Boiler with no pump overun to one with

[rhinosaw]

My old vented boiler of 40 yrs had no pump overun. WB system boiler has it built in so obviously pump will stay on for a while. No additional wiring but what about the 2 zone valves, s plan, how do they find out to stay open to allow the water to circulate till pump goes off?

 

[bernardgreen]

When the zone valves are closed and the pump is still running then the increase of pressure should cause an automatic by-pass valve to open.

 

[rhinosaw]

Thanks Bernard .so they will have add a bypass valve somewhere then as there isn't one at the moment?

 

[bernardgreen]

.so they will have add a bypass valve somewhere

They should have done,

 

[ianmcd]

you will need a by-pass installed before the zone valves and you will need a permanent live added to the new boiler, the pump will have to be wired from the new boiler

 

[rhinosaw]

The new boiler hasn't been fitted yet Bernard, I am assuming that they will fit a bypass valve when the work is done
Thanks again

 

[ServiceNumpty]

System Boiler or Conventional Boiler
System boiler has pump and bypass built in.
Conventional Boiler - Separate Pump and Separate Auto Bypass required.

 

[rhinosaw]

Ok Mike, thanks but how does the bypass work within the confines of the boiler, I would have thought it should be somewhere in the system linking flow and return??

 

[ServiceNumpty]

System boiler has a tiny bypass, just to allow enough flow through the heat exchanger. I normally fit an additional autobypass before any 2 port zone valves anyway.

 

[rhinosaw]

Ok , with a WB 12i would u recommend an additional bypass? Thanks

 

[bernardgreen]

System boiler has a tiny bypass, just to allow enough flow through the heat exchanger.

Isn't it necesary for there to be a few feet of pipe between boiler and automatic bypass such that the heat left in the boiler when it shuts down can be dissipated from this pipe work and thus cool the boiler's heat exchanger.