Caleffi Magic ?

Rich_49

I heard today that Caleffi has a device other than a ThermoCon that eliminates boiler short cycling . Hot Rod , what are you not telling us ? Please understand that this is sarcasm .

I am designing a hydronic heating & cooling job in Ny and a potential installing contractor advised to install a second radiant dedicated boiler ( Buderus SSB 80 ) without need for a buffer tank . Instead of using the ThermCon I have already spec'd for summer cooling and winter heating using a single boiler and it's ODR for spacepak heads in several areas and an I Series ODR mix valve for the radiant . Temps will vary from 120* to 150* for the Spacepak but the radiant ceiling's highest SWT will be 108* @ 0* odt .

Question , why would one use a second boiler for a Average load of 24,000 BTUh when only 40 - 60 % of zones will call except at night and on cloudy days in a really tight house while using another boiler that will hardly ever condense ?

Any ideas why one would do this and where would someone get the idea that Caleffi makes a variable something that eliminates the need for a buffer ?

hot_rod

Stick with your plan it's a good one, as I know of no other device on the horizon that would add the same function and benifit.

I do suggest hydro sep instead of primary secondary. They can add a few extra gallons of capacity to a low mass boiler, and the sensor in the sep basically turns the boiler, piping and sep into one "mass"

Rich_49

Thanks Bob . the 120 Caleffi buffer will be my separation . The thought of a second boiler and higher AWTs during heating season to one boiler and the short cycle issues with the radiant boiler was shocking . It may be worse than I thought out here .

I have to have this mass for the 2 SpacePak Solstice units regardless , might as well use them for the boiler also . Chillers in one set , boiler in the second set , system out of the third . Easy right ?

njtommy

Are you going to have isolation valves on the chiller to close off or automatically close in heating mode?

I only ask cause at 150f water temp is going to push the refrigerant pressure up to where fusible plugs or relief valves on the refrigerant side will blow. Any system I've ever worked that chilled water and heating shared the same piping we would have to go out and and close valves and drain the water at chiller every year.