Boiler Question

[cr0ft]

Hi all. Firstly I do appreciate I am not GSR yet, still have another 13 jobs to do. My issue is I am losing confidence in the guy that is supposed to be training me.

We serviced a boiler last week at a property. I got to do the service whilst being supervised by him. During the service the customer mentioned they were having to top up their heating pressure nearly every day. He didn't seem that bothered about it, just checking the boiler was safe and then off he went.

I asked them to call me if it was still doing it after the service. It certainly is and so I got a call to go and fault find it.

This morning I isolated the boiler from the flow and return pipework using the isolation valves under the boiler. It's a Remaha Avanta Plus combi boiler by the way.

I topped the system up to 2 bars prior to isolating it to give it a good pressure test whilst we did other jobs that day.

On returning 8 hours later the pressure had dropped to 1.7 bars. This was before I had opened up the valves under the boiler so there must be a leak inside the boiler.

I had a bag around the PRV outside all day. The bag was empty when I checked it on my return.

No signs of leaking when the case was removed on the boiler.

My gas fitter thinks it could be the expansion vessel but why on earth would that cause a pressure drop? I think he is speaking out of his rear.

I think the only possible explanation is a pinhole in the main heat exchanger. A drip running down and through the condensate trap and into the drain outside. We didn't remove the front of the heat exchanger as far as I remember in the service as the co/co2 ratio was fine.

That's how I've been taught by him anyway.

I'm going back there on Friday and my plan is to cut the condensate drain pipe and see if any water is leaking down it with the boiler off. If there is then it has to be a pinholed heat exchanger right? The boiler is around 10 years old as it's been in the house from new.

Thanks all in advance.

 

[hammers4spanner]

Conundrum regular poster asking gsr hmmmmm

I would say your gsr engineer should have investigated colour of condensate water and if it smelt like heating water
But obviously cutting the line will also help

 

[cr0ft]

I understand but hopefully you guys know I'm well on my way to getting signed off myself. I'm not going to be touching any gas parts without him being there (although I feel I would probably be safer I realise it's illegal). Cutting the condensate line is an easy way to check if I'm right though. I'm trying to get an idea of what else could be causing this before he comes back as I don't want to look like a ****.

I'm stuck with a gas fitter that's training me who doesn't even understand how an S-Plan system works - I literally had to explain it to him the other day.. I have got another gas fitter I work with who is brill but he works about 40 miles away and I travel to him for work experience. If I **** this guy off I won't have any more jobs with him.

 

[Leo21]

Tbh, you get a bit sick of people asking you to do a service with an ultimatum to get a repair done within the service cost.
So I often service the boilers knowing there's a fault, and advise them to call if the problem persists.Not a dangerous one obviously.
Then you go back and charge appropriate rates for the repair. So it back fires on them, serves them right for trying to con you.

 

[quality]

plumbing and heating systems are were the skill is were as gas is mainly about regulations, knowledge and safety

 

[cr0ft]

Understand where you are coming from Leo but this customer is top, has already been a repeat customer of mine before. I just want to make sure they are getting a good service from him.

Unless anyone can suggest any other things that might cause this issue I will head back and cut the condensate pipe and leave the boiler off for a day and see if water is coming out. At least that way we can rule the heat exchanger pinholing out of it. I can't really see how else water could be leaking at this rate in the boiler. 0.3 bars on a 100L system is quite a bit of water to lose in 8 hours.

@quality - couldn't agree more. I'm glad I've waited a while to approach my gas this way round. If I was servicing this on my own I would tell the customer I could investigate it for an additional £x and leave it up to them to decide what to do.

I think I'm lucky, I work for some really good customers!

 

[townfanjon]

Checking the ex vessel is part of a boiler service, he should have told you that.

 

[plumben]

did/have you checked the expansion vessel out of interest

 

[Leo21]

It'll be the heat x leaking down the condense.

 

[cr0ft]

Hi there. No he hasn't checked the pressure on any service yet, which I thought was a bit odd but I'm having to be a bit careful. If I hack him off I only have one other gas fitter who is 40 miles away.

