Combi upgrade-new piping?

Polin_ka

Hi, 
I spoke to a bolier company about upgrading to combi boiler from the regular system. We want to move it out of the bedroom to the airing cupboard. All fine but the engineer explained about the increase in pressure and that it might cause some leaks. He said they would test it first, but obviously leaks may happen later. Is it common to update pipework when upgrading to combi. It's 70s house with really old boiler, probably installed in the 90s. Not sure how old is the pipework.

Also, while checking how fast the cold water run in taps I noticed there is a considerable difference between kitchen (downstairs) and bathroom (1st floor). The kitchen has really fast pressure, and the bathroom is just ok (slow to average maybe). Is this any indication of whether I need to upgrade the pipework? 

vw100

Usually the new combi boilers require a 22mm feed from gas meter to near the combi boiler. It might be worth changing some pipes at the same time to prevent further costs down the line. This should be a conversation with the gas safe fitter with his reasons and a visual inspection at the same time of the pipes. I assume the first 1.5m pipe to the boiler will be replaced with new.

markin

The bathroom may be on a cold water storage tank, or the may be a valve mostly turn off.

And as for going to a pressure system i would guess most the pipes could be 40 years old, unless some one ripped it all out in the 90's so leaking may be a good chance.

Ectophile

As vw100 says, you may need a fatter gas pipe.  It will need to be at least 22mm and maybe even more.

When it comes to the water pipework, traditional hot water systems with a hot tank run at low pressure.  That applies to both the heating and the hot water systems.  An obvious sign of this is the difference in pressure at the kitchen hot and cold taps.  Combi boilers run the hot water at full mains pressure (though that pressure drops if you turn a tap on full), and the central heating system is also pressurised.  This means that if your plumbing is a bit poor, then it may start leaking even if it was fine before.

So you have the choice - rip out all the existing plumbing and replace it with new - which will cost money - or connect everything up to the new boiler and hope nothing leaks.

FreeBear

markin said:And as for going to a pressure system i would guess most the pipes could be 40 years old, unless some one ripped it all out in the 90's so leaking may be a good chance.

Same for the radiators - If they are 40 y.o. single panel jobbies, it would be worth replacing them with modern convector rad complete with TRVs. The old radiators will be full of crud, so replacing them will save on a power flush.

Polin_ka

I though power flush is a requirement when installing new boiler anyway 🤔
How much can I expect to pay for new plumbing in a 2 bed house? I'm going to get more quotes soon but would like to get an idea. 

vw100

Have think if you going for plastic or copper pipes for the heating system.

Polin_ka

vw100 said:

Have think if you going for plastic or copper pipes for the heating system.

Thanks. Is any of these better? Is there difference in costs? 

vw100

Plastic is cheaper and easier to install and therefore lower installation costs. Most new builds now have plastic piping fitted for heating and plumbing.

markin

A power flush is not needed if all the pips and rads are new. 

FreeBear

vw100 said:Plastic is cheaper and easier to install and therefore lower installation costs. Most new builds now have plastic piping fitted for heating and plumbing.

Plastic turns brittle in time and can be a right pig to fix if you get a leak.

Copper can corrode, especially if the flux residue is not cleaned off after soldering. Much easier to repair and modify.