Pressurising boiler - need to switch cold tap on?

[MattB83]

I was at my mum's recently. She has a stove with back boiler and an LPG boiler. The heating and hot water run off the LPG but also off the wood burner. This seems to cause no end of confusion when any plumbing work needs done and although she's just had the stove replaced it's not working very well.

One thing that confused me was at one point the boiler lost pressure after radiators had been changed. A different tradesman (joiner) showed us how to repressurise which involved opening a valve on the boiler and then running a cold tap. Could anyone explain what is going on there? Is this common?

 

[terryplumb]

The tap that was opened was likely on the filling loop ,kitchen and bathroom taps etc have nowt to do with filling a sealed system.

 

[Agile]

I don't think that it should be a sealed system used on a wood burner.

 

[DP]

The heating and hot water run off the LPG but also off the wood burner.

I think you meant to say hot water is heated by the stove as well as the boiler.
can you confirm that

 

[oldbutnotdead]

I don't think that it should be a sealed system used on a wood burner.

Hopefully there's a thermal store in there somewhere- sealed gas system via a coil in the store would be fine.

 

[MattB83]

I think you meant to say hot water is heated by the stove as well as the boiler.
can you confirm that

Hot water and radiators. Does that clarify? So if the boiler is off but the fire is lit there's hot water and the radiators heat up. There's a pump which we switch on if there's a hot fire and that increase circulation of water to the radiators (how I understand it).

 

[DP]

Hot water and radiators. Does that clarify? So if the boiler is off but the fire is lit there's hot water and the radiators heat up. There's a pump which we switch on if there's a hot fire and that increase circulation of water to the radiators (how I understand it).

Because heat source (fire) can cause water to boil over, safety precautions need to be in place. Failing to observe these could be hazardous.
With gas or electric, when desired temperature reached, fuel source is disconnected. Not easy for log or coal etc.

This boiler is at Beamish Museum. Basically has fire underneath. Told was not unknown for these to go pop

 

[MattB83]

Because heat source (fire) can cause water to boil over, safety precautions need to be in place. Failing to observe these could be hazardous.
With gas or electric, when desired temperature reached, fuel source is disconnected. Not easy for log or coal etc.

View attachment 295695

This boiler is at Beamish Museum. Basically has fire underneath. Told was not unknown for these to go pop

Thank you. Are you saying that the system sounds unsafe?. It's been working without explosion or loss of life for 30 odd years - it's just a real pain to get a plumber to so much as bleed a radiator!

 

[oldbutnotdead]

On the face of it, from what you've told us (a pressurised heating system heated by lpg boiler and a woodburner) yes that's a high risk system.
It is possible that an old gas boiler (running open vent) has been replaced by a boilerslinger who didn't know what he was dealing with.
Or there may be more to her heating system than you're letting on.
Photos of pipework, boiler, woodburner, hot water cylinder (which I'm hoping for her sake is actually a thermal store with 2 coils) would help- I'm not panicking cos it's not my house at risk. You might want to

 

[MattB83]

Thanks for your reply - I feel that I may have misrepresented the system by explaining badly. It was mainly the filling loop I was trying to get my head around i.e. why I needed to switch the cold tap on to fill up
I'm not panicking because like I say it's worked incredibly well for 30+ years with not so much as an explosion - this has included a few occasions where the fire has been left with vents open and forgotten about and got seriously hot. So my assumption is that although I'm not aware of what the safety precautions are - there must be some. I know that's not a completely logical argument. I will take some pics asap.

 

[Mister Banks]

Did you read about the WW2 bomb that recently exploded, it had been there for over 70 years with no problem. Something changed and boom!

Pics of your install will help the forum experts advise much better.