I have 14 more jobs to do and I'm thinking I will just bite the bullet and travel the 40 miles. The other gas fitter is an assessor at the college I will be doing my assessment and I'm not learning properly with this guy.

I will check the expansion vessel pressure when we go back. How could that cause a pressure drop though out of interest? If it fails the pressure is going to spike when the heating warms up which is different from what symptoms we are getting.

 

[quality]

I found this radiator to be the cause of a similar situation

 

[cr0ft]

It'll be the heat x leaking down the condense.

Thanks. At least my plumbing knowledge is coming in handy for something. I will pop back and cut the condensate line to verify it on Friday morning and re-attend to fix it back up on Friday evening. I think given the age of the boiler I will recommend replacing it if the heat X is knackered.

 

[cr0ft]

View attachment 21800


I found this radiator to be the cause of a similar situation

That's understandable. All the rads look in really good condition and there's no sign of water leaking in the house. Also the pressure drop was when the boiler was fully isolated for 8 hours so it's definitely in the boiler. I know the isolation valves worked fully as when I opened them the pressure actually went back up to 1.85 bars.

 

[Millsy 82]

I would say expansion vessel. What does the pressure do when you leave the heating on?

 

[townfanjon]

I doubt it does mate, but if the air pressure is low or failing , the water will displace the air, but dont think that is the problem.
Loads dont check vessel pressure, because to do it properly you should lower the water pressure, via filling loop, rad etc etc , then check the vessel , then top up the heating again .

 

[cr0ft]

Yeah I imagine they are exactly the same as any other expansion vessel. Need to let the pressure off and then top the air up to get a proper reading of the pressure.

If the water displaces the air it will cause a spike when the water is heating up. The pressure stays constant when the heating is on apparently.

Going to go there on Friday and cut the condensate line and see what's coming out. Hopefully we will find the issue that way. I'm a big believer in doing simple checks first and then working up from there. Can't see how it can be anything else. 0.3 bars in 8 hours on a 100L+ heating system is a huge leak really, must be going down the drain.

 

[Rickster123]

You sure there's not a slightly letting by AAV? If it's a slow drop the water could be drying before it's seen and I'm assuming that you didn't remove the case to check that when you isolated the boiler?

 

[Leo21]

He's had a bag over the prv, so not the vessel. You can check the vessel by letting the boiler heat to max from cold, and checking for a rise in pressure. It's quicker than draining every boiler you service.

 

[cr0ft]

Hi APP,

I know we had a good look round for leaks when we checked the boiler during the service and there wasn't any sign of a leak. 0.3 bars on a 100L system every 8 hours is a fairly substantial water leak though. With that sort of pressure loss with the boiler off for 8 hours today if it was leaking in the casing it would be pouring out the bottom of the boiler by now.

I think pretty much everything has been ruled out that it could logically be, except the heat exchanger.

 

[Rickster123]

Hi APP,

I know we had a good look round for leaks when we checked the boiler during the service and there wasn't any sign of a leak. 0.3 bars on a 100L system every 8 hours is a fairly substantial water leak though. With that sort of pressure loss with the boiler off for 8 hours today if it was leaking in the casing it would be pouring out the bottom of the boiler by now.

I think pretty much everything has been ruled out that it could logically be, except the heat exchanger.

And the boiler was stone cold when you isolated it?

 

[cr0ft]

And the boiler was stone cold when you isolated it?

Yes mate, pretty much. Flow and return pipework underneath was cold when I isolated it.

 

[IDCHAPPY]

Can only be the HE ****ing into the condensate..possibly

 

[Roger Welton]

May still be warm is they had drawn HW or the preheat was on (assuming its a combi)

There is a aav on the top of the casing as well as one on the pump that is easily overlooked.

I'd have checked the exp vessel on the service anyway as it doesn't take long and would have ruled it out.

 

[Nostrum]

Sound like you are on the right track and your gas fitter colleague is a plum.

 

[cr0ft]

Spoke to my missus about it. It's all a bit awkward. Going to phone the one in Mansfield tomorrow and book 3 days in with him to get myself through the last of the portfolio. He's the guy that trained me at the centre I did my training at so he will teach me properly!