On Sat, 24 May 2008 05:39:37 +0100, steve marchant wrote:
=================================A header tank (expansion tank)for an open vented system seems to be quite
standard at 4 gallons thus:
The size of expansion pipe will be specified in the boiler installation
manual (specifications) and for most domestic installations it will
probably be 22mm rising in an arc about 18" above the header tank.
Using Ubuntu Linux
sorry for not responding earlir - problems with the pc. Yes, i took a chance
and installed a 4 gal tank with 22cm expansion pipe. Reason i put the
questions was i found the feed (outlet) pipe, expansion pipe, and the water
in the supply tank was getting quite hot. couldn't understand why this was
happening and got alarmed..Shut the whole system down. Still trying to
figure it out and have been unable to get any advice.
I had that once after a new system was installed. It turned out to be
insufficient height of the expansion pipe. The head generated by the pump
was pushing hot water up and out of the expansion pipe into the header tank.
The system was thus losing water and drawing more in from the header tank.
This meant that hot water was effectively circulating through the header
tank. There was no overflow as it was effectively a self perpetuating cycle.
Easily checked for - with the system running see if water is coming from the
expansion pipe into the header tank.
Ours was fixed by increasing the height of the expansion pipe above the
tank. Possibly also fixable by reducing the speed if you have a variable
I'm in no way a central heating expert so you may get better suggestions.
Thanks, Mel, reducing the pump speed seems to have done the trick.The
temperature of the radiators has fallen some, but i'd sooner suffer the
slight loss of efficiency than have the tank soften and leak.
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