Though the pilot is on, it will not ignite.

Could be a thermostat or gas valve. Do you hear a click when the thermostat calls for heat?

Could also be a weak powerpile. If your heater has a power pile vs a thermocouple, it would be a good place to start. When powerpiles get weak, they tend to produce just enough power to keep the pilot lit, but not enough power to open the gas valve.

I will check tomorrow regarding clicking.

If I run the thermostat up and down and hear a click but no ignition this means??

If I run thermostat up and down and no clicks this means?

How to test powerpile? Thermocouple?

How to test gas valve?

Also someone mentioned (in another post online) that is could be a pressure switch? Any thoughts?

Could be a thermostat or gas valve. Do you hear a click when the thermostat calls for heat?

I will check tomorrow regarding clicking.

If I run the thermostat up and down and hear a click but no ignition this means??

If I run thermostat up and down and no clicks this means?

How to test powerpile? Thermocouple?

How to test gas valve?

Also someone mentioned (in another post online) that is could be a pressure switch? Any thoughts?

How old is this heater? Natural gas or propane?

I just bought the place so no idea how old but would guess it is at least 7+ yrs old. It is natural gas.

If it is indeed a wall heater, it will not have a pressure switch. Can you post a picture of the gas valve and wires that hook to it. If you can, I may be able to guide you through some test's

One other oddity - there is a 'light switch ' at about 6 feet off the ground just above wall heater. There is also a attic hatch right there. So no idea if it is something related to wall unit or a light in the attic (which I could not find). I will follow the wiring tomorrow to see where it goes.

Will see about posting pic tomorrow.

What does the switch look like, a regular light switch, or is it on a silver box?

looks like regular switch but the plate is a little fancy. Maybe to set it apart from other switches or maybe the previous owner was feeling fancy. This is just a random fancy wall plate just so you understand what I mean. The one on the switch a little thicker than average, is white with gold trim/accent... just in case that means something

http://www.learningoutlet.com/Chenille-Kraft-Wall-Switch-Plate/dp/B0044SH3DQ?gclid=COuXlOHD67ICFQQGnQodE2IAnw#.UG-wWE2wFrU

looks like image did not upload. Here is the link but again it just a random fancy plate for clarification

Chenille Kraft Wall Switch Plate - 3 3/4 x 6 inch - Each - Unfinished Wood : Wood Crafts - Cork (http://www.learningoutlet.com/Chenille-Kraft-Wall-Switch-Plate/dp/B0044SH3DQ?gclid=COuXlOHD67ICFQQGnQodE2IAnw#.UG-wWE2wFrU)

https://mail.google.com/mail/u/0/?ui=2&ik=91702003e3&view=att&th=13a411cd199c3cd7&attid=0.1&disp=thd&realattid=1415274576887152640-1&zw

https://mail.google.com/mail/u/0/?ui=2&ik=91702003e3&view=att&th=13a411cd1fb9535d&attid=0.1&disp=thd&realattid=1415274674615484416-1&zw

https://mail.google.com/mail/u/0/?ui=2&ik=91702003e3&view=att&th=13a411b7c11817dc&attid=0.1&disp=thd&realattid=1415274542802141184-1&zw

I did not get a chance to play with thermostat, etc. Hopefully get to it this weekend.

I was trying to find parts for this just in case. Sears indicates they no longer have the gas valve, thermocouple, ignition assembly, etc.

Anyone have idea how old this is? Anyone know after market place to get parts?

Sears roebuck
50,000 BTU natural gas
Model no. 867.736332
Mfr no. 506931

I have the same heater as you do in my house, with a "light switch" that you described. I figured out what it is for kind of. I am just a home owner not an hvac guy but this is basically what I figured out. That switch stops the gas from flowing to the furnace, the pilot light will light if the switch is off but the furnace burner will not fire until that switch is flipped on. I discovered all of this today while trying to troubleshoot my furnace.. the flame blows out including the pilot light every day.. which causes the room to smell gassy for a bit before it stops flowing the gas, then today I could not get it to stay lit at all but after getting the pilot light lit with that switch off and waiting a couple of minutes I flipped it on and now it seems to be working we will see come later today or tomorrow.

The switch is definitely power to the unit. Pilot light will ignite but nothing else after that no matter what the thermostat setting.

In my case not sure what was problem: switch wrong position, bad thermostat, broken wire from thermostat to unit, bad thermocouple, stuck gas valve, not getting power from circuit panel, etc... I ran through each item and made sure operating and then tried

Initially I had the PGE people out here to light pilot and get unit running as the house was new to me. They could not get it to fire up. If they had spent 5 minutes ensuring the switch, thermostat , etc were working and in correct position could have saved a lot of grief. The only problem I encountered while running through the options was switching from 'pilot' setting to 'on' setting - was a little tricky getting the dial to turn.

Initially mine was hard to turn as well, now it is free flowing.
I left the switch off for about 5 minutes, just ran the pilot light then flipped it on and turned the dial to on and it fired up. I have been in my house for over 6 years and only 2 winters ago started using that heater as it is for an addition on the house.

I hope the dial stiffness / trickiness is not a sign that gas valve is going bad. The house is in California SF bay and we hardly need the heat here and would hate to spend big money to change out unit ( as the gas valve is no longer available)

Like I said mine was initially sticky as well, but it has loosened up since I started using it. I wish you the best of luck. These heaters I believe are 20+ years old.