@derek-m Thank you. Yes black object is the thing that switches water from hot water to heating.
Not sure what large tank is for, so I expect you are right.
Noise is vibrating pipes. That, and the towel rail vibrate as the water flows round it (and one radiator in a bedroom does it to a lesser extent). I think it's velocity of the flow. There is a valve that the installer has changed the setting on - I'll attach a photo, at the bottom of the "volume tank". At 0.3 it was "snoring" at 0.5, where it's currently set, it's consistent flow noise. If I turn the towel rail valves off, it all goes back to "snoring". I'm absolutely not an expert but it feels like everything has to flow round those pipes too fast. It wasn't doing this when I had an oil boiler on the system. I don't think it did it when it was first fitted, but then it did that snoring thing. Is there any way of checking the velocity?
@derek-m Thank you. Yes black object is the thing that switches water from hot water to heating.
Not sure what large tank is for, so I expect you are right.
Noise is vibrating pipes. That, and the towel rail vibrate as the water flows round it (and one radiator in a bedroom does it to a lesser extent). I think it's velocity of the flow. There is a valve that the installer has changed the setting on - I'll attach a photo, at the bottom of the "volume tank". At 0.3 it was "snoring" at 0.5, where it's currently set, it's consistent flow noise. If I turn the towel rail valves off, it all goes back to "snoring". I'm absolutely not an expert but it feels like everything has to flow round those pipes too fast. It wasn't doing this when I had an oil boiler on the system. I don't think it did it when it was first fitted, but then it did that snoring thing. Is there any way of checking the velocity?
Hi Bridget,
The valve in the photo is the bypass pressure relief valve. What you describe as the snoring noise, I believe, is this valve opening and closing to relieve a pressure build up. Let me explain why the valve needs to be installed. If your heating system contains zone valves or TRV's, there could be situations when all these valves close at the same time. The water coming from the water pump therefore has nowhere to go, so the pump would cavitate, which is not very good. Under normal operating conditions the bypass valve should be closed, but if the flow through the heat emitters should become restricted, the pressure in the flow pipe builds up and causes the bypass valve to open, hence causing the water from the flow pipe to go through the bypass valve to the return pipe. Thereby keeping a water flow through the water pump.
In your system the snoring is caused by a build up of pressure opening the bypass valve, but when the valve opens the pressure falls and the valve closes. Then repeat. Adjusting the bypass valve to open at a slightly higher pressure has cured the snoring. 😎
The velocity with which water flows through the pipework is a product of the quantity and the internal diameter of the pipework. So if a 1 metre length of pipe has an internal volume, that if filled, contains 1 litre of water, and the flow rate is 20 L/min, then the flow velocity will be 0.333m/sec. If the internal area of the pipe is doubled, then the flow velocity would be 0.166m/sec, or half the original velocity. The same would be true if the flow rate is reduced from 20L/min to 10L/min.
There are specified limits for the allowed velocity of the water in central heating pipework.
Further causes of vibration in pipework could be if the pipework is not adequately secured, or even the length of the pipe between mounting brackets is such that the flow velocity is hitting a resonant frequency. Try holding an vibrating pipework and see if the noise is reduced or stopped.
@derek-m thank you. Holding it makes no difference. The noise is the water going round all those new hot pipes they've installed in the airing cupboard and into the adjacent towel rail. Its not effecting other radiators (other than one bedroom one) but the noise from the airing cupboard pipes and the towel rail is excessive.
@derek-m thank you. Holding it makes no difference. The noise is the water going round all those new hot pipes they've installed in the airing cupboard and into the adjacent towel rail. Its not effecting other radiators (other than one bedroom one) but the noise from the airing cupboard pipes and the towel rail is excessive.
I would suggest that you get your installer back to resolve the problem.
Thank you - I think you are all on to something here. This morning it was whisper quiet (bliss) - I took three photos and it got quieter, even in the bathroom as the flow rate decreased. Now you can hardly hear it at all and it's all warm and toasty.
I don't know what size my heat pump is, so I'll try and find out and post the results.
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