Condensing . . .

28W

Am I correct that it is the return water temperature that determines whether a mod-con system will condense? For example, right now my Vitodens system is reading 142 degrees in the hx, which is too hot for condensation, but the return water into the boiler is 122 degrees, which is cool enough.

Jean-David Beyer

Am I correct that

yes, as far as it goes. The colder the return water, the better. I currently run between 76F and 120F water into my radiant slab (depending on outside temperature), and between 110F and 135F into my baseboard zone. I get only a few degrees drop though the emitters.



So set your reset as cool as possible, consistent with getting enough heat. I put in lots of extra baseboard in the baseboard zone so I cold run lower temperatures.,

28W

Thanks

I've been experimenting with different circulator speeds on the radiator loop to try to get the return as cool as possible.