constant filling of F&E

[--tom]

the F&E tank keeps constantly filling and occasionally overflowing. It has a conventional boiler ( and a cylinder and Imm Heater is present in the system).
The stat on the boiler and room stat seems to be working OK
Any suggestions?

 

[Softus]

Usual suspects are:

1. Float valve not shutting off
2. Cylinder coil split or holed (if the F&E is lower than the CSS).

Shut off the cold mains for long enough to see if that stops the rise in level. If it does, then it's yer float valve, otherwise it's yer cylinder.

The first is about the cheapest and easiest plumbing job on the planet.
The second isn't.

 

[JohnD]

start by testing the ball valve to see if it is letting by or dripping. You can swap the valve if you have any doubt (this is quicker and easier than rewashering it and only costs a few pounds)

Adjust it so that you have only a couple of inches of water above the outlet near the bottom (this leaves max room for expansion)

Sit up there with your torch while someone turns the boiler and heating on and off, see if there is water coming out of the vent pipe (bent over the top of the F&E)

Look and see what colour the water is in the F&E, and when you bleed the rads. See if there is mud at the bottom of the F&E and what colour it is.

Bleed all the rads and tell us how much gas they have, and what colour the water is.

you may have a leak in the hot cylinder allowing water from the taps to leak into the boiler circuit If you have this, you may see HOT water flowing into the F&E at the bottom even when you have tied up the ball-cock in the F&E. this happens because the cold-water tank has a higher (relative to the ground) water level than the water level in the F&E

edited: bah too slow

 

[Softus]

start by testing the ball valve to see if it is letting by or dripping. You can swap the valve if you have any doubt (this is quicker and easier than rewashering it and only costs a few pounds)

Adjust it so that you have only a couple of inches of water above the outlet near the bottom (this leaves max room for expansion)

Sit up there with your torch while someone turns the boiler and heating on and off, see if there is water coming out of the vent pipe (bent over the top of the F&E)

Look and see what colour the water is in the F&E, and when you bleed the rads. See if there is mud at the bottom of the F&E and what colour it is.

Bleed all the rads and tell us how much gas they have, and what colour the water is.

Eh? Sorry John, but I don't think that's relevant.

you may have a leak in the hot cylinder allowing water from the taps to leak into the boiler circuit If you have this, you may see HOT water flowing into the F&E at the bottom even when you have tied up the ball-cock in the F&E.

Erm, I wouldn't expect the fact that the water is hot to be a visible thing, because if it's a cylinder coil then it will have been happening for quite some time, and the temperature in the F&E will already be hot. (This itself is a clue though.)

 

[JohnD]

I was thinking he would have brown rust and lots of gas if it has been refilling a lot, which brings up another relevant problem.

 

[Softus]

IMHO that brings up an irrelevant problem, but I'm a closet pedant.

A constantly filling F&E doesn't have a particular tendency to enter the system very quickly. However, I agree that it's worth bringing up the question of overall system health at some point.

 

[JohnD]

closet

 

[Softus]

Oh you're so picky.

 

[gas4you]

brown and lots of gas

Sounds like my missus backside

 

[--tom]

Thanks for the good info replies: the water in the F&E is hot and the water in the cold storage is higher than the F&E. I'll have to check out the other questions. Not certain, but turning on the cold water taps seems to affect the F&E business ie simultaneous noises can be heard from the F&E when the cold tap(s) are turned on.

 

[Softus]

Not certain, but turning on the cold water taps seems to affect the F&E business ie simultaneous noises can be heard from the F&E when the cold tap(s) are turned on.

If you have a noisy main, then using a cold tap [one that's mains fed] will end up conveying noise to the F&E via its cold supply.

The 'mains off' is the simple test - if the F&E level continues to rise then you need to replace the cylinder.

 

[--tom]

Thanks again. i will get back probably on mon or tue, with further results or info.

 

[Softus]

A three-day roundtrip between your computer and your loft is going to make diagnosis quite a cumbersome exercise.

 

[--tom]

I cleaned out the ball valve of the F&E - grit - and the problem has stopped.Now to watch and wait. Thanks for the help.

 

[JohnD]

It wouldn't hurt to top up the inhibitor. If it has been running for long, the old inhibitor will have been diluted or washed out.