A: Gas supply lines must be sized for the specific installation. Although the gas valve connection on an appliance may have a ½” that does not mean that a ½” gas line will provide enough fuel. I know that may sound counterintuitive but I assure you that is the case. If the gas supply line is inadequate the gas valve will not stay open. Upon opening the pressure drop will cause the gas valve to close. The gas valve closes for safety reasons as a weak flame can be dangerous. Based on the length of the run, the type of gas line being used, the number of fittings, the gas pressure, elevation above sea level and local gas codes, the gas fitter will calculate the pipe size that needs to be run. Proper calculation insures that you have an adequate fuel supply at the appliance. If you scroll down the Home Depot product listing page you will come to a section entitled Product Details where you will find PDF’s of the product documents. If you open the use and care manual you will find that this is discussed in detail beginning on page 10.
A: The rotational speed or any electric motor is fixed base on the design of the motor and the fact that our power in the US is based on a 60 cycle system. The only way to deviate from that consistent RPM figure is to have a rheostat. This is a fancy name for what is commonly called a dimmer switch. As these units are most commonly installed in warehouses where noise and fan speed are not a problem, Modine does not use rheostats in there design. However I would think a competent election could size and install an appropriate fan switch on it. But I would not do that. The fan is not there to move the air around the building. The fan is there to make sure you have enough air flow over the heat exchanger to take the heat away. Without the proper air flow the heat exchanger will over heat causing both damage and safety issues. So again I would tell you not to.
A: Modine is a US company based out of Racine WI. However I am pretty sure this particular model is manufactuered in there SC facility.
A: I am sorry but there is no consistent relationship between cubic footage or square footage of floor space and the amount of heat that should be installed. As I am sure you can imagine the same building if located in Alaska would need more capacity than if it were in Florida. The proper way to size heating equipment is to do a heat loss calculation. There are quite a few free online programs you can use for this. You enter the dimensions,window sizes. geographic location, construction type, etc and the software will calculate how much heating capacity the structure will need to satisfy the heat load on the coldest hour of the coldest day of the year.