overflow query.

[tunod]

Hello All, I have a problem with my heating system and before I get a plumber in I,d like to see what you may think the problem may be. Here goes, I have a Baxi bermuda back boiler with a gas fire fitted, it is a few years old but has been serviced annually. The problem is that the expansion tank keeps over filling. I,ve checked the ball valve and it seems ok. If I bail the tank out it refills within 2 days and the overflow starts dripping again. I should also point out that the rising main feed has a loud hum when filling, this I believe is due to bounce in the ball valve. I think the thermostat in the boiler is playing up, allowing the system to over heat. What do you think, any suggestions would be of help.

TUNOD the backward DONUT

 

[mrgas]

Sounds like the coil in your hot water cylinder has pinholed. It will need replacing. Sorry

 

[jamescarter1000]

yes that could be true; but may be overflowing quicker than every 2 days, and also this is only if the header tank is at lower water level than the cold storage tank.

also, your water level may be set too high in your header tank?

 

[tunod]

Thanks for the replys, I,ve checked the ball valve setting and it shuts off the water at the correct level, however when I have to bail out the ball is submerged and hard against the seat. I thought the vent pipe was putting excess into the expansion tank, is this likely.

 

[LeedsPlumber]

http://www.diynot.com/forums/viewtopic.php?t=170299

 

[TonyW2]

Somehow, more water is being introduced into the system, after the feed/expansion tank is filled to the correct level.
Note that the ball valve should be adjusted so that there is only a few inches of water in it when system is all cold.
If the hot water cylinder coil is perforated then you would get the symptons, assuming the f/e tank is lower than the cold water tank water level, but if you are wrong about the ball valve operating correctly, then you would also get those symptons. The latter is the cheapest, by far, so first check that ball valve properly.
Can you turn off the supply to the ball valve or (not as good) tie it up and really watch it for drips or even change it for a new one, then leave to see if the problem persists.

(Don't worry about overheating--that would not cause continous overflow, just overlow into the expansion tank and recirculation).

Leeds--is it not unlikely that the pipe layouts/height differences would have only recently affected things?

 

[tunod]

As far as I can tell,that is I can,t feel any water around the ball valve outlet and I tested it with paper to see if it had a dribble but nothing. Also there seems to be no water around the vent pipe nor is the water warm at all. However, I have made some alterations to the plumbing/heating system in recent months by fitting another toilet downstairs, and a heated towel rail instead of a radiator that had been fitted before. The pipework for the toilet was tee,d into the bath supply in the bathroom above, but all the towel rail needed was some alteration to the exsisting pipework. This work was done sometime before the symptoms appeared.
I,m getting a bald spot from scratching my head.

 

[swidders]

I suppose that you have checked that the ball on the FE tank hasn't punctured? Remove and check that it's empty of water!

Work to your toilet etc will have no bearing on the FE problem

 

[Stingray13]

The water is probably being pushed up through the cold feed in the f and e tank, my suggestion

Close the Ball Valve either turn off or tie-up
Bale out water to the water draw off level shouldn't be a lot and watch, see if water starts to come out of the draw off if so you have a coil hole and it is backing up.

 

[stevies62]

Is your cold water storage tank higher or at the same height as your central heating header tank? If it is, coil in the hot water cylinder has gone and is filling up the central heating header tank.

 

[Whitespirit66]

Tunod, you say that you did some alterations to your plumbing. Did you by any chance add a mixer tap? Are you sure that it is your feed and expansion tank that is overflowing.

When people say that their tank is overflowing, and they have replaced taps etc the two are often linked. Sometimes the cold water pressue at the mixer is higher than the hot, which forces the hot water back up the pipe and causes symptoms like yours.

I could be barking up the wrong tree, but its worth looking at.

 

[tunod]

The cold water storage tank is at same level as f&e tank. Yes I did fit a mixer in the downstairs cloakroom and the hot pressure is rubbish. I suppose one way to check equivilant water pressure would be to run the tap and watch the f&e tank level. Is there any way to check the coil without removal.
As the system is years old ie back boiler etc, I have thought of having the boiler replaced with a combi type.

Sorry stingray, did,nt see the test you suggest in your post, sounds good, I,ll give it a go.
Whatever, I think it may be time for the man from Corgi to call. I can feel my pocket getting lighter already. ouch!

 

[Whitespirit66]

How long did the problem start after fitting the mixer?

If you have been using this new tap, it may be the problem. Try not using it for a few days, and see if the problem stops.

If it is the tap, you will need to fit a check/non-return valve to the hot water pipe near the tap to stop the higher pressure cold water forcing the hot water back up the pipe.