Huge gas rate

[Dolf]

Hi.
Doing gas rate on Ideal Icos he12 condensing boiler,I've got result of 34kW input.Boiler got zero governor gas valve.Combustion test point is not present and flue terminal is somewhere on the roof.Can someone advise me,please,is that gas valve adjustable or it is just broken and needs to be replaced?Regards

 

[GrahamM]

You cannot work on a zero governed condensing boiler without a FGA or indeed the MI's.
If you look at the MI's you will find where the combustion test point should be.

 

[Dolf]

Thanks GrahamM.I've got MI,flue test point should be on first elbow but flue is going verticaly and flue terminal is unreachable (to stick FGA there) without long long ladder.Do you think it's worth to climb up the roof or better just buy new gas valve (£90)?

 

[SimonJohns]

Check your gas rate again. That high and you would have a loud banging from boiler and a over heat situation

There should be a small nut on the top which is a FGA point

 

[Dolf]

Thanks Simon.I did gas rate 4 times,still the same,found sensing tube damaged but this wasn't a problem (after fixing it rate hasn't changed).Boiler works ok,means no overheating or banging,fun is a bit noisy.Do you think the faulty gas valve can cause overrating or could be something else?

 

[Dolf]

To Simon again.I'm 100% sure there is no FGA point

 

[sparra1100]

there should be 2 small valves on top of the boiler case that your tube that you get with the analyser fits on to to check ,ones air ones co test point usually on ideals thats where they are ,altho dont work on them and try to avoid them like the plague

 

[Dolf]

Finaly I was able to do FGA (hired long long ladder) and surprisingly everything is fine :ratio 0.0011,CO2 9.9% (tried 2 times).Analyser is only 5 month old and never had any problems with it.I did FGA test in my home boiler to compaire and nothing is wrong.And gas rate still coming with huge result.Can some one explain me what I've done wrong?Normaly zero governor valves are set by manufacturer and sealed.I can't understand why with good FGA gas rate is so bad.

 

[nysk2008]

are you going your gas rate right mate?

Im sure you know your stuff but if anything like me, cr** with caculators

 

[Dolf]

I calculate it using formulas from G1 book and also got an app on iPhone.Results are very similar

 

[AWheating]

you can attach your analyser to the sample tube on the top of the boiler using a silicone tube.

have you tried to gas rate any other applainces in the property? check the cooker/fire gas rates to eliminate external problems.

 

[sparra1100]

thought ye couldnt gas rate an A rated boiler due to zero governer modulating

 

[Eddie Charlton]

many boilers have a facility to set to maximum so this can be done
.
can i ask what the two meter gas figures were for the two minute test?

regards

 

[Dolf]

you can attach your analyser to the sample tube on the top of the boiler using a silicone tube.

have you tried to gas rate any other applainces in the property? check the cooker/fire gas rates to eliminate external problems.

Yes mate,I rate gas hob in the house and was perfect

 

[Dolf]

thought ye couldnt gas rate an A rated boiler due to zero governer modulating

Maybe you're right.Could it be THE answer?

 

[Dolf]

many boilers have a facility to set to maximum so this can be done
.
can i ask what the two meter gas figures were for the two minute test?

regards

I don't remember now the figures as I left all my documents on site but I'm 100% sure the gas rate was done properly

 

[SimonJohns]

Have you got a major leak causing wrong gas rate

Have you identifiied the boiler correctly

Is there any other appliance on

 

[AWheating]

Maybe you're right.Could it be THE answer?

what? if the boiler modulated down then your gas rate would come out lower not higher.

 

[armourer]

sounds like someone is cooking their tea or next door is stealing the gas at the same time.

As above if tested on CH it could modulate down if there is not a test setting but if you open a hot tap , sometimes they rate above the badge. (eg a 28kw boiler could use 32kw for DHW)

 

[GrahamM]

Firstly, I mentioned in my previous post about referring to MI's. This will show you where the FGA point is. Unless there is some odd variant of Icos out there that I have never come across the FGA point is on top of the boiler. I work on many of these every week.
Secondly, not saying it is not possible, but I find it unlikely you are getting a compliant FGA reading from a 12KW boiler that you are gas rating at 3 times it's max rating.
Something amiss somewhere!

 

[Dolf]

Have you got a major leak causing wrong gas rate

Have you identifiied the boiler correctly

Is there any other appliance on

There are two apliances:boiler and hob.Hob rating is fine.Tightness test perfect.Only boiler was on,100%

 

[mfgs]

Something is wrong, you either have the 30kw model or are messing up your calculations by the sound of it. How big is the house? Also the combustion test point is on the top of the boiler, you need to unscrew the bolt on top of it.

 

[GrahamM]

thought ye couldnt gas rate an A rated boiler due to zero governer modulating

As you cannot take a burner pressure from a zero governed boiler, how do you work out it's gas consumption if you cannot gas rate it?
A lot of boilers have a service (chimney sweep) mode that will hold the boiler at max rate to give you time to gas rate and FGA. For the ones that don't you run the hot water at a fast flow for the combi or open all TRV's, room stat, cylinder stat up for the system/conventional boilers.

 

[Dolf]

I got an idea:some one in Ideal made mistake and labeled boiler as icos he12 instead of he28 or he32.
God,I'm tired

 

[sparra1100]

As you cannot take a burner pressure from a zero governed boiler, how do you work out it's gas consumption if you cannot gas rate it?
.

when i was doin my acs and had to do a portfolio there was a section for gas rate .operating pressure when it was a A rated boiler the section had to be 0 as we were told it can stil modulate even on engineers mode due to how the gas valve works,am not saying am right am just doing or saying, how i was taught and have done it that way ever since i was questioned on it and had to explain why so either the collage/center is wrong or somethings a miss