Advice on tankless gas water heaters

Old 08-31-13, 11:15 PM
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Question Advice on tankless gas water heaters

I'm thinking about making the switch to a tankless gas water heater and am looking for some advice.

First questions are, do I need to run a dedicated electrical line from the panel box to the tankless gas heater? And what electrical line do I need to route? Is a 12-2 gauge elec wire ok?

Second questions... Are the venting systems hard to deal with? I keep hearing that the vents get super hot and you need a special thick type of vent? What if the place I plan to vent through n the attic and through the roof goes right by a air conditioning duct? Is it ok for the tankless water heater duct to come in contact with the air conditioning duct?

Final questions... Do I have to attach the tankless water heater to a wall adjacent to an exterior wall of the house?
Old 08-31-13, 11:43 PM
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In the opinion of many, including myself, tankless water heaters are usually not recommended for residential use. There ARE some instances where tankless makes sense like having several people taking long showers back-to-back or filling a large whirlpool bath tub or similar. Otherwise, the storage tank heaters are generally preferred.

First question is no, unless the manufacturer of the unit states it as a requirement. Manufacturer's requirement ALWAYS take precedence.

Second question is a maybe. The vast majority of tankless heaters use a stainless steel venting system that is quite expensive. As such you want to run the shortest vent possible. I personally would not run the venting up and out the roof and I definitely would not allow the vent to touch anything. A very few tankless heaters use a condensing type burner and heat exchanger and are vented with PVC piping. Again, the manufacturer's installation instructions are the requirements and MUST be followed for a safe installation.

Third question is no, but. The answer to the second question explains why.
Old 09-02-13, 11:47 AM
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Additionally you need to increase the gas line size to the unit to get the supported BTU's there..Its a calculation and in almost all instances a dedicated line needs to be run right from the meter...

So you see this may be a costly venture....

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