Water heater in uninsulated attic in Chicago

[Svend W.]

Hi everybody

I recently acquired an old house which has the furnace and water heater in an uninsulated attic.

I intend to eventually finish the attic as an ADU--during which time time I'll move the insulation from the attic floor to the rafters--but for now it's uninsulated and gets really cold.

What would you do to protect the water heater (which I just replaced)? Is an insulation blanket enough for Chicago winter?

Thanks.

[Michael Barnard]

Is it a tankless or a traditional hot water storage tank?

Not all but many tankless hot water heaters have freeze protection add ons that you can buy if its installed outdoors or in an uninsulated closet for something like an RV application so I would check with the manufacturers installation manual and see what their recommendations are.

For a traditional hot water storage tank the risk of freezing while not 0 if very very low. I'm unfamiliar with building codes in Chicago but in Massachusetts where I do HVAC work we cannot allow the tank to be less than 120 degrees as below that temperature bacteria can grow in the tank. So given the temperature the tank will be at the only significant risk of freeze is if for some reason it stops heating the water. What I would be worried about is the pipes themselves. When you're not using the water it won't be moving which will let it freeze quickly if it's cold enough. I would get a self regulating heat trace cable on the pipes and cover that with armaflex insulation. A self regulating heat trace will only turn on when it's cold giving you a set it and forget it option.

In my opinion the risk of freeze isn't the biggest concern though, you mentioned its an old house which means it has operated like this without issue for many many years. My chief concern would be utility costs to operate it, if this is a house hack for you or you're paying utilities I would look for options to get it out of the attic.

Sorry long post hope it helps!