Water heater expansion tank conundrum

[Micky]

I forgot to say that these are electric WHs. I presume they make gas ones the same way.

[Paintedcow]

Ever heard of a backflow valve? They go into the sewer pipe to prevent water from backing up....

The reason you drain the valve is to REMOVE the sediment. If you begin draining it the first year it was installed, it should work fine. If it dont shut off, you need to replace the washer.

It's not a bad idea to drain the whole tank every few years too. Just shut off the gas valve or electric, before draining it.

[Micky]

Yes. It didn't work well enough. This was discussed at length here.

I know. I'm just telling what other people have said. And that I had only a tablespoon of sediment after 10 years, without ever having drained anything.

[clare]

The "correct" way to do it is the same way you do it with a well-pump system. You install an expansion tank at the water inlet into the building - right after the pressure regulator - consider the pressure regulator to be your water "source" - ie. the "pump"

[clare]

Generally not a good idea to trip the TPR for "testing" unless you are prepared to replace it when it doesn't seal properly afterwards - from expeience.

The higher end units usually have brass sediment drain valves. If you cheap out and buy one with plastic it is a very good idea to upgrade them to brass imediately, before they get brittle with age and become impossible to remove without breaking them.. Put a ball valve on while you are at it - - -

Use a "lockable" or "tamper proof" ball falve - has a sliding sleave that must be moved to operate the valve, and can be padlocked or zip-tied to prevent accidental (or malicious) opperation

[bob haller]

the reason for anti backflow prevention.....

lets say you have a garden hose filling your swimming pool. the main fails and the input pressure is now zero.

your icky pool water now siphons into the main all the way to your neighbors, they drink it and can get very ill

[Tony Hwang]

Over the years I had 6 houses custom built(5 in the city, 1 cabin; county jurisdiction) I used to dialise at home with machine supplied and installed by Alberta health care service until I had transplant. I heard of back flow check valve and have them in the house, never heard of expansion tank(not counting one with cabin well.) Nothing happened, two hot water tanks in the house for past 45 years or so. We always had pressure regulator set at 60 psi when water is running. Likewise out at cabin. Is my house gonna blow up without expansion tank. I'll let you know when it happens, LOL!

If city supplied water pressure is 120psi, that is insane IMO. House plumbing should be done to deal with that kinda pressure using heavier gauge piping or whatever....

[Doug Miller]

Don Y wrote in news:n2qc5h$41c$ [e-mail]:

news:n3605btdvs9avi246kpt1j8vvfrfptkeas@

Y -- if

forced

And that has absolutely nothing to do with expansion tanks. Water heaters explode due to a combination of runaway heating *and* a failed temperature-pressure relief valve. If *that* happens, no expansion tank is going to contain the enormous increase in pressure that precedes a catastrophic steam explosion.

[Doug Miller]

Micky wrote in news: [e-mail]:

news:n3605btdvs9avi246kpt1j8vvfrfptkeas@

-- if

forced

The water utility can guarantee its purity only until they put it into your house.

Nope, more like 20 yards.

Or your next-door neighbor's.

>

[Don Y]

Water heaters explode due to the fact that water EXPANDS when heated. (though some explode due to gas leaks) If you reread my post, you'll see that I didn't claim that they explode due to check valves installed upstream.

You'll note that the following paragraph expanded on this to indicate why you want to avoid "above nominal" pressures:

Regardless, you don't want to subject the various appliances in your home (water closets, dishwasher, washing machine, dryer, etc.) to elevated pressures -- possibly ABOVE their design limits!

regardless of whether or not the water heater will "explode".

OTOH, lack of an expansion tank *will* cause the pressure in the system to rise to levels well above "nominal" -- unless the occupants' usage patterns are frequent enough that pressure "vents" due to the normal opening of fixtures around the house. As such, when tanks corrode, over time, the increased pressure is more likely to force a leak and/or catastrophic failure of the tank -- before the TPR engages.

[Micky]

So if I had a yard 100 yards deep, I wouldn't need the tank?

Okay, I promise not to take the tank out, and to replace it if the bladder fails.

[Doug Miller]

Don Y wrote in news:n2rp7h$es8$ [e-mail]:

Don

supply,

to a

False. Water heaters explode due to the fact that water expands by several orders of magnitude when it is BOILED. Simple thermal expansion of water due to heating in normal operation does not cause water heaters to explode.

And I didn't say that you did make that claim.

True enough -- but lack of an expansion tank WILL NOT cause a water heater to explode.

[Doug Miller]

Micky wrote in news: [e-mail]:

Whether you need a tank, or not, depends on whether you have a check valve, or not, respectively.

[Don Y]

Do you know how to boil water *without* HEATING it? (bring the tank into the vacuum of space??)

[flakey714]

Phase change!

[Doug Miller]

Don Y wrote in news:n2snue$l24$ [e-mail]:

due

*that*

that

normal

Are you aware that water can be heated WITHOUT boiling it?

[Don Y]

And, does it NOT expand??

[clare]

If the thermostat on a water heater is functioning properly and the water heater is not on the top of a high mountain (or in an airplane) it is almost impossible for water to boil in the water heater, with maximum high limit temperatures for domestic water heaters in north america well below 190F or 90-ish C.

Years ago, many "boilers" had no thermostat or only rudimentary thermostats and a good friend of min's family home "blew up" one sunday morning when the rivetted copper water heater tank let go. Toot the floorboors off the joints on the main floor and upstairs except where the beds were located, took out all windows and doors, and unseated the roof. It was aver a month untill the farmhouse was habitable again and neighbors iver a mile away heard and felt the bang. Fortunately no-one was injured although their ears rang for a while. (and nobody fell through the floor getting out of bed!!

[clare]

0,00012 per degree F. So from 50 50 100F is 50F = expansion of 0.006. So 40 gallons of water at 50F = 40.25 gallons at 100F, and 40.5 gallons at 150F

[trader_4]

And what happens to the size of the water heater tank, when it's heated too?