What is it with 22mm pipe

[PLUMBBUDDY]

Morning all,
While fitting our new bathroom i've found that the towel/rad has 22mm pipework, is the normal? Also so does the hot water feed into the room, (the cold is standard 15mm, if 15mm is standard).
My question is, can i reduce these to 15mm with out effecting anything?

Anybody got an opinion about copper push-fit? [/i]

 

[evdama]

22mm gives less flow resistance to the water so its a good thing if a little more expensive.Only reduce to 15 if you have to but it shouldnt make too much difference.
Push fit works well but is horrendously priced in comparison with end feed.You have to cut ,deburr and clean the pipe in both cases so why is a bit of flux and solder such a hardship.!

 

[Malc]

What sort of heating system do you have? If an old gravity feed system then the 22mm is so that the resistance is low enough for gravity to circulate the water. Smaller, and it might not. A short length of 15mm might be ok but best to stay with 22mm I would think. More work to replace the 15mm when it doesn't work.

Similarly the 22mm in the hot and cold lines is also for less resistance because this water is only under pressure from the head of the cold water tank in the loft. With water under mains pressure 15mm gives plenty of flow. Bath taps are 22mm too so the pipework to the bath is normally 22mm all the bath so the bath fills quickly.

 

[PLUMBBUDDY]

Yes, Yes, Yes...
I get what you mean, i suppose i need to get my blow torch out now
Still i DO think copper looks better. but i'll still go for solder ring fittings - not much more, (than end feed) but looks good.
Thanks.

 

[PLUMBBUDDY]

Sorry Malc, i missed you,
Yes i get what you mean. I have a boiler in the kitchen (for the c/h) & a hot water tank upstairs. I was only trying to be lazy n cut corners with the push-fit. Like you say i think i should stay with the same size pipes. Most of it will be hidden behind a fitted wc & sink anyway. Still if a jobs worth doing......

 

[kevplumb]

if you origanally had a solid fuel boiler the towel rail was the heat leak to stop the water boiling
gravity hence the 22 pipe

 

[PLUMBBUDDY]

Sorry Kev, you've lost me

 

[kevplumb]

in days of old bg (before gas )
you cant control a solid fuel boiler as quickly
so one rad (or towel rail ) was always on with the water
ie heat leak it lost enough heat to stop the boiler boiling
well that was the theory
does the towel rail get hot when only on hot water ?

 

[PLUMBBUDDY]

Ahh. i c. That maybe why it seems to have a mind of its own. It comes off and on when when it wants.
There don't seem to be a bleed valve either, is this normal?
Also, as its not on the c/h system, does that mean i don't need to drain the c/h at all. Will i be able to move it when i turn the hot water off?
Thank for ya help.

 

[Malc]

What sort of CH do you have?

To expand, gas/oil you can turn off completely, coal can only go down to very low. Hence for coal you need to get rid of a small amount of heat all the while. Hence coal always has a gravity circulation loop which has a small rad on it. And usually the HWC. Some old oil/gas boilers used gravity circulation for HWC too but these they are all pumped on both circuits, the HW and the CH.

Gravity circulation is at least 22mm and I thought bigger at 28mm but it could be it is 28mm and dropped down to 22mm for the last bit.

 

[PLUMBBUDDY]

Hi guys, Thanks for all your help, but i think i've got it sorted.
I have gas c/h boiler & hot water tank. The towel rail is plumbed into the c/h system on its own loop (maybe installed after), with 15mm pipe??
Why its gone onto 22mm i don't know, so ill get rid of the 22 and use 15, why not?