working pressure at meter

[desrob]

18mbar.............at meter .....working pressure on boiler fine....is all ok....!

 

[Hobo128]

I would say to contact the supplier and let them know as it should really be between 19mb and 30mb but they will probebly say everything is ok or maybe send someone out. Check you manometer is zerod tho first hahaha

 

[CMairiD]

Working pressure at the meter between 19-30mbar? Think you will need to recheck those figures.

 

[SimonJohns]

30mb. Wow. Bet you cook your eggs in no time!

 

[Billy Bob Bob]

call the ESP you need a new Governor

 

[SafeGasInstall]

18mbar.............at meter .....working pressure on boiler fine....is all ok....!

how do you mean on boiler is fine ?

18 mbar at meter should have 17 at in let , did you ?

 

[Mike Jackson]

It may be a case of a faulty governor or just resetting but in Bexhill there are issues with working pressures as low as 17 mbar at the meter. This is down to inadequately sized pipes throughout the town and when you call Southern Gas Networks out there is nothing that they can do until the gas pipes have been renewed. You have to be really fussy with pipe sizing in Bexhill as you have hardly any leeway.

 

[desrob]

Working pressure at the meter between 19-30mbar? Think you will need to recheck those figures.

eh....i am asking you...i have 18mbar at the meter when the boiler is operating,the working pressures on the boiler are fine,is it ok to use or get esp in, 3 people liked it ,strange ,please explain

 

[gasmarc]

thats not right between 19- 30 millibar

 

[desrob]

thats not right between 19- 30 millibar

i know...21 +or-2mbar

 

[CMairiD]

eh....i am asking you...i have 18mbar at the meter when the boiler is operating,the working pressures on the boiler are fine,is it ok to use or get esp in, 3 people liked it ,strange ,please explain

desrob, my statement re rechecking those figures for working pressure at the meter was in direct response to hobo's quote below. I apologise if I didn't make that clear.

I would say to contact the supplier and let them know as it should really be between 19mb and 30mb

The reason three people may have like my comment is because he was not describing correct tolerance for working pressure at the meter. In fact, he is describing tolerance for standing pressure. I didn't give the full correction immediately because I was hoping that he, or any one else learning from this threads, would check their reference material.

You have now identified correct working pressure tolerances. You have found that it is below the tolerance so I personally would have turned off the meter, issued the appropriate documentation, reported it to the Grid and got a job reference number. If the Grid chose to do nothing about it, I'm not the last (wo) man on the job.

 

[desrob]

desrob, my statement re rechecking those figures for working pressure at the meter was in direct response to hobo's quote below. I apologise if I didn't make that clear.




The reason three people may have like my comment is because he was not describing correct tolerance for working pressure at the meter. In fact, he is describing tolerance for standing pressure. I didn't give the full correction immediately because I was hoping that he, or any one else learning from this threads, would check their reference material.

You have now identified correct working pressure tolerances. You have found that it is below the tolerance so I personally would have turned off the meter, issued the appropriate documentation, reported it to the Grid and got a job reference number. If the Grid chose to do nothing about it, I'm not the last (wo) man on the job.

you'll go green...apology
accepted

 

[SafeGasInstall]

21+- 1m bar not 2 mbar

 

[CMairiD]

Sorry, Stani, it is 21mbar +/- 2mbar.

 

[desrob]

21+- 1m bar not 2 mbar

the regulator range is 19mbar to 23mbar

 

[SafeGasInstall]

this is why I love this forum so much .

 

[SafeGasInstall]

the regulator range is 19mbar to 23mbar

i was on about permissible pressure drop from meter to appliance

 

[gasmarc]

likewise , Learning everyday :conehead: LOL

 

[Leo21]

Don't know if this is relevant but Vaillant accept 16 MBar at boiler because they've found that there is some suction via fan through the gas valve. Having it at 16 makes it really helpful on pipe sizing the gas.

 

[gasmarc]

Viessmann accept anything as low as 12 millibar

 

[Leo21]

That is low. Are they the boilers that still have aps switches on still?

 

[AWheating]

although it is correct that some boiler manufactures now state allowable figures below 20mb for inlet pressures at the inlet side of the gas valve, this does not excuse having more than 1mb drop from the meter and the appliance as required bu gas regs. Worcester for example will allow 16.5mb on some of its boilers. Taking into account 19mb at the meter, 18mb at the boiler isolator and a 1.5mb drop (16.5mb) across the gas pipework from its iso valve to test point on its gas valve.

