Baseboards getting hot when DHW tank calls

Unekone

I was out to a call yesterday and when its cloudy out and the boiler serves as the back up to the solar and fires on a DHW call the upstairs baseboards are getting hot. What I gathered is it was set up as a split loop . Supply leaves the boiler hits the air scoop then 90's then a flo check then hits a tee where it goes thru the DHW tank and returns to boiler . After the tee is where it goes to the baseboard. Im assuming when the DHW circulator calls what ever not pulled thru the tank is going thru the baseboards. Gravity Circulation ! Im assuming original design was a single loop system as the boiler was a tankless coil until they added the solare last fall.All they did was cut in a tee threw in a circ and cut it in the return.  What is the best solution to this problem ?

Mark Eatherton

Got drawings and pictures?

Those would be very helpful in seeings whats going on...



Could be gravity flow, or could be a failed check valve. Lots of potentials.



ME

Alan (California Radiant) Forbes

Each loop

should have it's own flow check and pump (or zone valve).