Remeha Quinta 85 combustion problems

[Nico]

Hi guys looking for a bit of advise for anyone that has had similar experience. While servicing 4 remeha boilers in the one boiler house 1 of them was giving me trouble with the combustion reading. While testing at low fire the CO2 readings were as low as 1.2% but while trying to increase the CO2 to manufacturers figures of 9.5% even when only increasing it by 1% the CO would go through the roof and I had to pull the analyser as fear of damaging a cell. Does the combustion clean itself up the closer I get to this figure or would this be an indecation of a fault? If so rather than risking the damaging of cells could I take gas rates at low fire until it is at stated rate in manufacturers instructions before testing with analyser so I know I am in the ball park rather than pulling the analyser out after a couple of seconds due to such high readings?

Any replies are much appreciated

 

[ShaunCorbs]

are you commercially?

 

[Nico]

Have both domestic and commercial yes but wouldn't have a vast amount of experience on commercial works

 

[ShaunCorbs]

sorry to ask again but have you had a new gas safe card? as it was flagged up your number has expired and i haven't had time to pm you

 

[Nico]

I had a new number yes as I done an LPG change over then moved company my new number is 4316328. So you could of had a new number notification for either of the reasons

 

[ShaunCorbs]

Updated ta

When were they last stripped and cleaned as there normally buggers for dirty hexs

 

[Nico]

These boiler would be a good few years old and running constantly as are sitting in an extension of a hotel. I gave the hexs a clean but maybe not as well as I thought. Could this be the cause of the bad readings if there was maybe a slight blockage. Just found it strange as with the slightest adjustment of the gas valve the co then went through the roof and I could literally only dip the analyser in for a quick reading as fear of damaging it. So I ended up putting it back to the setting I found as It gave good CO reading and i am back on site tomorrow so can have a better look at it again

 

[Nico]

Also in high fire the boiler was running at stated values in M.I. which threw me off as well

 

[ShaunCorbs]

Did you get the service kit as the gaskets are one shot

 

[ShaunCorbs]

What fga you got?

Also did you check the alu sump as these tend to rot also check the plastic flue way (right hand side at the back) these normally split

 

[Nico]

The company I am with use the testo 327. I had checked the flue way as I had to replace a couple on a different site and they had rotted at the bottom and internal seal had shrank. I hadn't gave the sump an in-depth look. Could something like that cause an effect on the co on low fire but give you better reading on high fire?

See because on low the CO2 is at 1% and is recommended at 9.5% from memory. As I increase it the CO goes thro the roof but if I was to hold me nerve and continue to increase it would it start to come back down the closer I got to that percentage or would it just continue to get worse and is a fault else where?

 

[ShaunCorbs]

TBH sounds like it's fine 9.5 is your high setting

What's your air on high and low ?

Also high and low ppm ?

 

[Nico]

Am sure it said in the manual for both full load and part load CO2 should be 9.5% +/- .2% but I could have read it wrong

High was
CO2-9.21
CO-58
O2-4.7

Low was
CO2-1%
CO-4ppm
O2-19.4

 

[ShaunCorbs]

My mistake just had a word with rem (was ordering a service kit for another model)

High and low are the same 9.5

Check the fan speed specs in the manual only thing that adjusts from high to low

sorry

 

[Nico]

Will have a look cheers