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Bob4
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join:2012-07-22
New Jersey

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Bob4 to Jeff

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to Jeff

Re: Water Hammer: Possible Causes?

A bit of a long-shot, but... If you have an expansion tank on your water heater, make sure it hasn't failed and filled with water.

bbrcat
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bbrcat

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said by Bob4:

A bit of a long-shot, but... If you have an expansion tank on your water heater, make sure it hasn't failed and filled with water.

Not a longshot by any means. Mine had "failed" and had to be replaced after just 12 years or so.

sempergoofy
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join:2001-07-06
Smyrna, GA

sempergoofy

Premium Member

How does one determine if the expansion tank has failed? Tap it and listen? Or is there another a procedure?
Bob4
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join:2012-07-22
New Jersey

Bob4

Member

said by sempergoofy:

How does one determine if the expansion tank has failed? Tap it and listen? Or is there another a procedure?

Tapping it, if you have a good ear. Another way is to turn off the main water shut off, then open a faucet for a sink. If the water flows under pressure for a while (30 seconds?), the expansion tank is OK. If the water flows under pressure for just a few seconds, the expansion tank is no good.

Perhaps someone else has another way to test it.

Subaru
1-3-2-4
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join:2001-05-31
Greenwich, CT

Subaru to Bob4

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to Bob4
said by Bob4:

A bit of a long-shot, but... If you have an expansion tank on your water heater, make sure it hasn't failed and filled with water.

Hmm I never knew water heaters used expansion tanks.. I know the furnace here uses it but I don't see one for the water heater.

Coma
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join:2001-12-30
NirvanaLand

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Coma

Premium Member


In lieu of an expansion tank, I have seen a short length of pipe, capped and plumbed in vertical to the water supply line.

Old plumbers trick.

rfhar
The World Sport, Played In Every Country
Premium Member
join:2001-03-26
Buicktown,Mi

rfhar

Premium Member

said by Coma:


In lieu of an expansion tank, I have seen a short length of pipe, capped and plumbed in vertical to the water supply line.

Old plumbers trick.

This is the way most houses have been piped for decades locally. And the air can get out of these risers. the way to fix it is to drain all the water from the pipes and than turn the water back on again.

Lurch77
Premium Member
join:2001-11-22
Green Bay, WI

Lurch77

Premium Member

Agreed, the water will absorb the air and eventually fill the riser. Same thing with the old style open expansion tanks. You have to periodically drain them as they would become water logged over time.

Piping in a riser, old school style, is an interesting idea. A guy could put in a couple valves and tee to empty it without pulling down the entire house. But if you are going to go that far, just stick an expansion tank in the system.

Jeff
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join:2002-12-24
GMT -5

Jeff

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Thanks for the replies everyone. I never thought of the expansion tank. We had an issue with the hot water heater in Jan of 2010. The pressure release valve got stuck open, and hot water poured out in the basement. Luckily, we were home and I can't imagine it was going on for more than an hour, so it wasn't a huge deal, but the valve and the expansion tank were replaced at that time.

I'll check out the little test procedure anyway. For now, the hammer arresters have done the trick.

Thanks for the info/explanations.

jrs8084
Premium Member
join:2002-03-02
Statesville, NC

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jrs8084 to Subaru

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to Subaru
said by Subaru:

said by Bob4:

A bit of a long-shot, but... If you have an expansion tank on your water heater, make sure it hasn't failed and filled with water.

Hmm I never knew water heaters used expansion tanks.. I know the furnace here uses it but I don't see one for the water heater.

They didn't in the past, but when city water services started installing check valves (to prevent back flow-say I pipe in a well or somehow taint my water lines), these became necessary.) Fill a cold water heater, and the water expands. In the past, it just pushed back into the city water supply. With the check valves, you PSI goes through the roof. Hence the need for an expansion tank.

robbin
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join:2000-09-21
Leander, TX

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robbin to Bob4

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said by Bob4:

said by sempergoofy:

How does one determine if the expansion tank has failed? Tap it and listen? Or is there another a procedure?

Tapping it, if you have a good ear. Another way is to turn off the main water shut off, then open a faucet for a sink. If the water flows under pressure for a while (30 seconds?), the expansion tank is OK. If the water flows under pressure for just a few seconds, the expansion tank is no good.

Perhaps someone else has another way to test it.

The expansion tank should have an air valve on it like a tire does. Turn off the water and open a couple of faucets. Then use a pressure gauge to check the pressure. It should be set a few psi lower than the water pressure of the house. Best to use a bicycle pump if you need to add air to it as it is very easy to add too much when using a compressor.

Subaru
1-3-2-4
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join:2001-05-31
Greenwich, CT

Subaru to Coma

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to Coma
said by Coma:


In lieu of an expansion tank, I have seen a short length of pipe, capped and plumbed in vertical to the water supply line.

Old plumbers trick.

I will have to check.. the tank is not old old... maybe 10 years at this point.. BUT the pressure release valve is on top of the tank and has no pipe to move it away and down from the tank, it's just the valve it's self and it's somewhat leaking a bit.