Well I've screwed myself-need a heating design person

[NCPABill]

I thought the expansion tank indicated a closed system. If I was wrong, I apologize. For what it's worth, I have just over 4% additional capacity for expansion, calculated by gallons. The heating supply store locally was helpful, but online was where I found that answer. The standard sizing is based on Btus/hr, which won't work with pressurized storage.

Is it a closed system (which mine is and I love not having to check or add water, etc.). Did my previous boiler to tank explanation make sense?

 

[NSMaple1]

I thought the expansion tank indicated a closed system. If I was wrong, I apologize. For what it's worth, I have just over 4% additional capacity for expansion, calculated by gallons. The heating supply store locally was helpful, but online was where I found that answer. The standard sizing is based on Btus/hr, which won't work with pressurized storage.

Is it a closed system (which mine is and I love not having to check or add water, etc.). Did my previous boiler to tank explanation make sense?

Guswhit has an open boiler (I think), and a closed system. Therefore the FPHX in between. Your explanation made sense if you've got a closed (pressurized) boiler. And yes expansion tank = closed. Therefore the expansion tank in Guswhits, on the system side of the FPHX.

 

[kljahnz]

If having not bought the pressurized storage tanks, and going non-pressurized storage was an option, I think this system would be easier to get up and running. Wanting to use radiant floor heat along with water to air heat exchangers, will make wiring the controls, way over my head.
Water to air like higher temps"140plus" my Infloor radiant never is allower to see temps above 130. I have a 3 way mixing valve with outdoor reset. works great for floor heat, my garage uses water to air hx, feed by that same mixing valve. So, it just takes a little longer to bring the temp up, compared to having say.... 160 flowing through them. I'm not saying you can't make your proposed system work, it's just over my pay grade.

 

[hupte]

based on the schematic, it appears the water to air HX are plumbed before the 3 way mixing valve/ in floor heat. so the water to air HX could have, for example, 160* water while the in floor heat can have 130* water.