Posted by: @razz

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I found this thread on reddit:
https://www.reddit.com/r/ukheatpumps/comments/1r97882/noisy_home_not_the_heat_pump/

Does this seem like something I should ask from Octopus?
https://www.reddit.com/r/ukheatpumps/comments/1r97882/noisy_home_not_the_heat_pump/o6engbb/

Acoustic decoupling with flexible pipe, very possibly.   It depends on whether the noise is water borne or pipe-borne.  The best bet would probably be the same or similar flexis as are used outside, but the are expensive so Octopus may be reluctant.  Before my ASHP I had a shower pump coupled with flexis.  It still made one hell of a racket but without the flexis it was much worse, so they can help!

Some water pumps (often called circulators) are quieter than others, maybe worth considering swapping the circulator out, depending obviously on which one you have.  

Also worth trying to work out whether the noise is coming from the pump itself, or the passage of water through the pipework.  If the latter it could be elbows that are causing problems and replacing key ones with swept bends may help.  I had a section of pipework in my old gas system that was very noisy indeed, fortunately it was in a place where it didn't matter.  The odd thing is that the noise has completely disappeared now the ASHP is fitted, even though the section of pipe concerned is still in use and the water in it is presumably flowing faster!

Possibly not relevant but I can hear noise from some radiators.  These are ones where the TRV has been adjusted down; turning them back up again removes the noise.  I changed them for decorators cap and turned these down to restrict heat but still allow some flow and the noise hasn’t returned.  I suspect some valves are better than others although the problem occurred with valves fitted by Octopus and those not replaced.  

Posted by: @andrewj

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Possibly not relevant but I can hear noise from some radiators.  These are ones where the TRV has been adjusted down; turning them back up again removes the noise.

These will be ones that are at a state of almost closed.  The water whistles through.  I have occasionally experienced the same with LSVs but a tiny tweak usually fixes it without materially affecting the apparent room temperature.  Its an inevitable risk if you try to force a viscous liquid through a small orifice!

@jamespa I think they were at setting "3" although I don't know how near to fully closed that is.  It only stopped when I fully opened them - setting "5".  Anyway, it was just a thought for the OP: if his install was "over estimated" with larger radiators that he's had to turn down it may be relevant...

Posted by: @andrewj

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@jamespa I think they were at setting "3" although I don't know how near to fully closed that is.

Unless you have unscrewed them from the valves then it depends on the room temperature, TRVs close or open according to room temp.  I think 3 may be around 20-21 but I doubt the calibration is accurate!

We had water hammer with our gas boiler and lived with it.

Since installing the HP our water hammer has gone, so I'd agree that replacing your HP with a gas boiler may not solve this.

@bash what was the cause? How did you get it fixed?

@razz 

I have no idea. I suspect it was down to the HP engineers and the quality of the installation.

Another question for those with knowledge on the subject.

So, here's the situation:

1. The HP engineer came by on Friday to balance the radiators. 
2. Since the balancing, a room in the house which was previously very cold at night, is now quite warm.
3.The radiator in this room has not been changed, it's still the small raditor from before the HP install.
4. How is this achieved?

I ask because the ringing/resonance I've been complaining about has gotten worse since the balancing was done.

Posted by: @razz

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2. Since the balancing, a room in the house which was previously very cold at night, is now quite warm.
3.The radiator in this room has not been changed, it's still the small raditor from before the HP install.
4. How is this achieved?

By opening up the lockshield valve on the radiator in question, or closing down a bit lockshield valves on other radiators (the lockshield valve, often abbreviated to LSV, is the valve opposite the TRV).  This forces more water to flow through the radiator.  Thus for any given output the temperature drop (delatT) across the radiator reduces, its average temperature therefore increases and thus its output increases.

Thats what balancing is.  If you want to read up on it there is an article here.

Posted by: @razz

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I ask because the ringing/resonance I've been complaining about has gotten worse since the balancing was done.

Thats unfortunate.  It would be useful to know flow rate before and after as it might tell us something.  Changing the balancing is not the way to fix it however, unless somebody has closed down LSVs too much.

Have you tracked down definitely that its coming from the secondary pump.  Are all your TRVs fully open (ie set to max) and if not what happens to the noise if they are?

My strong advice to you is to stop clutching at straws and knuckle down to some detective work.  You are much more likely to track it down that any visiting engineer is, because you are there permanently.  Once its pinpointed and the characteristics clear in terms of what stimulates it or suppresses it, fixing it will be easier.  Im not saying that tracking it down will be easy, but you have a better chance than anyone else.

@jamespa thanks again.

I'll read the article and try to undo the balancing right now.

Also, do you think a big, super wide radiator with a bend like this could be causing some of the noise?

This is the hallway radiator next to the living room.

Posted by: @razz

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I'll read the article and try to undo the balancing right now.

Balancing can be a long process (it can also be very quick especially if the settings are almost right) and its possible to mess things up if you turn down LSVs too much.  If you are happy with the temperature I advise you to leave it unless you have positive reason to suspect its causing a problem.  If you wanted to you could, without changing anything, check that at least one radiator has its LSV fully open.  It would usually be the one furthest from the heat pump or one nearby.   Its important that at least one LSV is fully open and everything else is balanced to that, otherwise you are creating unnecessary restrictions which compromise performance and increase noise. 

Elbows in pipework may exacerbate noise, but are unlikely to be the cause unless the radiators are so poorly balanced that a disproportionate flow is going through one or two rads.    But if this were the case you would notice it in the heating characteristics.  If it is causing it here, the noise will be especially apparent.  Is it.

I would focus on the original source of the noise which I thought you said was the pump.  Is it?