Pumping over issue

[Beboers]

Hi Guys,

I have a customer with an ancient gas boiler which is connected to a hot water cylinder above it which then carries on to the f&e tank in the loft. The problem that is occurring is that over the period of a night the overflow starts flowing to outside from the cwsc which is being made warm by water pumping over from the hot water tank vent pipe. I thought it must be the boiler (if you can call it that) thermostat playing up and boiling the tank over but we turned the stat down and ended up with Luke warm hot water and it still overflowed after the evening!There are no other controls just two flow and returns feeding a cylinder and a heat leak rad controlled by a thermostat on the gas heater. Any Ideas chaps??
Thanks in advance!

oh I also presume it is not a split coil as th f&e is sited below the cwsc which is the on overflowing.


please help!

 

[Beboers]

Hi Guys,

I have a customer with an ancient gas boiler which is connected to a hot water cylinder above it which then carries on to the f&e tank in the loft. The problem that is occurring is that over the period of a night the overflow starts flowing to outside from the cwsc which is being made warm by water pumping over from the hot water tank vent pipe. I thought it must be the boiler (if you can call it that) thermostat playing up and boiling the tank over but we turned the stat down and ended up with Luke warm hot water and it still overflowed after the evening!There are no other controls just two flow and returns feeding a cylinder and a heat leak rad controlled by a thermostat on the gas heater. Any Ideas chaps??
Thanks in advance!

oh I also presume it is not a split coil as th f&e is sited below the cwsc which is the on overflowing.


please help!

Anybody??

 

[TBServices]

Do you know for sure it's venting over?

May be a case of trial and error. First job, change the ball valve and make sure increased pressure on a night isn't causing valve to pass.

 

[Beboers]

It has been changed by the customer a few times as they thought it was faulty which would make sense but again it has overflowed?

Thanks for advice any thing else?

 

[Beboers]

No I don't know for sure but the water in the tank is warm I was not there when it was doing anything unusual.

 

[shaunsinky]

do you mean the small f+e tank or the larger cws? do they maybe have an immersion heater in the cylinder thats not switching off

 

[boabgti]

check any mixer taps or valves maybe be a cross flow from the mains being pushed up through the pipework and filling the tank.

 

[Beboers]

It is the cold water storage tank not the f&e, checked the immersion it is switched off. I can not see it being a mixer tap as the water in the tank is being made warm, and it is happening over the period of a night when nothing is being used? An immersion if left on has a safety cut out which would stop this happening anyway.
Thanks for all the ideas so far guys anything else?

 

[shaunsinky]

ive been to plenty of jobs like you described and its been a faulty immersion being on 24hours but you only notice in the morning due to no hw being ran off overnight.

 

[BLOD]

Might be worth checking the open vents are over the right tanks.

 

[GasmanxxxR1]

Mains water in a mixer tap, causing reverse flow in hw side, pushing hot water up the cylinder cold feed?

 

[Beboers]

Ok Thanks for this guys I will check all of these next time I am there and hopefully will get somewhere with it

 

[GasmanxxxR1]

Turn mains off over night and see if it happens again

 

[Beboers]

Hi Guys,

Thanks for your helpful replies! this problem is now resolved it was a downstairs wc monoblock tap with the mains pushing up through the hwc and in to the loft tank as gasmanxxxr1 suggested!

 

[Rickster123]

Thanks for the update. Glad it's all sorted.

 

[TBServices]

Hi Guys,

Thanks for your helpful replies! this problem is now resolved it was a downstairs wc monoblock tap with the mains pushing up through the hwc and in to the loft tank as gasmanxxxr1 suggested!

Ahhhh, that old chestnut. Classic

 

[tamz]

Ahhhh, that old chestnut. Classic

Aye taps fitted by a numpty with no check valves.

 

[gassafe]

How would the cold water push up the hot if the tap is turned off!?

Why did it not always do this? I rarely see check valves below mixers taps!