water heater insulation

thanks for all replies.. went to local hardware and got the wrap for regular water heaters and just cut and taped.. havent heated it up yet but should work just fine..

Two considerations to balance. Expanded polystyrene (Styrofoam) next to a gas/electric appliance still appears to me to be a huge fire hazard.

Balance this against mice nesting in fiberglass insulation. My preference is fiberglass.

Mine doesn't have any either, for about 6 years now. Had to take it off to fix leak (tighten connection). Makes it easy to inspect for leaks. Haven't noticed any difference in propane usage and easy to inspect.

Yes, you can get the styrofoam insulation separate.

I replaced the old water heater in my motorhome with a new one. The old one was basically wrapped in fiberglass insulation and contained in a cardboard box. The new one was contained in a Styrofoam box with no fiberglass.
When you consider that under normal operation the tank doesn't exceed 120 degrees F, I would imagine that you could simply wrap the water heater in a single batting of fiberglass insulation.