Did my water heater blow up???

Heatermon

I almost forgot about those "new" flow through tanks from Watts. We've started using them more and more on water heaters for a couple of reasons. 1. They can be easily attached to the water heater itself along the side of the tank (we use the "earthquake strap"). 2. The "loop" you create by going down the side of the tank creates a pretty good "heat trap" (it also makes installing a W.A.G.S. valve easier) 3. It eliminates that awkward brace that is needed to secure a "traditional" expansion tank.

One othe question that occurs to me: If you do have a W.A.G.S. valve hooked up to your water heater and a pressure build up like a spike from the main water supply causes the water heater to leak, what happens to the rest of the system when the W.A.G.S. activates and shuts off the cold water supply? If the elevated pressure levels remain in the cold water side of the system, wouldn't other fixtures be in danger of "blowing up" also? Years ago, we used to install pressure only relief valves on the main water lines when a water heater and its relief valve were inside the building. We would set the outside pressure relief at 125 pounds so it SHOULD go off before the inside valve. I wonder if in todays world (think backflow prevention) we should be installing that "extra" relief valve on the main water line, after all the equipment (backflow preventer, regulators and any other equipment that "holds back water".

Just thinking out loud,

Heatermon

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Stray

Did my water heater blow up?

Something has happenened to my DHW unit.

40 gal nat gas. As you see in the pic, the taps on top for the water intake and outfeed have been somehow pushed/bent toward the flue. They actually pushed the flue off! (yes, yes CO danger and all...).

I managed to get the flue back between the soft copper lines, and the unit has been working fine for a month like this. I had opened the T&P just to make sure there wasn't some kind of crazy presure built up (and now the T&P drips of course).

What happened here?
Is it dangerous?
Is it effecting the efficiency of the unit?

Never seen this happen, and lookin' for some guidance. Thanks,
Erik

Mark Hunt

I had an EXACT situation


with the same make water heater a few years ago!!

You NEED a new water heater!!

I wish I could tell you why this happened but the manufacturer NEVER got back to me.

To make matters worse, the unit that I had that did that was in my mother-in-law's house!!

It looked like the tank expanded and rolled the hot/cold taps over just as your photo shows and water pressure was NOT the problem. Bad tank is what I think.

Do not wait to get a new water heater!

And I thought no one would ever believe me when I told them abouty this!!

Thanks for the picture, didn't get a chance to take pictures of my mother-in-law's water heater.

Mark H

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Unknown

This is typical

of center flue water heaters. They build up very high temps at the point of introduction of dilution air at the draft hood. The high temp area is just below the draft hood. It will cause the tank to expand and with it the piping may be bent. The worst design of water heaters their ever was.
The old full floaters and back flue heaters worked much better.

Replace the tank NOW as this is also a CO problem many times with water heaters. The baffle inside the flue will also be warped and affect the flue gas removal.

hot_rod

Thermal expansion

Get thee a suitably sized potable water thermal expansion tank (not the 2 gallon variety).

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clammy

d.h.w.tank

i've never seen that but i've seen the sides of tanks rupture.i don't know if it's code but i usally always install a domestic water water expansion tank on most jobs,because of thermal expansion i believe tanks are not made as well as years ago plus most houses have p.r.v. on the water mains or water meters with backflow devices or volume rest. a few years ago i saw the same promblem with indirect tanks sides splitting on alot of unitsthe cause of witch was all thermal expansion.my bosses did not believe me untill the tank i installed ruptured the next day in disbelief they sent someone else to install yet another tank that nite that tank ruptured .the next day i went back installed another tank with a portable expansion tank and that was it.now all hot water tank i do get a portable expansion and if the people don't go for it i let someone else do the job and deal with voiding the warranty in the instruction they write about this but who reads them anyway that my 2 cents worth

Starch

Right on, Mr. Yates!!!!!!!

That picture shows a CLASSIC example of thermal expansion damage to the water heater. I too have seen them rupture, when the relief valve sticks closed.

Install a new tank TODAY, along with a properly sized thermal expansion tank.

Dave, what did you mean when you said, "not the 2-gallon variety."

