Extending pipework - Central Heating System

[desktop987456]

Again without a lot more detail it's hard to assess your scheme. It sounds like rather a large house, just adding a pump may not solve anything. This 'plumber', is he the only one quoting? Is he planning on insulating the link 22mm tubes?
Is there any zoning or other control gear on the system? (At the moment, you can heat the extension completely independently of the rest of the house- different times, different temperatures. Without some zone valves or smart radiator valves you will lose that control, heating the whole house will always cost more than heating part of the house).

I may not be heating the whole house or all 6 bedrooms but the idea is to maximize the use of already 'on' boiler which is oversized under current load. We use 3 bedrooms out of 6. I get guests and extended family in winters so utilizing the spare capacity in my boiler makes sense.

 

[Londoner2]

5-6c in winter sounds freezing there, Northern parts of that continent is cold, however a bbc wheather check reveals daytime temps of 15c to 20c and night time of 2c to 7c.

 

[desktop987456]

5-6c in winter sounds freezing there, Northern parts of that continent is cold, however a bbc wheather check reveals daytime temps of 15c to 20c and night time of 2c to 7c.

Correct.

 

[desktop987456]

I may not be heating the whole house or all 6 bedrooms but the idea is to maximize the use of already 'on' boiler which is oversized under current load. We use 3 bedrooms out of 6. I get guests and extended family in winters so utilizing the spare capacity in my boiler makes sense.

I thought I'll close out the post with some comments and hope it may help someone trying to do something similar.
- I was advised not to use Plastic pipe and put copper pipe, I took the advice and went with copper and the cost paid off.
- I upgraded couple of radiators (with K22) which were not putting up with the room requirements for heating.
- In the extended pipework; we added a shutoff valve and made a separate zone of 2 guest bedrooms at the back which can be turned on when needed; at the moment it has been turned off.
- My main concern was the gas usage; with 9 radiators the boiler now consuming 1.1 units/hr (prior to this work with 6 rads it was consuming 0.85 units/hr). Will check the gas usage with guest bedrooms and how much does it consume with all 12 radiators.
Thanks again.