Posted by: @adamk

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@jamespa in eco or NR mode it is pretty silent until i go in the utility room about 4m away from the outside wall the unit is sat near, then i can hear it. if i turn off eco or NR i can hear it over the TV like ive left a sub woofer on.

In the latter case is it all the time or at certain events only.  

Vaillant are, according to others, pretty sensitive about their heat pumps being called noisy and have been known to send an engineer out.  It might just be worth sending them a recording.

It does sound as if it could be pipework related.  I think you mentioned that the pipework vibrates beyond the flexis, which it shouldn't.  Is it well fixed to something solid (like brickwork) on the house side of the flexi and before it enters the ceiling void.

@jamespa

Here’s a pic of part of the pipes. They have used some wall supports on the pipework before the flexis and even in the middle of the flexis.

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I just looked at mine.  My flexis (which run horizontally) are more or less, but not quite straight, have one support in the middle (like yours around the insulation), and the fixed pipework is supported beyond the flexis.  There is (naturally) a right angle bend more or less immediately either side.  There is no support between the ASHP and the support in the middle of the flexi.

I think maximum isolation will occur if there is no support between the ashp and the end of the flexis, the flexis themselves are curved and unsupported, and the pipework beyond is well supported.  A bend either side of the flexis is an alternative to the flexis being bent, but probably not as good, and a support in the middle may not harm.  It seems to me that having no support between the ashp and at least the middle of the flexis is important for longevity, otherwise any vibration of the ashp or pipes is constrained by the support rather than being relieved by the flexis!  This is all informed guesswork not definitive.

I think mine probably provides a bit more isolation than yours and is probably also better for longevity, but perhaps still not as good as it could be.  At the currently modest modulation level of perhaps 40% I can very distinctly feel vibration on the ASHP side of the flexis, but cannot feel any vibration at all on the house side, so they are doing their job.

I think you said earlier that you can feel vibration both sides, and if this is the case at relatively modest compressor modulation I would suggest that it could be improved by rearranging the supports.  As yours go vertically they probably don't need support so I would be tempted to support the pipe beyond really well, and leave the flexis completely unsupported (or maybe a support in the middle but towards the house end if it feels vulnerable given the tap nearby.  I would certainly remove the support on the ASHP side of the flexi.

No idea if this will make a material difference but definitely worth a try.

@jamespa well I set it to on yesterday and have a night setback of 18 until 6am. This morning at about 6:15am it roared up and I could hear the humming for about 2 min in our bedroom with the door mostly pushed to, and that’s the diagonal opposite in the house to where the hp is outside. I’m concerned it’s going to be noisy 24/7 in the depths of winter.

i did notice today even when the compressor is probably not running that I can hear a random rumbling sound in the kitchen where the primaries and flow and return pipework is. I’m guessing it’s the water pump, but why is it making noise in the pipes?

@adamk One possibility being that the pump is running at a high flow rate and causing disturbance (turbulance?) due to the water movement. Are there any valves / hard right angle joints / lengths of pipe run that have inadequate support? Is the pump itself supported and is it running quietly? (Try placing a screwdriver on metal parts whilst holding the handle end to your ear / or use a stethoscope for the job). Regards, Toodles.

@toodles it’s just doing an ECO water run as we speak and power consumption is about 1500w and I can only here the humming in the utility. The rumbling noise looks like being the circulation pump as power consumption was 58w when I could hear it. There are some hard 90 bends along the pipe run 3 outside and one inside, that’s excluding the valve stuff. There is a couple of 45s near the top of the wall 90s as well had to get under the steel lintel and then back up in the ceiling.

@adamk Might be worth the screwdriver / stethoscope test on those pipes. As @transparent often mentions in connection with pipe noise, ‘swept’ bends are preferable to hard right angled joints.

Ours was a retrofit when the gas boiler and many of the radiators were replaced for our ASHP installation and every joint up until the existing runs of pipes underfloors were replaced with swept fittings (solderless, machine formed joints). The rising pipes to radiators were also joined in with swept fittings where required too. Happy hunting! Regards, Toodles.

