hum/whine from Wilo circulation pump

grumpidoc · 2025-01-07T16:10:13Z

Hello, very much a newbie here, and I don't know anything technical. I'd very much like to pick more knowledgeable brains! We've had an ecodan 8.5kw heat pump installed for about a month, and are generally very pleased with it. However now that the weather is colder we have noticed a VERY annoying noise, especially when the frost cycle is running at night. It is a very quiet sound midway between a hum and a whine, (pitched at about 277 or 554 Hz - i can't tell the octave - if anyone is interested!), but despite the low volume it is intensely irritating and stops us sleeping. It appears to be coming from the circulating pump. Interestingly, in the airing cupboard where the circulating pump is situated the noise is much louder, but sounds more like a general pump noise. As you close the door and move away different frequencies seem to fall away and we're left with almost a pure tone. My husband says it sounds like motor noise. We had the installer back for a couple of other issues so asked him about this, and he changed the pump setting from radiators (which we have) to underfloor heating (which we don't have) but this made no difference, and I don't really know why he did this. We have tried reducing the flow rate, this changes the pitch of the noise to something a little lower in tone but just as annoying. We've bled the radiators a couple of times and the pressure seems fairly stable at about 1.2-1.3 The frost cycle is set to come on at 5 degrees. We keep the house fairly cool with thermostat set at 15 in the day, 16 in the evening and 14 overnight, which usually means no further heating is required till morning so it's really the frost cycle that causes the problem. The sound is still present intermittently during the day but is much less noticeable due to more general background noise in the house / outside The circulating pump is a Wilo Yonos Pico 25/1-8 We have messaged the installer again, but would be very grateful for any suggestions on what we might do to remedy this. Thanks

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Toodles

(@toodles)

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30/01/2025 11:08 am

@richard24738 Good to hear you are getting there now, we have a bedroom that gets the most solar gain in the whole house and we resort to a limiting setting on a Hive PTRV to control this.Good Tweaking, Toodles.

Toodles, he heats his home with cold draughts and cooks his food with magnets.

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grumpidoc

(@grumpidoc)

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Topic starter 12/02/2025 8:28 pm

@toodles @richard24738 and @gary Just reporting back. It became clear that much of the noise was from the primary pump. We have finally had a visit from the installer who removed some debris from the filter, and turned the Wilo primary pump down from 3 (which gave a flow rate above the recommended on the FTC controller) to 2 which has helped a lot. Even better, my other half - who is usually much more confident and technically minded than me - now feels comfortable that we can further experiment without the risk of causing damage. So thank you all for your very helpful input to a pair of newbies.

I have lots more questions about other aspects of the heat pump, but I think they need to go in a new thread!

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Toodles

(@toodles)

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14/02/2025 3:53 pm

@grumpidoc Glad to hear that the speed change has improved matters; please ‘enquire within’ in the future as someone on the RHH is almost certainly ‘been there -done that’ and will be able to advise.😊 Toodles.

Toodles, he heats his home with cold draughts and cooks his food with magnets.

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