Starch

Mark Hunt

Dave


I agree 100% that a thermal expansion tank should go on every water heater however, the water heater that was in there before was 12 years old and never had a problem nor did the one prior to that.

There is no back-flow preventer, pressure reducing valve or flow checking device in my in-law's home. No change in water pressure and the tank that expanded was about 4 years old. The T&P valve was not stuck closed.

The manufacturer of that tank had nothing to say on the subject. That usually indicates a larger problem in my experience.

Mark H

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Starch

Possibly.....

In our little 'burgh, the water department has been installing BFP's in the meter barrells anytime they have to pull a meter for service. I had a long talk with the plant superintendent about the problems this could cause, as they had no policy of notifying the homeowner when this retrofit had been done. They now make a point of notifying the HO, and advising them to have an expansion tank installed. My preference would have been for them to notify the HO PRIOR to the BFP installation, but I'll take what I can get!!!!

Starch

Starch

One other thing....

just because the water heater has a pressure relief valve, that doesn't guarantee the PRV is working! In fact, my experience has been that the majority of them do not work after a few years. This issue was discussed here on the wall in detail a while back.

Starch

Mark Hunt

All valid points John


but I am not convinced that this was the case. If this was do to faulty T&P valves, why didn't the old tank show any signs of this and the T&P valve never even dripped on that one?

The new water heater does not have an expansion tank and it has never blown off nor has it expanded.

If the picture that was posted here was of a different make I would say that there was another force at work here, but because it is the same make I am beginning to wonder.

As stated before, I have found that when a manufacturer or rep tells that a situation that has confronted me is the only one they ever heard of I take that to mean that I am not alone.

There was a certain boiler manufacturer that had an issue with gas valves eating thermocouples like candy. When I asked the rep about it he told me that he had never heard of the problem from anyone else but me. He then suggested that I try "crimping" the pilot tube! I asked him how hard I should squeeze.

I later found out that the factory was very much aware of the problem and had in fact started installing repair kits to remedy the problem.

To be honest, I never persued the issue of the water heater and chalked it up to one of those things that will remain unknown. Now seeing that it has happened to someone else my curiosity has been piqued.

Mark H

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Heatermon

Seen this about 30 or so times in my carreer

Very common reaction to PRESSURE buid up (Not a thing to do with temperature). I"ve even done one on purpose to prove the condition (had a hand pump that I got the unit up to 500 psi before it moved metal. It scared the s**t out of me so bad that I've never tried it again). The most common type is yours (partially collapsed flue, crossed pipes, and reversed bottom). Have seen many heaters NOT leak after the event and only become a problem after flue gasses can't properly escape and the gas extinguishes itself. The T&P will stick shut during this event, but you can sometimes lift the handle afterwards and water will release. Then it will constantly drip water beacuse the washer was "glued" onto the seat and when it was manually opened the washer tore enough so it won't seat back properly. A couple of scenerios to think about when you say "This can't happen to me because there are no check valves between the water heater and the main water line"": 1. Not all pressure regulators have pressure by-passes built into them, and they too can fail. 2. Water districts, as a result of cross-connection control programs, are adding checks at the meters everyday, without informing homeowners. 3. If your main line freezes, it will stop water from backing out of the line, just like a check valve.

There is no "conspiracy" theory between the water heater manufacturers. I've seen this happen too many times and across too many different sizes, types and manufacturers' products. A good insurance policy is to install that "properly sized" (thanks PAH) expansion tank and test the T&P every 1-2 years (but be ready to replace it when it keeps dripping because you tore the washer when you lifted it off the seat). Otherwise, just put a new water heater and "hope" it doesn't happen again - but it will, if the conditions are right - 1. Closed system 2. Pressure increase 3.Relief valve stuck shut 4. No where else for water to go.


You will see "something" like this again - trust me.


Heatermon

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hot_rod

V1 x P1 = V2 x P2

Boyle's Law.

Why not the 2-gallon variety? Keep Boyle's Law in the back of your mind. What do the instructions indicate you should do with the tank's air pressure prior to installing? Pump it up to match the incoming pressure. Yeah, right. When did that become a static number??? So, let's agree we'll lose some tank volume to incoming water prior to accepting any thermal expansion. OK?

