Leak in central heating system.

[Ecosseven]

Morning all,

I had a new system boiler installed earlier this year and in the last few weeks I have been having to top up the boiler every 5-6 days. I set the pressure at about 1.5 bar with the boiler off and then it gradually drops over the following few days down to around 0.8 bar.

Not sure if the problem is with the heat exchanger in the boiler or if I have a leak somewhere in the system.

I've spoken to a heating engineer this morning who advised NOT to add a liquid sealer to the system to try and find and seal the leak. this assumes that there is a leak in the system somewhere

I've checked all the radiators and there is no sign of any leaks in the above floor pipework. I may have to lift the floors but this is a last resort and I want to rule out any problems with the boiler first.

Any advance gratefully received.

[MattyD803]

I'd have not expected an issue within a brand new boiler and even if so, this would likely cause a leak from the boiler casing itself. Surely the installer will pop back to open up the casing and take a look for you?

If above ground floor, I would have expected the leak to have made itself apparent by wet patches on the ceiling, walls etc.

Is your ground floor suspended timber or concrete?

Edited by MattyD803 on Tuesday 29th October 10:50

[JimM169]

I'm no expert but might need to check if the expansion vessel in the boiler has any pressure in it?

[gmaz]

Ecosseven said:

Morning all,

I had a new system boiler installed earlier this year and in the last few weeks I have been having to top up the boiler every 5-6 days.

Have you gone from an unpressurised system to pressurised? We had this issue and had to get most of the piping renewed and rerouted. It was a bungalow with the existing pipes buried in concrete floors, so with constant heat expansion the movement wore out the joints. With the old header tank system we never noticed the issue as it topped itself up.

[OutInTheShed]

If the CH hasn't been used until now, the system may still be bleeding itself.
Our boiler auto-bleeds and can take a few goes at topping up,

If the expansion vessel isn't pumped, then the pressure would rise as the system heats up, dumping water via the pressure relief valve.
What does the gauge do as it warms up?
Likewise if the EV is too small because you've got loads of big rads, same can happen.

Rad valves can leak a little when hot, the water evaporates with no trace often.

At my old house, I made an adaptor to pressurise the system with a bike pump to look for leaks.

[hellorent]

The should be a overflow/pressure relief valve on a pipe outside, pop a plastic bag over that and see if
it fills with water.

[RLE]

gmaz said:

Have you gone from an unpressurised system to pressurised? We had this issue and had to get most of the piping renewed and rerouted. It was a bungalow with the existing pipes buried in concrete floors, so with constant heat expansion the movement wore out the joints. With the old header tank system we never noticed the issue as it topped itself up.

This would be my guess. Likewise had the same issue when we went with a new pressurised system. Initially found some weeping on radiator valves but it was clear we had a bigger issue as we would need to top up the water every morning. Ruled out the overflow and pressure valve quickly with the bag method mentioned above. Hoped it was the expansion tank on the new boiler but everything inside was bone dry.

Due to access issues and not wanting to rip up floorboards in certain parts of the property unnecessarily, we fitted some isolation valves which helped us locate and resolve the problem. New section of pipework required and has been fine since.

[Fastpedeller]

gmaz said:

Ecosseven said:

Morning all,

I had a new system boiler installed earlier this year and in the last few weeks I have been having to top up the boiler every 5-6 days.

Have you gone from an unpressurised system to pressurised? We had this issue and had to get most of the piping renewed and rerouted. It was a bungalow with the existing pipes buried in concrete floors, so with constant heat expansion the movement wore out the joints. With the old header tank system we never noticed the issue as it topped itself up.

We had several 'heating engineers' who came round and quoted for our new boiler 13 years ago, and they all wanted to fit a pressurised system against our wishes. Telling them the 50 year-old pipes in the concrete floor may give problems didn't convince them. We eventually got someone to fit a simple heating boiler, but he was also 'questionable' as he wanted (indeed insisted) on fitting the boiler model HE wanted, until I stated unless we got the boiler WE wanted he'd lose the job. Our experience of 'heating engineers' wasn't a good one. Family 5 doors along from us went with a pressurised system and had all the concrete floors up within a year, costing thousands. I guess that's the result some traders prefer.

Edited by Fastpedeller on Tuesday 29th October 16:00

[RLE]

gmaz said:

Have you gone from an unpressurised system to pressurised? We had this issue and had to get most of the piping renewed and rerouted. It was a bungalow with the existing pipes buried in concrete floors, so with constant heat expansion the movement wore out the joints. With the old header tank system we never noticed the issue as it topped itself up.

This would be my guess. Likewise had the same issue when we went with a new pressurised system. Initially found some weeping on radiator valves but it was clear we had a bigger issue as we would need to top up the water every morning. Ruled out the overflow and pressure valve quickly with the bag method mentioned above. Hoped it was the expansion tank on the new boiler but everything inside was bone dry.

Due to access issues and not wanting to rip up floorboards in certain parts of the property unnecessarily, we fitted some isolation valves which helped us locate and resolve the problem. New section of pipework required and has been fine since.

[Ecosseven]

MattyD803 said:

I'd have not expected an issue within a brand new boiler and even if so, this would likely cause a leak from the boiler casing itself. Surely the installer will pop back to open up the casing and take a look for you?

If above ground floor, I would have expected the leak to have made itself apparent by wet patches on the ceiling, walls etc.

Is your ground floor suspended timber or concrete?

Edited by MattyD803 on Tuesday 29th October 10:50

Thanks. I have contacted the boiler installer and they can't come out and inspect until 18th November!

There are no wet patches on the ceiling or walls and no obvious leaks from the radiator pipework or thermostatic valves.

The ground floor of the house is a suspended timber so I should be able to get underneath if required.

[Ecosseven]

gmaz said:

Ecosseven said:

Morning all,

I had a new system boiler installed earlier this year and in the last few weeks I have been having to top up the boiler every 5-6 days.

Have you gone from an unpressurised system to pressurised? We had this issue and had to get most of the piping renewed and rerouted. It was a bungalow with the existing pipes buried in concrete floors, so with constant heat expansion the movement wore out the joints. With the old header tank system we never noticed the issue as it topped itself up.

Thanks. No the old boiler was a pressurised system and the new boiler is the same.

[Ecosseven]

Ecosseven said:

Morning all,

I had a new system boiler installed earlier this year and in the last few weeks I have been having to top up the boiler every 5-6 days. I set the pressure at about 1.5 bar with the boiler off and then it gradually drops over the following few days down to around 0.8 bar.

Not sure if the problem is with the heat exchanger in the boiler or if I have a leak somewhere in the system.

I've spoken to a heating engineer this morning who advised NOT to add a liquid sealer to the system to try and find and seal the leak. this assumes that there is a leak in the system somewhere

I've checked all the radiators and there is no sign of any leaks in the above floor pipework. I may have to lift the floors but this is a last resort and I want to rule out any problems with the boiler first.

Any advance gratefully received.

Just to add that the valves on the main flow and return pipes located just below the boiler are always in the open position. there is a second valve located in the inlet that is normally closed - I open this valve temporarily to top up the boiler but always leave the other valve open. Is this correct?

Thanks again for all the advice.

Edited by Ecosseven on Sunday 3rd November 15:43