by High Performance HVAC | Gas Furnaces |

Automatic Vent Damper System | Gas Heat Flue Economizer. The automatic vent damper adds efficiency to water heaters and furnaces. The automatic flue damper traps heat in the furnace, boiler, or water heater. It holds heat in and around the heat exchanger instead of allowing it to rise up the flue.
The control voltage from the appliance powers the automatic vent damper. The automatic vent damper has a little motor that powers it to the closed position. It leaves all the heat trapped inside the furnace, boiler, or hot water heater. Prior to the existence of automatic vent dampers, the heat escaped up the flue and vented to the atmosphere. (more…)
by High Performance HVAC | Gas Furnaces |
Gas Furnace Components 3 - Gas furnace ignition controls vary from furnace manufacturer to furnace manufacturer. Some are proprietary and some are from an engineering company that specializes in gas furnace ignition controls. Honeywell being a major manufacturer of controls for HVAC also makes several gas furnace ignition controls.
Gas furnace ignition controls have advanced by leaps and bounds over the last 20 years. The standard was standing pilot ignition. Solid-state ignition controls are safer and more efficient than ignition controls of yesteryear.
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Gas Furnace with Drain Pipes to Drain the Condensation.
Furnace Water Leak Condensate Problem - Richard, My furnace is leaking water. It is summertime, so I am not using it for heat except for the blower fan which is hooked up to the air conditioner and the heat. I know the pipes from the outside units run into a box on top of the furnace. I think that is a part of the air conditioner. What can I do to fix the problem if you know what the problem is by my explanation here? Dan
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by High Performance HVAC | Gas Furnaces |

Natural Gas Versus Propane | HVAC Heating Fuels - What is the best for you when choosing between either natural gas or propane? What is your heating system fuel supply? In some cases, you will not have a choice between the two. Having natural gas supplied to your home or business will require a natural gas pipeline near your home or business.
If there is a pipeline near your home and you do not have a meter, you can call the gas company. Most of the time, they will install the meter next to your home at no cost. However, it is always good to ask if they are going to charge you for installing a meter for use in your residence or business. (more…)
by High Performance HVAC | Gas Furnaces |

Furnace with Hot Surface Ignition
Hot Surface Ignitor - Whenever we talk about electronic ignition systems in gas furnace ignition systems we must first look at the key components which make these systems work and understand how they work. Hot surface ignitor systems work in various ways.
This all depends on what the electronic ignition manufacturer and design engineer determined in the design. Furthermore, some are direct main burner ignition while others light a pilot, and the pilot lights the main burners.
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by High Performance HVAC | Gas Furnaces |
Honeywell Temperature Fan Limit Switch Control – The fan limit control turns the fan on and off in furnace applications. It works off of temperature and also provides a high-temperature safety limit. This is a switch, actually two switches, which turns the furnace blower on and off based on the temperature of the heat exchanger.
A helical bi-metal probe extends from the back of the fan limit control. This probe is located inside the heat exchanger and the bi-metal of the probe reacts to temperature.
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by High Performance HVAC | Gas Furnaces |
Standing Pilot Gas Valve Propane Heating | HVAC Heating - How It Works. The standing pilot gas furnace uses a standing pilot to light the main burners. Many gas-fired water heaters have a standing pilot ignition system. The standing pilot gas ignition system is often referred to as a safety pilot because it increases safety.
Safety of ensuring the main burners are lit. The standing pilot can be used on a natural gas ignition system or an LP ignition system. These heating ignition systems are older and are slowly being replaced by more modern and safer electronic ignition systems.
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by High Performance HVAC | Gas Furnaces |
Gas Furnace AFUE Definition | HVAC Terminology. AFUE or Annual Fuel Utilization Efficiency Heating systems consume approximately 35% to 50% of a typical home’s energy budget. Therefore the government has come up with a way to measure efficiency ratings of furnaces so they can set a standard for minimum efficiencies.
The definition of AFUE is – Annual Fuel Utilization Efficiency. AFUE is a rating that reflects how efficiently a gas furnace converts fuel to energy. A gas furnace with an AFUE of 95 means that approximately 95 percent of the fuel is utilized to provide warmth to your home, while the remaining 10 percent flows up the flue and into the atmosphere.
Therefore you are actually using 95% of the fuel you are paying for and the other 5% is being wasted up the flue vent.
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by High Performance HVAC | Gas Furnaces |

High-Efficiency Electronic Ignition Gas Furnaces are here. They are the next step up from the standing pilot gas furnace. These gas furnaces are more efficient than the standing pilot furnaces but more complex in design. There are three types of electronic ignition gas furnaces: the intermittent spark pilot, the intermittent hot surface ignition pilot (Honeywell Smartvalve and ignition assembly), and the hot surface ignition furnaces.
While the three are different they all offer higher efficiencies and are both controlled by solid-state circuit boards. Many of these furnaces also have higher efficient heat exchangers.
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by High Performance HVAC | Gas Furnaces |

Electronic Control Board for an Electronic Ignition Gas Furnace
Gas Furnace Ignition Control Operation | HVAC Heating. This furnace control board controls much of the functions of this gas furnace with few exceptions. The main control comes from the thermostat and once the thermostat tells the gas furnace control board it is time for the heat to come on the gas furnace control board takes over from there except when the thermostat is satisfied the system shuts down.
On a call for heat from the thermostat the gas furnace control board starts its sequence of operation. This article relates to the sequence of operations for electronic ignition gas furnaces. Some furnaces will vary in their sequence of operation from what is written here. However, most electronic ignition gas furnaces use this sequence of operations. For the sequence of operation for a standing pilot gas furnace see this article.
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