re: Pro's and Con's of installing a tankless water heater in attic

Are there cons to tankless?

I only ask because I've floated adding them to different plumbers at two different houses and I think every one has suggested sticking with the tank

3 years with mine and I like it. Replaced several 50 gal tanked units with this one.

Outside is easier to clean maintain and repair and replace plus if anything goes wron its on the exterior of your home also no holes through your roof for venting.

I moved mine outside when I switched over. Cost me about $2k with the water heater and plumbing rework.

I recently rented a small place for 90-days while looking for a new house. The owner had a gas tankless installed in an upper kitchen cabinet closest to the exterior wall with venting out the exterior wall. It was loud AF as it was right by the kitchen sink, but never lost hot water. If you are going electric you may have to upgrade to a 220V connection.

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Need electricity to operate it, even if it’s gas.

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This is a deal breaker for me.

Hurricane Zeta hit last year, power out for a day or so. Could still cook on gas cooktop, and never ran out of hot water from gas water heater tank.

Seems like if you lose power with tankless, you're out of luck.

I have 2 Rinnai tankless heaters in my attic. They are both condensing units. They work great and need to be direct vented outside through the roof with a roof jack. The condensing drain needs to be tied into the plumbing and you need a pan underneath it just in case there is ever a leak. I have had mine for 5 years and the original installers didn’t divert my condensing drain into my plumbing and it rusted out my drain pain by constantly dripping water when running, which is normal. The only thing not normal is it was suppose to be diverted to the plumbing drain and not into a drain pan. 5 years later and a rusted out pan, I finally got it installed correctly.

Gas is the only way to go as it is more efficient and placing the unit in close proximity to where it’s needed the most will prevent the wait for the water to get hot. Mine takes about 30-45 seconds to get hot, which is tolerable.

The only cons I can think is it usually needs to be flushed every 2 years to prevent calcium and lime build up and the cost. They are usually a good bit more expensive but the benefits definitely outweigh those issues.

I would look to relocate a water heater out of the attic. Asking for trouble there.

I did it, cons are the cost. Also, in the winter, on really cold mornings, it takes a while to get consistent hot water as it’s pulling water out of the supply line and that water is real cold. With a tank, the water from the tank is already hot

Pros, less space, less fuel cost, they last a long time sine there is no tank to rust out.

I’m overall happy with it.