Pointers for planning a new radiator system

[gwernybwch]

I've bought a Victorian 2 up 2 down which I am in the process of renovating. The mains fed central heating system has been altered and added to several times resulting in a hotch potch of different size and types of pipes with many joints and blanked off ends.
The one good thing is that it had a new combi boiler installed a couple of years ago, so that doesn't need altering (not that I could do any work on it anyway).
As I want to move the positions of some radiators and install other new / additional ones, I figured that I might as well rip all the majority of hot / cold water pipes out and start again.
Trouble is I've got limited knowledge of planning such a system and are struggling to find any resources on the internet.

Would anyone care to share some pointers or links where I can start doing some research?

Thanks in advance for any replies.

 

[dcawkwell]

Run a back bone of 22mm flow and return pipes from the boiler across the house.
This will need to go upstairs and downstairs.
From this branch off in 15 mm to each radiator. If piping is easier
you can drive two radiators off one 15mm flow and return pipe.
Relatively straightforward.
I would expect the back bone of flow and return is already pretty well
thought out in the house from when it was originally installed.

An alternative system is to use the 22mm but then branch off in 10mm manifolds to the radiators this makes the piping very quick you can go back up to 15mm piping for the radiator tails as this looks better.

Use plastic piping if you haven't done any plumbing before. Speedfit
is just about idiot proof.

 

[Galoka]

To add to that.

You need to do heat loss calculation for the rooms so that you can size the radiators correctly. Looks a bit technical, but actually not that hard, basically add up losses from conduction , air changes for ventilation etc. Have a look at this page:

http://wiki.diyfaq.org.uk/index.php?title=Heat_loss

As well as working out with a spreadsheet, there are online calculators you can use. Some are a bit basic, but this one looks ok from the quick play I had

http://www.starsapp.co.uk/

Once you have your heat loss figures, you can then size the radiators for each room - look manufacturers websites, retailers etc. for the rads you like and the relevant sizes.

As DCawkswell says, don't necessarily junk all the piping, See what there is and then keep or bin it as appropriate. Though if it is old, watch out for old 1/2inch and 3/4 inch pipe instead of 15/22mm pipe

 

[gwernybwch]

Thanks for the replies.

I’ve done the calculations for the radiators and then looked at the pipes are actually in place and it is something along the lines of –

From the boiler there are two pipes (one 15mm, one 22mm / 7/8) that go into the cement floor. From there, there are four 15mm pipes that go up into the bathroom.

Of those four pipes that go into the bathroom, one changes from 15mm to 22mm and the other three remain as 15mm. Of those three pipes, two of them then branch off into the central heating ‘circuit’. These two 15mm central heating pipes then go into 28mm (from where the hot water cylinder used to be) and then back into either 15mm or plastic pipes for the rads.

As DCawkswell says, don't necessarily junk all the piping, See what there is and then keep or bin it as appropriate. Though if it is old, watch out for old 1/2inch and 3/4 inch pipe instead of 15/22mm pipe

I’ve given the pipe width in mm as the pipes measured nearer to metric than imperial. But is there any definite way of telling what pipes are there?

Run a back bone of 22mm flow and return pipes from the boiler across the house.
This will need to go upstairs and downstairs.
From this branch off in 15 mm to each radiator.

It seems that the backbone of my circuit is 15mm, would this cause much of a problem for a what is a two up / two down house running 11 radiators (although I may extend it in the future)?

What impact would there be on having a central heating system that goes from 15mm up to 28mm and then back down to 15mm? i.e. is there any benefit to leaving that 28mm pipe in the system?

Use plastic piping if you haven't done any plumbing before. Speedfit is just about idiot proof.

I was planning to have a go at soldered copper joints. I’ve done gas welding and soldering on electronics before, is it something that is particularly hard to pick up?

Thanks in advance for any replies.