15mm gas pipe to combi?

[gasbanni]

Would be, unfortunately that specific part of the floor with the elbow isn't up and has a 110mm branch pipe and kitchen ventilation fan/intake fan in front of it. I'll have to remove them before hand. Got to be done though!

Where you've got access and it looks like you've got access from the images you can always get around getting pipes in !

You know those metal puzzles when you were young ? where two pieces of bent metal are interwoven and you have to seperate them and put them back together ??
Early training devices for plumbers !!

On odd occasions I've had to make up a pipe assembly using benders and fittings, sweat it up and then wiggle and manipulate it in to position to leave two ends that you can then easily connect to ( because it would have been impossible any other way )... you just have to think outside of the box sometimes .......

 

[John D v2.0]

Where you've got access and it looks like you've got access from the images you can always get around getting pipes in !

Ah right actually that image is all 22mm and good access as we are insulating the floor, that's the bit near the meter that could do with reorganising. But the 15 is harder to get to below the boiler.
I'm sure it's doable at some cost, although now you've got me thinking maybe I can just fit the pipe in place with bare open ends ready for a fitting, then the gas guy just has two joints to attach, then I can pull out the old pipe. Soldering a pipe isn't a problem for me it's just the checking the combustion afterwards.

 

[gasbanni]

Ah right actually that image is all 22mm and good access as we are insulating the floor, that's the bit near the meter that could do with reorganising. But the 15 is harder to get to below the boiler.
I'm sure it's doable at some cost, although now you've got me thinking maybe I can just fit the pipe in place with bare open ends ready for a fitting, then the gas guy just has two joints to attach, then I can pull out the old pipe. Soldering a pipe isn't a problem for me it's just the checking the combustion afterwards.

You are gas safe registered ? You shouldn't be doing this work if not !!

I wouldn't use a pipe where some one else has put it in and I can't inspect it all !!!!!

 

[fezster]

Ah right actually that image is all 22mm and good access as we are insulating the floor, that's the bit near the meter that could do with reorganising. But the 15 is harder to get to below the boiler.
I'm sure it's doable at some cost, although now you've got me thinking maybe I can just fit the pipe in place with bare open ends ready for a fitting, then the gas guy just has two joints to attach, then I can pull out the old pipe. Soldering a pipe isn't a problem for me it's just the checking the combustion afterwards.

Remember you can have the pipe size upgraded anywhere on its route to decrease the pressure drop on the entire run. Just have the bits done which are accessible to 22mm or even 28mm.

 

[Wildcat1961]

Soldering a pipe isn't a problem for me it's just the checking the combustion afterwards.

 

[John D v2.0]

Remember you can have the pipe size upgraded anywhere on its route to decrease the pressure drop on the entire run. Just have the bits done which are accessible to 22mm or even 28mm.

Trouble is by my calculation there's nearly 1mb drop just on the hard to access 2m plus 2 elbows of 15mm, so the whole rest of the run which is not all accessible either would have to be 28mm or more.

 

[gasbanni]

I shouldn't say this because the standard is 1mb drop over the whole system. Big deal !!!!!! the amount of times the drop over the system has caused a problem in any way that I've come across can be counted on one finger on one hand !!!
I had a gas fire years ago that used to go out if a multi point was turned on !!!! But honestly in my experiance pressure drops causing problems is very rare.
I've also found jobs where theoretically it's undersized but it's all checked ok out with heat input calcs and test point readings.

This isn't to say blockages in gas pipe works don't cause problems and heat input calcs are the best way to ensure somethings working correctly.

 

[John D v2.0]

amount of times the drop over the system has caused a problem in any way that I've come across can be counted on one finger on one hand !!!

Interesting, well in our case turning the hob on full and then turning the boiler to maximum input test programme, you couldn't really tell when the boiler fires up just by looking at the hob flame. So no issue there.
My worry is having to rip the floor up unnecessarily when the boiler needs replacing to meet the regs.
Or we can get you round to do the job using the old 15mm pipe, no questions asked

 

[John D v2.0]

Well just to close this thread, thanks for the help and we decided to sort it all while we can, so the whole run is 28mm apart from 3m of inaccessible 22mm and the last few cm of 15mm at the boiler.

According to the tests the meter working pressure is 19mb, the boiler is 17.5 which is within spec and the hob is 21.5. I was surprised but apparently that's not uncommon depending on the pipe run? Everything else looks ok but I get the impression the testing isn't as strict at I thought.

Anyway it all looks good and we should be future proofed,I took a pic for posterity before we finish insulating.