Plumbers - bending 15mm copper - how tight can it be done?

I need to install some pipe under my boat floor where I'd never know if there was a leak + a leak there would be impossible to get at when I've finished.
So... I'm thinking a run with the ends bent up through the floor - no joins under the floor this way. I looked a flexible copper or stainless pipe but can't find a long enough one.
I won't be bending it myself, I'll find a plumber with a proper bending tool. There isn't much of a cavity under the floor, maybe only 30mm, but the bend could be part under, part above I think.

Ta.

 

Probably 2 bends each end, one sideways/horizontal, then one to bring it up through the floor. Doable? I'll be able to lay the pipe down then fit the floor ply, but eventually there will be a wall on top of it so once it's in, it's there to stay.

 

What about running a small drainage pipe under the floor level, say 32mm plastic pipe. You could then run plastic pipe (alkathene?) inside it. Only large swept bends (100mm?) and it would be replaceable.

 

It's for a radiator and I've only got 30mm gap under the floor. However much of the bend ends up above floor needs to be inside a quite narrow box/skirting hence the two bends at that end and at the other it will pass under the wall the rad will be on hence two bends that end too, to keep it close to the wall. Hope that makes sense!

 

I'm no plumber I'm afraid. Was trying to think out of the box. I'll climb back in

 

I'm sure that a proper plumberista will be along shortly. In their absence, the radius of the 15mm pipe bender die is 60mm to the centreline. Would that work for you?

 

Me neither. I can picture what I'd like to do but read variously that the minimum bend radius for 15mm is 100mm or 4x dia which would be 60mm.

Ah-ha! that would be doable more so than 100mm which would be a pain.

 

Brazed copper elbow joints ? Will dissolve a lot slower than soldered joints.
Or get somebody to TIG weld the joints - or TIG weld a stainless pipe..

 

I don't want any kind of joints under the floor, I explained that several times so why suggest it?

 

Have you thought about putting a join under the floor?

 

What is the radius of a 15mm pipe bender?


When bending pipe, it's important that you know the parts of the bender and the radius of the bend that it will produce. For 15mm pipe it will be 15mm x 4 = 60mm radius to centre line. 67.5mm.

Any good ? According to Google !

 

That'll work for me, I'll have to get my lengths worked out and find a plumber to make them up.
Once I get above floor I'll just speedfit plastic pipe it like the rest of the system was. It's only to take the chill off the bathroom, keep it from getting cold a damp/mouldy over the winters fed from the stove back boiler which has extra heat I need to get rid of once it's been on for a few hours. That'll be the last unheated part of the boat sorted.

 

I'll push fit onto the ends, they come off clean IME, but yes, I'll get plenty above floor to get the fittings onto and I think the rad valves will need copper tails, it'll be a bit bodgy but nobody will see it but me.

 

Because there are joints that will last as long as the pipe. Just not soldered joints.

 

If it's for a boat, would microbore pipe be any good?

 

I believe that's for pressurised systems? This is old school solid fuel stove, back boiler with a header tank and a 12v car coolant pump switched with a pipe thermostat.

 

I think we've all seen good looking joints that leak, brazed or soldered. I can't test until way past the point I could inspect. No joints is the only way and TBH why the heck would I get someone to tig weld pipes together when I could get a continuous piece bent and rule out any possibility of leaking joints I can't see or check? I know you like to find the most complicated way to achieve your goals Mike, but I prefer simple and doubt free.

I could be extremely unlucky and get a freak piece of porous pipe but otherwise I'll be able to rest easy and move on, it's just a tiny part of the entire project.

 

This /\/\/\ and specifically a decent (50mm?) straight bit after the bend because even the best pipe bender will turn the pipe a bit oval on the curve and make those end joints iffy without the straight section to work off

 

I had a couple of rented properties , In about 2005 to 2010 problems arose with leaks, not joint leaks but pinhole leaks in the main ( copper ) pipe run. A nightmare couldn’t understand it. Plumber ( now heating engineer ) said it all had to come out…he was right. Lengths of copper basically had pitting causing pinhole leaks.
So whilst I accept @Zed viewpoint what @mikedjames is also correct. Just coz there is no joint don’t mean it ain’t goin to leak .