11:05PM | 12/06/03
Member Since: 12/06/03
1 lifetime posts
My furnace won't fire up. I changed the thermostat with no results. When I shut the gas valve off, then reset it, it does light the pilot automatically but not turn the burners on. What am I overlooking? Could it be the thermo coupling?

plumber Tom

05:56AM | 12/08/03
Member Since: 05/10/03
801 lifetime posts
Check something simple 1st. A single pole switch is usually installed somewhere near the heater, but that's not always the case. Sometimes the switch can be located at the top of the basement stairs (emergency switch) Check the breaker or fuse. Alot of older single pole switches will not be labeled "on" and "off"

R Man

12:56PM | 12/10/03
Member Since: 12/09/03
7 lifetime posts
Just had a similar problem with my Lennox. It was the air sensor. There is a small hose from the blower to the round disk-shaped sensor. Cut power to the unit and pull off the hose at the blower. There is a nipple or stem protruding from the blower. Take a thin coat hanger and fashion it into a poker. Use it to push the clog out of the nipple.

If the nipple isn't clogged, pull off the hose completely and check it for obstructions. Also poke the nipple at the sensor. If that doesn't work, pull the combustion air duct off the top of the unit and make sure it's drafting. You should feel air turbulance at the duct opening. If it's not drafting, you probably have a bird's nest or leaves stuck in there.

If it's not the air sensor, then it may be something serious like the control module. Run the furnace and let it shut down of it's own accord, open up the combustion chamber on the bottom and check the LED code. It will probably be blinking, or perhaps have an error code. Check this against the troubleshooting guide in you owner's manual.

The unit will not run with the combustion chamber open, so you will have to put the access panel back in place to see if its working.

plumber Tom

04:26PM | 12/10/03
Member Since: 05/10/03
801 lifetime posts
Post back with the make and model. R Man the part you are referring to is called a pressure switch. A coat hanger should never be used to clean the hoses on this switch. If A DIY'r cannot and SHOULDNOT attempt to troubleshoot any gas appliance without proper training and experience. The user manual that was supplied with your unit will tell you the sequence (order) of operation. Yes if the pressure switch detects a blockage or a negative draft condition it will prevent the gas valve from opening. If you have a newer higher AFUE furnace check and clean the flame sensor. If you have no idea what these parts are call in a trained technician.
Click to reply button
Inspiration banner


Post a reply as Anonymous

Photo must be in JPG, GIF or PNG format and less than 5MB.

Reply choose button


Post new button or Login button

To test the boundaries of small-footprint living, interior designer Jessica Helgerson moved her family to a 540-square-foo... Filling an underutilized area beneath the stairs is a smart way to save space. Doing so with a stash of wood, however, is ... The Audubon Society inspired wallpaper in this Adirondack-styled mudroom will get you in the outdoor mood. Grab your coat ... Chalkboard paint opens up endless possibilities for customizing your dresser time and time again. Use chalk to label the c... A fireplace in the bathroom creates the ultimate setting for relaxation. Homeowners often choose electric or gas over wood... This roomy boot tray made from punched metal stands up to all the elements. Station it in your mudroom or at your back doo... There’s nothing like a new set of cabinet hardware to refresh a room. The possibilities are endless: Go modern, rustic, or... FLOR tiles are an affordable way to customize a carpeted floor covering for any space. Make anything from runners to wall-... Chalkboard paint features prominently in this elegant yet unpretentious headboard design. Add a new message daily to reflec... Salvaged boards in varying widths and colors make up the dramatic accent wall in this attic space. The high-gloss white of... The indecisive homeowner need not fret over choosing one (or even two) cabinet colors. The kitchen cabinets in this artist... Incorporate nature into your lighting scheme by securing a dead tree in a concrete mold and draping your pendant lamp from... Simple and striking, a couple of pieces of "lovingly used" furniture creates a special kind of charm. A weathered chair fo... First dress up your metal shelves with a coat of paint in an accent color that complements your kitchen decor. Then arrang... Dark wood shelving and a matching upholstered bench keep this closet sleek and refined. The large window brightens the sub...
Follow banner a
Newsletter icon Flipboard glossy Facebook Twitter Pinterest Youtube Rss icon