condensing vs conventional boiler

jfgh1

Looking for opinions on conventional cast iron boiler vs condensing for a new installation.  New house with a heat load of 60,000btuh which includes garage and basement @ -10F exterior temp.   Radiant tube inslab for garage and basement, baseboard and radiant panels for all other rooms. 

Have sized emitters for entering water temperature of 160F.  Does it make better sense to install a conventional boiler with buffer tank in lieu of a condensing boiler which may short cycle during other than design load conditions.

CMadatMe

Does it Make Sense

To install a boiler that has the capability of giving you 90% plus AFUE vs a boiler that will give you 80-83% AFUE all heating season?

Does is make sense to throw away a $1,500 tax credit plus any utility rebates you may get?

Just a couple of questions to qualify your train of thought. The questions I have are. What is your plan to control the radiant? What is the plan to control the panel board? How about the fin-tube? What if you could have a boiler that has the ability to control multiple water temps without having to use multiple controls?



On a heating curve that starts at 160 degree water based on -10 outside you would be running roughly 100 degree water on your 50 degree day and 110 on your 40 degree day. I don't think the rate of short cycling would be a major issue. What is your piping/zoning strategy? I'm asking because if you use a hydro seperator you may want to use the 150 degree ratings for the board and panel rads due to roughly a 10 degree drop between the boiler temp and system side temp of the hydro seperator.

jfgh1

zone control

My  plans at this time are to utilize a variable speed pump, whilo or grundfus, which will run on a master t-stat.  All baseboard and panels will be on zone valves or thermostatic valves unit mounted.

Garage loop will be a glycol loop with heat exchanger and three way valve on the primary side. 

Basement loop will be off the primary loop with a mixing valve.