I need the mains to fit a garden tap in the terrace on the first floor of my house.

I have lifted the floorboards near where I think a mains pipe could be. I see many pipes, most of them 22mm and 28mm, all of them become hot, plus the mains in my house is 15mm.

There are two 15mm pipes running parallel, one becomes hot, the other does not become very hot but somewhat hot, although I do not know for sure if this is due to the heat of the other pipes nearby.

I have opened and closed the valve to the tank in the loft, that is fed by the mains, I cannot tell for sure if there is flow of water when the valve is opened or closed.

Other than cutting the pipe, which I want to avoid, is there a good way to tell if that second 15mm pipe is the mains?

Wouldn't be more likely that the mains is there if there were three or any odd (not even) number of 15mm pipes?

Thanks,

Antonio

In message , asalcedo
writes

I need the mains to fit a garden tap in the terrace on the first floor
of my house.

I have lifted the floorboards near where I think a mains pipe could be.
I see many pipes, most of them 22mm and 28mm, all of them become hot,
plus the mains in my house is 15mm.

Heating circuit and/or HW cylinder heating pipes most likely

There are two 15mm pipes running parallel, one becomes hot, the other
does not become very hot but somewhat hot, although I do not know for
sure if this is due to the heat of the other pipes nearby.

I wouldn't expect the cooler 15mm pipe to get 'somewhat hot' really,
from other nearby pipes, warm maybe. I suspect a radiator feed/supply
from your description., but then it hard to tell from words.

I have opened and closed the valve to the tank in the loft, that is fed
by the mains, I cannot tell for sure if there is flow of water when the
valve is opened or closed.

Other than cutting the pipe, which I want to avoid, is there a good way
to tell if that second 15mm pipe is the mains?


you need to work out were the pipes are going and what they are feeding.
Is there a likely radiator or sink etc.

OK to check if they are heating pipes. Find a time when the heating has
been off for while. Or turn it off and wait sometime for the pipes to
cool a bit. Turn the heating on, feel the two 15mm pipes, wait for the
hot one to get hot first, if the 'cooler' one warms up a little while
later then it's the heating return.

Wouldn't be more likely that the mains is there if there were three or
any odd (not even) number of 15mm pipes?

Well it depends on what the pipes there we doing. the feed to kitchen
sink for example is normally two 15mm pipes - one cold mains and one hot

I suggest checking if you don't already what is fed by the mains supply
directly - obviously the tank, normally the kitchen sink, sometimes
toilets, sometimes other bathroom fittings, some sorts of showers.

Then work out where the pipes are likely to be run to these things.
--
Chris French

In article , asalcedo.1wk560
@news.diybanter.com says...
snip
Other than cutting the pipe, which I want to avoid, is there a good way
to tell if that second 15mm pipe is the mains?

Close the isolation valve on the main cold water tank in the loft (or
tie up the ballcock if there isn't a valve) and drain the tank by
opening your cold taps, then close the taps again. Now open the
valve/untie the ballcock and listen while the tank is refilling.
Holding a large screwdriver against the pipe, and pressing your ear
against the handle, can help to tell exactly where the sound is coming
from.

In article ,
asalcedo wrote:
There are two 15mm pipes running parallel, one becomes hot, the other
does not become very hot but somewhat hot, although I do not know for
sure if this is due to the heat of the other pipes nearby.

If you leave the kitchen cold tap running, if one of those is the mains
and has simply got warm by the proximity of the heating pipes, it will
become cold.

--
*Cover me. I'm changing lanes.

Dave Plowman London SW
To e-mail, change noise into sound.

Hi Rob,

Thank you for your reply and thank you for all the other replies.

In the end, it was the mains and the tap is already in place (plants are happy).

Your tip is a great one and it is more or less what I did.

By keeping very quiet and holding my arm around a 90º bend I was able to feel the small turbulence of the water flowing through a 90º bend. Additionally there were some tiny vibrations the timing of which coincided with the noise coming from the ballcock in the water tank in the loft.

That gave me enough confidence to cut. It was a great feeling when only air came out!

I thought of an fonendoscope, that doctors use, but your tip is much more practical.

Thanks,

Antonio