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Bill Robinson

System Greenstar Danesmoor Utility Regular 18/25 Oil fired. Danfoss pump and Drayton mid-point valve, vented indirect Gledhill Stainless cylinder and immersion heater. Installed last October and installer does not reply to my calls or emails. Boiler in garage and airing cupboard on the other side of the garage wall.

The CH and HW are working okay however a loud alternating vibration noise has started up in the last few months and lasts while hot water is being heated. I have tried to address any potential causes by placing some pipe insulation and trimming wooden shelf in airing cupboard. Also packed holes in wall temporarily with cloth around pipework but parts of the flow and return from and to boiler are still touching the wall. The noise has now a steady tone but loud enough to hear around the house still.

I have tried different speeds for the pump and at fast speed the noise is less and there is no air the system. Mid-point valve works okay.

I have found though that if the CH is on and running there is no noise with HW running as well.

If the boiler comes on for the HW only then the vibration noise begins immediately. The vibration can heard in the flow and return pipes boiler to cylinder to boiler only.

The noise is loudest in the airing cupboard where the hot water cylinder is and very slightly moving of the cylinder changes the tone of the vibration to a lower sound temporarily.

TEST

Boiler on, CH not running but on, HW running and on, vibration occurs CH stat then turned up CH started to run and vibration stops.

I suspect with my limited knowledge that the cylinder is the cause due to a defect (coils touching??) or immersion heater touching coils?? Pipe work against wall??

Thanks
 
It might need a permanently working bypass between the flow and return at the cylinder. That is simply 2 tee joints and a gatevalve, which only needs open partially.
I know Telford unvented cylinders now require this as an update on their MIs.
But Last Plumbers idea of first fitting a gatevalve on the return at cylinder to balance it by reducing flow, should be done to see if that works and will be easiest and cheapest way.
You should be speaking directly to Gledhill for their opinion. The cylinder will still be under warranty, so get it sorted now.
 
It might need a permanently working bypass between the flow and return at the cylinder. That is simply 2 tee joints and a gatevalve, which only needs open partially.
I know Telford unvented cylinders now require this as an update on their MIs.
But Last Plumbers idea of first fitting a gatevalve on the return at cylinder to balance it by reducing flow, should be done to see if that works and will be easiest and cheapest way.
You should be speaking directly to Gledhill for their opinion. The cylinder will still be under warranty, so get it sorted now.
Thanks
 
I find a manual gate valve on the return would help to balance the central heating but wouldn't solve the noise problem.

The old fashioned manual byepass method can make balancing the system difficult.

The noise is being caused by excess heat and pressure having no where to go, an auto bye pass senses this and opens to allow flow back to the boiler.

This is why you don't hear it when there's central heating demand, the excess heat is taken up by the radiators. Boilers have a minimum heat output, your boiler is likely quite powerful and the minimum output is greater than the demand of the dhw coil.
 
I find a manual gate valve on the return would help to balance the central heating but wouldn't solve the noise problem.

The old fashioned manual byepass method can make balancing the system difficult.

The noise is being caused by excess heat and pressure having no where to go, an auto bye pass senses this and opens to allow flow back to the boiler.

This is why you don't hear it when there's central heating demand, the excess heat is taken up by the radiators. Boilers have a minimum heat output, your boiler is likely quite powerful and the minimum output is greater than the demand of the dhw coil.
Thanks for all your help .
 
Thanks for all your help .
Gledhill stated that it needed a gate valve on the return and it would stop the noise. When asked they said it was a common problem. Worcester Bosch service engineer said it was definitely a cylinder problem and both he and a colleague (who has had Gledhill cylinder problems) said my system pressure would not cause the noise with HW only on. Also a heating engineer /plumber friend has heard the noise and concurs its a cylinder problem. All suggest getting Gledhill to inspect but I don't hold out much hope of their help plus I do not want another Gledhill to replace it. Might cut my losses and just get a new cylinder from different manufacturer installed. Your advice would be appreciated.
 
