On Thu, 15 Mar 2012 04:18:20 -0000, John Rumm wrote:

On 15/03/2012 01:34, Lieutenant Scott wrote:
Someone was telling me that it's important to connect the flow and
return to the right ends of a radiator. But I cannot see a problem in
water running the wrong way.

"The wrong way" would mean water flowing into the radiator through the
balance valve and out through the thermostatic valve, but the radiator
is symmetrical, and the valves are not one way (are they?), so what
would be the problem?

Some TRVs are one way. Some are described as two but work better on the
flow side, and some are fine either way.

I've seen some which can be positioned with the knob vertically or horizontally, I assume these take it either way.

(There's going to be a few naughty replies to the above line.....)

The reason this came up is I'm plumbing in a new radiator and I've not
marked which pipe is which that I've threaded out of sight under the
floor. Although I can actually tell which is which as it's HEP pipe with
metre markings on it, I wondered if I really have to know?

Make sure the TRV is a two way one, and it should be ok.

(Some of them begin to whistle a bit as they throttle the flow when on
the return side).

I think I'll just connect the pipes correctly, in case of whistling (which would annoy the occupants (African Greys)) or future replacement of the valve by someone (or me being forgetful) who doesn't know the pipes are backwards. I've been told by a plumber he's had to correct a flow/return mix-up which caused a radiator to only get luke warm.

The HEP pipe metre markings will tell me which is which, as I bought a 50 metre length of pipe and used the two ends of the length to enter the house, with the middle being in the garage. Therefore the metre markings increase in one direction on one pipe and decrease on the other.

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