Latest Discussions : HVAC


04:42AM | 07/18/05
Member Since: 07/17/05
1 lifetime posts
My husband and I are not familiar with gas furnace and central air. When we turn the thermostat to cool, warm air comes out. Do we have to turn the pilot light on the gas furnace off to run central air? Please forward any other info we may need to know about. Thanks!


06:43AM | 07/18/05
Member Since: 04/25/05
1915 lifetime posts
With the common basic forced warm air gas furnace and central AC system the two parts are independent except for the fan and the thermostat.

The basic thermostat has 2 switches and the tempature setting.

One switch is FAN, if it is ON the fan runs all of the time. If it is in the AUTO(matic) position them it runs when the system needs it to run. In the cooling mode that is whenever the AC is called. In heating there is a short delay before the fan starts while the furnace warms up and runs a few minutes after the furnace stops.

The other switch is HEAT - OFF - COOL. That selects either the furnace or the AC or nothing.

When it is the heat position and the house is cooler than the thermostat setting the furnace will start and after about a minute the fan will start.

When it is the cooling position and the house is warmer than the thermostat setting the AC will start and the fan will run at the same time. However, it will take about a minute for the AC to start cooling off the air. So for the first minute or two you will feel warm air.

It does not matter if the furnace pilot light is lite or not.

BTW, most newer furnaces do not have pilot lights, but rather electronic ignition systems.

But are many different variations. You might have a heat pump with gas furnace backup (dual fuel). It might be a zoned system. It might be have a humidifier that has summer/winter settings. Thermostats that automatically switch between heating and cooling.

I would call an HVAC contractor for servicing and make sure that you are there at the time.

And have them show you the basics parts of the system that you need to know about and what can check.

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