Gas h2o heater sizing, new installation

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jparrie

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We are doing a complete rebuild on our home, and I'm looking for advice on what to use for water heating. The plans call for a Tankless unit in the attic, but after much research, I'm not sold on tankless. The final straw against tankless is I have better things to do than flush out the water heater 2 to 4 times a year.

I would like to keep the water heater in the attic location as it is very central to master bath, office bath, guest bath and kitchen pretty much eliminating the need for a circulating system. The roofline in this location allows approx 5'-7" between the base for the tank and the roof sheathing. My plumber tells me that a 75 gallon tank would have enough capacity for our needs. He is not aware of any low profile 75 gallon gas heaters.

Questions:

1. Do you think 75 gallons is adequate? There are two full baths, two half baths. Kids are grown and gone, day to day use is my wife and myself. We rarely use a tub, but the master bathroom will have body sprays and a rain head.

2. Are there any low profile gas heaters made, or would a standard 75 gallon have enough clearance to be ok in this location?

Any other concerns? I would definately install a catch pan under the heater with drain piping to the exterior of the structure.

I would really like to keep the heater in this location, as the design allows for this area to contain the forced air unit, network hub, catv hub, whole house exhaust equipment, etc and it would be great to have all this equipment in the same place.
 

Mikey

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One concern I'd have would be the loading on whatever surface supports the water heater. You're looking at over 200 pounds per square foot, and I doubt any residential attic is designed for that static load.
 
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Jadnashua

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I'll second Mikey's comments. A WH generates a fairly concentrated load - you may need to beef up the ceiling joists, or ensure it is placed over a load bearing wall. A full 75-gallon tank would weigh over 600 pounds - probably in the order of 700 (about a 100 for the tank, which may be low).
 

Master Plumber Mark

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get a 50 gallon and be happy

Instead of a 75 gallon which is almost too big
for both of you ,

just go out and get a 50 gallon RHEEM gas hot
water heater with a 65,000 or 75,000btu burner...
( I cant remember which it is right now)

that is much smaller, and yet the thing heats
as fast or faster than a 75 can........


the cost is less than a 75, but more than
a normal 50.....


all it needs is a 4 inch chimmney.....

ww have put in a few and never have heard a peep
from anyone about running out of water.

its basically like a glorified boiler
 

jparrie

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All good feedback, exactly what I was looking for. Thanks guys!

I have my architect looking into the weight issue.

MP Mark, do you happen to know the height dimension of the Rheem tank you're talking about?
 

Master Plumber Mark

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Standard height...

I think it is a normal stardard height...

you will have to call around.....


Bradford White makes a LOW BOY 50 gallon

gas heater comming in around 49 inches tall....

Call some Bradford Dealer and see what they have

available in the larger BTU input levels....


either way you go you will still be much much cheaper
than the tankless ...
 

Mikey

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Also have your architect ensure there's sufficient access to remove & replace the thing in 15 years or so...
 

Jimbo

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I am not a fan at all of WH in the attic. First: climate. Are you somewhere where freezing of pipes would be an issue? Second, are you somewhere very hot, like Texas or the Southwest? There are known issues keeping pilots lit in extreme hot attics. Third, the consequences of a major WH leak from the attic are enormous.
 

jparrie

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I am not a fan at all of WH in the attic. First: climate. Are you somewhere where freezing of pipes would be an issue? Second, are you somewhere very hot, like Texas or the Southwest? There are known issues keeping pilots lit in extreme hot attics. Third, the consequences of a major WH leak from the attic are enormous.

Climate is mild, no frezzing issues, summer temps rarely exceed 95 degrees.

The possibility of a leak has me concerned as well. I'm not in the trade, so my experience with leaky water heaters has been limited to my own and those of family and friends. I have never seen anything more than a slow drip from a tank or a small stream from a tired relief valve.

Assuming that the relief and a drip pan are properly plumbed to outside the structure, what should I be worried about?
 

Jadnashua

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If you've got a good pan and its drain is not plugged, one hassle is that you might not see that it is leaking for awhile. And, in SoCal, you have to anchor the thing for earthquakes...not that much in an attic to tie it to reliably. This is just a guess, that may be a problem with the inspector all by itself.
 
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