New Install Gas water heater 5 questions

[Jsmallberries]

Replacing a 20 year old gas water heater with a new one that has a sealed combustion chamber.
1. No longer required to be up off the floor?
2. However, for ease of install it makes sense to put it on the old aluminum stand, any reason not to?
3.Can re-use the old one?(see pic)
4.I've never seen an expansion tank installed around here. There is a pressure release valve on an exterior hose bib, does that do the same thing?(see pic)
5. If you needed an expansion tank and none was installed, would any increase be released through the TPR valve on the side of the WH?

 

[Phog]

Answers, in order.

1. That is correct ** always check local codes though
2. It's fine to put it on the stand
3. Should be OK to re-use as long as the new unit fits on the stand. The insulation thickness in water heaters has increased in the past 20 years & your new unit might be larger size, in both diameter & height, for the same rated gallon capacity
4. No not the same thing, the expansion tank buffers the system pressure (holds the pressure to within a relatively small variance). The PRV will allow the pressure to rise & fall unimpeded, only having a relief effect if & when its cracking pressure is exceeded. Such pressure cycling is hard on all the components in your plumbing system but especially on your hot water tank. (Not all plumbing systems need expansion tanks, it depends on whether there is a check valve on your incoming city water line.)
5. In this scenario, the TPR will not necessarily open, but it definitely could. It will function in almost the exact same way as the PRV on your hose bib, letting the internal pressure out only above a certain high limit.

 

[Sponsor]

 

[Jsmallberries]

Thanks Phog,
Just gathering info prior to the change out.

Not one expansion tank in sight around here

 

[WorthFlorida]

If you follow the water heater installation instructions it most likely will require an expansion tank. They are relatively inexpensive and easy to install. In Florida we have high water temperature, about 75 degrees as compared to north states where cold water can be in the 40’s which mean a lot of expansion of water when heating it. You’re better off with it. If you’re going to have it installed the plumber may insist that one is installed. Some areas local codes are now requiring it.

The stand that your current water heater sits on looks too small for the new water heaters. One advantage is having the water heater off the floor is flooding. Should the burner ever go under water let alone the gas valve the heater is now toast. My son’s home in Altamonte Springs sits near the Little Wekiva River (more like a creek) and after Hurricane Matthew the first time ever this creek overflowed since the neighborhood was built in 1977. Just a 100’ away from his many homes went underwater. His house sits on a hill so he was ok. You may never know.

Another is the gas line. Not sure if that copper tubing is large enough for a new water heater. I have a feeling that you have propane? The installation instructions will list the required gas flow specifications.

 

[Jadnashua]

Many water utility companies are (sometimes, slowly) updating their systems to install check valves in their supply lines. Once that happens (if it hasn't already), your home becomes a closed system, and when heating water, it will dramatically raise the pressure until something leaks. that could be a leaky faucet, toilet fill valve, that pressure relief valve, or if all else fails, the safety valve (T&P) on the water heater. So, to prevent that from happening, if not now, in the future when they get on the ball and follow national recommendations to install check valves, it's wise, IMHO, to install an expansion tank now.

Depending on where the tank is located, code may also require a vacuum breaker on the installation.

 

[Jsmallberries]

Thanks for responding. I will install one anyway. So makes no difference with current set up with no check valve?
The gas connector will be replaced with one that matches the new BTU requirements(it is natural gas)
It's probably undersized now, but builder installed going on 20 years same heater
I will get the appropriate stand, depending on new dimensions

 

[Jadnashua]

If you have an open system (i.e., no check valve), other than to future-proof things that may or may not happen soon, yes, there's no technical reason to use an expansion tank.

One is required by local code where I live.

 

[Jsmallberries]

Okay 6 questions,

The WH dimensions...21.75D x 21.75W x 58.5H, will a 22" stand suffice, as per spec the 22 inch stand is 21.5 x 21.5.
Slight overhang, still fully supported as outer portion is just a shell right?