Discuss Adding 3 metres of 28mm pipe at the end of a 15 metre 22mm run in the Plumbing Jobs | The Job-board area at PlumbersForums.net
It was all part of the building work (so the builders who i kicked out) so they would have contracted someone I think. Don't have the details of the actual person who did it so can't get him back to sort it. The original pipes were put in by another company.so who re-routed the pipework ?
Only problem is that it will either involve digging walls in addition to lifting floor boards (we would need to lift some floor boards in any case for upgrading sections to 28mm) so would rather not look at this option unless absolutely necessaryyou can buy a 15m tracpipe rerun for about £240, might be easier to rerun the whole gas carcass than fart about putting bits in.
I don't know - just trying to summarise the points from the posts. Looks like the later posts say that increasing pipe size anywhere will increase volume, decrease resistance and increase working pressure at the appliance. The issue I am facing is that the pressure drop from gas meter to boiler is too great (around 6mbar) so am trying to determine ways of reducing this pressure drop. I am assuming the gas supply people won't change the governor to increase the gas meter pressure to above 22mbar?
increasing the pressure at the govener would not alter the drop in pressure across the system, they wouldnt do it anyway. you could do some pipe size calcs and work it out, normally its just a case of upsizing. Have you checked youve not got the manometer on the wrong size of the appliance have you and getting burner pressure? wouldnt be the first time somebody done that
should be zero thenThe vaillant ecotec has a zero pressure govenor so no burner pressure to check.
Not sure I follow. What pressure would they have checked at the boiler then? He seemed to connect a manometer to something in the boiler. Would this be the pressure of the gas just before it hits the burner?Is anyone able to run a quick calculation to see what improvement I get in terms of pressure drop if I swap 5m of 22mm pipe with 5m of 28mm pipe?The vaillant ecotec has a zero pressure govenor so no burner pressure to check.
dont forget with a vailant you can lose 2mb wk press through the inlet elbow to the test point this is in the manual. i fitted a a large kw glowworm flexicom a while back and used a rear piping jig which only allowed 15mm pipe to the boiler from the top that reduced the wk press i cut a tee in and fitted test point on the 22mm part and got 20mb wk there .
ant
true indeed I was told at one of their courses that they allow 2.5mbar to be lost at inlet
Ignoring the hob.
The pressure drop you have is down to more than you are stating.
A 15m x 22mm run with 10 elbows to the tee
then
3m x 22mm + 1m x 15mm + 1 elbow from tee would give an overall drop of around 1.68mb (it would be around 2.34mb allowing for a 7kw hob)
The 15mm part somewhere under the floor has never been upgraded. Get it done again and done right this time.
increasing the working pressure at the meters govner will increase the working pressure at the boiler, who ever said it wont is wrong because while the gas board was out i got him to up it a little while he was upgrading it, which did help a lot
it would yes but the pressure drop would still be the same
I am assuming you are referring to my question about the gas board increasing the pressure at the governor. In terms of the pressure drop being the same, I could live with that as long as the pressure to the appliances is high enough. So my next question is whether having a large pressure drop in the system is allowable as long as the appliances have their minimum required working pressure?
doesnt matter if you can live with it or not, there should be no more than a 1mb drop across the system. there are reasons why the working pressures are controlled at the meter governor, if not you could run it in 10mm and just boost the pressure, but then its not safe
The minimum that vaillant allow is 17mb, I would disconnect the boiler and hob and blast some compressed air through the pipes, as the pipes have been cut to install a tee for the hob the installers may have got dirt ect in the pipe.
the working pressure is their to make sure a hob or another gas appliance doesnt go out while a boiler is running, also most boilers wont work properly with a working pressure of say, 15mb..
if you only have a boiler and nothing else, and the burner pressure is spot on, just the working pressure is down its only ncs, it wouldnt be dangerous.
Thanks Fuzzy - that's why I asked the question as I wasn't sure if there are regulations that state it can't be more than 1mb or not. Sounds like you are saying that there are regulations that state there cannot be more than a 1mb drop, full stop. So even if they were to up the pressure at the governor (to say 25mb), to allow about 19mb at both appliances, there would still be a "breach" of the regulations as the drop is 6mb.
So it sounds like the only option I have is to fix the fact that there is a 6mb drop across the pipework (either find source of blockage or re-lay new pipe), and reduce that to no more than 1-2mb. Is that right?
I have a boiler and a 4-burner hob. What's the difference between burner pressure and working pressure? I thought they were the same thing? There is also a concept of standing pressure, right?
burner pressure = appliance
working pressure = pipework
both got with appliance running
feeling a bit uncomfortable now, a little too much info
is compressed air etc a standard piece of kit to expect RGI's to have with them?
Reply to Adding 3 metres of 28mm pipe at the end of a 15 metre 22mm run in the Plumbing Jobs | The Job-board area at PlumbersForums.net
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