F & E Tank Overflowing

[denso13]

Header tank

Header cistern, just trying to spread professionalism.

Mention storage tank or rising main when I was learnin' and you were suitably chastised...

 

[bennyd]

Normally a blockage in the pipework where the feed joins at the T piece (blue line). If a magnet is attracted to the area it will point to that.

And read my sig ⇩!

I put a magnet on the T piece and it does stick, it also sticks on the pipe down to the pump and the curve above to where it meets the other T piece. I assume this is where the blockage is? I put the hot water on for a couple minutes and the pipe heating up evenly so i couldnt tell where a blockage may be.

The cistern is not filling through the ball valve or the overflow (over the top of the tank), i have been in the loft while the hot water has been on to check this, which only leaves the other pipe which was indicated in blue on my photo. This enters/leave the cistern at the bottom.

I have a Magnaclean filter near the boiler which i have just cleaned (it wasnt that dirty) and i do this yearly.

I'm not confident to cut pipes, so i assume the only way is a heating engineer to remove and replace this section?

 

[denso13]

I put a magnet on the T piece and it does stick,

Copper isn't magnetic, but the blockage normally is, sounds like this is the problem.

I'm not confident to cut pipes, so i assume the only way is a heating engineer to remove and replace this section?

It isn't difficult but if you know your limits, then yes, get someone in. It is the obvious thing to try first.

 

[Johntheo5]

If its not the mains makeup, ballcock etc, then it simply can't overflow from the primary side, how can it??.

 

[denso13]

If its not the mains makeup, ballcock etc, then it simply can't overflow from the primary side, how can it??.

It's a very common problem. With the pump on the blockage causes water to rise up the feed into the cistern. the water has to go somewhere and it takes the path of least resistance.

 

[Johntheo5]

Where does it get the water from??, it can only draw it down from the vent which only holds less than 0.5L or so??

 

[denso13]

Where does it get the water from??

The heating system. It doesn't take much to fill the feed and expansion cistern.

 

[Madrab]

The pump (circulator) is creating positive pressure in the system all the way around to the feed, that pressure added to the heated expanded system water then hits the restriction in the pipe between the feed and the pump, that positive pressure then pushes the system water back up into the cistern through the feed, if the volume is great enough it overflows.

 

[denso13]

The OP has also confirmed it is worse when the pump is set at 2, rather than 1.

 

[bennyd]

Thanks everyone. It seems i have my answer. Time to spend some money!

 

[Johntheo5]

Thanks everyone. It seems i have my answer. Time to spend some money!

Just before you go, when the heating and pump stops does the water stop dripping/overflowing from the overflow?.

 

[bennyd]

Just before you go, when the heating and pump stops does the water stop dripping/overflowing from the overflow?.

after a little while yes

 

[Johntheo5]

I'm amazed that the pump (even with blockages) can raise the level by 200mm, 8 ins, from the system itself, maybe from the rads, if higher than the pump, but every day's a learing day.

 

[Johntheo5]

This is a very interesting problem, wonder if the pump is drawing air in through the vent which when heated will displace the water to cause overflow, I know you said system worked OK since pump renewal in Dec but can you check sometime that the pump is pumping downwards to the midposition valve, you might also hold a plastic glass of water under the vent with pump/HW on and see if it's drawing air in. If the level overflows each Time the HW is on and if the ballcock never makes up then I can only think that air is the problem.

 

[HERTS P&D]

Do we know how high the expansion pipework is above the F & E?

Andy