Heater blows hot air then cold

[SweetOneN]

We have a Train XE80. Lately it will only stay on when we turn the thermostate all the way up. If we set it lower it just keeps kicking off. But now it has started to blow cold air after the warm air has been blowing for a while. We wake up in the middle of the night to a freezing house. It's like we've turned the air conditioner on.
We have had to replace the igniter twice. The last time was just one year ago. We also replaced the thermostat at that time. Why does it blow warm air then cold? [V]

[Jake Jones]

quote:Originally posted by SweetOneN

We have a Train XE80. Lately it will only stay on when we turn the thermostate all the way up. If we set it lower it just keeps kicking off. But now it has started to blow cold air after the warm air has been blowing for a while. We wake up in the middle of the night to a freezing house. It's like we've turned the air conditioner on.
We have had to replace the igniter twice. The last time was just one year ago. We also replaced the thermostat at that time. Why does it blow warm air then cold? [V]

Had a problem with my XE78!! Check your gas valve. Once the furnace goes through the initial stage of igniting, it should continue to burn until furnace reaches desired temp. If the gas shuts off prior to this stage (due to the valve) the fan will continue to blow and cool down the house to undesirable levels.

[SweetOneN]

Is this dangerous? My husband was going to try and fix the problem, but now I'm wondering if I should call someone out first thing in the morning.
Thank you for your reply.

[Jake Jones]

YES! If you are not comfortable of course call a professional. Please note though, this is a simple procedure that requires a little common sense..... Purchase gas valve and the correct Gas thread sealant for pipe. Turn off electric and gas at furnace if able to or at main valve, turn off any open flames i.e. pilot lights etc. in area. Disconnect electrical connections at valve. Open connection with wrench, wait 15 minutes for any residual gas to purge. Install new valve in reverse. Get a bucket or cup of sudsy water. Turn gas on, but not electric yet. Slowly pour the water over the connections and if they don't bubble you have a good connection. If you can get down low to the floor and smell for gas (since natural gas drops) and if you are confident of no smell turn your electric back on and check.

"If man can install, man or woman can repair regardless of the situation".

[SweetOneN]

Thank you very much for the help. I've passed it on to my husband. We're not using the heater until we can fix it. Using space heaters in the mean time.

[Joel]

Just for starters gas is litter than air and rises propane is hevier and drops ,i wouldn;t change the gas vale without a few checks of other components such as the flame rod which can be cleaned with light sandpaper or it may be going off on limit which could be a # of things including a very dirty filter if you;d like more info let me know

[Utilitygirl]

I am a utility tech. I ran into a puzzleing application the other day. This was an older Bryant gas furnace, The shut off valve had a tapped in thumb valve on it. The valve had been totally bypased and the tubing went into a small device(maybe a flame switch) then straight into the pilot tubing and thermocouple which feed the gas to the unit. The lady told me she had to run her heat and air at the same time. Very confuseing. But it had a leak at the pilot tubing and I ahd to disconnect it, but did not get a chance to see it work. Can anyone explain this to me, or if she was crazy or someone just wired it to work that way,by luck.

Patty Redmon