Sizing of speedfit piupes for GCH and water

[diyreg]

I've replumbed my flat previously in copper qwith 15mm everywhere except the last stretch to the boiler.

I'm now installing GCH and a new bathroom into a three bed house and will be using Speedfit. A couple fo questions about pipe sizing (I've got a combi boiler):

I'm creating a new ensuite next to the existing bathroom. SHould I run 22mm pipe then split and have a seperate 15mm supply to each room?

Also, for the GCH, there are 11 radiators in two main circuits (upstairs and downstairs). I'm thinking of running in 22mm to each floor and then fully in 15mm from there. Does this sound sensible and do I need to run each radiator on it's own supply from there or can I say run two in series from the same supply pipe?

 

[slapper]

do you think some of us spend years doing an apprenticeship that includes calculations on flow rates,pressures,volume,heat loss and other calcs so you can do a DIY job at home.NO

 

[bengasman]

If you don't have the knowledge to work sizes etc out by yourself, it is unlikely that you have the required skills to do the job yourself. As a result, you will have years of problems and more cost to get it all sorted than it would cost to do it right in the first place.
There are far too many variables to be feasible to be instructed how to do this by email.

 

[diyreg]

It was actually teh plumber on my last flat who suggested I could have run the GCH in future. I thought the same as you guys are saying - that you need training, but having seen that I'd replumbed the entire hot and cold water in teh flat and built a kitchen he said that in comparison running the GCH would be pretty straight forward.

I've now found details of most of it, just need to know if I can run it all in 15mm or whether I shoud supply in 22mm up until teh point where I fork for each floor?

 

[spada01]

I've installed my own central heating system. Pretty straight forward if you've a good level of DIY skill and I know a few people who've done it DIY. I did it all in 15mm plastic once I got away from the boiler and it works brilliantly. I've even heard of some people doing it in 8mm pipe so think you'd be okay with 15mm all round.

You need to consider if you want to zone areas or do anything fancy such as underfloor heating as it get's trickier and a vented system I believe requires BC approval. If you're just after a basic combi setup though - it's pretty easy!

There are some real cowboy plumbers out there and I didn't fancy having another system where the pipes to the rads weren't vertical. I did use copper for the on sight piping to the rads though. Looks tidier.

Good luck!

 

[gasbanni]

The problem with 15mm plastic is that mice chew it, bear that in mind not that they might chew it never heard of them chewing copper pipes.

 

[Biggles..]

badly installed copper pipes run the risk off pin holeing.

what you find is that mice dont chew the pipe(its too smooth) they chew the fiitings and im still yet to see it in a standard house set up.

 

[Kev F]

you cant just run 15mm everywhere cos someone else does it in 8mm, it depends on rad sizes and flow rates which can only be determined after a heat loss calculation, rule of thumb is 3 rads on 15mm max and 22mm to that split minimum but if 3 rads are huge it may have to be 22mm to more.

 

[numpty1]

badly installed copper pipes run the risk off pin holeing.

what you find is that mice dont chew the pipe(its too smooth) they chew the fiitings and im still yet to see it in a standard house set up.

lcgs,living in a rural location i have seen the damage mickey and roland do to plastic pipe,only seen it twice in the big bad city and they were sh1teholes.

 

[gasbanni]

badly installed copper pipes run the risk off pin holeing.

what you find is that mice dont chew the pipe(its too smooth) they chew the fiitings and im still yet to see it in a standard house set up.

They chew the pipe I've seen it they cant manage 22mm but 15 yes
just because you havent seen it doesnt mean it doesnt happen

 

[gasbanni]

badly installed copper pipes run the risk off pin holeing.

what you find is that mice dont chew the pipe(its too smooth) they chew the fiitings and im still yet to see it in a standard house set up.

Advanced search on this forum brings up examples of mice chewing pipe some in cc .

 

[Biggles..]

Didn't say I hadn't seen it,just not in your average home.

At the end of the day there's no point getting your knickers in a twist over plastic versus copper.both have pro's and cons,just that some people have a preference.

Do we stop running water services in mdpe because they also have a good go at chewing that.

 

[gasbanni]

Didn't say I hadn't seen it,just not in your average home.

At the end of the day there's no point getting your knickers in a twist over plastic versus copper.both have pro's and cons,just that some people have a preference.

Do we stop running water services in mdpe because they also have a good go at chewing that.

No cos its over 15mm and too big for em to chew

 

[gasbanni]

what you find is that mice dont chew the pipe(its too smooth) .

Thats what I took exception to because it just aint true, wasn't getting in to copper verses plastic or plastic verses copper

Just a little advice to the original poster cos he may not have known ....thats all.

 

[ajrobb]

The problem with 15mm plastic is that mice chew it, bear that in mind not that they might chew it never heard of them chewing copper pipes.

Run them next to the plastic wiring and hope they chew that first.

Heating engineer friends said I was OK to supply up to 3 rads off a single 15mm supply. That seemed OK for smaller rads but larger rads need more flow.