I am getting ready to insulate and heat my 2+ car detached garage. I have 2 quotes for similar sized heaters. One is a 45K BTU Reznor UDAS-45 and the other is a Modine 45K BTU unit. No model specified, but I assume it is one of their Hot Dawgs as that was the only sealed combustion 45K Modine I could find online. The prices are only a few hundred apart, Reznor $2589 and the Modine for $2215 (this includes installation and running a gas line from the house to the garage).
Does anybody have any preferences between Reznor and Moding. Ability to heat, quality, reliability, etc. I live MI about 3 hours north of Detroit, so our winters can get pretty cold, but usually only for a short period of time. I am only looking to keep the garage around 50-55 so I can keep my batteries, paints, etc in there over the winter and also to make it at least somewhat comfortable to work in during the winter.
Any advice is appreciated.
Ben

Both heaters are very good. I would look into part availablity for each and pick the one where the parts are easy to get. Reznor is always more expensive. But both will work fine in your garage.
However I would look into a radiant tube heater instead. The price is about the same. It will keep the garage warmer and will recover faster once the doors are opened and closed. They work by heating the objects in the garage rather then the air. This includes the floor. Once the objects warm up they then heat the air surrounding them. Its less expensive to heat space like this then with scorched air systems.
http://radianttubeheaters.com/

Home Care Club - I was looking at the heaters in the link you gave and I have a concern. The website says that they need at least 41-48" of clearance on the bottom. With an 8' ceiling, how will they affect my car/truck if they are parked under it? I worry that even over the hood area of my truck, there could be some effects to the coat after long term storage. The only other option would be to put it over my work bench, which would meet the clearance requirements (unless I am standing there), but I would worry about leaving anything on there to dry (I do woodworking/furniture projects in the garage).

What do you think? I have seen these heaters where work, but always with 12' ceilings.

The primary reason for the distance to the floor is the area in which the tube will heat.
In otherwords think of the heater like a flood light. If you bring it closer to the ground the less light you end up with, so even with a high wattage bulb you only end up with a small amount of light out of it if its real close. As you bring it farther away the more the light floods the floor and the more efficent it becomes. The same holds true with this type of heater. If you bring it to close to the ground it will no longer provide the heating BTU's your putting into it as it only will heat what it sees.
Some people put it down the middle between the two garage doors. If that is what you have that will work as well.
If you contact the manufacture for a local supplier in your area, they will be more then happy to engineer the system for the garage.
They do make electical units for closer use as well.

The tube heaters can be put at an angle. along the front of the wall where the car noses would be. This angle will then allow for the distance they suggest to the floor. Ideally the higher they are the more surface area is seen by the tube thus the more heating output. The closer the more concentrated the heat becomes.

If your not familure with how this works. Next time you go to the Home Depot stores look up. They always seem to have them by the check out area.

Also if you choose this type of unit. Be sure the thermostat does not see the tube. It has to be out of direct view of it, othewise the radiant heat will heat the stat before the room gets warm enough and you end up staying cold.