Another reason of such blockage is the presence of air in the gas line.
Propane wall mount heater shuts of after 30 sec.
On wall mount heaters it is usually located on the front of the heater near the floor.
If heater shuts off do not relight until you have provided fresh outside air.
There could a fault in the gas valve s main burner solenoid causing it to draw excessive power and starving the pilot flame solenoid.
If you re sure the unit has gas clean the aperture of the gas valve with a needle.
Keep all air openings in front top and bottom of heater free of objects and debris to ensure adequate air for proper combustion.
If heater keeps shutting off have it serviced.
Gas valve are allowed 30seconds to fall out.
How to troubleshoot gas wall heaters.
If so replace the entire valve.
The third reason of why your propane heater keeps shutting off can be a blocked up gas valve orifice.
Also there may be a pilot adjustment valve on your gas valve.
This might happen due to corrosion to the orifice and you don t have any choice apart from replacing it with a new one.
Gas wall heaters whether vented or unvented can supply enough heat to warm a small or medium sized room and they can operate with propane or natural gas.
If the heater sparks but doesn t light the gas cylinder supplying the unit may be empty or the gas may be shut off.