Gas Central - Valve Leak + Re-pressurising

recycler1

I have a gas central heating system, pressurised from the mains.
It emptied when my mains water froze in the freeze.
My mains is back but I have a steady drip from one of the bolier isolating valves.
(This is most likely what caused the original loss of pressure.)

I have two questions, I would appreciate help with:

1. Are there any special washers for the isolating valves?
(The leaking valve was replaced by a plumber last August.
It's fitted with a plastic red ring less than half a mil thick.
It doesn't look right and I suspect it has always leaked.
I'm nervous about replacing a washer adjacent to the boiler.)

2. When the system is refilled should the pressure vessel be pumped up?

Thanks.

items

recycler1 wrote: »

I have a gas central heating system, pressurised from the mains.
It emptied when my mains water froze in the freeze.
My mains is back but I have a steady drip from one of the bolier isolating valves.
(This is most likely what caused the original loss of pressure.)

I have two questions, I would appreciate help with:

1. Are there any special washers for the isolating valves?
(The leaking valve was replaced by a plumber last August.
It's fitted with a plastic red ring less than half a mil thick.
It doesn't look right and I suspect it has always leaked.
I'm nervous about replacing a washer adjacent to the boiler.)

2. When the system is refilled should the pressure vessel be pumped up?

Thanks.

Most gas boilers have isolation connections with fiber washer seal to boiler, if this is your case, fiber washer could be worn again, I'd say isolation connection is strained, badly piped up to valve so its not sealing right, you can pick up all kinds of 3/4 fiber washers, thickness tends to be the same, size of face can differ, find the largest face without restricting the valve opening, double even triple the amount of wasters. Rubber washers available to, some use them some don't, try not to use rubber ones as they become brittle with heat over time.

Expansion vessel should be fine, it holds a constant pressure sealed from heating water unless vessel diaphragm is ruptured or lacking in pressure should be fine. If it's lacking in pressure you would have known about it, heating acting up.

To change washers you have to drain boiler, re fill, vent etc unless you really know your stuff, prob best call a RGII person, tell them how you've had trouble, same isolation valve leaking twice.

recycler1

Thank's for the reply!

items wrote: »

Most gas boilers have isolation connections with fiber washer seal to boiler, if this is your case, fiber washer could be worn again, I'd say isolation connection is strained, badly piped up to valve so its not sealing right, you can pick up all kinds of 3/4 fiber washers, thickness tends to be the same, size of face can differ, find the largest face without restricting the valve opening, double even triple the amount of wasters. Rubber washers available to, some use them some don't, try not to use rubber ones as they become brittle with heat over time.

I 've already had to refill the system - hence my question on the pressure vessel.

I wouldn't touch the gas side but very comfortable with the water side. What I have is leaks at the circuit side of the isolating valves - i.e. no leaks into the heat exchanger. The fittings have a single fibre washer fitted in each case. They were changed by a plumber last summer, when he fitted an external pressure vessel. I didn't check at the time, but I suspect they always leaked a little. (It would explain why I lost pressure, once the mains froze.)

I'll have a go with replacement washers before I get (another) plumber. The boiler is ten years old and I'd prefer to replace it with a high efficiency unit rather than spending any more money on it!

items

Re filling just to top up lost water is no problem, disconnecting boiler pipe work means draining boiler, its a different ball game. Water side and Gas side all come under the same works once its inside boiler casing, if your opening up boiler casing your going against regulation, should anything bad happen as a result, you wont be covered by Bord Gas or home insurance. All Boiler works are carried under certs, if last works have been done recently, works would have been certified, Bord Gas will have a record, they can trace back and can easily find boiler modifications made outside of certs.

Still not sure where you've got leaks, only time you see washers used is during flanged type connections, where two flat faces meet, washer inserted between two flat faces. The other side of isolation valves normally have compression fittings. Could be a case where you've some flange type isolation valve away from boiler. If so then belt away, have a look at pipe work, could be some strain, if you can fix that, any 3/4 fiber washer will do, if not might have to stack up a few larger faced fiber washers, bit more acceptance.