Design of circuit and Boiler type query

[HugoCarter]

Hello,
I am new to the forum and certainly not a plumber so please forgive me if my questions are particularly stupid.

1) I am renovating a house and the heating system has been removed to be replaced from scratch.
To reduce costs I am attempting to do the first fix myself.
The plan is to send 22mm pipe to manifolds in convenient locations where they will then feed 10mm pipes to the radiators.
There are 14 radiators.
I've been told that the 10mm pipes really want to be less than 5 metres long.
This would mean that 2 upstairs and 2 downstairs radiators for example might be connected to the same manifold to place it in the most economical position for pipe lengths.
Would this be wrong?
Do the radiators going to the same manifold need to be on the same floor?
The way I've read it you can pretty much hook them all up wherever you like as long as they are all in the same circuit but of course I have no idea what I'm doing.

2) There will be a shower room and another bathroom with bath and shower.
I don't want to put in a system with a tank so would a Vaillant 938 combi storage boiler be ok or would I even get away without the need for the storage element?

Thanks in advance for your patience.

 

[Ben-gee]

It depends on how you intend to control the heating, if it is to be zoned then you’ll have a strange mix in each zone which is not what would be expected.
If however the system is to be run as a single zone- then as you say it doesn’t matter which manifold each radiator uses.

You need to get a plumber involved at this stage. Let him/her/them/they spec the boiler for you and design the layout. If they are willing to let you run the pipes then crack on - to their design.

Unless of course you are just flipping the house and don’t really care if/how it will work in the future…😊

 

[Ben-gee]

Two bathrooms, I wouldn’t use a combi but again be led by your plumber.

 

[ShaunCorbs]

Also due to new regs your heating system must be designed at 55dc flow this effects pipework and rad sizing so tbh might be best speaking to a heating engineer even if you pay him to design the system

Also I wouldn’t use 10mm plastic