Issues with new radiators heating up!

[Ben Walters]

Water takes the path of least resistance, so no I don’t think so. The fact these new rads heat up when everything else is off suggests again like I said either undersized burner output and extension rads are only receiving adequate heat when other rads are up to temp, or again the pump/pump setting. Have you personally calculated the system load demand when full and compared to burner output?

There’s also brand new pump on system

 

[SJB060685]

The burner output might be the problem, I’m not saying it is! However if you adjust nozzle and pump pressure output you will obviously need to redo FGA and adjust accordingly. With regards to calculating heat load I’m not an installer so others who do may have quicker ways to calculate but You can find either stuff online or even apps I believe to input numbers and it will do it for you, however it’s not as simple as adding rad outputs up, other factors like wall insulation, types of windows etc etc are all needed to get an accurate representation of output required. To be honest this should have been done before a new boiler is chosen and installed anyway. Sizing the pump is again quite a lengthy process and like I say although I understand that process others on here are better to ask.