Cold feed & Vent pipe

[Mark Edward]

Just started my college course after being in the navy for 12 years so please dont drill into me, regarding the cold feed and vent pipe it has to be 150mm apart on the suction side of the pump what i dont understand is if its on the suction side wont the pump suck all the water out of the central heating f&e tank or what stops it from doing that.. no 2 ,why does the pump being on the return cause negative pressure. Many thanks

 

[bernardgreen]

the pump suck all the water out of the central heating f&e tank or what stops it from doing that.. no

It doesn't happen because there is nowhere for any water sucked from the f&e tank to go. The pipes are already full of water so the pump cannot pump more water into them. All the pump can do is make the water in the pipes circulate round the pipes, radiators and boiler.

 

[dilalio]

Just started my college course after being in the navy for 12 years so please dont drill into me, regarding the cold feed and vent pipe it has to be 150mm apart on the suction side of the pump what i dont understand is if its on the suction side wont the pump suck all the water out of the central heating f&e tank or what stops it from doing that.. no 2 ,why does the pump being on the return cause negative pressure. Many thanks

It's all about balance! The head of water in the F&E tank and the vent pipe is in equilibrium, with the level in the vent pipe fluctuating as heated system water expands and contracts when cooling. This balance allows the "circulating pump" to... circulate the system water. Over pumping occurs when this balance is lost due to restrictions in the circuit such as blockages.

 

[45yearsagasman]

It's actually plumbing black magic.

 

[Dan Robinson]

Try not to think of it as a pump..... Call it a circulator....

 

[dilalio]

It's actually plumbing black magic.

Well it is if you don't maintain the quality of the system water!

 

[Mark Edward]

So the water in the cold feed does not move,So why does the guage on the boiler move down when the pump starts?? Thank you

 

[picasso]

Your getting your systems mixed up, open vent boilers/systems dont have a gauge, sealed systems have a gauge that moves but that is the gauge reacting to the lowering of the pressure on the suction side of the pump.

 

[vulcancontinental]

The water level in the F&E cistern does move due to expansion of system volume up the copld feed. The level in the open vent rises because water always finds it's own level.

 

[Mark Edward]

Can any of you guys give me a ring please have a few questions to ask dont mind even paying to come meet you to teach me, who wants to teach me willing to pay 3-4 hundred for the day

 

[Nige F]

Can any of you guys give me a ring please have a few questions to ask

Where in the country are you ?

 

[Mark Edward]

West midlands-coventry