[buffalobillpatrick]

Thanks NiHaoMike, I like lots of it!

Let's call the pumps P1 - P6 from upper left to lower right.

The Burnham RV3 boiler requires P1 to be on it's output, due to it's internal P/S loop & variable speed internal pump setup This is called pumping away & allows the Air seperator & Expansion tank below it to function properly.

"One valve selects whether the boiler/DHW loop is interconnected or isolated"
that would be the top 3-way valve (#1).

"Another selects whether the solar goes through the heat pump or is directly used"
that would be the 2-way valve (#2) just lower left of #1

I don't see path for Solar to heat 120G tank?

I don't see path for 120G tank to heat Radiant floors without going back through the Solar HX OR through HP condenser -> P4 & back through unfired boiler, which is not good practice as heat would be lost up vent pipe to outdoors?

Same comment on HP heating 120G tank "back through unfired boiler, which is not good practice as heat would be lost up vent pipe to outdoors"

"The thermal storage tank can go above the 90F or so point when using direct solar"
Is that the 40G tank?