What might cause a drop in gas pressure?

Hey, and thanks both in advance for any responses to the following, and also (while I am here) for all the information I have learned from this site in the past as a guest.

I live in privately rented accommodation. At the start of November I was having problems with a MicroGenus 23MFI combi which, subsequent to inspection by my landlord's contractor, was replaced with a new Greenstar. After completeing the work and running a check on the system, the engineer declared that there was a drop in pressure of 4 millibar between the gas meter and the boiler which "should have been sorted when the original boiler was put in," (before my time here).

I'm just curious, as I am now having to have time off while they make two more visits - one to inspect the pipe-work and one (of indeterminate length) to rectify the problem - as to what sort of thing you might speculate would be the cause of this drop in pressure. I realise you can do no more than offer some guesses, but humour me and knock yourself out, just so I can have some idea whether the guy is talking out of the right orifice when he comes round to do the inspection tomorrow.

I am rather suspicious of any engineer my landlord contracts, as the previous guy couldn't find the filling loop on the MicroGenus, and even denied that the silver thing with taps on either end directly beneath the boiler which I pointed out to him was such. And yes, he was CORGI certified as well - I checked. I wonder why he no longer works round here?

Cheers,
Mark

You are perfectly within your rights to check his Corgy card, although I doubt it necessary as he knows what he's talking about.

The gas pipe is obviously undersized and needs to be replaced with a larger size, he will work out the length and number of fittings and calculate the required size to deliver the correct amount of gas according to the output of the boiler.

If you want to post the total length and the number of bends etc we can tll you what size pipe it should be.

Thanks, I won't go into specifics just yet - I'll wait and see what he says exactly after he's been, but you have illuminated me I think.

To be fair to the new guy, I am actually a lot happier with him than with the previous contractor. Also I see now, having read your reply, what he must have intended when he described the problem as being an issue with "the pipework." I mistakenly took this to be an ambiguous/vague description of the problem, but evidently the generalisation was actually his point - that it is not a specific localised fault but rather a general flaw in the installation of the pipe in my property.

Not that surprising actually, considering that we had to have the shower and some of the bathroom plumbing replaced because the pipework had originally been embedded in concrete in the wall and when it developed a leak caused a lot of damage to our flat and the one below us. Whoever originally plumbed this flat did a seriously screwy job.[/i]

doitall said:

You are perfectly within your rights to check his Corgy card, although I doubt it necessary as he knows what he's talking about.

The gas pipe is obviously undersized and needs to be replaced with a larger size, he will work out the length and number of fittings and calculate the required size to deliver the correct amount of gas according to the output of the boiler.

If you want to post the total length and the number of bends etc we can tll you what size pipe it should be.

Click to expand...

listen yer old git i thought the 8mm would carry it

kevplumb said:

doitall said:

You are perfectly within your rights to check his Corgy card, although I doubt it necessary as he knows what he's talking about.

The gas pipe is obviously undersized and needs to be replaced with a larger size, he will work out the length and number of fittings and calculate the required size to deliver the correct amount of gas according to the output of the boiler.

If you want to post the total length and the number of bends etc we can tll you what size pipe it should be.

Click to expand...

listen yer old git i thought the 8mm would carry it

Click to expand...

Probably would marra if the total run including bends was less than 10cm

On the other hand what would you know about sizing gas pipes

Just because your the Members Secretary of The Association of Registered Gas Installers, don't mean you know anything about gas.

So behave or I shall get thescruff to sort you out.

doitall said:

kevplumb said:

doitall said:

You are perfectly within your rights to check his Corgy card, although I doubt it necessary as he knows what he's talking about.

The gas pipe is obviously undersized and needs to be replaced with a larger size, he will work out the length and number of fittings and calculate the required size to deliver the correct amount of gas according to the output of the boiler.

If you want to post the total length and the number of bends etc we can tll you what size pipe it should be.

Click to expand...

listen yer old git i thought the 8mm would carry it

Click to expand...

Probably would marra if the total run including bends was less than 10cm

On the other hand what would you know about sizing gas pipes

Click to expand...

cheeky hairy faced old git

oh BTW nowt

you have seen some of my handiwork

So behave or I shall get thescruff to sort you out.

Click to expand...

had to prise yer from the table the last time we met marra hungry nosed git

and i still have the pics £500 plain brown envelope

you know the adress it's on the ARGI website

kevplumb said:

So behave or I shall get thescruff to sort you out.

Click to expand...

had to prise yer from the table the last time we met marra hungry nosed git

and i still have the pics £500 plain brown envelope

you know the adress it's on the ARGI website

Click to expand...

That was the first time I've slept in a four poster