This is the problem with manufactures stating low figures, some engineers will use this as an excuse to ignore undersized gas carcus. The best solution would be to include a test point at the isolation valve to ensure we can be sure we have got things correct.

 

[AWheating]

18mbar.............at meter .....working pressure on boiler fine....is all ok....!

as other have said 18mb is too low and you normally need to call the grid. This said it can be allowable to have it lower than 19mb during peak periods. which if i remember correctly (but not 100% sure if correct) is a period of no longer than 5% of the total use of the appliance. I think there may be a technical buletin about this.

call the grid and let them decide if its ok.

 

[Leo21]

Surely if mi says lower MBar at boiler its ok. I always thought mi,s over ruled every thing else. Surely this rule only applies to appliances that state it in mi,s. Fires cookers and not anything with a zero governor.

 

[AWheating]

Most of the stated MI relate to losses inside the applaince before test point. MI does not overide the need for correct pipe sizing and never will. Especially when more than one applaince is installed in a property.

 

[AWheating]

its a grey area for sure, the last worcester i fitted i had a total drop from meter to gas valve inlets of 0.9mb (wp) in therory i could have allowed 2.5mb allowing for 1.5mb across the gas internals of the applaince. If i had a test point at the iso valve i could determine that any drop over 1mb was not all on pipework. I know of some engineers that will fit an test point before iso valve to allow correct measurements and peace of mind.

 

[Mike Jackson]

As far as I'm conerned it's quite clear for example Ideal state that the logic plus range is able to deliver it's full output at inlet pressures as low as 14mbar they also state that pipework should be fitted in accordance with BS 6891.

BS 6891 states

5.2.3 The pressure drop between the outlet of the meter and the points to be connected shall not exceed 1 mbar at maximum flow conditions.

This is not a case of MIs over riding British Standards but requiring that they are complied with. The low inlet pressures are not a get out for sloppy pipe sizing and installation but a safety net in case of low pressure problems with the supply.

 

[cascas]

This is the problem with manufactures stating low figures, some engineers will use this as an excuse to ignore undersized gas carcus. The best solution would be to include a test point at the isolation valve to ensure we can be sure we have got things correct.

Agreed. This is also suggested in gas safe bulitin re Worcester inlet pressure. The low pressures quoted do not mitigate the fact that only 1mbar loss is allowed over the pipework - the low figures are because the test point itself is causing a 1.5mbar loss, and therefore the supply to the appliance is actually correct,.

In theory in the event that pipework is undersized at what point would it start to affect flow rate/gas rate. I assume that as if gas demand is higher than the design limits of the pipework it will still be able to supply the required gas rate to the appliance and pressure would start to fall, until it got to the stage where the pressure was less than that required by the manufacturer before it would cause problems.

 

[cascas]

. .

 

[Leo21]

Ok, if the mi,s state a figure and there no way or no call for it from mi,s to put a test point in. Obviously you'll test with other appliances operating and anyone who adds an appliance is responsible for correct sizing up or down stream. Mi,s do some times over rule the regs, dfe fires for example over 7 kw need ventilation unless stated in the mi,s.

 

[AWheating]

yes i understand the argument about MI over riding the regs, but a gas carcus will in most situations have more than one appliance so cant be effected by any one appliances MI, and i think if you asked any manufacturer the opinion you will get the reply stating the same and pipework must comply to the current gas regs.

If they changed the regs then thats a different matter of course.

as reguards test point, my opinion is it would be helpful if manufactures fitted one. If on your gas safe inspection your inspector asked how do you prove the pipework has less than 1mb drop what answer would you give? a test point would help you prove this. But why would manufactures help us out??

 

[Leo21]

Fair one, gas regs are some times not as clear as they could and are open to interpretation . Be nice for some clear guide lines. Oh how it gives me a head ache deciphering it all.

 

[gasmarc]

yes someone should write a common sense book that we could all understand

 

[Brendan Rodgers]

The fact is it should be 19mlb min but if you make the call to get them to come and change thye gov. they may refuse as petty to them. Providing no appliances are effected and all burner and working presures are achieved dont worry about it..thats just my oppinion...
Bren.

 

[Leo21]

Speaking to one of the ESP guys the other day, and they've got a loophole they use. They say that in a situation where work is required to the mains as long as it's 6" in old money it's passable.