I live in the home I grew up in, my parents are deceased, the home will be 48 years old in June 2010 and it still has the original Rheem natural gas tank water heater in it which needs a new one run right up under it if you get my meaning. I don't know the capacity of the tank nor are there any visible model or serial numbers anywhere that I can find on the tank. Like I said it's a Rheem and since this tank has lasted so long I'd like to replace it with another Rheem if the price isn't too expensive. I live alone, no kids or family so I wouldn't need a high capacity tank. I have contacted a few plumbers who have taken my name and number and said they would get back with me. If the Rheem replacement tank ends up being too expensive should I consider buying another brand from Lowe's or Home Depot? Rheem told me yesterday that G.E. natural gas water heaters sold at Home Depot are made by them, Rheem. What should I look for in selecting a new natural gas tank water heater to replace my current 48 year old one which doesn't seem to be keeping the water hot as long as it did years ago? I live in coastal Mississippi and my current water heater is installed in my utility room outside from the main part of the house, my utility room is not cooled by AC during the summer or warmed by heat during the winter and both doors to my utility room are louvered for ventilation.

Have I posted my question in the wrong forum? 46 views and no replies?

A 30 gallon tank is typically more than enough storage for a single person, and the smaller the volume the less surface area, and lower standby loss, all else being equal.

What parameters are important to you- fuel efficiency? Space? Low up-front cost?

I'm assuming the old heater had a standing pilot ignition, and was burning 75-100therms/year in pilot + standby losses (half your fuel is standby.)  Going to an electronic ignition version would cut that by at least 50 therms up front, but you'd have a higher installation expense since you'd have to run electricity to it.

For similar or sometimes lower installed price you may be able to install a Bosch 1600H tankless on-demand with water-powered ignition (no wiring necessary).  It's standby loss would be zero, and you'd only heat the water as needed.  But since it's burner is 3-4x the size of a tank, it may mean upgrading the natural gas plumbing, which would again start to be expensive.  But it would take up a lot less space, and be dramatically more efficient for the low-volume user.  Your biggest issue with it would be keeping it from flaming out at very low flow since it doesn't modulate below 30KBTU/hour. This would be more likely in summer, but it doesn't take long to train yourself to always turn the hot water on to a good clip to get it/keep it going.  It'll still be more efficient than a tank in your application, despite sending a higher than necessary flow down the drains just for washing hands, etc.   There are similar smaller units (Marey, etc) mostly used in tropical climates that might be sufficient for your use, but watch out for safety agency ratings on some of them. Similarly, there are some electronically controlled versions from other vendors that can be plugged in to a standard outlet. If it can be used with inexpensive double-wall "B-vent", the installed cost will be hundreds lower than if it needs stainless "Z-vent", which is why ~80% efficient versions are probably a better choice than an 82% version, even if the cost of the heater is the same or less.  A tankless is typically good for 20+ years even with 3-4 people using it- probably decades more, in your case.

But a 30 gallon atmospheric-drafted unit is attractively cheap, and the standard form-factor for the US. It's hard to make up the difference in installed cost with fuel savings, for a single person in an area where the incoming water probably averages well over 60F. If you go that route, note that the 6-year warranty tanks are physically identical to 10year or 12 year versions, the only difference is the up-front cost and the terms of the warranty (which typically only covers the cost of the tank, pro-rated, and not the installation costs).  If your last tank went over 40 years with little or no maintenance it means your water isn't to mineralized or corrosive, and a new tank should last well over a decade anyway, so paying the extra money front is a waste (usually is, no matter where you live.)

I don't want to incur any additional expense so I could be able to use an electrical tank, I want to stay with natural gas, you recommend I drop down from a 40 to a 30 gallon tank? Another discussion board recommended the opposite, to go from a 40 to a 50 gallon tank. I spoke to Rheem.com last week, they told me that G.E. tanks sold in Home Depot stores were made by them, made by Rheem. I have put in calls to 2 licensed plumbers last week who say they sell and install Rheem tanks, they've got my number, haven't heard back from either plumber just yet. Lowe's sells Whirlpool tank natural gas water heaters, I have Whirlpool appliances in my house, frig, dw, washer and clothes dryer, would their hot water tanks be any good? As good as a G.E. tank built by Rheem?

The standby loss on an electric tank would be lower, but it's heating expense typically higher (and recovery time much longer). Stick with gas if you can.

Unless you have a large soaking-tub to fill, the only advantage to going larger than 30 gallons would be when selling the place to a family of 3.  The operating cost of a larger tank will be typically higher due to higher standby losses, but that can be determined by the EF number on the rating label (a higher EF # indicates lower standby loss.)  If you typically host multiple overnight guests who all want to shower in the morning, then go with 50gallons, but if it's usually just you, 30 should suffice.

What Rheem was building 50 years ago isn't necessarily a good indicator of what is built today- don't get too hung up on the manufacturer, but DO google specific models for problems associated with that model.  It's a competitive marketplace, and vendors just can't survive without rectifying design & manufacturing issues.  That said Whirlpool units are currently made by A.O. Smith, and GEs are made by Rheem, the latter of which has a somewhat better recent reputation, so it may be "safer" to go with GE.  Rheem also builds goods for Ruud, Vanguard, and Richmond, but whether any are built to a different spec using different parts is beyond me.  But it's a moving target, and I may be trading on dated information...

The electrical portions of those other heaters I mentioned was just for the ignition & controls, and not electric tanks, but electric-ignition gas fired tanks or modulating gas-fired on-demand heaters.  If the gas lines are fat enough/short enough to support a Bosch 1600H on-demand heater.  It would have a lower operating cost and runs without needing electricity.  With an on-demand you would never run out of hot water, and it would take less space than a typical tank. They're about the size of a medium sized backpack or airline carry-on suitcase, and hang on the wall, and it operates by adjusting the flame up/down based on the flow rate of the water to heat it instantaneously as-needed to the output temperature you set:



"Look ma, no wires!"

It's probably a couple or three hundred more (installed) than a decent 30-40 gallon tank, but it will save ~$50-75/year or more in fuel costs for a single-person household. And they outlast most tanks by a decade or more.

Thanks for that detailed post. I plan to stick with another natural gas water heater but last night I took a shower, the very hot water lasted about 10 minutes then suddenly the water went from hot to warm to a luke warm. I think I'll go check the temperature setting on the tank to see if it's on all the way hot. Assuming the temperature is not set all the way to hot but just to warm, considering the age of my tank, 48 years, should I just leave it set to warm or turn it up to hot, that is if it's not on hot now? I don't want to worry about the tank blowing up and starting a house fire if I did move the dial from warm to hot.

Based on the syptoms it's highly likely that the dip-tube that directs the flow of incoming water to the bottom of the tank has corroded or fallen away, creating a mixing of cold & hot in the top or middle of the tank instead of at the bottom as-designed.  This may be repairable with a replacement dip tube (either a stock replacement, or fabricated by a competent plumber.)



If the anti-corrosion anode (aka "sacrificial anode" ) has never been replaced, a compromised dip tube is a likely outcome.

Raising the temperature won't damage the tank, but it isn't likely to cure the symptom, may make that first 3 gallons drawn dangerously hot, and will increase the standby losses.  Crank it up a bit to see what happens, but not all the way hot all at once. (Some older tanks could get as high as 150F, which is nearly-instant scald territory.)