Mod # FPSH-40 Series 237
Looking to convert LP to Natural Gas Can U help??

May or may not be able to do so. In the old days, change the orifice and regulator and you werew good to go. Now, due to liability issues, many units are not changeable. AO smith has an online help desk, http://www.hotwater.com/customer-support/. I'd start there.

In order to switch over to natural gas you have to change orifices that put the gas into the burner. The natural gas orifice is bigger than the propane gas one. This should have been supplied with the water heater, but it is available if it was not taped to the unit. It is a little hex head nut with a hole in it in a plastic package attached to the gas valve. It is always supplied with the water heater. DrTom4444

Contacted AO Smith a conversion kit is no longer available for this model tank, I remember that the kit to convert was included with tanks, 20some years ago, with sticker, burner orifice, pilot orifice, gas valve regulator kit, I'm sure one is still out there somewhair. Thanks for the input
FPSH-40-Series237 Propane to nat gas

Could try eBay but it may be a stretch.

I don't know if you solved your problem but I have 2 conversion kits for AO Smith propane water heaters. One is going on Ebay soon. Contact me if interested.

[email protected]

I have a AO Smith water heater. I need to convert from propane to Nat gas. Mod # KGA-40-859. Please let me know if you can help. Joseph LaBate
(909)890-6704
[email protected]

Try this, call gas company and ask if they will convert it for you. Bet they do.