Monitor's are not all that reliable, so I have been told, and do not come close to the reliability of Toyo or Toyotomi for either an oil or kerosene direct vent, space heater.
There's an internet retailer in southern Maine who ships them all over who supposedly has the lowest prices. What's his name?
www.alsheating.com in Brunswick, Maine
Toyo or Toyotomi is best for oil, and Rinnai is best for propane, is what I hear through the grapevine. Both are made in Japan.
Al's website has a dirty laundry list of problems common to Monitor.