Water heater safety valve

OP here- small update, I followed directions in the owners manual for getting air pocket back, turn off water supply, open closest faucet on hot side, open pressure valve and keep open till finished dripping- took about 20 min was very slow, it says let valve snap back closed- well it does not really "snap" back. So I closed it and let it heat up after 20 minutes as before it started to drip, not quite as bad, water was very hot after this time. I did order a new drain plug as it is plastic and will only come out one more time with out breaking. Will do a drain , re-fill and try again. Also just in case I ordered a valve . Do you think after 20 minutes the flame would turn off ?

Thanks for any more replies
Marty