I've had mine 8 years with zero issues. It has the electronic ignition and vents to the outside. Was yours purchased used or is it a newer model? Don't know what else to tell you but hope you can straighten yours out.

I think the "pilot stat valve" would be the next part to replace if you keep having that problem.

Here is a link that might be useful: Heating & Air book

THANKS -
Mine has a pilot light that stays lite, I wish it was electronic
I checked out the heating and air book. It is very helpful
Since my post and my home made fix, the pilot has went out once. I will contact the repair person and find out which parts he replaced, - thanks for the help !

Hello, you said you ran a dryer house vent directly outside. Did you not have a 4" (preferably dbl wall) vent kit already coming out the back of the heater and running out of the house and then turning up? If there was no vent pipe it would explain the soot build up. A tighter house gives no where for the products of combustion to go and those same products of combustion could cause the pilot to go out which puts stress on all the parts. They are working hard for nothing. Make sense? Is your heater a model #PD100AE N.G. or L.P? Also if there is that much soot build up BE CAREFUL not only could the products of combustion be harmful to your plants but to you as well.

Here is a link that might be useful: Modine HD Heaters

Mine is not like the Hot Dawg shown
I will get the model # - but it is similar to the one I linked, jsut older without the ignition
Originally I did not have a vent as described. So for the first few years it worked ok - The Funance did not include a vent kit originally - It was a very basic model, pilot stays on all the time, no power vent. I have created my own vent now. But it may not be enough. I plan to cut a hole and direct vent it out the back of the house as described. Right now the vent is a dryer vent hose ,run down to the floor and out under the wall to the outside. I did it very quickly at night!
It seemed to work, but perhaps the "out the back" vent will allow more air.
Again all this happen after I put on new covering. The flue exhaust air that may not be replaced easily -

thanks _ Mike

Here is a link that might be useful: like this one

OutDoor Jen,
The more I think about your reply the more I am in agreement. When I recovered the GH I allowed the double poly to extend over the bottom clip down past the bottom board - thus covering any leakage from the bottom board. Which was probably enough to make it though each year.
I seal up the exhaust vents to prevent heat leakage , but just sealled up one more place for fresh air to come in.
Then created the make shift dryer vent. During the coldest part of our winter. It worked for a few days then - out went the pilot. So - the hose is not big enough and not allowing enough fresh air in. I have unsealed some the exhaust fans in back near heater. and will create a better vent - see linl below. The elbows in the pipe may help with my big concern of allowing air but not a draft of cold air that will force heater to run more.

For those who may consider unvented heater - I now understand the NEED for a fresh air vent to feed the heater allowing proper combustion.

Here is a link that might be useful: See vent pipe diagram