quick Hep20 pipe question

[dextrous]

ok so the supply from a combi is 15mm.

i would as soon as practicable after the boiler,increase the pipe to 22mm to feed all hot water outlets in property.

Not being a heating engineer, I wonder about this - the boiler can only heat a given amount of water over a given time, so why would an increase of pipe diameter improve the bath-fill time if the available flow rate is the same? Apart from that, what about 22mm requiring 4 times the amiunt of water displacement than 15mm before hot water gets to the outlet, and the amount of heat loss when that tap is closed and this heated water in the pipe isn't used

and i am not taking the p iss

My mistake- just seemed to be going in circles until you explained.

 

[fatplumber]

You only need 22mm when you have a low pressure system If you have a combi or unvented then 15mm is fine. I would even go as far as to fit 10mm to basins and sinks in this case. You want to reduce water wastage as much as possible and also reduce the amount of heat that you are wasting in displacing long runs of standing water.

 

[grrrinch]

Yeah it's a combi boiler. My flow rate was only 12.5 litres a minute from the hot tap (which I think is all the boiler is capable of outputting anyway)I'm hoping this doesn't change too much. I dont think 22mm pipes would do anything as I'd still only be able to get 12.5 litres a minute anyway.
Just out of interest why is Hep20 an "amateurish" option? Is it because it's not as traditional as copper or because it's easier to fit?
cheers

 

[HarrogateGas]

ok so the supply from a combi is 15mm.

i would as soon as practicable after the boiler,increase the pipe to 22mm to feed all hot water outlets in property.

if someone at some point has done a boiler change,removing a system or regular boiler, and a hot water cylinder, then the original hot pipework for the house would already be in 22mm(or older propertys 3/4")

i have altered "plumbers" work before where they have used 15mm plastic underneath floorboards( a lot easier than notching out for 22mm,or they just didnt bring any 22mm) to feed a bath. it took an eternity to fill using 15mm.

and i am not taking the p iss

Muppet! Learn your trade!

 

[HarrogateGas]

Yeah it's a combi boiler. My flow rate was only 12.5 litres a minute from the hot tap (which I think is all the boiler is capable of outputting anyway)I'm hoping this doesn't change too much. I dont think 22mm pipes would do anything as I'd still only be able to get 12.5 litres a minute anyway.
Just out of interest why is Hep20 an "amateurish" option? Is it because it's not as traditional as copper or because it's easier to fit?
cheers

The only thing 22mm pipework would acheive in your case is waste water by having more to run off before hot came through!

Hep20 is not amaturish. Its cheaper and easier than copper keeping cost down for you, the end user.

The only people who slate plastic pipework is the 'old school' plumbers which are still getting there head around boilers not having thermocouples!

They never use it so really can't comment on its effectiveness.

In my 14 years plumbing ive seen a lot more leaks from soldered, compressions joints and pin holed copper than i have plastic joints.

 

[fatplumber]

Just out of interest why is Hep20 an "amateurish" option? Is it because it's not as traditional as copper or because it's easier to fit?
cheers

Cos' "real" plumbers do it in lead. Or cast iron with luverly hot-run caulking. Mmmm golden days.





Ah I suppose I'll have to learn this new fangled pumped heating. Wots wrong with gravity? I worked for me great grandad. If god had meant us to use pumps then he would have fitted leckertricity to the well.

 

[kirkgas]

if the hot supply comes off a combi in 15mm is there really any advantage to upping the pipe to 22mm? most new build with a combi run all pipework in 15mm is that just to save on cost?

 

[dextrous]

Hep20 is not amaturish. Its cheaper and easier than copper keeping cost down for you, the end user.

"Easier" is the key word here. Plus it looks s**t.

The only people who slate plastic pipework is the 'old school' plumbers which are still getting there head around boilers not having thermocouples!

Don't they?

In my 14 years plumbing ive seen a lot more leaks from soldered, compressions joints and pin holed copper than i have plastic joints.

Possibly because there's not so much of it about, so quite obviously you haven't come across many leaks yet
It will be truly interesting to see if such longevity of the fittings and pipework comes anywhere near that of copper - I have my doubts[/b]

 

[glasgowgas]

Muppet! Learn your trade!

where did you crawl out from.

can only comment on OPs original post.
they are talking about a bathroom refurb.
i assume this is not a new build,and,as i have already stated,every possibility,original pipework was 22mm.
which would mean plumbers have ripped out 22mm and replaced with 15mm.

would not be the way i would do it, so balls to the lot of ye!!
i do not have a problem with plastic, use it all the time.as well as copper.malleable iron.galvanised iron.cast iron heating pipe replacement,molar piping,low carbon steel,18" ABS for new commonwealth pool.

enjoy yer night ladies

 

[swbjackson]

As long as the pipe size is capable of flowing the amount of water needed at the outlet the smaller the better to minimise heat loss and water wastage. On a combi system 15mm will normally easily carry the flow rates so it's best practice to use 15mm for as much of the run as possible.