Perforated cylinder coil, F&E tank overflowing (Ed.)

[Dorsetrugby]

Hi everyone,

About a month or two ago we noticed that the F and E was overflowing quite a bit. We also had some rusty coloured water. I can see now from research that this would naturally point to a hole in the coil.

I had a plumber out, who I wouldn’t use again because he seemed completely useless. He put some chemicals in the radiator to clean them out. That instantly bled in to the hot water, which my kids couldn’t bath in, so he came & flushed it out. He said the fact it bled in to the hot water pointed to a coil hole & that we’d need a new cylinder.

Without going in to the reasons, we have 0 money & wont have any for a good while yet. I can’t get a plumber back any time soon. As a cheap fudge attempt, we bought two bottles of miracle seal & put them in to the system. We no longer have discoloured water & the miracle seal didn’t blead in to the hot water like the chemicals the plumber used did. So we thought maybe we’d fixed the hole. But the f and e is still regularly overflowing. Obviously the biggest concern I have is that we’re in winter now. Even though the f and e water is often / mostly warm & that the water runs or drips & therefore may not be as susceptible to freezing up, it’s still a major concern.

Theres also a lot of gurgling / crackling in the pipes & the upstairs radiator needs bleeding every day. The f and e ballcock seems fine from what I can see.

I have no idea what to do as I am useless with anything practical & have 0 knowledge of plumbing. I’m losing sleep over this though. I’m baffled a bit about the miracle seal because even though it hasn’t stopped the overflow, it did stop the discolouration.

Any ideas on any potential simple fixes that won’t involve using a plumber? I’m sure there aren’t, but it’s worth asking. We have an immersion heater too, but I guess that wouldn’t make much difference if we used that in place of the range cooker that we usually use to do the hot water & heating..

Thanks to anyone kind enough to reply..

 

[stem]

It's a fairly rare occurrence, but from the symptoms you describe quite possible that the plumber is correct.

Inside the hot water cylinder is a coil that is heated by the same (often mucky) water that circulates through the radiators. The cylinder itself is filled with clean water from a dedicated cold water storage tank. The two water systems are not connected, the coil simply heats up with hot water from the boiler and then warms the clean water in the cylinder around it.

If the coil inside the cylinder starts to leak, water will transfer from the coil to the cylinder, or vice versa, so contamination of the two water systems takes place.

Depending on the system you have (there could be two cold feed tanks) a small one to keep the boiler and heating system topped up and a larger one that fills the hot water cylinder. Because of a leak, water would be able to pass between the two systems, so the system with the highest cold water level will fill the one with the lowest level thus increasing it to the point of overflow.

Unfortunately, if the cylinder coil does have a hole in it a new hot water cylinder is the only solution.

Perhaps you could get another plumber to inspect the system and get a second opinion. Or if you'r short on cash, do you have a friend that is competent DIY plumber that could help?

 

[oldbuffer]

The F&E can overflow for two reasons (assuming you have an open vent system):
1. There is a hole in the hot water cylinder coil. If the F&E is below the level of the cold water storage cistern, hot water will be forced from the body of the hot water cylinder, through the hole in the coil, into the coil and up into the F&E.
2. The vent for the boiler hot water is pouring hot water into the F&E tank. This can be caused by the pump being on too high a speed or (more likely if nothing else has changed) a blockage in the feed from the F&E into the primary circuit. Because the boiler can't get water fast enough, it overheats what it has got which can cause the boiler to be noisy, and also force water to vent over into the F&E.
3. If you can, trace the pipework from the base of the F&E to the point where it joins the system (should be very close to the pump). Run a magnet along this pipe. If it is attracted it suggests a concentration of magnetite blocking the pipe. The only real cure is to cut out and replace the blocked section of pipe. If you have one, you could use a wet vacuum cleaner to suck from the pipe where it joins the F&E, and you might get lucky and clear any blockage. You would have to empty and clean the F&E tank first, after isolating the water supply to it. Boiler off first of course.

 

[denso13]

But the f and e is still regularly overflowing

Is the feed and expansion cistern lower than the cold storage cistern (the larger one)?

 

[Dorsetrugby]

Thanks so much to you both for your replies. I’ll try to take a look at some of the things you’ve mentioned tomorrow, but I’m so blimmin’ useless.

What baffles me is that to start with it was pretty obviously a hole in the coil because of the discoloured water as well as the f and e overflow. Those things both started at around the same time. Then when the plumber’s cleaning chemicals immediately got in to the hot water, that would seem to confirm it. But since we’ve added the miracle seal the discolouration has gone away & the miracle seal (which was a dark brown colour) didn’t bleed at all in to the hot water like the plumber’s chemicals did. So it’s almost like the miracle seal has fixed a coil hole because of the discolouration points, but then we’re still left with the overflowing f & e.

The other odd thing is that there seems to be no clear pattern to the overflowing. It does stop for a few hours per day. But sometimes that’s when the hot water tank’s full, sometimes when then hot water has all been used, sometimes when the heating has been going off a lot, sometimes when it hasn’t.

Just wish this would go away because I have absolutely zero money & I’m terrified of the tank overflowing if we get a bad freeze and the overflow freezes up

 

[stem]

If you do have two cold water storage tanks and the larger one feeding the hot water cylinder has a higher water level, here's a test that might be possible, that would confirm if the coil was leaking but it depends upon the setup you have.

Tie up the ball valve in the larger tank so that no more water can fill it then run some hot water so that the level in it falls lower than the level of the smaller tank. [This might not be possible depending on the location of the tanks and their water levels in relation to each other]

If it is possible to do the test, and as long as you don’t use any water, if the coil isn't leaking, the water level of the tank with the ball valve tied up should stay the same.

If there is a leak in the coil the water levels of the two tanks should now start to equalise. The water level in the partially drained tank will slowly rise to the same level as the smaller tank. Depending on the size of the leak though it may take a while for the water levels to equalise. Possibly a few hours.

 

[Dorsetrugby]

Thanks again for your replies yesterday. I’m really grateful. So what makes things even more baffling: for the day or two after we put the miracle seal in, the f and e did stop overflowing (as well as the water suddenly becoming clear even though the miracle cure was brown & didn’t bleed at all). The overflowing happened again the last few days while we had all the really cold weather, but now nothing (other than a few drops this morning) again today? Could the weather have some sort of bearing on this? Nothing was frozen up in the loft though & we didn’t have the central heating on noticeably more because we lit the fire & so it was probably going off about the same as today. It’s all very baffling

 

[Nige F]

Thanks again for your replies yesterday. I’m really grateful. So what makes things even more baffling: for the day or two after we put the miracle seal in, the f and e did stop overflowing (as well as the water suddenly becoming clear even though the miracle cure was brown & didn’t bleed at all). The overflowing happened again the last few days while we had all the really cold weather, but now nothing (other than a few drops this morning) again today? Could the weather have some sort of bearing on this? Nothing was frozen up in the loft though & we didn’t have the central heating on noticeably more because we lit the fire & so it was probably going off about the same as today. It’s all very baffling

so you have a solid fuel range (rayburn ? )heating the water and the central heating . Or is mentioning lighting the fire co incidental ?

 

[stem]

Perhaps when the central heating / hot water are being heated, the pump will be running and increase the pressure in the heating system pipework and make it worse, or maybe the temperature has an effect on the expansion / contraction of the area where the leak is.