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Humming sound on new install.

AdamK · 2025-09-11T21:20:11Z

Had a new Vaillant 7kw installed with new 28mm runs for primaries and flow and return. I’ve got a variable pitch humming sound that resonates through the house depending on how hard the heat pump is running. Admittedly this is just a test run I’m doing tonight but it worries me as i can hear it above the TV. one thing my plumber who ran the 28mm’s did do was clip them against the wooden ceiling trusses. Could this be transferring noise into the house? With the old boiler setup and pump you could only really hear the pump where the pipes were exposed in the kitchen just below the pump in the cupboard above.

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JamesPa

(@jamespa)

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13/09/2025 8:48 am

Posted by: @tim441

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Just a thought... can you check flow rates?

@adamk

Yes, Live Monitor on the 'HPAI' (not the Sensocofort) tells you the flow rate. It also tells you lots of other very useful things and is worth getting to know! Unlikely to be this unless there is air trapped somewhere, but possible of course. Get the flexi fixed though whatever you do.

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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AdamK

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Topic starter 13/09/2025 11:06 am

@ashp-bobba yes the flexis are there.

they didn’t do a base they just sat it on some paving edging pieces stacked on top of each other then on top of my old concrete path that runs along the back of the house.

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AdamK

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Topic starter 13/09/2025 11:19 am

@jamespa this is the third attempt to sort the flexis as the first time they were fitted they were not insulated properly and they changed one when they returned to finish off. But I then found out they were supposed to be straight and not bent 90 degrees so they returned and fitted new ones on the wall as it was about the only place they could go in a straight line.

the insulation is primary pro so is outside rated.

im pretty sure I’ve had this noise with the flexis in different positions so not sure it’s that. I suspect it’s either the base transferring noise up the wall, which would explain why I can hear it in the lounge which is about 5m away along the back wall, as I would have thought if it was the pipe work it would be near silent apart from the kitchen where the primaries are.

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JamesPa

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13/09/2025 12:35 pm

Posted by: @adamk

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@jamespa this is the third attempt to sort the flexis as the first time they were fitted they were not insulated properly and they changed one when they returned to finish off. But I then found out they were supposed to be straight and not bent 90 degrees so they returned and fitted new ones on the wall as it was about the only place they could go in a straight line.

the insulation is primary pro so is outside rated.

im pretty sure I’ve had this noise with the flexis in different positions so not sure it’s that. I suspect it’s either the base transferring noise up the wall, which would explain why I can hear it in the lounge which is about 5m away along the back wall, as I would have thought if it was the pipe work it would be near silent apart from the kitchen where the primaries are.

I agree with the logic, the installer needs to sort it, you shouldn't be experiencing the noise!

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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AdamK

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Topic starter 13/09/2025 1:36 pm

@jamespa just spun it up to do a hot water boost and turned off eco mode. Then I’ve gone round with a cheap stethoscope and can hear it where the primaries run through the ceiling, but it seems loudest on the French door glass which is about a meter or so from the heat pump.

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Tim441

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13/09/2025 1:50 pm

Does your heat pump have a Silent/Quiet mode?

Some heat pumps have that for running at night etc. Just wondering if it reduces hum in that mode? Afaik it runs the compressor at slower pace? Not sure what it would prove - if anything!!

This post was modified 6 minutes ago by Tim441

Listed Grade 2 building with large modern extension.
LG Therma V 16kw ASHP
Underfloor heating + Rads
8kw pv solar
3 x 8.2kw GivEnergy batteries
1 x GivEnergy Gen1 hybrid 5.0kw inverter
Manual changeover EPS
MG4 EV

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