I have a Glowworm Ultimate 50BF wall-mounted boiler, which is a pumped/gravity fed system.
However, I can't find an overflow/expansion tank for it anywhere in the house! I can't find any connection to the water supply either.
Should there always be such a tank? And should there a mechanism to top up the circulating water when someone bleeds a radiator for example?
(I'm investigating a possible leak under a concrete floor, and half the CH pipes are under concrete.)
There are no pipes leading to the boiler then?
It's usually where they protrude from concrete for some reason, I think it's where condensation runs down and keeps the bit wet that disappears under the floor....the part encased in concrete is usually corrosion free
Five pipes in all: one is a gas pipe.
Then there are two fat pipes (28 or 22mm) to an indirectly heated hot water cylinder.
One 15mm pipe down behind the kitchen units, via a pump hidden under there (took me a while to find that too!), then disappears into the concrete floor. In a corner somewhere else, one pipe leads upstairs from the concrete.
Another 15mm pipe from the boiler goes directly upstairs. No other pipes lead to the loft, other than three to do with hot water (one 15mm mains pipe into the cold-water tank, one 22mm outlet from the tank into the hot water cylinder, and the third seems to be a 22mm venting pipe from the top of the cylinder which also supplies the hot water taps).
Which is another strange thing: instead of a flow/return pair going to each radiator, there seems to be just one: feeds the radiator at one end, and then goes straight to the other end! Seems to work though...
(A lot of the damp problems are likely rising damp; but sometimes there is an explicable flow of water from the meter in the road outside, which stops when the stop-c*ck inside is turned off. But that's intermittent. No overflows or leaking taps that I could see. The flow this morning was 2.5 litres/hour, which you think you'd notice draining somewhere! Usually it's less or zero.)
Not if you have a primatic cylinder.
I put my money on your having a Primatic cylinder - where the primary system is automatically topped up from the domestic hot water system without requiring a separate header tank. The work of the Devil!
See
Thanks for the replies. This primatic cylinder sounds like the most likely (only!) option!
That makes it a little more difficult to isolate the CH circuit, but it sounds now it can't be the main cause of the leak, as that could only have been the water header tank filling up, and I would have heard it. More tests needed I think.
The downstairs CH pipes in concrete are copper with no protection, so that still needs to be considered. (A couple of places, the concrete over a pipe has crumbled away, and the pipe feels clammy.) Although ultimately the downstairs can be replumbed (if I can figure out how to drain and refill such a system).
The most critical damp point is at the bottom of a door frame, away from likely CH pipe runs. The timber extends below floor level a few inches, and is actually wet, not just damp! (And is now rotten.)
Can rising damp cause this? There is no measurable leak (on the meter) between the outside and the stopcock when the latter is turned off, and this run is probably under concrete as well, so hopefully it is not the incoming water pipe.
Another possibility is that you have a combination cylinder, this is essentially a "normal"cylinder combined with a header tank on top of it.
It is hard to tell the difference between a normal cylinder and a combination cylinder on account of the expanded insulating foam put onto it, but a combination cylinder will have a plastic lid on the top which you can lift off. You will then see the header tank and a ball float valve.
Regards
Stephen
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