Pipe layout for a y plan system

I'm adding a radiator and have found that the pipework wasn't as I thought it was and I'm limited on what does I can pull up to investigate further.

I've attached a quick drawing of the upstairs. The red lines are 22m pipes that I can see, the blue lines are 15mm pipes that I can see.

I can take up the floor in bedroom one.

I can take up the floor on the landing.

Bedroom 2 and 3 would be a pain to take up. Bedroom 4 would be nearly impossible to take up! The bathroom would also be a pain to pull up.

The purple blocks are upstairs rads.
The green blocks are to show where the rads are downstairs.
The pink block shows where I need to add a rad.

Obviously I can see the flow and return at the boiler end of things and they go off into Bedroom 4.

Bedroom 1 is an extension built about 30 years ago. The 15mm to there would have been added then which I presume joins in under bedroom 4.

The rad under bedroom 1 was added about 10 years ago, and I was under the impression it joined 22mm pipe but it doesn't. It is just tee'd off the 15mm to the bedroom 1 rad. (It all works well though)


The airing cupboard contains the cylinder. The pipework drops down and heads off into the bathroom first underneath the bath.


I could do with some advice on joining the gaps and working out where it would be best to join in to add a new radiator.

I expected to see a pair of 22mm pipes for the flow and return. Could the 15mm and 22mm pipe that run together under the landing be the flow and return? Do you have a 15mm return?

Could I tee off those pipes there in the landing and run those across into bedroom 1 and then across to the new rad? If so how far would the 22mm need to go?

If I do, do this would it be worth redoing the pipework to the rad under the garage so it doesn't tee off the bedroom rad?

 

A Y plan means one side of the valve feeds the HW cylinder coil, and the other side feeds the radiator circuit, sorry your post makes absolutely no sense

 

I know what a Y plan is, just not exactly how the pipework works!

In very basic terms, I would like to know how the pipe work that comes out of the Y valve would normally be arranged. The image shows the pipes I can currently see. I expected to see a 22mm flow and return for the rads.

 

1. You need to tap into the flow after the 3 way motorised valve.
2. You can tap into the return anywhere, PROVIDED that the return from the hot water cylinder remains the last connection before the boiler.
3. If you can, run all pipework in 22 mm except where you are going off to a radiator, which can then be in 15 mm.
4. For more commentary, please add the location of the 3 port valve to your diagram.

 

The 3 port valve is in the airing cupboard directly off the cylinder.

 

There's nothing really normal as it depends on a number of factors. Some can be quite abnormal and can take a bit of working out.