Ventpipe in F&E Tank is constantaly running.....

[EssexDIY]

Hi,
Moved into a property and noticed that the vent pipe from the CH circuit into the F&E tank in the loft is constantly running, even when the system starts up from cold.
I have replaced the old F&E tank as the orginal had a missing lid and replaced the circulating pump, as the old one was a seizing up now and again. (The vent pipe was constantly running into the old F&E tank before I changed it and the pump).
System is fully pumped indirect fed off an old valiant boiler.
I have made sure the new pump is in the correct direction of flow from the orignial one that was removed and it is set to the lowest speeed setting.
I Have flushed the system out as I had cold spots at the bottom of the radiators assuming this was sludge, yet i still seem to be getting overspill coming up the vent pipe into the F&E tank. Any ideas ???

 

[stevehayes]

there could be a split/hole in your coil (inside the hot water cylinder).

 

[EssexDIY]

Hmm, dont think so....as the vent would run all the time in to the F&E tank even without the pump running and I would also expect to see the heating circuit water getting into the DHW (eg dirty water coming out of the taps) plus I would assume the F&E tank would be overflowing as the cold feed tank for the DHW cylinder would constantly pressurize the CH circuit via the the DHW cylinder via the split coil back into the CH circuit????

 

[seco services]

i would opt for a restriction/blockage in the pipework

 

[JohnD]

..I Have flushed the system out as I had cold spots at the bottom of the radiators assuming this was sludge, yet i still seem to be getting overspill coming up the vent pipe into the F&E tank. Any ideas ???

plain water flush or did you use a chemical?

did you take the rads off?

what did you get out?

 

[JohnD]

Hmm, dont think so....

nor me

....as the vent would run all the time in to the F&E tank even without the pump running ...

no, it would rise up the F&E pipe. the vent is higher, no reason the water would rise up that extra height.

I would also expect to see the heating circuit water getting into the DHW (eg dirty water coming out of the taps)

no, because the F&E tank is usually placed lower than the CWC to prevent that.

plus I would assume the F&E tank would be overflowing as the cold feed tank for the DHW cylinder would constantly pressurize the CH circuit via the the DHW cylinder via the split coil back into the CH circuit????

correct

 

[twgas]

i would opt for a restriction/blockage in the pipework

or system piped wrongly

 

[Goldspoon]

Maybe your pump is not in the best place on the circuit and so it is creating excessive pressure leading to pumping over (water pumping into F&E). I believe best place for the pump is on the FLOW and after both the cold feed and vent.

Disclaimer: Still learning so could be wrong...

 

[Eeejit]

if you`r certain you have the pump flowing in the correct
direction, then the cold feed from the F&E cistern, usually a
15mm pipe, should tee into the flow pipe( from the boiler)-on
the suction side of the pump. within 6ins of this, the vent pipe
(usually 22mm) should tee in, beyond the cold feed.
it is possible that the vent and cold feed have been joined
before it tee`s into the flow from the boiler.

 

[JohnD]

photos of the pipes round the pump, the boiler and the cylinder would be a great help.

I still want to know what cleaning chemical was used.

 

[jontheplum]

close coupled feed and vent vent pipe first at high point of circuit cold feed next and within 150 milimetres of vent pipe and then pump then circuit will be under possitive pressure and vent and feed pipes in neutral point

 

[doitall]

Has anyone said blocked cold feed yet

 

[seco services]

afraid so

 

[jontheplum]

specially if u aint got no lid on ur f&e cistern ?

 

[seco services]

specially if u aint got no lid on ur f&e cistern ?

surpose you could have a birds nest.