Condensing Boiler secondary pump

[Robert22]

Help! My 7 year old Viesman Vitodens 100 boiler is struggling to keep up with the 15 rads running off it and is missing out some rads no matter how well balanced.
One solution put forward is to have a secondary pump installed to give the boiler a hand in getting to the far reaches of the system.
Would this present any danger to the existing pump and are there any other possible hidden nightmares from such a solution?

 

[1983]

You can turn the pump 'up' on this boiler from speed one to two, try that first, could there be any issue with sludge in system?

 

[Robert22]

Thanks for the info 1983,, I will check the setting on the pump. I tried isolating the radiators that currently work ok -about half those downstairs- and the remainder then came on. It may be a balancing issue but I just sense that the water is not flowing around the system as quicly as it should. Power flush carried out last summer.

 

[1983]

Circulation restricted somewhere, can you tell us the boiler model should start with W.

 

[Robert22]

Hello,

The model is WBIA

 

[ALEC1]

what size pipe is it...all in 15mm?