flue gases with old CI rads on conventional gas boiler

kensheets2

Hello
I understand that with low water temp installations such as radiant floor heating, return water temps will naturally be less than ideal. My question is if I am running an application using old cast iron rads with a conventional gas boiler and running water around 170-180 will I realistically still need to be concerned with low return water temps in relation to flue gas condensation?

Thanks
Ken

Jamie Hall

Probably not. The concern arises when the return water to the boiler drops below about 140 -- and stays there -- while the boiler is running. Mostly a control issue. Make sure the boiler is set to hold a source temperature high enough, and to make sure there is enough circulation.