Water heater in uninsulated attic in Chicago

Member since 2018 · 78 posts · 31 votes

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.

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Michael BarnardPro Member

Member since 2021 · 11 posts · 11 votes

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!

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Michael BarnardPro Member
Member since 2021 · 11 posts · 11 votes
4y
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!

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John Warren
Real Estate Broker · 3412 S. Harlem Avenue Riverside, IL 60546 · Member since 2015 · 6k+ posts · 5k+ votes
4y
@Svend W. the most practical solution to be 99.9% sure is to have a small electric heater on a thermostat. This is a set it and forget it type of situation where you don't ever have to think about it again. The heater will kick on if it gets below a certain temperature (maybe 45 or something like that). You can wrap the pipes in insulation which helps some, and you definitely want to make sure the areas where the pipes are at are properly insulated.
I ran into this in Berwyn in a basement at a larger apartment building. The building had been converted from steam boiler to forced air, and of course none of the contractors thought about one of the basements where there were no furnaces.... we installed electric baseboard here and it has been a perfect solution.
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Svend W.Pro Member
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Member since 2018 · 78 posts · 31 votes
4y
@John Warren Great idea. I will look into that.

@Michael Barnard It is a traditional one. The heat trace is an interesting idea and that's a great point about the impact of the temperature up their on the bill. The tenant below will be paying the gas and electric, but I wouldn't want them to be getting sky-high bills needlessly.

Thanks.

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Drew SygitBusiness Member
Property Manager · Royal Oak, MI · Member since 2012 · 12k+ posts · 9k+ votes
4y
@Svend W. what happens to the HWH if the furnace goes out in middle of winter?
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Jonathan KlemmBusiness Member
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Contractor · Chicago, IL · Member since 2016 · 4k+ posts · 2k+ votes
3y
Hey @Svend W. - That's a really good question. @John Warren stole my thunder with the electric space heater, but that might be tough in an open attic. If there was a way to enclose the HWH & furnace that would be ideal. There is also a decent chance it might be fine....but not sure it's worth the risk.

Was the previous water heater up in the attic as well? Are the pipes insulated?

You are smart to be proactive against the Chicago winters because they do get pretty bad.
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