Vaillant British Gas boiler under warranty

benson1980

I would be inclined to turn everything off and bleed a radiator again until there is no residual pressure in your sealed system. Take a cap off a towel rail if you have one and then you can directly monitor if there is water ingress into the system I.e if water starts dripping (or pouring) out despite dissipating the pressure. This would surely 100% confirm a faulty isolating valve on the filling loop would it not?

I cannot see how pressure can increase in the way you describe, as others have said, unless the filling loop valve is faulty. 

NannaH

Vaillant has very helpful tech support for Gas engineers,  it doesn’t sound like the BG guy has availed himself of their services.  

For anything under warranty, Vaillant themselves should be fixing,  unless the engineer is Vaillant accredited.  

My husband ( Boiler engineer) rings them on behalf of the customer and if it’s covered under warranty, they take over,  they also offer fixed price replacement parts on out of warranty boilers that he often can’t match on price because they are so reasonable. 

Vaillant are very reliable and their heat exchangers are fairly bullet proof.  

NannaH

He’ll know if your system is dirty by checking the magnetic filter,  they look like they are covered in sooty/inky sludge when opened up.    You can take out the magnetic bar and clean it 😉
After 3 years I wouldn’t expect it to be gunged up if the system was properly cleaned beforehand but it depends if inhibitor was used properly and topped up when serviced.  

Trapdoor

Have you actually disconnected the filling loop? It should really be a flexible hose with two taps and a non-return valve… and mine can be removed as it has ‘washing machine hose’ type fittings  … at least that was what was installed with my EcoTec 3 years ago … that would prove the filling loop as being the culprit.

of course, if your loop has been hard plumbed in (which I was led to believe by my installer was against the regulations … then that wouldn’t be possible.

Ectophile

I wonder if water could be leaking through a hole inside the hot water heat exchanger.  That has mains pressure water going into it, as well as the hot water from the heating system.

nadsat

Ectophile said:

I wonder if water could be leaking through a hole inside the hot water heat exchanger.  That has mains pressure water going into it, as well as the hot water from the heating system.

I assumed it is a system boiler - I presume that would concern a combi boiler. 

macman

Call Vaillant out under your warranty, as it's clear that the BG RGI doesn't have a clue how to fault-find and is simply parts-swapping. If he has changed the EV then it can only be the filling loop valve.

LondonS30

Hi everyone,
thank you for your help and advice.

so to update he managed to fix the boiler (leak and the pressure issue). The pressure normalised after he replaced the heat exchanger plate (the smaller plate at the bottom of the boiler). He also replaced the expansion vessel, pressure sensor and diverter cartridge before that. He thinks the pressure issue was due to the exchanger plate.... I still do not understand why this has become faulty in less than 3years

when I asked why this has happened he advised there was a lot of sludge and rust in the system - the water was a murky brown/ red colour. He advised I need a power flush which is fine BUT I did pay extra for this when BG installed the boiler in 2019 (think it was £400 but I live in a small flat with 6 radiators). He said that because it was done by them when boiler was installed, it is under the warranty and I shouldn’t have to pay but what I’ve read online says otherwise. So I will need to speak with the department who do it. He said that the water shouldn’t have been this rusty/ dark if id had the power flush that recently when boiler was put in. 

LondonS30

Despite the rust/ sludge issue he replaced all the parts and did the work and I have not been charged for any parts or Labour. Maybe because I had done this power flush thing when boiler was put in who knows. On the BG T&C, it does say the warranty doesn’t cover if damaged caused by sludge/ debris but I don’t know how easy it is to know that that is definitely the cause..

LondonS30

Olly_J said:

A boiler can't really create much of its own pressure, aside from the slight increase you'll see with the thermal expansion of water as it heats up and the pump running, so if the pressure is climbing on a meter independent of the boiler itself, then in my mind you have to be seeing an influx of water main pressure into the boiler system.

I think the upper max for Valiant boilers is around 2.8bar which is considered toward danger level, so I would not be surprised if that has damaged the seals causing your leaks, given you are seeing values of up to 4.5. With regards to the dirt you might want to check they have installed a magnetic filter in the system, as that should catch a lot of the usual metallic debris, and have enough inhibitor added to help stop it being generated in the first place

Thanks. Yes there is a magnetic filter cylinder near the filling loop and boiler - is that what you mean?

despite this the water still looked quite brown/ rusty.