Oil Condensing Boiler on 1980 Gun Barrell

gidxl03

My parents would like to install solar panels but in order to be eligible for the grant, they need to install an oil condensing boiler to get to a C3 BER after the panels are installed. They had a plumber out but he didn't want to do the job when he saw that the pipes were made of GB (https://en.wikipedia.org/wiki/Gun_barrel). I'm now aware that GB normally has a lifespan of 35 years and that anything that adds stress is risky. I've since heard that

1) condensing boilers run at higher pressure than the older type (curious to know why and could we tune it to run at a lower pressure even is less efficient)

2) pressure when the pump turns on is briefly higher that normal and this may stress the GB piping.

3) there is some sort of valve that would reduce this pressure.  I can't imagine what kind of valve this would be, I can imagine that an expansion-vessel with internal diaphragm located beside the boiler might reduce the fluctation of pressume. The system is open so does not currently have an expansion-vessel.

Can anyone comment on the above points? And can anyone estimate the likelyhood of changing to a condensing boiler trigger a failure in the GB piping over the next 5 years?

Many thanks!

Wearb

I would leave well enough alone and do without the panels. The payback time is too long anyway. Add to that, the request that you change your boiler, to get about 8% more efficiency.

A c3 is next to a D1, so I am sceptical if that ber couldn't be reached with insulation etc.

#1 is nonsence, unless you misunderstood, in that he want to change to a pressurised system (if not already like that)

#2 Same no matter what type of boiler.

#3 Yes, but wont reduce the pressure on the system.

My guess is that these obstacles are being presented because he will have to flush the system and that could show up problems that are masked by rust at the moment.

My first line stands as best option imho.

gidxl03

Thanks Wearb - we took your advice and gave up on the solar installation. Its a pity because they would like to do their bit for climate change but having to dig up every room in the house to replace the GB piping is a step too far. The walls and attic were insulated recently and a porch installed to reduce draft. The house has a lot of windows with old double glazing and so to make the C3 they were told that they would need to replace the boiler (supposed to be 25% more efficient that the old one so has a big effect on the BER). Pity that the gov doesn't allow say 80% of the solar grant for a house with less than a C3 BER - perhaps that will change in future as Ireland still needs to catch up on renewables.