I bought a duplex last year, where the bottom unit (which is rented) is heated by a boiler and the upper is from a forced air furnace. My tenant in the lower unit was commenting on how high his utility bills were, especially the gas. I went down stairs to check the boiler, and low and behold the pilot was lit and is essentially sounded like the boiler was running. I proceeded to turn the gas off and also the electrical supplying the boiler in the hopes that this would lower his utility bills as this is the only appliance in the unit that runs on gas.
If anyone with some HVAC experience could help me out it would be appreciated. I can handle furnace maintenance pretty well by myself, but boilers are something that I do not have much experience in.