Central heating improvement of old system - simple rules (?)

[Brigadier]

Hello all,

Forgive some of the "obvious" questions, but I'm a householder who has a certain "reluctance" when it comes to plumbing - it never goes as easily as I think it ought to, yet I keep going back to it with renewed optimism, only for it to be dashed again.....

I plan to rip out all but the boiler, in the hope of making the system more efficient.

It's a three bed detached, with a potterton performa 2 combi boiler, and will have 7 or 8 radiators.

Solder / copper push-fit / compression? Which would YOU use, and what "leakage rate" would you pros expect from each?

For a house as described above, is 22mm flow and return overkill, with 15mm tees to each rad? Is 15mm flow and return too small?

Separate flow and return for upstairs and downstairs - good or bad form?

Can separate flow and return on each floor be "rescued" by rad balancing?

TRVs - yes / no / depends which rad?

How tight a bend in a pipe is too tight a bend?

Thanks for your patience and in anticipation, thanks again

 

[D_Hailsham]

7 or 8 radiators.

What is the total kW of the radiators? How have you determined the size of each rads?

22mm flow and return overkill

Your boiler has 22mm connections so you are stuck with that size until your first rad. What you need after that depends on the heat load.

15mm tees to each rad? Is 15mm flow and return too small?

You certainly won't need 22mm tees to any of your rads and, in theory, even 15mm could be too big for small rads. But you might as well stick to 15mm for all rads.

Separate flow and return for upstairs and downstairs - good or bad form?

Provided the heat load is similar for both floors, a separate branch for each floor should not cause any problems.

Can separate flow and return on each floor be "rescued" by rad balancing?

If the heat loads are similar, balancing should not be a problem.

TRVs - yes / no / depends which rad?

All rads, except the one controlled by the room thermostat.

Edit:

Read Copper Tubes in Domestic Heating Systems. There is enough info to help you design your layout.

 

[Brigadier]

Many thanks

Will post rad sizes when I get chance