indirect cylinder heated by back burner

[nick penfold]

Hey guys.

Hope you can help me gain some more understanding on this one.

Recently put in an indirect cylinder as a replacement to a direct one as the customer has bought a lovely lil backburner fire thingy..
The plan is basically so that when their fire is on, they can heat their hot water in the evenings via this set up.

Its not for central heating but we put a heat leak rad on with TBOE set up.

Customer has fired up the back burner and says all works fine and dandy........ however........

They have noticed that when the fire gets very hot and raging etc, there is a distinct banging noise from within the airing cupboard and they believe its from within the actual cylinder. After about 15 or 20 mins, this noise dies down.

Customer reports that hot water is great etc but was concerned with noise.

apart from the vent to F&E, theres no automatic air vent installed...

Please see my very quickly drawn sketch of the basic layout. Is this sounding like trapped air? or what other scenarios could there be.

I work for my fathers business and he's off to sort it out later but i was just hoping for some more insight off other plumbers if possible for my own education

thanks in advance

Nick

 

[tipper]

What are the relative levels of the fire, cylinder and rad?

 

[nick penfold]

back burner is approx 1 metre below cylinder rad (heat leak) is 1 metre below cylinder and f&e is about 2 metres above cylinder. hope thats what your asking for

 

[SmashyD]

i think you should t into the primary above the cylinder flow for the heat leak flow.ie into the vent pipe. Your heat leak will not function that well the way you have it connected and the cylinder may be getting too hot. Have you any pipe runs that run tight against timber?They will be 28mm for the primaries I assume? They will expand a lot especially if they are getting very hot and this will cause sudden knocking and banging sounds as they rub.
Is that of any help?