Boiler keeps losing pressure but we cant work out why

[yelf]

We've had an Ideal Logic 30+ in place for 18mo ths, and after some teething probelms has ben fine.

But a week ago when we put the heating on the pressure had gone. So we repressurised, and it lost it agin after a day. This happened for 3 days running so we called out the installer. There are no wet patches anywhere. He "isolated the boiler" for a few hours and said that when he reconnects the boiler he wil be able to tell if the probelm is with the boiler, of the rest of thr system, by whether the presuue goes up or doen on recnnection - but the pressure didnt budge. He was at a loss as to whats causing it. He put some anti-leak stuff in and its been ok for nearly a week, but its lost pressure again.

Has anyone got any suggestions please??

 

[Centralheatking]

On the average sized house to drop from 1.5 bar to zero might only be a litre or 2 of water.

Checking the boiler didnt leak is a smart move so you are now left with a v. small leak that will evapourate before it makes any visible signs.

Keep settin the pressure up at 1.5 bar and check outside under the flue 4 the boiler and see if there is any water drops wet patch etc - it might be the blow off or pressure vessel is mis behaving and report back -

centralheatking

 

[AWheating]

where does your pipework run? underfloor,surface, in concrete floor?

if you have old lath and plaster ceilings it would take some water to leak for it to show.

 

[acecharly]

Does this only happen when you run the heating?

If so sounds like already said above... faulty pressure vessel.

As the boiler gets hot the water in the system expands the pressure vessel takes up this expansion then as the system cools the vessel returns back to normal if it is ruptured then as the pressure builds the system pressure will release outside through your PRV / safety valve and then as it cools down you are left with no pressure again.

Hope this helps

 

[arran197]

Ye, you will need to observe the pressure when the heating is on and look at the pipe outside for the pressure relief valve.

 

[yelf]

I have attatched an image of the flue - it looks like something is leaking (bottom right looking at picture). We had a new kitchen with new sink and dishwasher put in, and thought it might be that. I ran the dishwasher 3 times and the pressure went twice. The kitchen fitter came and had a look but confirmed it had been hooked into the cold feed correctly. It also lost pressue when the washing machine was on, but that may have just been coincidence. We also had the stopcock moved in the summer, but the bolier installer did that so should know what he is doing.

Does the image give any ideas?i cant see the tube which carries the condensate waste it it is pumpred up through the roof into a drain pipe.

Many Thanks

 

[acecharly]

This has nothing to do with your boiler losing pressure. The flue should be angled slightly up to allow condensate that collects on the flue wall to fall back into the boiler and into the condensate trap. This needs to be addressed as condensate is acidic and will rot your brick mortar let alone anything else it drips on. Because this is an issue with your flue and regards to the gas regulations i cant give you anymore advice on this as the work has to be carried out by a competant gas safe engineer. The engineer will be able to diagnose the pressure loss at the same time. Sorry i cant help you anymore but safety is safety

 

[zzzjim]

Are all rads getting hot , as could still be some air left in system ?

 

[yelf]

Are all rads getting hot , as could still be some air left in system ?

all rads fully bled

 

[Millsy 82]

From the picture the flue looks ok thet looks like an old stain. Have you had any work done recently? Has it been connected to an old system? Do you have pipework under a concrete/screed floor? It could be a small leak on a joint no where near anything that has been touched that may have a slight leak and is drying up before it causes damage. It could be a leak under a concrete floor that will not show.

The best bet is to get a second opinion from a gsr.

 

[yelf]

From the picture the flue looks ok thet looks like an old stain. Have you had any work done recently? Has it been connected to an old system? Do you have pipework under a concrete/screed floor? It could be a small leak on a joint no where near anything that has been touched that may have a slight leak and is drying up before it causes damage. It could be a leak under a concrete floor that will not show.

The best bet is to get a second opinion from a gsr.

GSR - gas safety registered?

We have screeded floor downstairs but none of the piping is under it - it runs along the walls or under the floor boards upstairs. I think i may be re-pressursing incorrectly - should there be a loop tube. I have 2 pipes coming down with valves on, one red one blue. I open the blue one, then open the red one and the boiler re-pressurises. But the manual mentioned some tube to connect between the two.

 

[yelf]

answer: http://www.ukplumbersforums.co.uk/insurance-plumbers/40878-how-claim-against-plumber.html#post362727

 

[Worcester1]

Sounds a classic case of the pressure vessel lost pressure as previously mentioned try that before anything else. Also you shouldn't put leak sealer in to modern condensing boilers and it is always a last resort on any system