Water heater expansion tank conundrum

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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.
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On 11/21/2015 5:20 PM, Doug Miller wrote:

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.
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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.
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On 11/22/2015 7:06 AM, Doug Miller wrote:

Do you know how to boil water *without* HEATING it? (bring the tank into the vacuum of space??)
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On Sunday, November 22, 2015 at 7:47:43 AM UTC-8, Don Y wrote:

Phase change!
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due

*that*

that

normal

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

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On 11/22/2015 11:51 AM, Doug Miller wrote:

And, does it NOT expand??
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On Sun, 22 Nov 2015 12:01:11 -0700, Don Y

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
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On Sunday, November 22, 2015 at 4:45:51 PM UTC-5, snipped-for-privacy@snyder.on.ca wrote:

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

be

backflow

Of course it expands -- but not nearly enough to cause an explosion, unless it boils.
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On Monday, November 23, 2015 at 10:05:24 PM UTC-5, Doug Miller wrote:

Also, as I pointed out previously, water isn't the only thing that expands when heated. The steel tank does too, increasing it's volume.
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On Sun, 22 Nov 2015 08:48:08 -0700, Don Y

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!!
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On Sat, 21 Nov 2015 17:55:45 -0000 (UTC), Doug Miller

For the record, I'm not talking about the pressure valve. I can see that that's a good thing, and the house was built with one, which hasn't required a bit of maintenance in 36 years.

But what's wrong with my water going into the city supply. It's the same water they gave me in the first place. If it was good enough for me, why isn't it good enough for them again? Do they think I squeezed into the pipes and poisoned it?
And even if it does back up, is it going to back up all the way through my basement, under the front yard to the water main? Seems to me it will back up no more than 20 feet, and when I use the water again, the backed up water will come back into my own house.
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On Saturday, November 21, 2015 at 2:08:07 PM UTC-5, Micky wrote:

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
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wrote:

That would be terrible.
But I have nothing like that. I have a garden hose I use for less than 2 hours a year, and when i use it, it just has a nozzle and no container to siphon from.
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Water was off one day for 3 hours working on line own street. Told us to open big sink cold water spigots to clear the air out of the lines. The water was nasty brown. I guess that normal for old lines.
Greg
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wrote in 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.

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On Sun, 22 Nov 2015 00:24:09 -0000 (UTC), Doug Miller

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

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....
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