Downside to exterior gas tankless water heater?

Hello,
I've settled on getting a gas tankless water heater (no need to rehash the tank vs. tankless discussion). I realized that the place I want to mount the tankless unit inside the house is on an exterior wall, so I could just mount it on the outside of that wall. Is there a downside? I'm in Berkeley, CA, so it doesn't freeze here. The upside is simpler venting, and no need to get a sealed combustion unit (a requirement in my mind for an interior unit).
Cheers, Wayne
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Does the inspection department allow for installations like you suggest?
Personally I would think that the view of a heater outside would be a tad hideous. Arizona used to install heaters all of the time outside. Have not seen a new installation or remodel in 20 years.
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Good point, I will have to double check. Should be OK, though.

Well, this would be in a side yard 6' wide with a 6' fence at the property line, so it will be screened from view.
Cheers, Wayne
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Wayne Whitney wrote:

I don't think I have seen a unit designed to be used in an exposed area. Controls may not be water - rain tolerant.

--
Joseph Meehan

Dia duit
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Most models have a top vent connection, and an optional accessory is a vent cap for exterior installations. There are some models that are designed for exterior installations out of the box, e.g. the Paloma PH28ROF <http://www.waiwela.com/products.html .
Cheers, Wayne
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Wayne Whitney wrote:

We just did an exterior install last week and I found it to be much preferable to the interior installs that we have done. The unit that we installed has a thermostat that detects exterior temps and automatically comes on long enough to prevent freezing of the unit. This does not apply to the piping going to the unit, but the unit itself was protected.
The entire cost for venting of the unit was reduced to a $40 stainless steel vent cap that fits right onto the unit.
Minimum clearances from combustables was easily determined by the documentation and easy to comply with.
I would mount the unit as high as you can to avoid grasses and weeds from growing into it, but other than that, I cannot see why the unit should be taking up space inside when it works so well outside. Easier to service if it ever needs it.
The unit we installed even had a remote thermostat (purchased sepearately) which was mounted inside the home which allows the owners to change the temperature setting of the unit itself without having to go outside.
This is the unit that we installed:
http://www.plumbingstore.com/takagi_tk2_tankless.html
Good luck,
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Robert Allison
Rimshot, Inc.
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