back boiler feeding combonation cylinder

[ryan k]

Having nightmare getting circulation downstairs on system, tried new pump also when I open drain from return leg airs being pulled back into pipe, think return legs blocked, the pump fitted to return is not pulling heat back to back boiler. Any ideas

 

[stevetheplumber]

sounds like an airlock to me have you tried backfilling from the drain of ?

 

[ryan k]

Yes tried that still no further forward. Thank for reply

 

[diamondgas]

:welcome: to the forum ryan k

what's the system design ryan, gravity/pumped heating, 'y'or's'plan? Small bore or micro-bore pipework? Droppers or separate up and down circuits? Just a bit more info might reduce the possibilities and help us help you

 

[mountainman]

Has this just happened or has the system been plaing up for a while?
Has the system been drained or modified just prior to the fault appearing?

 

[ryan k]

Hi thanks for your reply as my knoledge in domestic is limited as have been commercial for the last 12 years, the problem is downstairs and all these radiators r drop feeds the pump is on return and its not pulling the heat back to the boiler. Thanks for any help

 

[ryan k]

All of the droppers are 15mm no micro bore on system. Thanks

 

[ryan k]

Basically been going on for a while all of down stairs r drop fed with 15mm and this is were the problem is. All of upstairs is ok heating but downstairs no hope tried backfilling, pulling water through each leg with no success. Thanks for your help.

 

[diamondgas]

Is there a diverter fitted ryan? Can you put the system on heating only? If you scale down the system you have a pump either feeding rads only (gravity) or there are valves controling the flow from the pump... Lot less complicated than commercial to be honest!

Sounds like you have a flow issue, maybe blockage. Could be a simple as a faulty diverter or more complex pumping over/ restricted diameter pipework due to sludge? Is this a personal or work related?

 

[ryan k]

Thanks for info you have supplied just found blockage under floor on return leg, also just discovered no stat on cylinder and no 3 port valve going to make modifications thanks for your help

 

[diamondgas]

Thanks for info you have supplied just found blockage under floor on return leg, also just discovered no stat on cylinder and no 3 port valve going to make modifications thanks for your help

You're welcome Blockages can be a pain to pinpoint!