Our hot water tank has a drain that needs to be permanently moved due to
work on an extension. The existing pipe is galvanised 15mm (or perhaps
1/2") that's a bit rusty where it's been exposed to the elements.

I could just cut it back a bit and extend it with copper but I'm wondering
about replacing the whole pipe. Unfortunately, the route is sufficiently
weird that doing it in copper would involve a lot of hacking and cutting of
floor boards & joists. (There's a swan neck bend in the pipe inside a
partition). I could potentially squeeze a plastic pipe (polybutylene or
similar) through though without too much trouble.

Is plastic allowed in this situation? I know CH drain pipes all seem to be
copper so I'm guessing possibly not although clearly plastic pipe can cope
with the temperatures.

Tim

"Tim Downie" wrote in message
...
Our hot water tank has a drain that needs to be permanently moved due to
work on an extension. The existing pipe is galvanised 15mm (or perhaps
1/2") that's a bit rusty where it's been exposed to the elements.

I could just cut it back a bit and extend it with copper but I'm wondering
about replacing the whole pipe. Unfortunately, the route is sufficiently
weird that doing it in copper would involve a lot of hacking and cutting
of floor boards & joists. (There's a swan neck bend in the pipe inside a
partition). I could potentially squeeze a plastic pipe (polybutylene or
similar) through though without too much trouble.

Is plastic allowed in this situation? I know CH drain pipes all seem to
be copper so I'm guessing possibly not although clearly plastic pipe can
cope with the temperatures.

Don't see why not. Polyb pipe is spec'd for central heating which is a
higher temperature spec than domestic hot water. I have a brass drain
spigot on my cylinder. In the unlikely event of having to drain the
cylinder I indend attaching a garden hose to the spigot.

Jim A

"Tim Downie" wrote in message
...
Our hot water tank has a drain that needs to be permanently moved due to
work on an extension. The existing pipe is galvanised 15mm (or perhaps
1/2") that's a bit rusty where it's been exposed to the elements.

I could just cut it back a bit and extend it with copper but I'm wondering
about replacing the whole pipe. Unfortunately, the route is sufficiently
weird that doing it in copper would involve a lot of hacking and cutting
of floor boards & joists. (There's a swan neck bend in the pipe inside a
partition). I could potentially squeeze a plastic pipe (polybutylene or
similar) through though without too much trouble.

Is plastic allowed in this situation? I know CH drain pipes all seem to
be copper so I'm guessing possibly not although clearly plastic pipe can
cope with the temperatures.

Tim
You wouldn't drain it whilst it was hot anyway, most people just push a
hose onto the drain cock

Tony

TMC wrote:

You wouldn't drain it whilst it was hot anyway, most people just
push a hose onto the drain cock

That would be simplest undoubtedly but as it has a drain plumbed to the
outside (that might be worth preserving, I was wondering if building
regulations have anything to say about it.

Tim

Tim Downie wrote:
Our hot water tank has a drain that needs to be permanently moved due
to work on an extension. The existing pipe is galvanised 15mm (or
perhaps 1/2") that's a bit rusty where it's been exposed to the
elements.
I could just cut it back a bit and extend it with copper but I'm
wondering about replacing the whole pipe. Unfortunately, the route
is sufficiently weird that doing it in copper would involve a lot of
hacking and cutting of floor boards & joists. (There's a swan neck
bend in the pipe inside a partition). I could potentially squeeze a
plastic pipe (polybutylene or similar) through though without too
much trouble.
Is plastic allowed in this situation? I know CH drain pipes all seem
to be copper so I'm guessing possibly not although clearly plastic
pipe can cope with the temperatures.

Plastic pipe is used for CH radiators so I can't see a problem.
http://www.hep2o.co.uk/



--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

On 17 Mar, 12:48, "Tim Downie"
wrote:
Our hot water tank has a drain that needs to be permanently moved due to
work on an extension. *The existing pipe is galvanised 15mm (or perhaps
1/2") that's a bit rusty where it's been exposed to the elements.

I can't imagine why a hot water storage cylinder would have a
permanently piped drain; can you post a picture somewhere? The
exception being an unvented cylinder which has a drain from the 2
PRVs; that wouldn't usually be galvanized and it can't be in plastic.
Can you clarify what you're talking about?

Onetap wrote:
On 17 Mar, 12:48, "Tim Downie"
wrote:
Our hot water tank has a drain that needs to be permanently moved
due to work on an extension. The existing pipe is galvanised 15mm
(or perhaps 1/2") that's a bit rusty where it's been exposed to the
elements.

I can't imagine why a hot water storage cylinder would have a
permanently piped drain; can you post a picture somewhere? The
exception being an unvented cylinder which has a drain from the 2
PRVs; that wouldn't usually be galvanized and it can't be in plastic.
Can you clarify what you're talking about?

Rest assured it is a drain (with a draincock) but I've decided to stop
fretting about it and just chop the d*mn thing off. Considering how often I
plan on draining my tank, a hosepipe down the stairs will work just fine.

Tim

On 18 Mar, 11:46, "Tim Downie"
wrote:

Rest assured it is a drain (with a draincock) but I've decided to stop
fretting about it and just chop the d*mn thing off. *Considering how often I
plan on draining my tank, a hosepipe down the stairs will work just fine.

Good plan.

It is not good practice to mix metals, so you wouldn't normally have
a galvanized pipe connected to a copper cylinder. I'd suggest you also
check the threaded fittings in the cylinder bushings. They should be
bronze; iron fittings are sometimes used and they corrode and
eventually fail, usually causing much damage.