I've recently had my gas central heating system switched over to a
sealed/pressurised with an expansion vessel taking a feed from the
main. But when I'm draining the system (attaching hose to drainage
valve and opening fully), it doesn't drain properly - the water
continuusly flows out of it. It's as if there's another, secondary
water supply going into my heating system. Yesterday I even knocked
off the water at the main stopcock so the vessel and the sealed system
didn't get a feed, but the water was continuously draining out of the
hose (I mean for over 12 hours). In the end I had to just close the
drainage valve.
Any advice gratefully received.

sherbo wrote:
I've recently had my gas central heating system switched over to a
sealed/pressurised with an expansion vessel taking a feed from the
main. But when I'm draining the system (attaching hose to drainage
valve and opening fully), it doesn't drain properly - the water
continuusly flows out of it. It's as if there's another, secondary
water supply going into my heating system. Yesterday I even knocked
off the water at the main stopcock so the vessel and the sealed system
didn't get a feed, but the water was continuously draining out of the
hose (I mean for over 12 hours). In the end I had to just close the
drainage valve.
Any advice gratefully received.

Is this for real? if so , what does the pressure gauge reach if you
fill it from the mains, does it go up and up and up or reach a (low)
level then stop?

12 hours of draining even if there was still a feed from a large header
tank, with the mains switched off, seems like something very odd is
going on!

Yep - I'm afraid it is for real. When the system's filled and working
the pressure continually drops to 0. I fill the expansion vessel up to
1bar then it drops steadily to 0 again (over about 3 minutes - quicker
if I have hot water AND heating on). I'm 99% certain there are no
leaks - the house has a basement on the ground floor so I can see all
the pipework - if there is a leak it would have to be under the
kitchen's concrete floor, but there are no visible signs on the
concrete or outside. The pressurising has been done by a good,
qualified plumber, but he's running out of ideas and I'm thinking I'll
have to get a second opinion during Christmas week :-(

Yep - I'm afraid it is for real. When the system's filled and working
the pressure continually drops to 0. I fill the expansion vessel up to
1bar then it drops steadily to 0 again (over about 3 minutes - quicker
if I have hot water AND heating on). I'm 99% certain there are no
leaks - the house has a basement on the ground floor so I can see all
the pipework - if there is a leak it would have to be under the
kitchen's concrete floor, but there are no visible signs on the
concrete or outside. The pressurising has been done by a good,
qualified plumber, but he's running out of ideas and I'm thinking I'll
have to get a second opinion during Christmas week :-(


If you turn the stopcock off, can you still run water from the cold taps ?
faulty stopcock ? or..... in our house the old cast iron water main ran
along the back of the house and entered in the kitchen with a stop tap.
Later a new plastic main was routed past the front and now enters under the
drive and into the front, they simply turned off the rear stop tap and put a
warning label over it. If that old feed is still 'live' and we turn off the
front stop tap, there could be some water entering by the old route ?

Pete

sherbo wrote:
Yep - I'm afraid it is for real. When the system's filled and working
the pressure continually drops to 0. I fill the expansion vessel up to
1bar then it drops steadily to 0 again (over about 3 minutes - quicker
if I have hot water AND heating on). I'm 99% certain there are no
leaks - the house has a basement on the ground floor so I can see all
the pipework - if there is a leak it would have to be under the
kitchen's concrete floor, but there are no visible signs on the
concrete or outside. The pressurising has been done by a good,
qualified plumber, but he's running out of ideas and I'm thinking I'll
have to get a second opinion during Christmas week :-(


Sounds like the header tank is still connected!?
....or, there's a leak in your HWC which means the tap water and heating
are mixing. but that wouldn't lead to constant 12 hour running water
with the stopcoc off.

"sherbo" wrote in message
ups.com...
I've recently had my gas central heating system switched over to a
sealed/pressurised with an expansion vessel taking a feed from the
main. But when I'm draining the system (attaching hose to drainage
valve and opening fully), it doesn't drain properly - the water
continuusly flows out of it. It's as if there's another, secondary
water supply going into my heating system. Yesterday I even knocked
off the water at the main stopcock so the vessel and the sealed system
didn't get a feed, but the water was continuously draining out of the
hose (I mean for over 12 hours). In the end I had to just close the
drainage valve.
Any advice gratefully received.


Do you have indirect hot water?

If yes it could be a leak in the heat exchanger.

David

Pete,

Thanks for the response. With the stopcock off the cold taps run dry
(once the tank in the attic drains) - not even a drop comes out. What
you have said is entirely plausible - a secondary supply would account
for the pressure dropping as well as the never-ending draining. The
supply with the stopcock appears to be the original (house is 100 years
old and the main is a lead pipe)...

If you turn the stopcock off, can you still run water from the cold taps ?
faulty stopcock ? or..... in our house the old cast iron water main ran
along the back of the house and entered in the kitchen with a stop tap.
Later a new plastic main was routed past the front and now enters under the
drive and into the front, they simply turned off the rear stop tap and put a
warning label over it. If that old feed is still 'live' and we turn off the
front stop tap, there could be some water entering by the old route ?

Pete

On Thu, 21 Dec 2006 03:09:08 -0800, sherbo wrote:

I've recently had my gas central heating system switched over to a
sealed/pressurised with an expansion vessel taking a feed from the
main. But when I'm draining the system (attaching hose to drainage
valve and opening fully), it doesn't drain properly - the water
continuusly flows out of it. It's as if there's another, secondary
water supply going into my heating system. Yesterday I even knocked
off the water at the main stopcock so the vessel and the sealed system
didn't get a feed, but the water was continuously draining out of the
hose (I mean for over 12 hours). In the end I had to just close the
drainage valve.
Any advice gratefully received.

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Then see what else you needs to know.


--
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