New boiler - pressure dropping

[vtechnician]

Hi All,

Its been approximately 3 months since we had our new boiler installed. The job involved removing/disposing old conventional boiler from kitchen and installing a new (system) boiler in the attic. Furthermore we dumped the small HW cylinder for a larger one and a new Grunfos pump was added.

Quite annoyingly its been requiring a top up of water quite regularly - It drops 0.5bar in 3-4 days.

Before i go down the arduous route of calling the plumber who installed it (long story) i thought id do some preliminary checks myself.

Theres no obvious sign of a leak anywhere and Ive checked the PRV valve outlet which is dry. The ground floor pipework is encased in the concrete foundation so no joy here (I'll assume this is ok until Ive exhausted other possibilities). I have read that a leaky heat exchanger could be a possibility. The condensate pipe connects directly to the soil pipe. I was thinking of disconnecting it from the hose at the boiler end and checking for drips overnight with the boiler off. What do you think?

Any advice would be very greatly appreciated!

 

[Scott_D]

Any more info?
Boiler make/model
Pictures

 

[Scott_D]

Any more info?
Boiler make/model
Pictures

 

[newcastle phill]

When you go to bed...
Pressurise the boiler and make an accurate note of the pressure.

Then turn it off amd also islolate the flow and return valves on the underside.

This will seal off the boiler from the rest of the system.

If in the morning the pressure is exactly as it was the night before - the problem lays with your system somewhere and not the boiler.

If you do this make sure the boiler is off and set the pressure cold.

 

[townfanjon]

Was your original boiler / system open vented ?

 

[vtechnician]

Thank you all for your replies.

The old boiler was a conventional type and the new boiler is a Valiant 430 system boiler. We did away with the F&E tank but the cold water storage tank remains.

I couldn't find any valves to isolate the flow and return pipes near the boiler. This pipes run into the airing cupboard so I'll take a look there but i dont expect to find any.

Tonight, with a cold system and boiler off, i'll check for leaks through the condensate pipe and feedback my findings.

 

[Last Plumber]

A 430 is not a system boiler.

If it starts with 4 it's a regular boiler. Vaillant system Boilers start with a 6.

It may well be on a sealed system !

As per usual, I cannot open the photo's you posted. ( Forum Fault I think )

 

[Last Plumber]

Double post removed

 

[vtechnician]

Ive checked the invoice and it says ecotec 430 - i'll check the boiler when i get home.

So potentially he's installed a regular boiler and pressurized the system?? This sounds bad!

 

[vtechnician]

Ive checked the invoice and it says ecotec 430 - i'll check the boiler when i get home.

So potentially he's installed a regular boiler and pressurized the system?? This sounds bad!

ps right mouse click and open in new window/tab works with the photos.

 

[Last Plumber]

No it's not bad. Don't panic !
It's sometimes a better idea dependent on your system.

If it's a regular boiler, it won't have valves like a system boiler would.

I would advise you get the Installer out to check it over. That boiler has a seven year warranty doesn't it ?

 

[Last Plumber]

No it's not bad. Don't panic !
It's sometimes a better idea dependent on your system.

If it's a regular boiler, it won't have valves like a system boiler would.

I would advise you get the Installer out to check it over. That boiler has a seven year warranty doesn't it ?

 

[vtechnician]

No it's not bad. Don't panic !
It's sometimes a better idea dependent on your system.

If it's a regular boiler, it won't have valves like a system boiler would.

I would advise you get the Installer out to check it over. That boiler has a seven year warranty doesn't it ?

thanks for re-assuring me! the boiler has 7 years warranty.

He told me he was installing a system boiler - oh well!

I hope this won’t invalidate the warranty.

 

[Riley]

It's a perfectly acceptable system set up. Don't worry and definitely won't invalidate anything. Get him back though to take a look

 

[vtechnician]

If it's a regular boiler, it won't have valves like a system boiler would.

Does this imply the condensate test mentioned earlier won’t work?

 

[Last Plumber]

Does this imply the condensate test mentioned earlier won’t work?

Not if you can't isolate the boiler and you probably can't. That's why it's best to get him back to check over it. It may be a problem with your existing system and therefore a separate. issue to the new boiler

Sometimes, changing from open vented to sealed will show up leaks that went unnoticed before the change

 

[Last Plumber]

Does this imply the condensate test mentioned earlier won’t work?

Not if you can't isolate the boiler and you probably can't. That's why it's best to get him back to check over it. It may be a problem with your existing system and therefore a separate. issue to the new boiler

Sometimes, changing from open vented to sealed will show up leaks that went unnoticed before the change

 

[Last Plumber]

Additionally and as regards the engineer that installed it.

The regular boiler is cheaper but there is more work and material involved in fitting it so it would possibly end up the same cost. He may have decided so fit that because it will work out a better idea for your particular circumstances !

 

[Last Plumber]

Additionally and as regards the engineer that installed it.

The regular boiler is cheaper but there is more work and material involved in fitting it so it would possibly end up the same cost. He may have decided so fit that because it will work out a better idea for your particular circumstances !

 

[vtechnician]

So I went ahead with the condensate test. With the boiler turned off, I simply disconnected the hose at the boiler end and placed a container beneath to catch any water over night.

This morning i measured approx 50ml of water caught in the container. I noticed it was still slowly dripping so i swapped the container for a fresh one. Having returned after an 1.5 hours there was approx 1 tablespoon of water in the container. I hope these results are meaningful.

Surely this water cant be condensate??

 

[Last Plumber]

Vaillant Boilers, siphon the trap out in one go so I would expect the trap to fill and then empty. Even if it was water from a burst heat exchanger !

I would expect you to find more than a few teaspoonfulls to be honest but I cannot say for certain.

My advice is to get an Engineer to check it for you.

You shouldn't work on a gas appliance unless you're Gas Safe Registered.

 

[zzzjim]

.......
Sometimes, changing from open vented to sealed will show up leaks that went unnoticed before the change

Concrete floors , corrosion & expansion issues are the enemies !

(When Hot any slow leaks elsewhere may evaporate .. installer may have some tricks up his sleeve for this )