Mains-fed header in the roofspace feeding indirect cylinder.

Hot water from taps begins at usual rate, slows down, splutters and then
starts again slowly. Any idea what is going on and how to fix?

Sounds like some sort of airlock in the cylinder feed.

I read somewhere about sending the mains supply up the hot water system to
clear blockages/locks etc. Was I right or would this be a recipe for
disaster?

Thanks.

Roger Cain wrote:
Mains-fed header in the roofspace feeding indirect cylinder.

Hot water from taps begins at usual rate, slows down, splutters and then
starts again slowly. Any idea what is going on and how to fix?

Has it always behaved like this, or is this new?

Sounds like some sort of airlock in the cylinder feed.

or blockage...

I read somewhere about sending the mains supply up the hot water system to
clear blockages/locks etc. Was I right or would this be a recipe for
disaster?

You can force water up a hot tap with some hose in order to clear some
airlocks. Make sure that the cylinder vent pipe is present and not
blocked first though. Many cylinders will not react well to being
pressurised to mains levels!

--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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"John Rumm" wrote in message
news:afqdnVLjgdRbEmPaRVnyigA@plusnet...
Thanks, John.

Has it always behaved like this, or is this new?

No, recent. The cylinder was replaced about 2 years ago and the header tank
about 25 years ago.
The guy who fitted the cylinder had to hack away some of the foam insulation
to fit the unions and I have seen very small abounts of this in the filters
in the hot taps. The header tank has a cover so I am unlikely to have
animals in there but I suppose that mains sludge may have built up over the
years.
The header is a devil to get at and inspect which is why I was looking for a
simple fix.

You can force water up a hot tap with some hose in order to clear some
airlocks. Make sure that the cylinder vent pipe is present and not blocked
first though. Many cylinders will not react well to being pressurised to
mains levels!

Oh, good job I asked. Sounds a bit risky. Yup, 3/4" vent is there; whether
blocked or not I don't know.
If I didn't chance the mains back-flow what options do I have? Drain,
inspect header-cylinder plumbing?

Roger Cain wrote:

No, recent. The cylinder was replaced about 2 years ago and the header tank
about 25 years ago.
The guy who fitted the cylinder had to hack away some of the foam insulation
to fit the unions and I have seen very small abounts of this in the filters
in the hot taps. The header tank has a cover so I am unlikely to have
animals in there but I suppose that mains sludge may have built up over the
years.

I expect if it were a lump of insulating foam, it would have caused
problems sooner than this...

The header is a devil to get at and inspect which is why I was looking for a
simple fix.

That will depend of if it is a simple problem! ;-)

You can force water up a hot tap with some hose in order to clear some
airlocks. Make sure that the cylinder vent pipe is present and not blocked
first though. Many cylinders will not react well to being pressurised to
mains levels!

Oh, good job I asked. Sounds a bit risky. Yup, 3/4" vent is there; whether
blocked or not I don't know.

If its 3/4" then it is very unlikely to be blocked. The problems usually
occur when only 1/2" vent (or none at all) is fitted, and frequent
boiling of the cylinder has allowed scale to deposit in the pipe.

In your case it sounds like it ought to be fairly safe to try back
feeding it.

If I didn't chance the mains back-flow what options do I have? Drain,
inspect header-cylinder plumbing?

Trying the back feed will answer that question. If its an airlock it
will fix the problem. If the water you back feed ends up flowing into
the main cistern via the feed pipe from the base of the cylinder, that
would indicate that the feed is not blocked, and if the flow out of the
vent then that might indicate a feed problem.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/