Depending on the age of your heater, from what you described, it sounds as if the Thermocouple needs to be replaced. because it's an Infrared Heater rather than just a Blue Flame model. I would recommend, that unless you are very handy with tools and gas heating appliances, not to undertake the repair yourself. The Thermocouple itself is not an expensive part at all ($10.00 to $15.00). So having a professional repair it is the safest way to go. Because, during the repair he/she can also clean the interior of the unit and check or test for any of problems.
Keep in mind, DESA International who manufactured the Vanguard Heaters is no longer in business. But, some parts (like the Thermocouple) are still available.
It's always best to have your heater cleaned and service at least once a year. Normally, in the Fall, before you fire it up for the season.
Answers & Comments
Depending on the age of your heater, from what you described, it sounds as if the Thermocouple needs to be replaced. because it's an Infrared Heater rather than just a Blue Flame model. I would recommend, that unless you are very handy with tools and gas heating appliances, not to undertake the repair yourself. The Thermocouple itself is not an expensive part at all ($10.00 to $15.00). So having a professional repair it is the safest way to go. Because, during the repair he/she can also clean the interior of the unit and check or test for any of problems.
Keep in mind, DESA International who manufactured the Vanguard Heaters is no longer in business. But, some parts (like the Thermocouple) are still available.
It's always best to have your heater cleaned and service at least once a year. Normally, in the Fall, before you fire it up for the season.