Hi ratio and ppm on a Vaillant eco tec pro 28 lpg (2015)

[Mikeplum]

hi, I am after some advice, I recently fitted a new gas valve to a vaillant ecotec earlier. the boiler was fitted in 2015 and has been serviced since

anyway I put my analyser in the combustion side of the flue and the readings were extremely high, something along the lines of

CO ppm —OR—
Ratio 0.2555
CO2 10.0 (lpg co2 perfect)

I thought the gas valve was faulty, so fitted another and still get the same problem, why am I getting ridiculous parts per million when it should be no more than 250? It’s that high my Kane anyliser doesn’t give a number.

I inpected the main burner and all appeared normal, I also cleaned it and then fitted a new vaillant graphite seal. I also inspected the flue and it was all perfect.

still I was getting these ridiculous readings so I put the analyser into the other side of the flue to get an O2 reading which was correct at 20.9 and there was 0 ppm.

can anybody point me in the right direction as to what the problem is as I have never had readings as high as this before. I often have to adjust them but they are always only slightly out.

 

[Knappers]

What's your working pressure?
I don't remember, should it have a restrictor in valve on this model?
Can you adjust by eye to get better reading?(make note of changes so you don't get more lost)
Technical will be able to give base settings for gas valve as a starting point.

Get 'Gas Engineer' tab on profile!

 

[Mikeplum]

What's your working pressure?
I don't remember, should it have a restrictor in valve on this model?
Can you adjust by eye to get better reading?(make note of changes so you don't get more lost)
Technical will be able to give base settings for gas valve as a starting point.

Get 'Gas Engineer' tab on profile!

The working pressure on the inlet is 33.83mbar.

A restrictor? No I don’t think so.

I phoned technical, all they said was it could be a dodgy gas valve or blocked heat exchanger. They said the only adjustment on the gas valve is for the co2%, i adjusted that to 10.0% which according to manufacturer’s instructions for LPG is perfect.

I’ve never had such obscure readings from an appliance without a valid reason, it’s baffling me a little.

 

[Knappers]

I use a metal blade to get between the tubes on hex and then flush with water. Might be worth checking bottom flue seals incase they've broken down and not showing on inlet test?

 

[Last Plumber]

Is your CO cell faulty?

Could something be impinging the flame?

 

[Scott_D]

Is it an LPG boiler?
Have you tried a gas family check

 

[Mikeplum]

Is your CO cell faulty?

Could something be impinging the flame?

If it was the co sensor, would that not bring up a fault?? (F 55). Also would the CO Cell throw the readings out that much? Or just cause them to fluctuate up and down?

I’ve inspected the heat exchanger and all seems absolutely fine, there’s no signs of flame impingement and no splits in the burner to cause an irregular flame.

Thanks for the reply tho! This really has baffled me.

 

[Last Plumber]

If it was the co sensor, would that not bring up a fault?? (F 55). Also would the CO Cell throw the readings out that much? Or just cause them to fluctuate up and down?

I’ve inspected the heat exchanger and all seems absolutely fine, there’s no signs of flame impingement and no splits in the burner to cause an irregular flame.

Thanks for the reply tho! This really has baffled me.

Is the air intake restricted?
Is this case on or off?

 

[Mikeplum]

Is the air intake restricted?
Is this case on or off?

Air intake is clear,
It doesn’t matter if the case is on or off, I’m still getting the same reading

 

[Scott_D]

Could be debris / oil inside the burner (cylindrical can with holes)

 

[Knappers]

Have you cleaned the heat ex?