Here is some research I have done o these heaters-- See if these links help:

Reddy Heater - Troubleshooting Torpedo Heaters


If you brought the heater to our shop, and gave the above description, the first thing that we would do is check the air pump pressure.

Then, if the pressure is correct (not just close) we would check the photocell for signs of insect nest or something similar blocking the view of the eye.

You must troubleshoot to find out if the problem is fuel related or electronics related- maybe these tips will help (click for link).

http://www.reddyparts.com/HSI_tips.htm