Changing a boiler so repressurising not required

[deepblue]

Hi

I have a combi boiler (Ideal +) sealed system and every few months in autumn/winter the pressure drops and I have to go up to the loft to repressurise. This is a bit of a pain especially if I am not around and my wife would have to do it.

Are all combi boilers like this or can a new boiler eliminate this chore?

Or, would that require a complete new (non-combi) system?

Any thoughts/ideas much appreciated. Thanks, D.

 

[steadyon]

1. The pressure shouldn't drop every few months. Re-pressurising twice a year is what I would regard as the maximum. Suggests you have a slight leak somewhere on the system, and given it happens Autumn / Winter, I'd suspect a small leak in the heating system.
2. I presume the boiler is in the loft, which is why the filling loop is there.
3. You could probably have an additional filling loop and pressure gauge fitted somewhere more convenient. No need for a new boiler.
4. If you have a leak on the system, any boiler except an open heat only arrangement will need topping up.
5. Don't forget that every time you top up you are the weakening the inhibitor which keeps the radiators from rusting from the inside out. Much better to find and cure the leak.
6. If you replaced the boiler with one having a feed and expansion tank, so that it topped up automatically, you'd still have the constant dilution of the inhibitor.

 

[deepblue]

Hi and many thanks for your excellent reply steadyon.

Point 3. Have an additional filing loop & pressure gauge sounds like a very good idea. What kind of specialist plumber would be required? Will it be easily understood?

Indidentally, British Gas Home Care have just been and fixed it (it coincided with the Anuual Service). When I asked about the pressure it is normal to be done every 3 months and looked at me as if I was from another planet when I said I was not checking it regularly.

Final question is this: what is a foolproof way to find a leak (if there is one!)? Could it be the pipes which run to the bath - which is also only used in Autumn/Winter?

Cheers, D.

 

[Darren Jackson]

No it will not be the pipes to the bath. The water to the bath is mains fed on a combi. You have a leak on the central heating side or a build up of sedement in the boiler, pipes or radiators causing a build up of hydrogen or a faulty part on the boiler. Your BG engineer is wrong it should not need frequently topping up. You need a GSR engineer to have a look for you and power flush the system check the boiler and check for any leaks. They could also provide you with a more convenient position for the filling loop and pressure gauge.

 

[deepblue]

Thanks Darren, I was a bit puzzled when he said it would need topping up every few months - as it is quite tricky procedure to do and I imagine some older people might have difficulty with it even with an easy to access boiler.

There has been a history of leaks in the system. The latest back in May was helped by this forum with fitting of manual release valves on the UFH manifold.

What process would the GSR go through to find the leak (if there is a leak)? The boiler just passed it's 'MOT' today with British Gas (and there was no dirt or deposit in the Magneto container thingy). I am assuming the boiler does not have some of the problems it had in the past with diverter issues.

Would the GSR test each radiator in turn, looking at the pressure change? I have been round to see if there are any obvious leaks at all of the joins already.

Thanks, D.

 

[steadyon]

Wish looking for leaks was that straightforward!

The most likely culprit is a compression joint(s) on a radiator valve, which may weep slightly when hot, but not when cold (just to make it more interesting). Look for lime-scale deposits (if in a hard water area) or other non-chrome / non-copper deposits (assuming copper pipework).

As a start, tie a "bow" of toilet paper (the blue industrial paper towelling is even better) around the pipe at each end of each radiator, trying to get the "ears" of the bow point upwards. Run the system for a few hours, and see if any of the bows have drooped. Any that have suggest (but don't guarantee) a slight leak on that pipe.

Do the same thing (can be done at the same time) wrapping the bow around the radiator tail, where the valve connects to the radiator.

If the above doesn't show anything I think you'll need to get someone in. There are a number of different approaches to leak detection, but its not cheap and the time required is unpredictable.

Given the slowness of the leak, I would not expect it to be the pressure relief valve in the boiler, but there's no harm in checking if there is any dripping from the copper pipe which leads from the valve to outside.

How easy it is to add another filling loop and pressure gauge depends on how the pipes are run. Essentially it needs a mains cold water pipe and a boiler flow or return (preferably return) pipe to run close to each other in a place where a small amount of extra pipework is acceptable. Old airing cupboard would be good, or kitchen.

 

[zzzjim]

If having a filling loop fitted , would some more expansion vessel capacity be an option ?

(may be un-professional but buy some more time - at risk of bigger puddle if damaged)