75 gallon gas hot water heater

My 6 year old Rheem 50 gallon gas hot water heater is seeping water out the top and about to die. The warranty expired last month, of course. It is installed in a corner of my garage and vents out the roof of our second story house. We have 3 1/2 baths and a family of 8 and often run out of hot water. We are considering upgrading to a 75 gallon gas model, with higher BTU and larger first hour recovery specs.
I have found a number of places that sell 75 gallons models, home depot, sears, lowes, and many different brands, etc. No one seems to have 75 gallon in stock since it is not a common size, and all say 2 - 3 weeks to special order.
Most of the specs list a 4 inch vent. Currently I have a 3 inch vent as far as I now. Does this mean the vent size all the way up and through the roof will have to be upgraded? or can it just be adapted above the heater from 4 back to 3 inch? I assume that would be unsafe and violate some codes.
I have thought about a tankless but have pretty much ruled that out due to higher initial cost and concerns about its ability to keep up with my family's usage patterns.
Does anyone have any advice on how I can get a 75 gallon in short order? or any suggested alternatives or advice? I like traditional gas hot water heaters and I am relunctant to try anything unusual. Thanks, Tim C.
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If you live in a larger metropolitan area, there should be plumbing supply shops that keep such heaters in stock. By pumbing supply shops I mean those that deal mainly with the trade - not the Lowe's/Home Depots.
Doug

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Why would you want to heat hot water?
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wrote:

maybe it's not hot enough??

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wrote:

Poor Oscar... He searches daily for "Hot water heater" posts....everyone needs some kind of hobby....
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That line was popular with my HVAC instructor in High school shop class LOL LIke 20 friggin years ago.
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You must replace the smoke stack or die. Unless you want to invest a little more money and have a direct vent model installed. Everywhere you are looking only carries low end water heaters, you would be much better off dealing with a reputable plumber who can get you a better brand of water heater, will have it in stock, will safely install it, demand a 10 year parts and labor warranty, and enjoy a safe and comfortable 10 years. At that point, without thinking about it, replace you water heater again!
Good Luck, Bob P.

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Tim C. wrote:

You could have a demand high enough to be running out of hot water, but frankly I doubt it. I suspect the heater you had either was not up to par, maybe a dip tube problem or just low recovery rate. I suspect that a good 50 gallon is going to handle your needs. The added capacity of 75 vs 50 is really not going to help that much in my opinion. A good 50 gallon with better recovery is going to do better in my opinion.
Some other ideas, that will also save you some money. Get some good new water saving shower heads and monitor where all that water is going. You could save a lot more than the cost of the water heater if you are really using that much water.
--
Joseph Meehan

