Bad vibrations Telford Tempest unvented cylinder

[stuart1990]

I have recently had a new Telford Tempest Unvented cylinder installed by my plumber and am now suffering noisy vibrations/resonation that sound like a whirling helicopter as soon as the hot water is switched on. This only stops when the central heating is switched on. The buzzing noise seems to be coming from the heat exchanger coil inside the cylinder. I have tried changing the pump speed but the noise seems to be independent of that.

My plumber has fitted an automatic bleed as he thought it could be due to trapped air in the system but this has had no effect.

I am not a plumber but would appreciate any thoughts ideas on how to resolve this.

 

[stuart1990]

It is a 50 litre expansion tank wth a 400 litre cylinder and the expansion tank was as supplied by Telford for the size of cylinder. The vibration is does not seem to be a function of not having clips as the piepwork is very rigid and when holding the pipe which has gate valve this doesnt seem to alter vibration.

 

[Gray0689]

Then I think you need to get the manufacture to take a look as could be a problem with the coil

 

[SafeGasInstall]

what size is your pump mate

 

[stuart1990]

Sorry I cant locate the pump it must be behind the boiler and I am not that conversant with plumbing. I will contact Telford tomorrow and let you know what they say!

 

[stuart1990]

Oh My Word, I am trying to understand why you have what looks like a 50L expansion vessel on what looks like a 300L unvented cylinder, It does seem excesive unless this is a commercial system with a lot of bathrooms, also is that a central heating 3 bar safety valve coming from the groupset these are normaly 6 bar
And the use of gate valves on unvented!!!!

Sorry for my ignorance but not being a plumber...what are the consequences or issues with a gatve valve on unvented system....is it a safety thing?

 

[SafeGasInstall]

tell us about your boiler then

 

[tackleburger]

In answer to your comments. Yes the boiler is on and then as soon as the hot water is switched on then this resonance commences. It seems to come and go and occurs every 45 secs and lasts say for 30 secs. The plumber has the qualifications for this type of installation and has fitted others before without any problems like this.
The noise is definately coming from inside the cylinder and thats causing the vibrations in the pipework as I can feel it when I hold the inlet and outlet flows from the cylinder. As stated I am not a plumber but it seems that the problem is created because the pressure or volume of flow exerted by the water in the primary circuit is causing the resonance because as soon as I switch on the central heating the noise vanishes. I am guessing this is because the water is now circulating round the house and the pressure exerted on the coil is reduced???
He has considered fitting a gate valve as a bypass to reduce the flow slightly. Do you feel this maybe a solution?

Has to be pump vibration combined with air in the cylinder circuit. can't see a fault in the cylinder has to be down to the system. I had a nightmare just today with a similar thing after removing an old Elson and installing unvented was finished a 1400 got away at 1800 after 4 hours messing about. It happens if your system is working you may find leaving it on for a good couple of hours to solve it.

 

[BLOD]

Please can you clarify, do the noises happen when a hot tap is opened or if they happen when the hot water heating is selected on the programmer (& no hot taps are open) - thanks

 

[SafeGasInstall]

for some reason i keep thinking that could be fitting in the coil

 

[stuart1990]

Boiler is a Worcester Danesmoor 35/50 and runnng at about 45kw

 

[stuart1990]

The noises happen when the hot water heating is selected on the programmer and no hot taps are open. As soon as the central heating is selected the noise stops! It makes me believe the is too much load/flow/presure on the heating coil when its just on hot water and this causes the vibration/resonance. (I am speaking as a layman but trying to apply a degree of logic)

 

[PlumbBobBob]

sounds like you could be on the right track. what speed is your pump set at? maybe turning it down might help.

 

[stuart1990]

My plumber claims he has turned it down so maybe I will call Telford tomorrow

 

[SafeGasInstall]

they will book you in ,just get plumber who install it to be in when they visit ! just that they explain to him everything and no info get lost

 

[Gray0689]

That not a standard install then it's a big system by the sounds of it so I'm guessing a big pump do you know what sort?

 

[unguided1]

Sorry for my ignorance but not being a plumber...what are the consequences or issues with a gatve valve on unvented system....is it a safety thing?

Sorry I am being unfair, there is no safety issue using gate valves on an unvented system, and many plumbers still use them
I have found through experiance that gate valves used on unvented systems tend to let water through the gate when you are using these valves to try isolate somthing so then you try to shut the valve even tighter and invariably you end up snapping the spindle, this means that the whole valve then needs replacing.
I prefer using full flow ball lever valves, and you will find that these are usually more expensive than gate valves

 

[BLOD]

I'd disconnect the flow & return from the cylinder & join them together.
If the noise dissappears it could be a faulty cylinder /coil, so would get on to Telford for a replacement or refund.

You also need to get rid of the gate valve on the pipe that goes from the inlet multiblock to the cylinder, this could be closed by someone, and would disconnect the expansion relief valve from the cylinder.

 

[stuart1990]

Just thought I would update everyone having spoken to Telford. They claim this problem can occur on big systems and advised me to put a balancing valve between the flow and return. I did this and this has resolved the problem. I only opened the gate valve slightly when the vibrations started and immedately system seemed to be fine.

 

[PlumbBobBob]

good to hear you've got it sorted.

 

[BLOD]

Glad it's working ok now.
But you must get rid of the gate valve between the inlet multiblock
& the cylinder inlet !