Hot water tank

[PlumbCrazy]

Can anyone throw a light in a plumbing problem I’m having please?

I live in a three storey new build townhouse and have noticed a continuous, low-level sound vibration from the pipework. It seems worse when I use the washing machine on the ground floor, dishwasher on the first floor or shower on the top floor. It’s never very loud, just a fairly continuous pulsing, grumbling sound. Plumbers seem not to be able to hear it. It’s driving me crazy.

I’ve also noticed that the pressure gauge on the hot water tank fluctuates. It is set at 1 bar but had dropped to 0.5 bar and is now rising again without me topping it up. Is this normal? The hot water tank is a mega flow and the system is a closed one.

Thanks in advance for any ideas as to what this could be!

Try a non return valve on the cold water mains coming in . had a similar issue when water was being drawn off and toping up the tank .

Thank you Henry. I’m not sure I understand what that is but I’m off to google!

Probably, next to your megaflow, is a tundish where it expels water throuh a pipe when the pressure is too high. It then runs off and finds a drain. Is there any sign of water there? If you stand next to the cylinder when the noise occurs, can you make out where it comes from?

The varying pressure: Megaflows have an internal pressure bubble; if yours has not been serviced for a couple of years it may have gone wrong or need recharging by a person qualified on unvented cylinders. Some plumbers are, and some boilermen. Not all.

It's is normal for pressure to fluctuate as the temperature of the water in the rads changes. Hot water actually takes up more space than cold. That's why we have expansion vessels in the system.

Thanks for the replies.

The tundish is dry. The vibration is coming from pipework next to the cylinder, both to the side and underneath. I can also feel the floor vibrating slightly in the living room which is on the floor below but adjacent to the hot water tank, if you see what I mean.

The tank is only 2.5 years old and was serviced last year.

I can understand how pressure can fluctuate but 0.5 bar over just a couple of days seems to be a lot.

Thank you for trying to help, I think it’s time to call a plumber.

And serviced by a properly qualified plumber.

I wonder if it might be the pump? Can you see one? In modern system boilers it might be inside the casing, but can also be beside the boiler or the cylinder.

Hi PigletJohn there is a pump on the outside of the tank, it’s a Wilo if that makes any difference? I did wonder if it might be the pump due to the pulsing nature of the vibrations.

Make sure the cold water main stop tap is fully open. You may be hearing the water rushing through it when you use water in the house.
Does the noise happen with just cold water or hot as well?

The stop tap under the sink is fully open. It happens both when I have the heating on and also when I use the washing machine and dishwasher which are all fed from the food supply. I can also hear the pulsing vibration, though very much reduced, when everything is switched off, ie no heating on and no appliances are being used.

Grateful to everyone for your suggestions!

Cold supply, not food!!!!!

Are you on a water meter?

Yes I am on a water meter. Might that have an effect?

sorry, wrong thread.

We had the pumps changed in the the local pimping station and never have a problem previously . after the change when other people further down the street turned water in the pipes would start to bang . we had a loose pipe in the utility room and you could see it move when water was being drawn off elsewhere . the new pumps only operated when water was drawn off and pressure was applied causing pipe vibration . you can also fit a rester which can help . item number 64117 tool station or 94454 just past the stop tap . different sizes for different pipes and applications available