Gas Rate and FGA

[mutley racers]

Hi, I have stripped down my own boiler today as it had developed explosive ignition. I am thinking it is the ignition electrode as just below it on the burner is a black soot mark. So that has been ordered. I gave my kane 455 ago for the first time since buying it and it says the ratio 0.0002. But when I do a Gas rate it is under what the manufacturer states. I have cleaned the heat exchanger, burner and fan is ok. Inlet working pressure is fine and burner pressure is correct.

Not sure what else to do really?

 

[diamondgas]

Leave it alone maybe

Gas rating isn't an exact science in my experience mutley racer. By the time you've got to the meter and done your 2 mins the boilers modulating down!! What's the make and model?

 

[mutley racers]

Hi Diamond it's a Main 15 HE heat only boiler

 

[mutley racers]

its in ft3. Are the tolerences 5% lower and 10% higher when gas rating? Like on most new boilers

 

[diamondgas]

Hi Diamond it's a Main 15 HE heat only boiler

Is there much discrepancy? You burning to much or not enough?

 

[mutley racers]

not enough

 

[mutley racers]

it says 57 in the book and I am burning 52

 

[Masood]

Like diamondgas says, gas rating isn't always accurate. I fitted a Halstead boiler recently (customer wanted cheap, cheap, cheap), out was a 1-bed flat, 4 rads, and a warm day. Couldn't get the boiler to stay on full burn for 2 minutes, even! No way of forcing full burn, no service mode, nada. Everything else was spot on, so that was that..

 

[mutley racers]

yea, no service mode on this either. The boiler seemed to be running all the time though as I could hear it. Also, I had a cold hot water cylinder to fill up and a heating system to warm

 

[diamondgas]

it says 57 in the book and I am burning 52

That's a good thing, Lower bills

Try an average over a period of time if your concerned. Obviously the gas rate is best done with the system cold on heating only to guarantee the boiler staying on max rate for the duration of timing. You could try timing over a longer period of time to give you a more acurate reading providing it stays on max throughout Did you get the temp clamps too Mutley R? Check out the diff F&R. I played about with mine when i first got it. Found out i have a 2mbar drop somewhere!!

 

[mutley racers]

I actually have timed it on 4 different occasions. Still coming up the same every time.

Yep i have got the flow and return clamps. i shall give those ago? Not quite sure what you mean by a 2mb drop on them though?

Did you plug them into the wrong part on the analyser or something??

 

[diamondgas]

I actually have timed it on 4 different occasions. Still coming up the same every time.

Yep i have got the flow and return clamps. i shall give those ago? Not quite sure what you mean by a 2mb drop on them though?

Did you plug them into the wrong part on the analyser or something??

LOL .... No I did the let-by and tightness test! Got a gas leak somewhere!! lol

Regards the gas rate though, what would you do to rectify the issue. By the way it may be worth checking the operation of the gas valve! Checking the p2 operation pressure

 

[GrahamM]

The 15 HE?
Is that not a standard gas valved boiler with burner pressure adjustment?

Ignore the above. Been a long day. Not long in.

 

[mutley racers]

the burner pressure is correct, 9mb. A leak hey, thats funny. You're allowed a 4mb drop or 8mb though hey. Am not sure how to fix it Diamond, that is why I am talking to you guys with lots of experience. I have only been on my own for 2 months

 

[GrahamM]

Burner pressure spot on.
FGA readings are good.
Your Gas Rate is within 10% (measurement error. you will very rarely get it spot on)

If the above is correct you have nothing to worry about.

 

[diamondgas]

Soz mutley for some reason I thought it was a zero compensating governor .. got the mi's now and it all becomes a lot clearer regard the boiler in question

You don't have a problem as such, by the way! However if everything is correct yet the gas rate is less than expected what would you check? rather than give you the answer I'd like to stretch you a bit if you don't mind

Hold on this is probably best in the gas safe only forum... puddle!!!!

 

[mutley racers]

10% either way is it GrahamM? For some reason I thought it was 5%below or 10% above. If you are right then it is just perfik. Thanks guys

I am a happy chappy now

 

[mutley racers]

I am really trying to get into the Gas safe only forum but am not getting a reply from dan. He is really busy apparently. I thought it could be a blocked burner, injector. Undersized pipe. But all of them are fine

 

[mutley racers]

Can puddle let me into the gas safe only part if i pm him my details? Also, Burner pressure is spot on

 

[AWheating]

10% either way is it GrahamM? For some reason I thought it was 5%below or 10% above. If you are right then it is just perfik. Thanks guys

I am a happy chappy now

5% above and 10% below. recent gas safe tech bulletin about it.

even more of a pain when you are gas rating on those meters that you keep having to press the button for a reading.

 

[GrahamM]

Doing a gas rate is not an exact science as mentioned. Too many variable affecting a correct answer.

There is an un-written rule that most engineers use to compensate for the measurement error which is inevitable. This is usually 10% bellow and 5% above the MI's.

 

[Masood]

I am really trying to get into the Gas safe only forum but am not getting a reply from dan. He is really busy apparently. I thought it could be a blocked burner, injector. Undersized pipe. But all of them are fine

Me too! I guess they're pretty busy, just have to be patient!

 

[AWheating]

Tb 141

 

[diamondgas]

I am really trying to get into the Gas safe only forum but am not getting a reply from dan. He is really busy apparently. I thought it could be a blocked burner, injector. Undersized pipe. But all of them are fine

Strange !!! Dan's normaly on the ball, Not sure if Super Mod can authorize your acceptance to GSR only mate You got it about right though .. issue would lie down stream of the gas valve within the appliance .. most likely suspect would be injector ... however in the old days they use to say check 'hot' which may make a bit of a difference as the injector expands?

 

[mutley racers]

shame masood, How long have you been waiting? Me over a week now.

Oh, so I had it the wrong way around. So all is fine. Thanks chaps.

Incidentally the things I mentioned Diamond are ok?