Boiler Loses all pressure - help/advice please?

FairyElephant_2

My first post! Please can someone help/advise...?

My combi-boiler loses all it's water pressure every time it switches off (on it's timer) and then won't restart my heating 'cos the prssure is too low, so I have to add water to the system.
If I leave it on low heat all the time, it keeps it's pressure (but the house is boiling and I dread to think what my gas bill will be!!!!).

B/F reckons we must have a small leak somewhere, which is sealed up when the pipes expand when the system is hot, and then leaks again when it cools down.

This seems to make sense, but we have examined all visible pipes/joints and can't find any evidence of leaks......

The onlt thing we can think is to lift all floorboards and check under floors (guess it's not upstairs as no makrs on the downstairs ceilings!)....but the back half of downstairs in concrete floors which have been set over the pipes, so no idea what to do there.....

Any plumbers/heating engineers out there have any tips on what to look for, or even if we are thinking in the right direction????

Many thanks for any advice!

kingshir

The first place to check is the pipes into/out of the radiators. The leak may be so small as to be almost invisible but there may be a touch of damp that will it give away' although if you are losing a lot of water then the leak should soon become apparent! Perhaps just topping the boiler up on a daily basis may be the only option for you at the moment though.

suki1964

We had the same problem with ours and didnt find the leak untill the paint started to bubble away from a wall Yep the pipes were under the concrete floor

So hubby bought some flexi pipe and run it from the boiler along the ceiling down the corner to the mains. Not perfect, mostly hidden behind coving and painted to match the walls, but will do untill we have the time and money to put a new floor down

Gaz_Hammer

Hi,
Have you checked the safety discharge pipe which should terminate outside the property, for signs of water dripping?
When the boiler is on does the pressure gauge needle rise significantly?
Also what pressure are you filling it to? - generally it should be about 1Bar!

It's not a good idea to keep topping the system up as all you are doing is introducing fresh water into the system which will cause it to scale up!

Gaz

FairyElephant_2

Thanks everyone for your suggestions....
Hi Gaz,
Yep we checked the pipe (which is the lane outside) but nothing seems to be dripping out of it.
If I fill it up to the 'ideal' pressure mark on the guage (which I think is about 1bar) it will stay at constant pressure while the system is on, then when it turns off you can see the needle drop slowly as it cools down.
I know it's not a good idea to keep topping it up, so I have it on permanently at as low a temp as poss for the mo - but as the weather gets warmer I need to find a solution!
I want to avoid calling in a heating engineer if poss as I suspect they will take a long time to find the problem, and I dread to think what they charge per hour..........

Gaz_Hammer

Hi Again,

I suspect they will take a long time to find the problem

You could well be right!

Hope you get it sorted :T

Gaz

YorkshireBoy

FairyElephant wrote:

B/F reckons we must have a small leak somewhere, which is sealed up when the pipes expand when the system is hot, and then leaks again when it cools down.

Exactly what we had 3 months ago! We'd been topping the system up for 2-3 weeks, and then saw a small brown circular stain on the kitchen ceiling. I lifted the carpet in the bedroom above and the chipboard floor was "slightly" discoloured, but not directly above the ceiling mark downstairs.

I lifted a section of floorboard out and found that there was a tee piece (yorkshire fitting) which was seeping (almost a "vapour" it was that small) and running down the pipe for approximately 600mm before dripping off.

We repaired the joint, but put the problem down to the fact that the plumber had not cut deep enough notches out of the joists. Therefore the chipboard flooring was resting on the pipe, not the joist (this is hard to explain - I hope you're still with me). I took a chisel to the joists and deepened the notch slightly to ease the strain on the pipe.

We've lived in the house nearly 11 years (from new), but the only thing we can think of is that we installed new fitted bedroom furniture last May and the additional weight (floor to ceiling Schreiber on full wall) found a weak spot.

HTH
YB

bestyman

Hi,
When the boiler is on are the flue gases outside steamy? I mean there could be a hole in the boiler heat exchanger so water is turning to steam through the flue, have a look and compare it with other flues if you are unsure .

Is it possible to isolate the ground floor? I would find the 2 main pipes that supply the downstairs ( might be easy, might be almost impossible) and have two stop valves fitted to them. As an experiment turn them off for a few days and see if the pressure drops, obviously this helps in finding roughly where the leak is .

The boiler could also be isolated by the two valves underneath already fitted on the flow and return pipes, try turn these off..DO NOT USE THE BOILER and see if the pressure drops overnight.

On one particular boiler I came across a problem where the water from the central heating was going out slowly throough the hot supply to the taps, again to check for this turn off the hot supply out or simply make sure no hot taps are used overnight ( this is very rare and unusual problem caused by a boiler fault.)

If you establish that there is a leak on the central heating side you should have it repaired properly BUT perhaps some fernox leak seal would be worth a try. Its similar to the stuff you put in car rads when they leak and might work ( about £20 a tub) . Some say not to use it but look at the fernox website and make your own mind up.

Hope this helps

Mark

FairyElephant_2

Hi Mark,
Thanks for your suggestions & advice....I will try again tonight and post the results!
Cheers,
Lisa.