Secondary circ. sizing

JK_5

I've been told I can size my secondary circulators for a 40 deg delta T to reduce pipe sizes & circs. Just want to confirm. I have 2 300mbh(Weil PFG7's) output boilers and have selected NRF33 11/2"(aprox 16 gpm @ 10tdh) for my secondary pumps feeding into my primary loop. Any problems in doing this.Input is greatly appreciated

hot_rod

Can your emitters

handle a 40 degree delta T, and have suffecient output?

Perhaps with a low temperature radiant and VS injection you could run a 140- 180 boiler operating differential.

I've pushed a few dual cast iron boilers into a 30 degree delta t on a VS injection radiant that Siggy helped me design.

Also be sure the boiler manufacture approves of a 40 degree delta t.

Be sure to have a smart boiler return temperature protection device if you plan on running down the 140 range.

hot rod