837 EcoTec Plus Making noise when full flame

[div_m108]

I am in need for some help on my Vaillant 837 EcoTec Plus combi boiler (installed in Dec 2009) that is making noise. Same noise as in this video.
https://youtu.be/y-yMEAgEtyM

While I was decorating the house I had taken off the radiators from wall and left the thermostatic valves on closed position. After many weeks (6 wks) the water from the closed thermostatic valve leaked and emptied the water. The pressure gauge on the boiler showed zero. Using the two valves at the bottom I re-pressurised the system to approx 1.5bar.

I accidentally turned the gas inlet valve to off while I tried to de-pressurise the system after I over pressurised. I put the gas valve in fully open position after realising that did nothing to the pressure.

After this point I noticed the boiler started to make some noise (as if the low flying jet passed over my house). I felt the water was not hot as before. I called an engineer as I also needed to service the boiler and put in the radiator chemical. Engineer did the service and I also made him aware of the noise that the boiler was making.

Engineer wasn't able to diagnose the fault so he spoke to the Vaillant Technical team and they advised the noise was due to the worn out gasket seal (part no. 0020038679) on the HE. This was replaced by the engineer but the noise was still there. Spoke to the Vaillant Tech team again and another advisor told to check the standing gas pressure at the boiler and at the meter. He also checked the pressure while the boiler was running and found the pressure drop was about 7-8mb at the meter while boiler was on. He advised to have the meter and governor changed by ringing National Grid. Both items were replaced for no extra cost by National Grid and Grid engineer reported the standing pressure of 21mb and after switching the boiler on it dropped close to 19mb at the meter. 22mm pipe is installed from the meter to the boiler. I see a very small variation in the cooker flame when the boiler is switched on.

My boiler engineer tried playing with the air inlet duct and found that when the air duct is off the noise was little less. Also if the air inlet was being partially covered the noise became worse. He cleaned the duct and put it back. The noise was there.

After all the above was tried and the boiler engineer left my premises, I thought to myself, it could be something to do with me closing the gas inlet valve accidentally that I have kept it fully opened. I started playing with the gas valve by slowly closing it and finding out if the boiler made noise again when hot water is running. I found a valve position that took the noise away completely and I am not getting any noise.

Just wanted to get an opinion on what I had done (tuning the gas valve) is correct or would this harm the boiler? Or the noise that I was getting is due to something else? Your advise would be greatly appreciated.

Sorry for such a long message.

 

[bazdaman]

You should not turn the gas control partially off at all, i suggest opening it back up fully and getting a different engineer to look, from what i can make of the video i would be checking things you should not be touching so please dont go messing!

 

[wannocks]

Second that. Try again with an engineer that knows what they're doing.

 

[ScottishGasMan]

The noise has nothing to do with the gas inlet, and stop playing with it.

Get a compitent engineer to look at it instead, or probably best get a fixed price repair from vaillant as its more than likley could do with a few parts and there very expensive.

When you were taking radiators on and off what was the water comming out them like? drinking water? bit dirty? Black oil?

 

[div_m108]

Thanks guys for your response. I will set the gas valve to fully open position and will get a fixed price quote from Vaillant.

@ScottishGasMan The water that came out from the radiator was brownish and has left a stain on my carpet (getting rid of the stain by using Rug Doctor spray). See attached pic.

 

[ScottishGasMan]

FYI dirty water in the system can block up multiple components which can easily cause the noise above. But there not easy to clean hence the possible high repair bill to get it sorted with replacement parts. Get vaillant or Bg on fixed price repair

 

[Agile]

I am always so surprised to read about engineers who seem so unable to properly diagnose and adjust boilers.

But the serious fault at the meter would indicate the OP was not very concerned by flame size varying at the cooker either!

Tony

 

[div_m108]

I am always so surprised to read about engineers who seem so unable to properly diagnose and adjust boilers.

But the serious fault at the meter would indicate the OP was not very concerned by flame size varying at the cooker either!

Tony

What does OP mean?

 

[wannocks]

Original Poster

 

[div_m108]

Guys what could be wrong? Can you hint me so I can specifically ask the engineer if he doesn't look into it.

 

[Wongfeifox]

This sounds more like the pump/circulation than the famous air plane noise that valliant/glow worm suffer from.
I only say circulation as you state it started after you played with the water system and with dirty brown water you probably have a air/leak issue causing oxyination of the water which on a valliant with its internal filter and small 8mm HE tubing is never good.
However the fact that it disappears when the air intake is removed leads me back to the flue/gas valve.
The infamous air plane noise is a combustion issue usually related to blocked air intake or a vertical flue that has come apart. It looks like you have a horizontal flue so I would start by checking that it is actually clear. If this is all good then you are looking towards the gas valve. The fact that the standing and working pressure was resolved by having the meter exchanged says you probably have shale in the inlet supply (had any gas work done in the road lately ?) which maybe on the inlet side of the gas valve filter.
As everyone else has said you need to get someone in who knows what he is doing and who can listen to the noise in person, it doesn't sound like the combustion noise, but from evidence presented to us that's where I would be going.

 

[div_m108]

@Wongfeifox I know the service engineer did take out the air duct and ensured that it was clean.
I can't recall any gas work taking place near the property recently. Could it be that any debris is caught in the boiler after the leak, which meant the debris has go into the main boiler. I do have a magnaclean filter fitted.

 

[div_m108]

I can confirm when I remove the air duct (black pipe) the noise is reduced considerably. As soon as I fix the air duct, after about 10-15seconds later the noise starts.
With the air duct on, I placed my fingers at the end of the duct to partially disturb the air flow and the noise gets worse. I wasn't able to open the air duct (to remove any debris) easily so I have kept the air duct as it is.

Am I guessing right here that, the gas-to- air ratio seems to have been causing the noise. Is there a gas-to-air ratio setting that someone is able to tune?

 

[ScottishGasMan]

No. You are almost entirely wrong. And Pretty stupid for even trying that. My advise is to turn boiler off and have someone compitent look at it like I said before, before you endanger yourself further.


This thread should be locked!!

 

[Agile]

No DIYer should be opening the boiler and certainly not touching the air inlet pipe.

Nor should Wei Wei Fox be giving you any advice on gas/combustion issues.

You need a competent gas reg engineer. Merely being gas reg is only an indication of being able to work safely with gas. That could be as limited to just turning off the gas supply and certainly not having any diagnostic skills.

Tony