Gas boiler Operating.

yoshytoshy wrote: »

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It's important if people give advice on this forum that they know what they're talking about.

lets see if you do - you recomended a 15kw boiler - how many cubic metres per hour would that use or call for ?

yoshytoshy wrote: »

I've a better one for you ,whats the maximum lent of 15mm copper allowing 1.5 cubic metres of gas ?[/QUOTE

who said anything about 15mm

if you put 1.5 m3 in to your 15 kw boiler you are going to overfire it by 2 kw -
1.5 x 11.39 = 17.08kw

yoshytoshy wrote: »

knighted_1 wrote: »

You've lost me ,seriously.

Boiler fans dictate the volume of gas going into a boiler ,apart from that it's the pipe that dictates it.

If you're going to start talking about rating a boiler etc. ,any boilers I've installed for the last three years are condensing.

so ,when you install a condensing boiler what do you do ? do you not gas rate it ?

gary71 wrote: »

knighted_1 wrote: »

I don't, I'd like to know why you do.

because its the law? IS 813 section 15.1 - comissioning appliances

three lines down

-that appliances are adjusted to thier correct gas rate

on the throttle on the gas valve ,where would you throttle back ?

gary71 wrote: »

I don't, I have a working pressure of 20 mbar and a fan controlled by the pcb, you can on some boilers mess with the fan speed but it's not advisable as it can effect flame picture and stability if done incorrectly.

you really should upskill gary -nothing to do with the fan speed its to do with the volume of gas multiplyed by the calorific value(11.39) to get the kw input (most manufacturers set the rate at the english calorific value 9) post any boiler make ,give me the kw and the manufacturers recomended gas rate on max and i will show you why they overfiring

http://www.boards.ie/vbulletin/showthread.php?t=2055804301&page=2

ring martin and ask him how to set up a condensing boiler -he told me most people setting them up wrong (or not setting them up) thats why they overfiring

edit - i googled martin and the first result is a post by you about him so i presumed you know him

well i did try - either he trained me wrong or you are right - you tell me which
i dont doubt your skill set but not gas rating a condensor boiler is wrong and if you ask him you could clear up weather i am wrong and you are right -

i apoligise if i came across wrong .that wasnt my intention -share the knowledge
it is the only part of manufacturers specs that is actually wrong (in this country nowhere else ) as our calorific value is much higher than the uk we at 11.39 - uk is 9.2 ? - if you do the equation on kw divided by m3 of gas you will end up with a figure very close to the uk calorific value - if you do same equation for ireland you will find that we are overfiring by 15 to 25 per cent because of the 11.39 figure - manufacturers state you can overfire by plus or minus 5 per cent

if we over fire by this much we put the co levels much higher than manufacturers allow so in theory we must throttle down to get the levels correct and safe - this can be done with the analyser connected and just adjust - there is no problem running a boiler on 12 or 13 milibar as that is quite normal ,once there is 20 milibar standing presure (regulations) - we cant measure other side of a zero rated valve and thats where a lot of confusion takes place with installers ,they think the boiler gas adjustments itself ,but it doesnt .
this is where the IS 813 regs come in section 15.1 about gas rating all appliances .installers are leaving potentially letal installs in houses if they dont gas rate and analyse during the commissioning of a new install

again i apoligise if i came across bad ,but i try hard to keep my standards extremly high and prob have a bit of a communication problem

gary71 wrote: »

Correct burner pressure or correct co2 setting = correct gas rate, I use gas rating as proof of what I already know from testing it's a tool, not a necessitie,
nothing less than 19mbar at the appliance working pressure 1 mbar drop allowed, there is no problem getting the correct co2 at the correct working pressure and your on your own ajusting boilers in away not reconised by the manufactures ie. me, you reduce the gas to a low working pressure then any igniton issues you be fixing because I'll be looking for more gas before I get involved, Viessmann work at 11mbar working pressure allday everyday and that's the main boiler Martin has worked on the other is mine and I would be telling him the same thing, lastly no need to apolagise, gas fitting comes done to opinions and we all have one

you see this is the thing ,a gas rate is required by law now .if as suggested earlier that someone hangs a boiler and fires it up i gaurantee it will be overfiring if someone wants to post a boiler make and kw and the manufacturers stated m3ph i will do the calculation and show you how its overfiring -