High Limit 1 Error Code On Raypak 406A

[ncrealestateguy]

My heater will cut off and give me a High Limit 1 error code and then after a few minutes will kick back on.
Gas pressure is fine at 11.2 inches of water, (it is a propane heater), I put in new burners and pilot, and cleaned the heat exchanger fins. Water flow going into the heater is fine.
Where should I look next?

 

[kadavis]

Probably need to check the unitherm governor, they are different depending on whether the headers are capron (plastic)or metal(bronze)

 

[ncrealestateguy]

Thanks. When you say check it, do you mean to pull it out and submerge it in hot water to see if it moves or what? I have the polymer headers.

 

[kadavis]

Yes, and check everything else in that area while you're there