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Have you thought of running two 40 gallon units?
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With a proper valve arrangement, it would be possible to run two fortys in series -- and be able to valve off one or the other in case one broke.
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Christopher A. Young
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Dual Takagi gas tankless or one high recovery tank system would be best. You need to know Btu and recovery rate. A good 50 will do it.
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They're probably giving you a worst-case senerio for the timeframe. IE:
If the plumbing "special order" was just placed, and there won't be another for a week, *and* there isn't enough special order in that week for the warehouse to make a special pick & delivery to the store, it could take as long as 3 weeks.
They told me my "not-in-stock" Anderson windows could take up to 4 weeks, but they came within 1 week.
As for your stack size problem, a 75 or 80 gallon wouldn't need to be "high recovery" and therefore require a larger diameter stack, this is a home not a motel. I'm sure with up to 8 kids you're used to showering in shifts anyway.
snipped-for-privacy@aol.com
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This is Turtle.
Yes i can get a commercial 75 to 200 gal. hot water tank in short order but get your bilfold out when you order one. Now there is very little difference in the price of a 75 gal. and a 150 gal. models. Now when we said the magic word Commercial Hot water tank you said well I have the need and the money to pay good money for a commercial hot water tank. I'm not in the hot water tank business but i can order them over nite but i would venture to say it would be north of a $1,000.00 + installation to start with the regular models. Then it would travel farther north when you said I want QUICK recovery ability.
Now let me pull out my United warehouse CD and look you up one.
Hummm i see here a very nice one Residentiual Gas Water heater by Bradford White ML75S6FBN with 75 gal. tank / Natural gas / flow rate 76 G.P.H. / Shipping weight 264 # / and a nice price of $1,732.66 but i do get some discount here but the shipping will eat that up.
Now here is a very nice one that i like and it's a Commecial type and will feed hot water just about as fast as you can use it in about 2 or 3 bath rooms. It is a Brad Ford D100T2503NA / 98 gal. tank / 250,000 btu burner / 242 G.P.H. / Shipping Weight 609 # / and is a little high at $9,226.36 .
Now these prices can be beaten if you shop around but it is hard to do as a customer dealing with the Commercial warehouses.
Now if you just want all the hot water you want for 3 bath rooms and never run out 24 hours a day 7 days a week and run the water all the time at a flow rate of 8.5 G.P.M or 510 G.P.H. and this being 2 times the ability of any Commercial hot water tank you can buy less than $10,000.00 . The local prison uses these type water heaters for they need hot water for 3,000 inmates taking showers and just about running water 24 hours a day. the have a show bank of 18 shower heads and hook up 6 rinnai heater to the show head piping bank and 18 inmates can use all hot water at 140F each and run the water contenously 24 hours a day and stay at 140F water coming out Non-stop. Just get you a Rinnai Instant Natural gas hot water system which has a 10 year warranty on the whole unit. The best part of this things is if not in use it will turn it's self off and burn NO gas at all and only burn gas if you ask for water by opening a focet and start a flow rate. If you don't open a hot water focet it will not cost you nothing to keep the hot water ready to go on demand but will have a multi-gas heat BTU rating depending on the flow rate from 1,500 btu's to about 200,000 btu heating rate. Also it has anti-freeze thermostat that will turn on the heat just a little to keep the water above 40F and even hung on a outside wall. Also it has no pilot lite and has spark ignition. Here is the Website to look at them. http://www.foreverhotwater.com/products.shtml For about $1,000.00 to $1,500.00 you can buy all the equipment [ it being two different types ] but will have to pay to have it installed. Now this thing can be installed by yourself for it is just really just can hang it on the wall and pipe to it if installed outdoors.
Now with all this said. the flow rate that your looking for will not come from a hot water tank but a instant hot water system.
TURTLE
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Get on short order? Talk to a plumber, most wholesalers will stock them. Also your 3" vent is going to be a problem. With a larger heater you will need to upgrade the venting too. If replacing the venting is impractical you can buy sidewall vent, and power vented units that you can vent out the nearest wall. Greg
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Greg,
Regarding venting, the outside of the house is brick. The current vent is on the roof. I realize that a hole could be knocked in the brick for side vent, but I prefer to use the existing path out the roof, just a bigger vent.
If we put in a 4" vent, and later some year down the road get anothe water heater that only need a 3" vent, can we use the 4" venting system with that heater? I assume that would be OK, just not the other way around.
Thanks.
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Tim C. wrote:

In most cases yes. You just should not keep a 3" when a 4" is called for.
ChrisGW
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Down the road you may be able to vent a smaller heater through 3", but it will depend on the heater. Most manufacturers will include venting requirements in with the heater.
How much trouble is it going to be to replace the 3" vent with 4"? If the vent goes up through an attic area it would be pretty easy. If it goes up through finished space you may have a problem! "B" vent typically needs 1" of clearance to combustibles. So 3" will fit in a minimum 5" wall cavity. 4" will need a minimum 6" wall cavity. It probably will not be as easy as stuffing 4" vent up where the 3" vent was! You may be ripping out a wall to install the vent! A power or side wall vent may be a less expensive option, but power vent heaters can be troublesome, so I would avoid one and go with a natural draft heater like you have. Greg
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To all, I have been out sick for a few days but am back to working on my hot water heater. After doing some shopping around and getting with some plumbers, I have decided just to replace the 50 gal I have with another 50 gallon. Apparently it is too much trouble / expense to update my entire vent system from 3" to 4" - - one plumber didn't want to take the work on, and another very reputable plumber is going to charge me a lot, so I will just replace like with like.
I have bought a 50 gallon and have a couple of installation questions, which I will post in a new thread.
Again, thanks to all.
Tim C.
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