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J

jolliffe81

Hello

I'm being told by some gas engineers that with all appliances operating at full input, the maximum working pressure difference between the meter outlet and any appliance inlet not greater than 1mbar is acceptable (i.e. cooker - 0.47 mbar boiler - 0.86 mbar heater 0.57 mbar is ok). So the total exceeds 1 mbar but as long as each individual appliance is below 1mbar its a pass

I'm then being told by other gas safe engineers that the total for the whole system has to be below 1mbar (i.e cooker - 0.47 mbar boiler - 0.86 heater 0.57 = 1.9mbar is not acceptable because it exceeds 1 mbar).

Can anyone please confirm what one is the correct method. Many Thanks
 
How many gas engineers have carried out these tests?
What's the rest of the story? New boiler fitted?
 
Last edited:
Yep more to this than meets the eye
 
Hello Scott and Riley

This is for an existing installation. I need to know if this is safe with all appliances under 1 mbar from meter to appliance or if I have to total all the drops together (if so then the system is not safe. Many thanks
 
Hello Scott

This is for an existing installation. I need to know if this is safe with all appliances under 1 mbar from meter to appliance or if I have to total all the drops together (if so then the system is not safe. Many thanks
 
If you total all the pressure drops, you are effectively counting the pressure drop in the pipework nearest the meter, before separation to individual appliances, more than once.
But all appliances need to be on maximum output when readings are taken.
 
Hello Joni
So as long as each appliance has a pressure drop lower than 1mb when tested on its own thats ok? But what if the user has the cooker on, the boiler heating the hot water and the oven on at the same time then all appliances are not gong to get enough pressure to them?
 
I'm not really sure what you want us to tell you mate if the drop is more than 1 mbar in total then that's not acceptable I am curious as to what has suddenly brought the issue to light. Unfortunately you aren't going to get any more information than that as you are not gas safe and as such we will not discuss The sizing of gas pipework etc. I'm sure you can appreciate that if we told you what sizes to use and you went ahead and did it we would be encouraging DIY gas work
 
Hello Riley
I should of explained this at the beginning. I am gas safe registered but waiting for gas safe to come and view me undertake gas safe inspections at three different properties. I passed my CCN1 about three years ago so am a bit rusty as havn't had to do any gas work since i passed. I have been undertaking WRAS approval works for past three years. I have been going through all my old notes to sharpen up on what I learnt. I looked through my pipe sizing calculations and realized that what I learnt was you can have a 1mbar drop from the meter to an appliance. I then realized if I add the totals up of all three appliances it is more that 1mbar. I have been asking about and getting two different answers. Some are saying this is ok and others are saying it isn't. I need to clear this up before I have my gas safe inspection which is in two weeks. The question I posted is an example of an existing installation at a relatives house I will be using as one of my three properties I will be taking the gas safe inspector to watch me undertake the gas safe checks. Hope this clears everything up.
Cheers
 
I'm not really sure what you want us to tell you mate if the drop is more than 1 mbar in total then that's not acceptable I am curious as to what has suddenly brought the issue to light. Unfortunately you aren't going to get any more information than that as you are not gas safe and as such we will not discuss The sizing of gas pipework etc. I'm sure you can appreciate that if we told you what sizes to use and you went ahead and did it we would be encouraging DIY gas work

I would say that it is each appliance when tested that can have a 1mb pressure drop. eg. test boiler with cooker going 1mb drop from meter - all ok. Then test cooker with boiler on and 1mb drop, again all ok.
 
I would say to the OP i think you will be fine for the inspection, in my experience they dont dig too deep into these things.

When your test an appliance inlet pressure you're only testing that one at that time. Each individual appliance is tested one at a time (with other appliances running) and if there is 1mb drop or less it will be fine.

When I have seen pressure loss problems on a water gauge it is normally so noticeably low that you cant fail to see it ie 12mb perhaps
 
Hello Joni
So as long as each appliance has a pressure drop lower than 1mb when tested on its own thats ok? But what if the user has the cooker on, the boiler heating the hot water and the oven on at the same time then all appliances are not gong to get enough pressure to them?
As post 10. ALL the appliances working, TOGETHER, at time of test.
 
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