Transplant production will soon begin in earnest if not already underway. It is sensible to check the greenhouse heating system before starting production to make sure it works and won’t pollute the air in the greenhouse. This checklist for gas or propane-fire unit heaters highlights some of the major points. If you are not familiar with the system a service technician can help. General Maintenance. Check for physical damage; Remove any obstruction in vent and exhaust systems; Make sure components are supported properly and securely.
Fans and Blowers. Lubricate as needed; Check for smooth operation; Inspect for physical damage; Adjust belts as needed; Check connections to electrical power.
Heat Exchangers and Burners. Inspect exchanger closely for cracks or corrosion where air-polluting gases can escape; Clean inside tube surfaces if required; Inspect for dark discoloration on metal which may be a sign of overheating and if found, investigate cause; Clean gas burners if necessary; Check burner and pilot orifices to make sure they are not blocked. Don’t use a wire brush to clean because it can scratch the metal.
Gas Controls and Supply. Check connections for tight fit and absence of leaks; Check electrical connections; Check that gas is turned on; Check gas pressure for proper setting; Check that gas regulators are not plugged.
Thermostats. Clean if needed; Check wiring and temperature setting; Check location and protection from sun and drafts.
Vents. Remove any obstructions; Check that connections are good and tight; Check drip leg and cleanout cap and clean if necessary. Air Inlets: Check that air inlets are free of obstruction so air needed for combustion can enter the greenhouse. Allow 1 sq. inch for each 1000 BTUs. References: Greenhouse Heating Tips, Pre-Season Checklist www.modine.com/download/1/76-500J.pdf
Unit Heater.