Posted by: @adamk

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@jamespa well I set it to on yesterday and have a night setback of 18 until 6am. This morning at about 6:15am it roared up and I could hear the humming for about 2 min in our bedroom with the door mostly pushed to, and that’s the diagonal opposite in the house to where the hp is outside. I’m concerned it’s going to be noisy 24/7 in the depths of winter.

 

i did notice today even when the compressor is probably not running that I can hear a random rumbling sound in the kitchen where the primaries and flow and return pipework is. I’m guessing it’s the water pump, but why is it making noise in the pipes?

Depending exactly how the setback was programmed a 12hour setback overnight means a lot of recovery and in particular means that the water will have reached almost equilibrium with the OAT at 6am, which was pretty cold this morning at least where I am.  So its likely going to ramp up to 100% modulation for a few minutes to kickstart the heating of the water, then settle down, and its doing it when the OAT is pretty low (6C here at 6am).  In winter you (hopefully) wont be doing set back at all and, unless its well undersized for your house, it will only be at 100% modulation or anywhere near during recovery from defrost.  

Incidentally if you look at 'live monitor' on the HPAI you can tell what the compressor modulation is at any time.  This can be useful in understanding what is going on (as can live monitor generally.

That said you seem to be able to hear it from a fair way away which is not something that occurs with me.  At present I can hear mine at all even if I stand right next to it and certainly not in the house.  Im still suspicious about the isolation or the faint possibility you do have a noisy compressor.  Send Vaillant a video and they may comment, they have been reported to attend site in some cases and do some remedial work if the machine is at fault, I think they are quite sensitive about noise.

Regarding the rumbling, is it rumbling or could it be low frequency gurgling or other water effects.  There is a 'purge building circuit' setting in the installer menu on the HPAI, my installer had that running for a fair while (perhaps 10-20 mins) after he finished doing all the plumbing work.  The objective of this is to force as much air as possible to the autobleed valve so that it is pushed out of the system.  More air will still appear later as it comes out of solution, but the purge function will make sure there are no trapped large bubbles. 

If you are in fact hearing the water pump then it indicates insufficient isolation or something acting as a soundbox.  I cant hear my pipework at all, and that makes it noticeably quieter than was the case with my gas boiler even though the water velocities are probably larger, presumably because the autobleed valve is continually expelling air. 

Another possibility is an almost-shut valve causing vibration, an LSV, a TRV or even a poorly shutting diverter valve.  I think I do have one of those, and occasionally it makes a noise (a sort of drone noise) for ~10 mins at a time then stops.  Its a bit annoying but so far I haven't been able to trace it, one day I will.

I used to have a setback at night, but found as you did the system turns on full welly when set back is over.

i now leave the system open loop at 20C and it hums to itself in the background, i dont get those sharp bursts of heat demand which was typically how i ran the previous gas system.

this is my second winter with ASHP so will be monitoring its performance both heat transfer and COP. Im currently getting high 4s which is very satisfying, all the extra work ive done in past year to insulate every pitched roof and rafters is paying back with a more relaxed comfortable heating 

On the subject of setbacks.... every situation is likely to be different according to factors including:

• Insulation levels/heat loss
• Daytime requirement e.g. if wfh  retired etc
• Time of use tariffs
• Batteries 
• Etc

In our case we used to use a setback of just 1 or 1.5 degree overnight to reduce heat pump usage without cooling the house too much. On Octopus Tracker tariff at that time.

However now on Intelligent Go tariff(7p overnight) so have switched to INCREASING target temp overnight by one degree as well as filling batteries. I'm optimistic that batteries plus a little solar will mean I can avoid peak tariffs on the majority of winter days. Coldest winter days will be topped up as necessary with Woodburner and/or peak rates elec

Target temps managed with cheap digital room thermostats. Our heat pump was a retrofit so standard room thermostats already in place.

@tim441 This year, we have replaced ~25 - 30 year old double glazing with argon gas filled triple glazing throughout the house and  look forward to seeing an improvement (reduction!) in heat loss this winter. Regards, Toodles.

@adamk Are the flexi's where the three fixings are? If so shouldn't be any as they stiffen the flexi and noise transfers though 6 fixings in the wall. Flexible pipes should isolate all pipe work from the heat pump, so they fit onto the HP not part way through pipe work.