2025 5:20 pm

Posted by: @jeegnesh

↑

The pressure gauge still has the same behaviour 1.7bar when off and 1.3 when running this is constistent behaviour, which I still don't know is right or wrong.

Mine does something similar, I'm not worried about it, I assume it's just dynamic pressure difference due to resistance in system. Without pressure differences, generated by the water pump, there would be no flow.

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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