Stainless flexi-pipe v. copper

[dwtowner]

Hi all,

I am planning on installing an inset wood burning stove with back boiler. This obviously needs plumbing connections for the back boiler. I had thought of using corrugated stainless steel flexi-pipe for the final connections, so that I can make the connections with the stove out of the inset, and then push it back into the inset on completion. The alternative is to cut a great big hole out of the side of the fireplace so that I could make the connections with the stove in position, and then plaster it up afterwards. A plumber I spoke to thought that using the stainless flexi-pipe was a very good solution. However, the stove manufacturer's technical people say that stainless flexi-pipe isn't tough enough to have boiling water flowing through it, and only copper pipe must be used. In the past, when I installed my solar panel I was told the reverse - the high water temperatures the panel could produce (mainly in power-cut mode when the pump isn't running, rather than on a daily basis) meant that only stainless flexi- pipe could be used because soldered copper wasn't up to the job! Who is right here? My solar panel is working fine with its stainless flexi- pipes, so I am inclined to believe that stainless can be used, but I don't really want to go against the stove manufacturers recommendations either.

thanks,

dan.

[Harry Bloomfield]

[e-mail] pretended :

Methinks there is some confusion between the stainless corrugated pipe you describe and the flexible pipe tails reinforced by woven stainless wire. I have never come across the corrugated type, but I would imagine it should be fine for the job.

[The Natural Philosopher]

well high temperatures and solar panels don't really belong in the same sentence do they?

A back boiler is perfectly capable of BOILING if not set up correctly..outflow temps are pretty high.

And I wouldn't trust anyone who had anything good to say about solar panels anyway ;-)

Let me guess.Stainless flexi pipe is much more expensive thn copper..

Cui bono?

I have to say that for other reasons..mainly solidity of connections., I'd be tempted to use solid pipe even if it meant gashing up the fireplace a bit. Steam pressure inside flexi-pipe? well if the safety valve blows..OK..but if it sticks and the pipe swells..no Id rather have the weakest link somewhere other than the living room!

As far as solder not standing the temps, well it goes at abut 150C or so depending on the type.

You will have boiled all the water away long before that.

[dennis]

You do know that some solar tubes can get to about 200C if you don't cool them. They just can't heat much water.

[dwtowner]

Why not? On a sunny day the circulating fluid temperature in the panels can be 80+ degrees. If the power fails, and the water stops circulating, then the system `stagnates', which means the fluid boils off in the panel.

Is stainless pipe less capable of handling boiling water than copper?

The boiler will be connected directly to an vented thermal store, so there shouldn't be any pressure build up.

thanks for you replies,

dan.