Gas and Oil Home Heating Furnaces - armstrong air furnace having many problems -

i've an armstrong ultra v tech 80 furnace that has been working intermittently. it usually gives a 7 code [not sure what it is, but it's not the 6 then 1 code, it's 7 blinks in a row].

if the heat is turned on, the fan will start, gas will start, then it cuts out. it won't ignite - tho when this problem first started the flame would start up, then turn off and the gas would start, missing any ignition. eventually it'd work again, but this time it's been out all day as opposed to an hour or so.

i've thrown the circuit breakers, turned it on and off, and it has a clean, new filter, all to no avail. now unless i turn off the heater and turn it back on again it won't try to restart. but it does the same cycle of fan starting, gas starting, then cutting off.

the unit is from 2005 and i only bought this place in july, with no issues till now. of course it's freezing!

thoughts? thank you!

If you haven't already had someone fix it, and one of us is online with our green light lit, we will try to help.

I experience the exact same problem as evilisa on my Armstrong Air 91% furnace. I've had the furnace for 4 years now. The problem started about 3 weeks ago. Sounds like it may be a common thing. Any ideas?

If you take the big cover off the furnace, and turn up the stat, and watch to see all that happens at start up, you should .....

1. Note a delay of a number of seconds after you turn up the stat. Then you will hear the inducer fan run. (That is the fan that exhausts combuistion air and spent gas to the outside of the house).

2. Then a number more seconds go by and then some sort of ignition process occurs (could be a glow coil that glows bright orangish-yellow, or a spark that directly lights the burner, or a sparking that lights a pilot).

3. Then the gas comes on and the burners light up.

But then if the burners shut right back down in a few seconds, the flame sensor is usually the culprit. Is that what your furnace does?

But tell us what kind of ignition source your furnace uses. (it should be one of the 3 types I mentioned)

Typical problems that can shut down the burner right away are a flame sensor that needs cleaning up.

Or a problem with the pilot flame size, due to a clogged pilot orifice which then causes the control module or board to not be able to sense the flame from the pilot. Or a corrosion problem or bad wire connection, as to why pilot flame can't be sensed.

Or a marginal wiring connection somewhere.

Or a marginal vacuum at the pressure switch that might be caused by condensate water not draining out of the furnace the way it should. Or even a clogged up vacuum port where the pressure switch vacuum hose plugs into the inducer fan housing.

Or something erratic with the thermostat.

My furnace has the coils that heat up. Then, the gas is released in about 3 chambers, producing the flames.

If it is the flame sensor needs cleaned, is that something I should call a heating company out for, or is it simple enough to do?

Thanks for your help.

Usually simple (depending on location) to do yourself. Usually only one screw holds it in place. Look for a single thin wire by itself that runs into the furnace burner area. It may be at opposite side of 2 similar thin wires that go into burner compartment to the glow coil.

Remove the flame sensing rod and polish off the oxidated coating with something that does not scratch very much, like a Scotchbrite pad. This restores the ability of that rod to sense and conduct minute current to tell brain control of furnace to go ahead and let the gas valve to keep open.

ECMAN51,

Thank you very much for your assistance. I believe the problem has been solved. I cleaned the sensor about a week ago and no problems!