recently i have updated a conventional boiler with a vaillant 831, the gas pipe is under floor and about 10m long, it looks ok so i did not replace the gas pipe, however after replacing the boiler i found that the inlet pressure is only 17mb, meter working pressure is 21mb, aothough the minimum requirement is only 16mb for vaillant and the boiler should work safely(flow rate is ok), the pressure drop is aoubt 4mb, must i replace the gas pipe under the floor boards? thanks all!
Discuss must i replace the gas pipe? in the Plumbing Jobs | The Job-board area at PlumbersForums.net
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1mbar pressure differential across the gas installation pipe to the inlet of the appliance. It may be you have got this as there will be restriction through the boiler gas valve and fittings. If your concerned, fit a test point at the boiler inlet and check the pressure.
The problem is I do not know what is gong on under the tiled floor, maybe some 15mm pipe there, I assume the pressure drop is more than 1MB, but is it mandatory for me to update the existing gas pipe?if I install new pipe work surely I need to make sure the pressure drop is less than 1MB, My job was only to change the boiler and what I know is the boiler working fine
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You need to replace the gas pipe so you only have 1mbar drop across the carcass with all appliances turned on. You cannot install the boiler without doing this. Well you can, but you shouldn't. If it is within what the manufacturer recommend and it doesn't affect the combustion of other appliances then it is all ok with analyser it is NCS. but you shouldn't be installing a new appliance with a ncs
does that mean all the installer have to make sure the gas installation is perfect when they replace a boiler: like make sure the gas hob must have FSD? the meter must have bonding? open the floor boards to make sure all the pipes clipped ok? replace all the lead pipes(this one as i know it is not mandatory),etc..... then all the boiler replacement will be a big job
You need to make sure your installation does, having a 3mb pressure loss between the meter and boiler means it NEEDS an upgrade. You need to determine what the pressure loss on the pipework is. If it is greater than 1mb with all appliances running then yeah you need to upgrade the pipework.
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Can u replace the pipework nearest the meter in 28mm? That should help, You have to measure it in worst case scenario hence all appliances on
Yeah and if the pipework is not sized correctly for the boiler then you cannot fit it on to the pipework, how are you not getting this?
If I decide I want to fit a 42cdi on to an old 15mm gas supply that used to feed a 30,000 btu baxi solo. Can I do this because the gas pipe is not my installation?
If I decide I want to fit a 42cdi on to an old 15mm gas supply that used to feed a 30,000 btu baxi solo. Can I do this because the gas pipe is not my installation?
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But you have to install it in accordance with manufacturer instructions and relevant British Standards. These will state that you must ensure you have adequate gas supply to the appliance. If I price work, I always look at the existing gas installation pipe if it looks border line I will allow for it into the job and make sure the customer knows its included in the price. If it doesn't need to be changed I will knock it off the price.
M
Mike Jackson
You will be signing the installation off to confirm that it complies with all current standards and it won't. Part of installing a gas appliance is ensuring that the gas supply complies with the regulations.
Perhaps I shouldn't bother ripping up the floors to upgrade the gas supply to the new 35Kw combi I'm fitting, after all I'm only fitting the boiler, I'm sure the 15mm pipe will be big enough.
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would you say that during an assessment and argue over it?
or would you emphasise you can only have 1 mbar across pipework?
Seeing as you're gs, you've already done the latter!!
whats changed now you're on the patch from being in the assessment area??
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