Gas pipe question..

[Naivtal]

Hello everyone,

For a bit of context - Our 15+ yearold potterton gas boiler started playing up, fairly quick fix, however we thought it'll be better to put that money into a new one, as this one still works. So, we had a few gas boiler engineers come over to have a look at our system - it's a boiler with a cylinder for hot water storage, which is the system we want to keep.

The first engineer didn't mention anything, just said he can fit a new top of the range Ideal boiler in 1,5 days for £3,500 pounds.
The 2nd one however, who specialises in Weissmann boilers, immediately noticed that the size of the pipe coming from the meter is 22mm, but the one coming into the boiler room is 15mm. Stating that all new boilers require 22mm.

The problem is that our house is a town house and the boiler is located in the 1st floor's bathroom, so we really want to avoid ripping up all the floors and walls to find where the transition from 22mm to 15mm has been done.
The house was built back in 2008, so we're wondering how far could the 22mm pipe go?

Any ideas?

 

[terryplumb]

Combi boilers would need minimally 22mm, however a system boiler or heat only boiler may well be ok on 15mm ,particularly if less than 18kw . The length and number of bends in the pipework would also need to be taken into account in order to fully assess the required pipe size.

 

[Naivtal]

Combi boilers would need minimally 22mm, however a system boiler or heat only boiler may well be ok on 15mm ,particularly if less than 18kw . The length and number of bends in the pipework would also need to be taken into account in order to fully assess the required pipe size.

Well, the 2nd engineer did say that almost all of the new efficient boilers require 22mm even if they are not combi.
However, he did mention that fitting a bigger water tank allowing the boiler to heat up more in longer periods of downtime that would provide enough hot water for our needs.
I'm just wonderring how far does the 22mm pipe go. If it's transitioned inside or just outside of the boiler room then shouldn't be a major issue. If it's at the entry point to the house then it's different.
Trying to fish for answers from others in similar dilemmas / houses lol.

 

[Madrab]

Well, the 2nd engineer did say that almost all of the new efficient boilers require 22mm even if they are not combi

Rubbish, the chap would need to do a few calcs to qualify that statement and then confirm what pipe size is required for a specific boiler. To just state that all modern boiler need a 22mm gas pipe just isn't correct, sounds like he's hedging his bets.

How many radiators and average sizes?

You need an experienced installer in to do a survey of the system, size the boiler appropriately and do some measuring and calcs to then confirm what pipe size is required.

 

[emerylloyd]

Its possible the gas main would run 22mm up to the point at which is turns up and out of the floor. This would be fine depending on the proposed size (KW rating) of the new boiler.

Worse case is the gas main is 22mm until it splits to feed the kitchen where it runs 15mm from this point onwards. To say all modern boilers need 22mm supplies is to generic and incorrect IMO (rings true for combi boilers though).

Your engineer could put an extra over cost together just in case the gas main needs upgrading. When he commissions the boiler he will soon verify whether the boiler is running within tolerance.

 

[kidgreen61]

A quick look at the gas pressure of the existing boiler will give a good idea of whether the pipe needs upgrading or not.

It is nonsense to suggest "all boilers must have a 22mm supply", all gas appliances must have no more than a 1mb drop in pressure from the meter, regardless of pipe size.