We have a williams heater model 1403622, it all seems ok but we noticed that there is a black film on the ceiling. We do not see anything coming out of the heater. what might be causing this

Hello, you can buy a thermocouple at any heating and cooling store, they cost between 7 and 15 dollars depending on the length of it.

If you mean that the pilot light does not stay lit, you could have a bad thermocouple or a loose connection at the gas valve. Make sure the flame is against the thermocouple. If you mean that the pilot won't light at all, bleed out the gas line a bit more.

When the units were converted, did the installer also adjust the burner's air intake valve to what's required for propane? Sometimes, that's forgotten. Also, I assume all of the connections were leak tested .... not just where the conversion kits were installed, but throughout the heater? The reason I asked this, is that propane enters the heaters at a higher pressure (water column inch) than Natural Gas. Almost twice as much. In which case, it may have loosened the seals in the regulators.

Those are the things, I'd be looking at.

Hi,
The problem is with the thermocouple.... this is the metal thing that the pilot flame hits when it is burning....if the flame is not hitting it then it does not get hot enough...

make sure the flame is hitting it....if not then adjust the hood over the flame to get it on the thermocouple...

If it is hitting it then replace the thermocouple....for that heater though the thermo is probably and OEM part and may have to be bought from the manufacturer...

heatman101

http://shopfnc.com/pdffiles/williams2man.pdf
Here is the installation manual that includes a section on how to light the pilot on your specified Furnace "Williams 1403622".
Let us know if this was helpful to you. Good Luck in your endeavor. :-)

Usually T and R if its a line voltage T-stat. R and C if
it is heating only 24 volt t-stat

sure. just make sure u use dual wall 'b' vent pipe n be 24" from a door

sounds like a blocked pilot or thermal couple fault get unit serviced

Venting problem probably!

try clean pilot ..... replace thermocouple on heater