New boiler - new heating system too?

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We're just starting to call in quotes for a new boiler - the old one's still chugging along but over 20 yrs old. A salesman yesterday noted what my usual plumber has often pointed out - the the early-1980s system has very thin pipes to the radiators (8 - 10mm?) and that this would mean problems in flushing the system, as well as other issues. The rads are those big old metal-and-ten-layers-of-paint kind too.

I feel like I've opened an expensive can of worms... But would it be sensible to get this all done now? It's a lot of upheaval as well as expense, but given the age of the system - and of me (nearly 60) - I'd hate to be dealing with this when I'm older...

I guess I'm answering my own question here... but, despite my age, I'm a house reno rookie and have to question everything... 😁

Getting an entire new heating system would be fearsomely expensive and disruptive and I would not do it unless absolutely necessary. Do you have any problems such as blockages, leaks, radiators not heating up at the moment, or is it all working just fine?

Yes, there can be challenges in draining and flushing narrower systems but it is just more difficult, not impossible.

It's worth noting that most new builds/installs have 10mm pipes to the radiators, albeit in plastic rather than copper. It seems standard to fit 10mm unless you specifically ask for the more expensive 15mm. I don't think they would do it if it was not fit for purpose.

Microbore pipes are fairly normal in installs these days. They are probably not great for heat pumps as the flow rate is less.

Swapping out the radiators is generally quite easy with plastic microbore though as you can extend the pipes easily with push on fittings.

Replacing radiators is relatively simple. But replacing pipework is quite hard and may involve ripping out the pipes from floorboards and walls depending on how your house is wired up, so replacing them is expensive.

I would probably get a power flush. I have never had one. But my guess is that when they do the flush they can get an idea of the flow rate though the pipes and make a decision based on that. It might be an idea to get the powerflush from a different company that wants to fit your boiler (and potentially radiators) :)

You could then make sure you get a magnetic trap fitted with the boiler to pull as much sludge out as possible.

I think as well it depends on how your system was maintained. If it has been well maintained using inhibitor and there is a magnetic trap on the boiler, there probably will not be too much sludge in it. if It has been left for years without inhibitor replacement and no traps then maybe it is worth looking at.

Just done exactly this. All new boiler, cylinder, rads and pipe work. Ours was a 1960s house with v compromised original rads, and thin pipes where not all of the rads would get warm. Cost just shy of £7k. We've added nicer rads in some places so that's a bit more on top.

We had a new system put in our new house and had much wider pipes, that was 1999. We've moved since and have the microbore pipes, this system was installed 2010, so has been used in recent years.

It's worth getting a few quotes and opinions, and depending on your area it could be more than the £7,000 quoted above. Our Ideal boiler we had installed in 1999 wasn't so ideal and we had to replace 2009 - it cost us £5,000 then - had three quotes £4,000-£5,000 for literally replacing boiler, no powerflush - we went with the highest because he shone out as literally been the best. Just remembered, my DM has the narrow pipes, hers were installed around 1984, she's had one power flush around 2010 and all radiators work (in a hard water area as well).

I had to replace a 20 year old boiler last September when I bought my 1930 house and it is working fine with the existing pipes and radiators.

The plumbers did a full flushing of the system and repaired a small leak in one of the radiator valves. Cost about 3K.

I would not replace the whole system if you don't have any issues with leaks and things work as they are...

Thank you, you are all so knowledgeable! I truly appreciate your input... That's interesting about new builds and 30s houses having the smaller/original pipes, we're not some woeful anomaly... 🤔 My plumber was all 'oh, you can't power flush, it'll cause leaks' and the salesman said the upstairs rads couldn't be flushed because of it - something about an inner filament?

I know the rads are black-sludged (decorator took one off and spilled it, grr), but we have soft Welsh water. And a part of me thinks 'May as well do it all proper in a oner', especially as we'll next do the 80s artex ceilings and decorate throughout (ourselves, slowly, a room at a time)... the last occupant favoured a flesh-coloured mottled wallpaper that looks like human skin... 😱 We also need the attic tanks cleaned/replaced and covered because they're currently not, and may be a squirrel swimming pool for all we know...

But oh my dears, the upheaval... really daunted by that. And our first quote for the whole lot was £10,500 from British Gas (we went for the most expensive first, just to give us impetus to find other quotes). The lad was really comprehensive, love him, but keen to push a combi boiler, and we've been happy with a conventional and wonder if a four-bed, one bathroom, two-person house would be okay with that, especially if we needed a second shower in future. We like a strong shower, and he assured us we could have that with a combi, but he would, wouldn't he...

Decisions decisions! But thank you, you give me the ammo of information to bring to future quotes. 😄

Can I reassure you about running showers off a combi-ours are almost too strong-and I like a strong shower!

@Jeezitneverends it's got to borderline-hurt, hasn't it?! 😄 He reckoned our current cold water pressure was 13 litres per minute, our hot was 7 litres p m.