Megaflo Eco System Unvented Cylinder Loud Bangs

[Richard84]

Hi Everyone,



Hoping for some advise / assistance on an issue I have on my Megaflo Eco System Unvented Cylinder which is making a loud band.



This occurs when the hot water heating is on and when the cylinder heats up to temperature, once at temperature the motorized valve closes and there a loud bang, which causes the pipework to vibrate.



I have attached a video which shows the problem occurring.

 

[ShaunCorbs]

Sounds like maybe the auto bypass has failed or one isn’t installed does it do it when another item is on eg one heating zone ?

 

[Richard84]

Sounds like maybe the auto bypass has failed or one isn’t installed does it do it when another item is on eg one heating zone ?

It doesn't do it when the heating is on upstairs, only when the hot water has heated up to temperature.

What would the auto bypass look like?

I did manually open and shut both valves and there was a clunk from both motorized valves when shutting.

 

[ShaunCorbs]

Might be angled or might have a red cap on it

 

[Richard84]

View attachment 75751


Might be angled or might have a red cap on it

Thanks for sending photo, I cannot find the auto bypass as above. There is only 2 Honeywell motorized valves, there is a valve above the motorized valve for the hot water tank, but it does not have a red cap. See below

 

[ShaunCorbs]

That’s your problem one isn’t fitted

The one in your picture is a lockshield valve to slow the flow through the cylinder

 

[Richard84]

It doesn't do it when the heating is on upstairs, only when the hot water has heated up to temperature.

What would the auto bypass look like?

I did manually open and shut both valves and there was a clunk from both motorized valves when shutting.

Thanks for the help on this Shaun!

Should this be fitted as standard to this system or is it only required for certain configuration of heating systems?

The only reason I ask is that the house is a new build and is only 4 years old. When the house builder visited site for the bang (although not that loud at the time) they said it was to do with the internal air gap needing to be regenerated. This did not do much then COVID hit and they tried to wash their hands of it saying that it was no longer there issue due to length of time we had been in the house. However, if it is a fundamental part of the heating system then I will go back to them again.

 

[ShaunCorbs]

Yes should be fitted at time of install