Laars EPG 250 gas valve

[aestey]

The gas valve on my Laars series one EPG 250 is a BMVRFT (Robertshaw 700-511), which needs to be replaced as it is sticking closed. Seems as though some of the 700-511 valves are "slow open" as where others are not. How can I tell if mine is "slow open" or not?

I have a spare valve, a 700-506 with identical specs to the 700-511 except it is not slow open. Do I need a slow open gas valve or could I use the 700-506?

Thanks