I have a Glo-Warm 30K BTU wall mounted propane unit. Installed 3 years ago. Designed to cover approx 1000 sq feet, covers first floor of home which is 994 sq ft overall, approx 650 sq ft if I close of unused rooms to just heat living space in use.

Unit connected to less than 8 feet of iron gas pipe, last 1 foot of which passes through wall to exterior of house. Iron pipe then connects to approx 30" corrugated line, then regulator / fitting which connects to 100LB propane tank. I have a stryofoam cover over the tank connection / regulator that I fashioned out of a cover normally used for an outside water spigot in winter, the sides are cut out. (Reason: used to have rain / snow freeze onto regulator).

Iron line installed with a "trap" beneath the heater for debris / water, this is clear. Iron line "slopes" downhill slightly from heater as line passes through wall to exterior of house, then meets corrugated line which curves gently upwards to meet the tank (no kinks). Corrugated line does no appear to have water or debris in it.

Operational details are as follows:
-- unit worked flawlessly when first installed 3 winters ago
-- unit has manual pilot / piezo igniter and variable gas control
-- last winter, and now progressively moreso this winter, unit does not work when outside temp drops below approx 20 - 25 degrees F
-- if outside temp is above 20 - 25 degrees F it works absolutely flawlessly, strong clean blue flame, output as if brand new
-- unit usually has pilot, but pilot "shrinks" when you turn up the unit to "ON" , possibly due to the "draw" of feeding the main burner
-- when very cold, pilot will ignite for a few seconds, then burn out, must wait a while to try to reignite pilot, unit rarely works to fire burner afterwards (perhaps pilot runs on propane in line, then poor volume or pressure causes it to exhaust the propane in the line before it "backfills"?)
-- if I am using unit as the outside temp drops, flame height in the unit decreases with occasional "orange": (oxygen?) "spikes"

Should I:
-- replace the thermocouple
OR
-- replace the regulator
OR
-- perform other troubleshooting?

Thanks very kindly for any assistance or advice ... J V

Heating & Cooling - Desa International - Blower Glow Warm Wall Heater