Heater will not stay on when you release the button

Hold the Red Button for much longer than you think. It has to fully heat the thermocouple safety device. Then release VERY slowly. There are tips here

https://www.google.com/search?safe=off&rlz=1C1QJDB_enCA643CA644&sxsrf=ALeKk019mViwcH7XzWSqfLTcR2JQMQz9Og%3A1614104534374&ei=1kc1YNilFquawbkP3IGz8As&q=all+pro+propane+heater+won%27t+stay+lit

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Sounds like the button is bad. Try replacing it

Blocked pilot flame too small or thermocouple needs replacing

Hi,
The thermocouple is bad and you will have to replace it...
The thermocouple is the thing that sticks up in the flame to sense that the flame is on... if it goes bad the pilot flame will not stay lit when you release the button...

heatman101

replace your thermocouple

thermocouple probablly bad, is the flame covering the thermocouple.
the flame has to hit top portion of thermocouple to work correctlly.

THERMO COUPLER, COPPER PEICE INSIDE TUBE MAKE SURE THE FLAME IS IN CONTACT WITH THIS PEICE, 99 PERCENT OF THE TIME IF A UNIT HEATER, WATER HEATER ETC WILL NOT STAY ON AND DOES WHEN YOU HOLD IT IN IT IS THE THERMO COUPLER

It sounds like a thermocouple has gone bad. this is a very common problem with gas powered things ie; water heaters, furnaces, hot tubs. The telltale sign is when you release the pilot light button it won't stay lit. This is a safety feature and is relatively inexpensive and easy to repair.

most likely you have a thermopile that has low output. it takes about 100mv to maintain pilot light