Central heating through joists, Plastic or 30 soldered copper joints?

[ATTQ]

Short version is it mad to cut 22mm copper into small sections to run through joists and solder back together?

Need to get heating 22mm F&R and 15mm hot/cold to a bathroom. really dont want them visible, Victorian solid brick walls and not very thick plaster on inside, so thinking pass through joists. the 140 year old timbers already have 2 badly placed (and occupied) notches in the top so i don't want to add more. 14 joists.

I want to run 22mm copper under this mezzanine floor before splitting to 15mm branches for each floor up and down, but properly drilling through the center of joists i'll not be able to get it in unless i cut the copper pipe into 15 sections and solder it back together, an option i've gone around in a circle and am back to thinking I'll do. (I'd have done it already in the time i'm wasting trying to think of a better way.) Some of the joins will be where i'd have taken tails for 2 rads but its still 26 extra solder joints for the 2x CH pipes.

Plastic option - I'm not going to use push fit. I can live with reduced flow in the hot/cold pipes to bathroom from having inserts in 15mm plastic pipe to use compression fittings so i'll use plastic for that.

But the 22mm plastic by the time i add inserts the ID is same as 15mm copper. I could upsize to 28mm but the holes start to get bigger, the pipe less flexible, the fittings expensive, but its an option. But in the end is a few compression fittings better than lots of soldered copper joins. Hidden and inaccessible under the floor

What would you do?

 

[CountryFan]

Probably best using plastic if it’s concealed and notching not an option.

 

[ATTQ]

Probably best using plastic if it’s concealed and notching not an option.

28mm plastic to get the ID? Is it flexible enough to feed into the holes in joists? compression not a worry under a floor?

I was looking online and seeing the americans have more options for crimping and compression joints, seems I could get those clips and tools from amazon but when i look for the pipe it got very confusing. What is this https://www.amazon.co.uk/Hydraulic-Crimping-Ø12-28mm-Plumbing-PEX-AL-PEX/dp/B098KW4BV7 for instance. Anyone using these newer things?

 

[CountryFan]

I wouldn’t use compression in the same scenario because you’ll be cheaper soldering. You can use press fit as we’ve started using them, but joints I believe can be pricey. 22mm plastic I don’t think will cause you too many issues ID wise.

 

[ATTQ]

I wouldn’t use compression in the same scenario because you’ll be cheaper soldering. You can use press fit as we’ve started using them, but joints I believe can be pricey. 22mm plastic I don’t think will cause you too many issues ID wise.

its the wall thickness and bore after adding compression fitting stiffening inserts thats the problem. Ends up 50% reduction in bore area compared to 22mm copper pipe. I'm right back to having 15mm copper for the whole system (works but not ideal)

Before plastic what did people do? must have just cut them up and soldered

 

[Harry Bloomfield]

Before plastic what did people do? must have just cut them up and soldered

Notched the joists, where it was allowed, ran on the surface, where not.

 

[ATTQ]

Notched the joists, where it was allowed, ran on the surface, where not.

No one cut them up? I really can't notch more or run on the surface. Live update though, I've just realized what I'm looking at in one of the notches I've just found is a 22mm section of lead gas pipe. I'll have to have that replaced with tracpipe which is too big for a notch, so i can use one existing notch for a 22mm CH pipe. Leaving just one to take through the joists. I'm going to cut it up and solder it. Might raise an eyebrow if someone finds it one day but it wont be as bad as the things I've found in this house

 

[endecotp]

Short version is it mad to cut 22mm copper into small sections to run through joists and solder back together?

Short answer, yes it is.

But the 22mm plastic by the time i add inserts the ID is same as 15mm copper.

Is it really? in any case, that’s only at a couple of fittings, not along the whole length of the pipe. It would be fine.

 

[Madrab]

But the 22mm plastic by the time i add inserts the ID is same as 15mm copper

Seen this a few time now but it really is a bit of a red herring. Yes the inserts drop the ID to 15mm but that is only for those small sections, It doesn't really impact greatly on the energy carrying capacity of the pipe as a whole. All that will really happen is increase the water velocity at those points.

Notching 14 140yr old joists for 22mm pipe wouldn't be an issue, as long as the standards are followed and the joists are deep enough.

Compression fittings are normally not advised where they can't be accessed later.

 

[Deluks]

You could use a steel insert which would give you a slightly larger ID, just make sure it's the same make as the pipe.

 

[ATTQ]

now i've got more floorboards up i find most of the existing notches are wider and deeper than needed for the 15mm pipes that are there so i only need to widen them slightly to put two 22mm copper pipes in their place. Its been alright for a long time so it doesn't feel risky to widen slightly keeping the same depth. Sorry I should have got more boards up before posting!

I can go plastic to replace the 15mm hot/cold through new holes. But they would have compression fittings as it seems to be either that or push fit in the uk. Its a puzzle why the yanks have so many more options for pipe fittings than Brits.

 

[Madrab]

Its a puzzle why the yanks have so many more options for pipe fittings than Brits.

No it's not - The US standards are a bit of a joke, basically you can get away with just about anything and using any materials you want as long as it doesn't affect anyone else. That and they are state enforced so there are no real common standards.

In the UK the regs are much tighter and we have better/higher standards and we are mostly better off for them, though of course that's only a real benefit when they are actually adhered to. Governance/Enforcement is our real issue.

BTW there is absolutely nothing wrong with push fit fittings - they are now a tried and tested system as long as they are used properly.