I am completely new to the heating and air conditioning field and this is my first post in this area. I moved into a house with this Sears Gas Heater unit. I started remodeling the house right away and did not use the heater for quite a while. I now "resurrected" the unit and turned it on a few short times to examine the condition. I noticed a few things and had some questions about this unit:
-With the thermostat on AUTO, the Heat comes on but the Fan stays off. I can then manually turn on the Fan at the thermostat by moving the switch from AUTO to ON. This tells me that the issue must lie in the thermostat. Is this assumption correct?
-The unit does not have a pilot light. Instead it uses a spark igniter. When the burners are on I can hear an arcing sound, which I can locate in the igniter area. With a unit like this, would it be normal for the spark igniter to always be on when the burners are operating? Is there a need to re-ignite a burning gas flame? I see a flame sensor is mounted next to the igniter. Would a defective flame sensor cause the unit not the "see" the flame and thus continuing to try to ignite the gas?
-The blower seems to have taps for slow, medium and high speed. It seems to be running on one speed all the time. The unit is located in the middle of a small, single store house and the blower noise is very loud. Can the speed of the blower be reduced? Would reducing the blower speed require a reduction in burner output power? Can this even be adjusted? What other considerations should be made before reducing the blower speed?
-A motor controlled butterfly valve is mounted at the beginning of the exhaust tract. Is this valve for preventing escape of warm air from the inside of the house through the exhaust while the heater is turned off? With the heater off, the valve is open. Does this mean it is broken? The valve does not seem to be seized, but the actuation mechanism could be defective, I assume?
-Where could I obtain any information about this unit in the form of manuals or other drawings?
I also want to mention that the unit is used for air conditioning as well. On the unit it says "sized for air conditioning" and above the heater a radiator was installed.
Attached are pictures of the unit, the igniter, electrical drawings and name plates.
Thank you very much for your help and advice.