Towel radiator on secondary system

[Onetap]

No reason legionella should be a problem, as that is bred in the storage tank and stagnant water.

No; it multiplies in any water that provides a suitable environment, mainly between 20 and 50 degC, not just storage cylinders and not just stagnant. It inhabits the biofilm and the limescale deposits on the inside surface of pipes.

As an example, a DHW system was modified and a branch cut off and capped. The engineer had the capped tee cut out and straight pipe inserted. I thought that was OTT; he produced documents relating to an installation that had persistent reinfection by legionella until a few such capped tees were removed. The 50mm or so of dead-leg provided a safe environment for legionella where it survived numerous attempts to pasteurize the system.

Installing a towel rail, a heat emitter, on a DHW system is just daft. It was done in the old days, but they didn't know about legionella; they thought asbestos was great stuff too.

 

[Onetap]

Does this help with why the rads are developing holes after a short period of time?

No; I don't know why that would happen. I think I'd have a look to see if they have any chemical treatment plant that might account for it (softener, disinfection) . Mention the legionella hazard and suggest they connect the towel rails to the primary system. Test the water with litmus paper and see if it's acidic and/or get it tested. Test any immersion heaters for a short to earth (RCD fitted?).

 

[doitall]

Yes it does multiply in any water that provides a suitable environment.

Circulating water isn't one of them.

Dead legs should always be removed, not just capped. As per the regs.

As I said the OP needs to get the water tested as a priority.

 

[Onetap]

Yes it does multiply in any water that provides a suitable environment.

Circulating water isn't one of them.

Look up 'boundary layer'. The water velocity at the pipe wall is zero.

The bacteria will colonize the bio-film and cack adhering to the inside of the pipe.

Dead legs should always be removed, not just capped. As per the regs.

Indeed; why would the regulations require that? I didn't know that was in the rags, I'll have to have a look.

If a capped tee with 25 or 50mm of pipe is not acceptable, how can a towel rail be OK?

 

[doitall]

But that theory would be the same as a length of pipe with a load of bends.

been a water reg for a long time, that you should remove the tee and not just cap the branch.

Don't know about modern stuff, I have no need to read them now. I been retired nearly 7 years

 

[Onetap]

But that theory would be the same as a length of pipe with a load of bends.

The pipe has to be insulated.

And the towel rail is usually several parallel large pipes, so the flow rate through any pipe will be very small.

 

[doitall]

You can buy rails fit for purpose usually Brass.

I bet you made a few rails out of copper for airing cupboards as well.

 

[Onetap]

I'm fairly certain that any fitting connected to a potable water system, which includes DHW, should be WRAS approved. I doubt that a towel rail would be approved, for the reasons given above.

And no I didn't, but I'm sure I'd have been asked for them if I'd done more domestic plumbing. The only heat emitters on DHW secondary circuits I ever saw in commercial premises were those being ripped out by the NHS 30 years ago.

 

[doitall]

Mostly find them in larger houses, and yes you can still buy them for connection too secondary circuits.

Any insulation would be on the pipe runs the same as heating pipes. heat emitters are no different to a normally rad in that they are designed/installed to do a job.

What the OP could do, is see whether a magnet sticks to the SS rail, indicating cheap , poor quality stainless steel.

Reading the thread again, Is there a rad in the towel rail.

 

[Norcon]

Some signs of white deposits on circulating pump.

You do have a bronze pump fitted?