Glenwood
I have one of these units in use, made by Glenwood, Taunton, MA. The gas heater on the side rated at 40,000 BTU. Works as an excellent heater for more than one room. I usually leave the flame on lowest setting, continuously, during the winter. Heater is vented to the chimney.
However, these types of stoves/heaters are outlawed in Massachusetts, with existing ones grandfathered. Only repair I've ever done is to replace a very inexpensive thermocouple (used to keep the standing gas pilot lit).