Tankless water heater - flue choices?


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Old 11-26-12, 03:23 PM
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Tankless water heater - flue choices?

For a basement installation where through-wall is not an option can any natural gas tankless heaters use a standard lined or unlined clay chimney?

I'm considering flying in the face of logic and going with a tankless. This is for a 1-bath vacation cottage that's unoccupied 90% of the time, only 2 at home when there, no dishwasher, short shower--if at all, no tub, no hot tub I see whole house 4GPM 80°+ rise units for under $500 but this is NOT to save money--I know there's no way a tankless will pay for itself--this is to avoid having 40 gallons of water sitting in a tank unused for a month at a time.

The installation would be within a few feet of the gas meter so running a dedicated supply line would be cheap & easy, and the chimney is right there as well.
 
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Old 11-26-12, 03:49 PM
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You need to check the installation manual for whatever product you chose. Some use stainless steel concentric venting, some use pvc, and others may use B-vent.
 
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Old 11-27-12, 09:47 AM
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Can I assume some are naturally vented through ordinary galvanized pipe? Makes sense to me since many of these heaters have similar BTU output & runtimes like a standard furnace of 80%-ish efficiency.

I'm interested in the middle-road units. Not 200,000 btu large family nor 50,000 btu point-of-use appliances.
 
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Old 11-27-12, 10:07 AM
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At a minumum and to keep cost down use a unit that utilizes PVC. The Nrc 83 dv (indoor) from noritz is a good choice.

Residential Tankless Water Heater - Residential Gas Water Heater | Noritz

Install manual to show venting options. It does not show here but in the bosch unit I installed it listed as being able the run pvc up the old steel flue.

http://support.noritz.com/download.p...llation Manual

You would have to post your unit as I have not seen any that use regular flue pipe as the vent.
 
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Old 11-29-12, 09:48 AM
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That Noritz would do it and PVC flue would be very easy to install but it's about 2X the price of comparable concentric-vent units like Rheem. Is it because it's a better unit or because there's more "stuff" inside? A PVC ventable unit would need a fan & all the sensors, sail switches, etc that go along. Are those present in concentric units?
 
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Old 11-29-12, 10:38 AM
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IDK the kit for this is about $90 - $120 bucks. I would think your talking this unit.

Rheem Tankless Mid-Efficiency 64 Direct Vent Indoor Series

And this kit?

Rheem RTG20210 Horizontal Termination Kit - Complete Kit for Standard In - Amazon.com

You need to make this fit where you exit with what the kit gives you. You need to be exact. This pipe you cant cut as far as I know.

PVC is mor flexible. Cut to size.

The units are the same. Power vent (fan), controls , sensors etc....
 
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Old 11-29-12, 03:51 PM
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I'm sure PVC would be a lot less challenging than trying to install concentric into the old chimney. I was hoping there were units that ran hot enough to vent directly into the masonry--like a regular water heater does. My chimney preference is just because I don't like the look of plastic pipes coming through the walls. With my big chimney in the center of the wall and a window on either side my options are a little limited but there should be enough clearance. My first choice (unfortunately) is right where the gas meter is

For this basement installation I would have to come through the rim joist & up high enough to insure it won't be blocked by snow...and away from the window. With a stepped-up vent pipe like that is it possible to slope it for condensate run-off or will I need to use a condensate collector?

 
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Old 12-01-12, 05:56 PM
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Anyone else noticing Guy's chimney looks bad?
 
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Old 12-01-12, 06:16 PM
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Just a skim coat.......No?
 
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Old 12-01-12, 08:01 PM
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Yes needs re-done with mesh. Then the stone. Give it time I've only had it a couple months.
 
 

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