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Boiler/heating Megathread - advice & recommendations, no jobs/quotes

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My boiler drops in pressure after every time it is in use.

 

I'm constantly having to top it up and i've noticed that water is coming out of the pipe to the exterior of my house.

 

Any ideas what the problem might be and how much it could be to fix.

 

 

Any help appreciated

 

 

Thanks

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I had that, some valve or diaphram needed replacing. It was not that expensive but you need a Corgi registered plumber.

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There may be a leak in the systemm - I'm having that problem right now.

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It won't be a leak if it's coming out the pipe at the back as that's where it's supposed to come out.

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Maybe the filling loop is bypassing. Easy way to check is to fill the system to 1.5 bar and then disconnect it. If you not happy to do this then fill to 1.5 bar but DONT use either hot water or heating for 6-12 hours. If you see the pressure valve rising then filling loop is the culprit.

 

HOWEVER, more than likely the expansion vessel has either lost pressure or the expansion pipe is blocked. This causes the pressure to rise (when the heating is on) to above 2.5bar and the safety PRV kicks in - hence noticing water outside. You will also need the PRV replacing

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It won't be a leak if it's coming out the pipe at the back as that's where it's supposed to come out.

 

That pipe should always be dry unless the boiler has a problem. Its linked to the safety pressure release valve.

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Sorry, I was not very clear. I did not mean all the time, just when there is something wrong! it's what happended to mine.

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Maybe the filling loop is bypassing. Easy way to check is to fill the system to 1.5 bar and then disconnect it. If you not happy to do this then fill to 1.5 bar but DONT use either hot water or heating for 6-12 hours. If you see the pressure valve rising then filling loop is the culprit.

 

HOWEVER, more than likely the expansion vessel has either lost pressure or the expansion pipe is blocked. This causes the pressure to rise (when the heating is on) to above 2.5bar and the safety PRV kicks in - hence noticing water outside. You will also need the PRV replacing

 

 

 

This sounds like the problem. How much is that to be fixed approximately

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This sounds like the problem. How much is that to be fixed approximately

 

Need to know make and model of the boiler first.

 

On some boilers you cant get to the expansion vessel (unless you remove the boiler from the wall). Therefore you 'tie' a new vessel into the existing system. Also gotta drain down. Again some boilers have quality isolation valves on the flow/return AND a drain off internally which makes for a quicker job. Unfortunatley most do not :rolleyes:

 

You also need a new 3bar PRV fitting as the old one will continue to leak.

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mine did that, I had a leak under a tiles floor!! :-(

 

A leak outside of the boiler, ie in any of the pipes below/above the boiler, will NOT make the pressure release valve (PRV) discharge.

 

Gauge rises from its normal 1bar to 2.5bar (at which point the safety valve kicks in) mainly due to:

 

faulty filling loop

expansion vessel needs repressurising

the DHW heat exchanger is leaking so cold main water passes over to the heating side

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