system noise and pipe vibration

[AnonymousImport]

I've got a Potterton boiler system which is about ten years old and the hot water tank was changed by the house's ex-owner two years ago. Now, it is making terrible noise and vibrates badly after it is on for some time. The symptom is like this:

1)If I turn the hot water on (but the heating is not on), after about 30 minutes, I can hear some wherring sound from the airing cupboard, but it is usually not too loud, I can also feel some light vibration on some of the pipes and from the floor. But after 1.5 hours, the noise will suddenly become very loud and the pipes around the hot water tank start vibrating very violently (as if some body is banging the pipes very forcefully). At this point, even if I shut the whole system down, it will take a couple of minutes for the noise and vibration to stop.

2) If I only turn on the heating but not the hot water, it will take longer(about 2.5~3 hours) for the above symptom to happen.

3) If I turn both heating and hot water on at the same time, the above symptom will happen a lot quicker, usually about 40 minutes after the system is turned on.

I will appreciate any suggestion on where the faults lie?

 

[AnonymousImport]

pump giving up?

 

[AnonymousImport]

How would a faulty pump cause such a fierce vibration?

 

[AnonymousImport]

only a thought. but suppose its impellar was broken it would spin off centre causing vibration. only a thought

 

[Mikes]

When the hot water tank was changed was any form of water flow control added or changed? Could it be that once the Hot water tank is full of hot water there is a flow control device coming into operation i.e to limit the hot water temperature?. If so where can the boiler send its hot water?. Normally there would be a permanent circuit through something like a towel radiator or similar that would always provide a flow and return for hot water.

 

[AnonymousImport]

cool