atwood GC6AA-10 hot water heater

Also if it fails to start,short put those 2 pairs of wires in the picture above one pair at a time. The red and brown leads. They are connected to the high and low temp thermostats behind the black foam. If shorting one of them solves the problem, it could be defective. Easy to change and about $20 for the replacement kit.

It is acting normal… once the propane is flowing it will work fine and yes mine sounds like a jet engine to…

I had one that would try to light and go out. Cleaned the terminals on the circuit board with sandpaper and Bingo.There was a sticker in mine that said to clean the terminals before replacing the circuit board.
I pulled the 2 terminals to the right of the pressure relief, and the ones just below it and sanded them clean.

Getting propane flow initially can cause water heater (Fridge and/or furnace) to attempt 3 times to light off then 'lock out' Resetting by turning switch OFF/ON

So lighting off stove top burners on high helps get the propane flow established and the LP regulator to come into play for demand.

LOUD is subjective.....

Yes you can hear the main flame BUT it should NOT be extremely loud.

When it lights off check the flame:
Is the flame nice, steady blue with tinges of yellow at tip?
Loosen set screw on air shutter (yellow arrow)
Slide air shutter on burner tube (yellow circle) closing/opening slots until flame is correct........and less LOUD.

Also make sure flame engulfs the spark electrode

It is normal for air to be in the line that has to work it's way out. 4 or 5 tries sounds like quite a few tries though. After turning on the gas at your tank light a burner on the stove before you try the water heater. This will get most of the air out of the line.

Ya, there kinda loud.

Mine takes about 20-25 minutes to get up to temp and shut off.