What size pipe from HW cyl to taps?

[Deansplit]

A number of yrs ago my HW cly was moved from 1st to 2nd floor (3 story house) The supply from the cyl comes out at 22mm so I continued to bathroom in 22 to feed bath, shower (which had 22mm valves anyway) and basin on 1st floor. Kitchen is on ground floor and this continued in the original 15mm pipe. Hot water takes some 25 secs to get to kitchen tap, very annoying!

With the house apart for restoration and a new kitchen extension in progress I have the opportunity to change anything. Do I keep the 22mm from cyl to bathroom or replace this with 15 to speed up hot water to kitchen tap (but presumably the bath will take longer to fill?)

TY

 

[newbuildinstaller]

what you want is a secondary return pipe. This requires a BRONZE pump. What you do is connect a pipe to the hot at the furthest point from the cylinder (kitchen sink?) and run this pipe back to you cylinder and into the bronze pump then into the hot cylinder near the top. You may need to cut an Essex flange into your cylinder if there isnt a tapping at the top on the side of your cylinder. This system works by pumping hot water continually around your hot pipes meaning instant hot water at your outlets.

 

[JohnD]

there are various ways of handling it

If it takes a long time for water to come through your kitchen hot tap, it will be because the rate of flow through the tap is such that a certain volume of water has to go through it. Actually, a 22mm pipe holds twice as much as a 15mm pipe, so it will be quicker if you run it in 15mm all the way to the cylinder, rather than branching off a 22mm pipe. Make the pipe run as short as possible, and insulate it with Climaflex or similar.

DON'T change your bath tap supply to 15mm, you will find the bath very slow to fill.

The other thing might be that you have a stylish modern kitchen tap, possibly Italian designed, intended for high-pressure water, which has small waterways, and maybe tap tails the size of a pencil, and does not deliver much flow from the hot. Run it into a bucket and calculate how many litres per minute you get. The flow will also be slowed by any stopcocks or service valves in the pipe, especially if you have those little ballofix valves, which are very constricting.

A bronze circulating pump is fairly expensive (ordinary pumps are iron and will go rusty inside), and will also waste some heat as the pipes will be kept hot all day. Not that I mind, as I have a spare Grundfos Bronze I am thinking of selling

 

[Deansplit]

In answer to both your help here - I installed a hot water return when I replumbed it all - I had it looping as far as to the bathroom basin and back (ie. so kitchen would only need to pull from the the bathroom area above it. I put it in with all good intentions - was actually misled - was told it'll 'convect' its way round. Then when realised it didn't, found out about the bronze pump required (and cost!), and then how much heat would be lost - outweighed the practicality. I ironically removed the 9m of return pipe last night to use elsewhere!!

If I change to 15 to feed kitchen, I'll be changing the 22 which goes via the bathroom so I'm stuck really - a separate 15mm feed would be twice the length so no gain there that what I have!

Guess I just need to lump it!?

 

[Perfectionist]

I is best to have 22mm to the bath and shower. From the cylinder draw-off port at the top, have a separate 12mm plastic pipe to the bathroom basins then tee off in 10mm to the kitchen tap. Lag all the hot pipes. If the cylinder is a low pressure cylinder have low pressure taps, if high pressure have high pressure taps. The dead-leg delay will be reduced substantially.

 

[Deansplit]

The dead-leg delay will be reduced substantially

Unfortunately I can't get access to teh bathroom basins without tearing down a stud wall - so would be it be best to do a totally separate feed to the kitchen in 10mm then? Can u get 10 in plastic?

 

[Perfectionist]

The dead-leg delay will be reduced substantially

Unfortunately I can't get access to teh bathroom basins without tearing down a stud wall - so would be it be best to do a totally separate feed to the kitchen in 10mm then? Can u get 10 in plastic?

12mm is available in Hep2O. I am not sure if Hepworth do 10mm.

 

[newbuildinstaller]

12mm hep20???? they dont make it. Only 10mm if you are using plastic or 15mm

 

[Perfectionist]

12mm hep20???? they dont make it. Only 10mm if you are using plastic or 15mm

I stand corrected. I have used it occasionally.