HeatMan wrote:

"BuddyBiancalana" wrote:

... I checked the unit and its a Weil McClain, kind of hard to read the
stamped plate with the specs on it, but it looks like model number on
the boiler is "PCG-5", "Series 3". It says it has an A.G.A. rating of
114,000 BTU's per hour input and 112,000 BTU's output per hour.

.... 100x112/114 = 98% efficiency sounds high. You might check further.

No incoming air supply from what I can tell. Would the standard
aluminum tube (I believe it to be either 4 or 5 inches in diameter),
connected to the garage window and outflowing to the floor be good
enough/beneficial?

Sounds fairly useless, in an average US house that naturally leaks
2400ft^2x8x0.7ACH/60 = 224 cfm of air. The boiler might need about
10 ft^3 of combustion air per ft^3 of gas, something like 10x114
= 1140 ft^3/h, or 19 cfm.

Would it be beneficial? No clue.

Typical :-)

5.) What's a sealed combustion unit? Benefits? How much?...

Sealed combustion uses air directly from the outside and then vents the
waste gas out, using NO inside air for combustion. They aren't cheap, but
they are efficient, regardless of what that moron Nick says...

So far, it seems the main advantage would be to fatten an HVAC installer's
wallet :-) You might say using outside air for combustion reduces the need
for winter humidification, but maybe the energy used to humidify air comes
back in the flue as more condensation, and winter humidification seems like
a bad idea for energy savings, in any case. You might say it's more efficient
to heat that 19 cfm from 30 to 70 in the boiler at 100% rather than in the
house at 98%(?), but that only saves 19x(70-30)0.02 = 15 Btu/h, no?

Nick