No need in throwing the baby out with the bath water, fit the gate valve and auto bye pass. They are cheap and easy to fit and all systems should have them anyway.

Here's a link for a Honeywell auto pass, which I fit on every cylinder I do.

http://www.honeywelluk.com/documents/Installation-Guide/pdf/950.pdf

I'm sure a plumber on here will tackle it, if your in North Yorkshire I'll do it!

If it doesn't rectify the problem then you can look towards the cylinder. However you should be reporting it to Gledhill, as if the cylinder is faulty then they are obligated to replace it. Most cylinders have at least a 5 year warranty some 25.
 
Gledhill stated that it needed a gate valve on the return and it would stop the noise. When asked they said it was a common problem.

Given the cost of this solution, which Gledhill have recommended, compared with the alternatives I'd suggest you give it a go. The symptoms you describe are consistent with a mechanical resonance, e.g. the coil vibrating, inside the tank and restricting the return has got a good chance of fixing it.
 
No need in throwing the baby out with the bath water, fit the gate valve and auto bye pass. They are cheap and easy to fit and all systems should have them anyway.

Here's a link for a Honeywell auto pass, which I fit on every cylinder I do.

http://www.honeywelluk.com/documents/Installation-Guide/pdf/950.pdf

I'm sure a plumber on here will tackle it, if your in North Yorkshire I'll do it!

If it doesn't rectify the problem then you can look towards the cylinder. However you should be reporting it to Gledhill, as if the cylinder is faulty then they are obligated to replace it. Most cylinders have at least a 5 year warranty some 25.
Thanks for the advice and offer but I live in Kent
 
Given the cost of this solution, which Gledhill have recommended, compared with the alternatives I'd suggest you give it a go. The symptoms you describe are consistent with a mechanical resonance, e.g. the coil vibrating, inside the tank and restricting the return has got a good chance of fixing it.
Thanks for the advice Gledhill would want this done before any further action any way I expect.
 
Thanks for the advice Gledhill would want this done before any further action any way I expect.
Can anyone explain why when the pump is set to 3 the cylinder noise can only just be heard when standing next to it but on setting one as stated it can be heard throughout the house?
 
Can you hear any noise from the pump itself, i.e. noisy bearings?
If you remove the cap from the front end of the pump (be very careful), does the water squirt out under pressure?
Was the pump installed new with the system?
 
Can you hear any noise from the pump itself, i.e. noisy bearings?
If you remove the cap from the front end of the pump (be very careful), does the water squirt out under pressure?
Was the pump installed new with the system?
New Danfoss pump with system and pressure test done already, no bearing noise just noise of water moving. Thanks
 
Can anyone explain why when the pump is set to 3 the cylinder noise can only just be heard when standing next to it but on setting one as stated it can be heard throughout the house?

The pump speed affects the frequency spectrum of the driving force transmitted from the pump to the cylinder via the pipework and the water it contains. The amplitude of motion in a resonant system depends on the frequency spectrum of the force driving it. In addition, the pipework in the house forms a complicated system of coupled oscillators and dampers. How well it transmits sound between points is also frequency dependent.

Conventional piping and clipping rules mean that one doesn't usually experience problems, which usually manifest themselves as 'water hammer'.
 
The pump speed affects the frequency spectrum of the driving force transmitted from the pump to the cylinder via the pipework and the water it contains. The amplitude of motion in a resonant system depends on the frequency spectrum of the force driving it. In addition, the pipework in the house forms a complicated system of coupled oscillators and dampers. How well it transmits sound between points is also frequency dependent.

Conventional piping and clipping rules mean that one doesn't usually experience problems, which usually manifest themselves as 'water hammer'.
Thanks
 
Thank you all for your help and advice as I have no TRV's installed I will go for a simple gate valve on the cylinder return as and when time permits and will let you all know the outcome. Take care all
 
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