Right now my home has two 40-gallon tall gas water heaters cascaded together. They are installed in the attic and about 15yrs old. Have a family of 5 in the house. I think 60-gallons is enough for our usage.

Is it cheaper for a plumber to replace with a single 60-gallon unit or two 40-gallon units?

Is a 60-gallon too heavy for the attic?

Personally, I have never understood the concept and accident/water damage waiting to happen by having a water heater in the attic. With 5 in the house it might be best you look into a tankless water heater.

My 0.02's worth on the matter.

As far as cost goes, a decent 40 gal. gas WH is around $400, and a 60 gal. is around $600. So right off the bat, you are saving money by just buying the one unit. As for installation, I would guess that installing 2 units has to be more expensive than installing 1.

Sort of the same thing with the weight in the attic. 60 gallons is going to be lighter than 2 x 40 gallons. If you are worried about the distribution, just get a couple of 2x8's and spread it over 3 or 4 rafters.

I would install a tankless and use the tax credit at the end of the year.

if you have gas, use tankless, about 700-800 plus the vent pipe for gas unit, the electric tankless will not perform as well as gas.

Tankless takes 3/4" gas line supply, which might be costly to run.

Do not let someone use a 1/2 to 3/4 nipple reducer to get the 3/4" supply line you need, It will starve your tankless and make it run lean, which is bad.

You will also need Class 4 Vent Pipe, which is stainless steel and very expensive.

I don't do alot of water heaters, but I think 50 is biggest most make, after that it becomes a boiler like the ones used in apartment to heat multiply units.

Purchase a good brand, Like A.O. Smith or Bradford White (Both available thru a Plumbing Store), I would stay away from Home Depot/Lowes water heaters

I dont like water heaters in the attic either. Tankless is the way to go. Especially if you can have a propane tank in your yard.

The difference between a WH and a boiler is the BTU input rating not the storage. You might have to go to a commerical grade past 50 but I am not sure about that.

Correct about the difference between a water heater and a boiler. Anything over 199,999 btu is a boiler and thing less is a water heater.


A family of 5 is also considered high usage. A big tankless is the way to go if you have enough gas to support it. You will spend more but it will eventually pay for itself plus you have unlimited hot water. If you put the tankless in the attic you will have less vent pipe to buy. Just use the 1" thick insulation on the water lines and cut the corners at 45 degree angles so they line up and duct tape to seal. I'd still recommend a pan below the tankless to be safe.

do you know how many comanies actually manufacture water heaters?