open vented system sucking in air HELP PLEASE

[benthetroubled]

banging, cant remeber the name of boiler will find out tommorow when im passing the place

 

[benthetroubled]

ohh forgot to mention that the expansion tank is filling up with hot water from the system every time the banging occurs

 

[picasso]

make sure the valves either side of the pump are fully open, did you close any valves ect when you changed the pump ?

 

[benthetroubled]

If you mean isolation valves there wernt any had to drain the system completely just to get the old pump off

 

[picasso]

and the pump valves ?

 

[Biguns]

Sounds like kettling through electrical fault. Reproduce the symptoms and check that the pump is powered when the boiler fires up
Could be pump overheat stat or 3 port valve etc.

 

[picasso]

why would he need a 3 port valve, its only running 3 rads

 

[benthetroubled]

sorry i had to remave the valves from the main pipe work as they were stuck onto the pump to tight to work on them in place so didnt have to close them in first place.

 

[Biguns]

why would he need a 3 port valve, its only running 3 rads

Just read original post again
Make allowances for old timer
I still think its kettling though

 

[vulcancontinental]

sorry i had to remave the valves from the main pipe work as they were stuck onto the pump to tight to work on them in place so didnt have to close them in first place.

did you open the new ones fully?

 

[onlyfitidealboilers]

sounds like its pumping over if the tank is hot. when the system cools down and the water re enters the ch system (water carries oxygen) hence then reason air coming back into the system.

 

[DP]

sounds like its pumping over if the tank is hot

Why?

Think about it. COMBINED F&E pipe.

OP, go to the nearest radiator. Is the radiator, or the inlet pipe to the said rad getting hot? If yes, reduce the setting on boiler thermostat and run boiler. Do you then get same symptoms?

 

[5TIMES]

Just because its a combined feed & vent does not mean water carn't bubble up into the tank.

maybe you could explain why you think just because the openvent is submerged under water, the system carn't pump over??

 

[bengasman]

... just because the openvent is submerged under water, the system carn't pump over??

Some hot can bubble up, but as there is no second pipe, you can't get the flow that an overpumping system can have.

 

[DP]

Just because its a combined feed & vent does not mean water carn't bubble up into the tank.

5times, what do mean by that statement. Can you explain as I fail to understand what you mean.

It is single pipe we are talking about and pumpover (as in circulation) not convection currents.