3 Radiators Working, 4 Not So Good

[restoman]

About 1 year ago, had an old back boiler removed and replaced with a Ravenheat Combi boiler. With the back boiler, all radiators were lovely and hot. With the combi, only 3 out of 7 radiators are consistently hot.

The other 4 are luke warm at best, although once in a while you'll catch one of these radiators pretty hot, but not for long. I've seen the FAQ talking about the system being balanced and I'm guessing this may need doing, although would this have to be done following a change of boiler?

Any advice would be really appreciated.

 

[Forest Grump]

You might need to balance your system properly.

 

[Pete enthusiastic amateur]

You might want to look at this.
http://www.diyfaq.org.uk/plumbing/rad-balance.html
I used this system and achieved exceptional results.
But that was after I did this as well,
http://www.diynot.com/forums/viewtopic.php?t=38902
thanks very much to chrishutt, excellent topic.