Water heater questions from a newbie

CA codes do not require the expansion tank, not does the local code here in San Diego. They haven't caught on yet. All manufacturers ( read the details in your Rheem/GE install manual ) RECOMMEND an expansion tank.

Your unit has probably a 40,000 btu burner, where 10 years ago a similar tank may have been 34,000, or even less. The overall efficiciency is also higher. SO, it heats the water faster, thus the expansion becomes an issue, whereas in the past it may not have been.

Your inspector, if you call for a permit, will want to see self-tapping sheet metal screws in the connection of the elbow to the draft hood.

Excessive pressure inside the house is detrimental to hoses (like on your washing machine, icemaker, dishwasher, and possibly any other flex hose feeding a faucet or toilet). The bypass in the PRV only works if the house pressure exceeds the incoming pressure. If the supply pressure is very high, it may never bypass, and you'll still end up with high pressure in the house. Save wear and tear on any of those flexible fittings, o-rings, gaskets, etc. in the house and install an expansion tank when you have a PRV installed. Things will likely last longer, and your T&P valve won't cycle, possibly rusting out the bottom of the WH from periodic wetting.

Water Pressure

I Am Sorry To Disagree With Jimbo, And Your Topdog Inspector,

But The State Of Calif. And "all" Local Jurisdictions Go By The Uniform Plumbing Code Which Since The Early 90's Has Required
The Use Of Thermal Expansion Tanks Anytime There Is A Closed System On The Water Heater

This Is Defined By;
#1 Having A Check Valve Installed On The Cold Water That Prevents Thermal Expansion,
#2 By " Excessive Street Water Pressure That Is Equal Or The Same As 150 Psi" Which At Nite Is What Your 120 Psi Pressure Go's Up To
Remember What I Said About The Double Gage You Leave It On Over-nite The Red Hand Will Stay At The Highest Pressure Reached Overtime,

The Reason This Bad Is When The T&p Weeps Constantly It Causes A
Lime Buildup In The T&p That "could" Freeze The T&p Closed

Which Is Equal To Cutting Your Emergency Brake Cable Loose
Before Coasting Down The Grapevine ! ! !

The Possibility Of All This Happening In That Order Is About The Same As A Space Shuttle Blowing Up On Takeoff Or Burning Up Trying To Land,
But Remember It Only Has To Happen Once To Your Family

All This I Quoted From The Code Book Can Be Backed Up At Your Local Library Or By Calling The County Building Dept,
Since Your Local Inspector Seems Not To Know The Plumbing Code

Water Pressure

This Is Also The Way Water Heater Mfg's Look At Your Warranty Claim If Your Heater Starts Leaking Under Warranty

I Know This Because I Have Done Work As A Mfg's Service Agent For All Water Heater Mfg's Full Time Since 1989 And Each Co, As
A Journeyman Plumber Since 1976

And Have Had To Correct Both Lic. Plumbers And Plumbing Inspectors In Regard To Both, Code And The Mfg's Warranty
Rules

UPDATE:

1. The valve stopped leaking a few hours after it was installed and hasn't dripped since.

2. Vent has been secured at every joint with 3 screws

3. I'm checking into an expansion tank.

4. I'm getting up a 3:00 am tomorrow morning so I'll recheck the water pressure to see what it will rise up to. I did call the city yard and they said in some areas of the city they are pushing 125-150 psi to get it up the hills. I live about a 1/4 of the way up so they said I should see more pressure that the homes at the top. They are coming by tomorrow to check my pressure though.

5. I've got a new PRV to install this weekend. (unless they get mine adjusted)

What size expansion tank should I get for a 50 gal water heater. I've seen ads stating a 2 gal would be the right size but have also seen 5 gal?

You can buy a pressure gauge which has a "second hand" which will stay at the maximum pressure even when the regular hand drops to a lower pressure. Very handy for seeing what the max PSI is overnight.

Another good test is to measure the static pressure, then run 10-20 gallons of hot water quickly (e.g. open a tub faucet), then shut off the faucet and watch the pressure gauge for the next 5 or 10 minutes as the water heater heats up that big slug of cold water. With a closed system and no expansion tank, you will be surprised how high your pressure may go (was 180 in my house before we put in the expansion tank).

www.watts.com has a nice expansion tank calculator on their website. It depends on several things: normal incoming water temperature, max temp at the WH, and the size of the WH tank. Make sure you get a potable water one, and not one for hydronic heating.

Ok...it looks like you have made a believer out of me with the expansion tank...even though the city says it it not required. It looks like a 2.1 gallon expansion tank will work for me. I do have a couple of questions though.

1. Can the tank be oriented in both vertical or horizontal positions? I have not found in any of the literature that states this. My available space is next to nothing.

2. Does this need to be mounted to the wall? All the diagrams look like it is just sitting on the piping. What about earthquake strapping, is it needed?

Water Pressure

Yes It Can Be Eather Way But You Want To Make Sure That You Have Access To The Air Nipple On The End ! !

Set The Air Pressure About 75 Psi. With A Air Gage Before You Mount It

Yes Most Installs Show Mounted On Pipe, But Knowing What Kind Of Room You Have In The Garage Thats Why I Said About Using Earthquake Strap To Mount To The Side Wall As Long As You Find The Studs To Mount It To,

Thinks Steve For Your Input That Is What I Was Trying To Say

You tellem Mac!


Did you try calling?

Water Pressure

One Last Thing If I Was You, ! !
Get The Model #, Date Mfg, Or Serial Number If It Has One
Plus The Same Information Off Your New Water Heater And Start A File In Your Computer,
That Saves A Lot Of Look Up Time If Their Is A Warranty Issue,

If You Call The Mfg, Or A Service Agent The 3 Things They Want To Know
#1 Model Number
#2 Serial Number
#3 The Date Purchased Or Installed

On The Expansion Tank It Depends How You End Up Mounting It
If You Can Later Read This On The Wall

I found a pressure gauge with a second "lazy hand". I will have to rig up an adaptor because all of the hose bibs have vacuum breakers on them and they have a small stem that sticks out and blocks the hole for the gauge.

Well, macplumb is right. Sort of. 608.3 does require an expansion tank on any system provided with a check valve, backflow preventer, or any normally closed device. Apparently the inspectors condisider that most PRV are bypass type, and consider that a "loophole" in the law, because they are not failing installs for lack of expansion tank.

Water Pressure Testing

Put Your Gage On The Water Heater Drain Hose Connection

Or Disconnect Your Cold Water Washer Hose Over Nite And Use That One

Does an expansion tank need to be close to the water heater? My WH is 30ft away from the meter. There's a good mounting spot near the meter.

Which side of the water softener should the tank be mounted on?

Actual distance doesn't matter - the pressure in the house should be essentially the same all over unless a section is closed off. That's the problem, if you turn off the input supply to the WH (and you do want it on the supply side), if the expansion tank is on the supply side of the valve, if the WH is still on, there'd be no place for that expanding water to go...it'd be as if you didn't have one. So, ideally, that tap is after the WH incoming shutoff and before the tank on the cold side. Now, that doesn't mean the tank has to be physically located there, but you may not want to run a pipe back to it in what would end up being mostly stagnent water since there' be no flow, or at least not enough to purge the line as water moved in and out of the expansion tank.

If you can have your shutoff to the WH back there, too, then it would work fine.

Thermal Expansion Tank

Yes You Need The Expansion Tank Between The Cold Water Ball Valve And The Water Heater It's Purpose Is To Protect The
Water Heater From Too Much Thermal Expansion,
That Is A Requirement Of The Mfg's Warranty