2 fuel oil is required for proper combustion and venting. How much air is necessary for good combustion? With most gas burners adjusted to operate with 50% excess air, 20 cu ft/1000 Btu of heater input is generally considered adequate. This is usually due to the lack of oxygen for combustion. It is not uncommon to hear of greenhouses that freeze up during a cold night even if the heater has been operating. Make-up air – The recommendations to tighten up the greenhouse for the winter may adversely affect the operation of the furnace or boiler. Higher pressures than those recommended result in over-firing and possible damage to the heating unit. The pressure should be checked and adjusted if necessary. On atmospheric types of burners, the usual ranges of manifold gas pressure are 3 to 5 inches of water for natural gas and 10 to 12 inches for propane. Gordon Siebring, Siebring Manufacturing, George IA has reported that savings of up to 15% can be achieved with the installation and proper adjustment of a barometric damper.įuel pressure – The normal operating pressure of a fuel oil pump is 100 psi. Its purpose is to maintain a constant draft on the fire. A barometric damper (oil fired heating unit) or draft hood (gas fired units) should be located in the first 12” of the stack nearest the burner. Excessive draft increases the heat loss when the heating unit is in the standby. Draft is also greater in the winter due to cold temperatures. Increasing the height, flue gas temperature or wind speed will increase the draft. This problem is quite common in hoophouses where long wires are needed to power heaters that are located at opposite ends.īarometric damper – The draft on the fire is affected by the height of the chimney, the temperature of the flue gases and the temperature and wind speed of the outside air. Two causes of low voltage are inadequate power to the electric distribution panel in the greenhouse and too small a wire size that feeds the furnace. Voltage at the heating unit should be at least 110 volts. It can also affect the operation of the transformer creating a weak spark. When done on a regular basis, the test can indicate when problems are beginning to occur.Īdequate voltage to the heating unit – Low voltage causes motors to burn out by overheating the windings. A 2% increase in efficiency in fuel usage in a 30’ x 100’ greenhouse will save about 200 gallons of fuel oil during the winter. Adjustment of the air to the burner can improve efficiency and reduce carbon buildup on heat exchangers and lower emissions. It consists of measuring the flue gas temperature, carbon dioxide content, smoke level and draft reading over the fire. The following are a few of the things that may be overlooked by service personnel.Įfficiency test – This 10 minute test should be done by the technician each time a furnace or boiler is serviced. The cost is usually more than offset by the 5 – 10% gain in efficiency. When the heavy gauge gate moves, only the knife edge rests on the bearing for minimum friction and maximum sensitivity to draft changes.Fall is a good time to have the heating system serviced in preparation for the cold winter months. The moving part (gate) rests on a long, thin, stainless steel knife edge which, in turn, is supported by selfaligning and self-cleaning bearings. For any installation with 10" or larger diameter smoke pipe, specify our standard M+MG2 Draft Control, the unit that can be adapted to any fuel. Use the M+MG2 as a single-acting draft control for oil or solid fuel applications. In a duel fuel oil/gas or a gas-fired only application, use the M+MG2 as a double-acting draft control with the optional Field Thermal Switch accessory. In a gas installation, the double-acting Type M+MG2 is specified instead of a draft hood to give the appliance the assistance of the chimney. The Field Type M+MG2 Draft Control provides precise draft regulations for solid fuels, oil, gas, or oil/gas appliances requiring only the simplest, on-the job adjustments depending on which fuel is to be utilized. This is a series of compact, rugged, heavy-duty controls for use on large residential, commercial, and industrial applications.
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