Re: Radiant heat is not keeping my rooms warm
Just to clarify, this si a boiler not a furnace correct. A furnace heats air, a boiler heats water.
I suspect someone designed or installed your system wrong.
How large is the boiler (BTU's). Does it also heat you domestic hot water?
Where do you live (climate)? You house isn't that large. It shouldn't need more than 50-80 BTU's depending on insulation values and air leaks. IT does sound like the garage is getting a lot of the heat.
Can you balance the zones with flow control valves. So reduce the water flow to the garage and thereby force it to the other zones?
Can you tell if the boiler is run at maximum capacity and running continuously? If not, I suspect either your water pump is too small or you don't have enough radiant loops installed. I'd be suprised if the boiler is undersided. But it could be as simpler is having a larger pump installed or possibly adding a couple baseboard heaters if you're getting enough water flow.
Do you know the water temp leaving and returning from the boiler?
1925 Two-Story Stucco Beaux Arts Neoclassical