Our plumbing code books all state there will be 1 gallon of thermal expansion in 40 gallons of water heated from 45 to 140 (I think those are the delta-T numbers, but they could differ slightly - don't have my code books here at home).

Just for the fun of it, lets say there's no loss of expansion tank air volume because you've pumped up that bladder to match the 70 PSI "static" pressure. V1 (2) x P1 (70) = 140. OK, let's introduce Mr. 2-gallon thermal expansion tank to Mr. Thermal Expansion who has an all-day pass and can't be barred at the door. V1 now = 1 after accepting that 1-gallon of thermal expansion so P2 must now equal 140! Lose just a tad of air pressure (about 1 PSI per year through the bladder) or accept just about any volume of water due to the "static" pressure changing & you'll be seeing P2 exceed 150 PSI.

Do the same exercise with a 4.4-gallon thermal expansion tank & you'll see why that's all we install on our water heater installations.

The difference in cost is but a drop in the bucket compared to the cost of a new water heater installation - or worse.

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Unknown

Hey guys

it is over temperature at the top of the tank. A.O. Smith has had a problem with this for years. I have seen it with expansion and without. We ran a test and found that very high temperatures are created at the top of the tank internally and externally in the flue passage. The combination causes the metal to expand due to temperature, the ones we tested did not seem to have any apprecible increases in pressure. Our deduction was temperature. We changed many of the tanks over to Bradford White, problem went away.

[Deleted User]

ouch

lucky it didn't explode

Stray

Wow, I am

> lucky it didn't explode

Stray

Wow, I am...

enlightened by this site once again! Thanks all, for the time and detailed feedback. Suppose I'll shop for water heaters tomorrow...

Dave, while my physics math is a little fuzzy, I'm intrigued that all you ever put in are 4.4 expansion tanks. Never seen anything but the 2 gal ones installed in this application.

When you say the $ up-charge is minor....how much are we talking?

Also, am I crazy (probably) but could I pipe in another stand-alone T&P in the supply line near the DHW unit? I'm thinking this could be a failsafe (ie both T&P's would have to be defective/fail to open). Maybe that's not much solace considering how frequently these this fail anyway...

Rocky

I agree,

> Boyle's Law.

>

> Why not the 2-gallon variety?

> Keep Boyle's Law in the back of your mind. What

> do the instructions indicate you should do with

> the tank's air pressure prior to installing? Pump

> it up to match the incoming pressure. Yeah,

> right. When did that become a static number???

> So, let's agree we'll lose some tank volume to

> incoming water prior to accepting any thermal

> expansion. OK?

>

> Our plumbing code books all

> state there will be 1 gallon of thermal expansion

> in 40 gallons of water heated from 45 to 140 (I

> think those are the delta-T numbers, but they

> could differ slightly - don't have my code books

> here at home).

>

> Just for the fun of it, lets

> say there's no loss of expansion tank air volume

> because you've pumped up that bladder to match

> the 70 PSI "static" pressure. V1 (2) x P1 (70) =

> 140. OK, let's introduce Mr. 2-gallon thermal

> expansion tank to Mr. Thermal Expansion who has

> an all-day pass and can't be barred at the door.

> V1 now = 1 after accepting that 1-gallon of

> thermal expansion so P2 must now equal 140! Lose

> just a tad of air pressure (about 1 PSI per year

> through the bladder) or accept just about any

> volume of water due to the "static" pressure

> changing & you'll be seeing P2 exceed 150 PSI.

> Do the same exercise with a 4.4-gallon thermal

> expansion tank & you'll see why that's all we

> install on our water heater installations.

> The difference in cost is but a drop in the

> bucket compared to the cost of a new water heater

> installation - or worse.

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 98&Step=30"_To Learn More About This Contractor,

> Click Here to Visit Their Ad in "Find A

> Contractor"_/A_

hot_rod

well.....

99.99% of the failed thermal expansion tanks we see are the 2-gallon variety & often that failure results in killing off a perfectly good water heater. It's not just me though cause I checked with others and then went to a reliable source - our local water co guru of backflow - Steve Hengst. Steve confirmed my suspicions. He indicated my numbers were a tad low and said it's more like 99.999999%! So I set out exploring the issue & stumbled upon Boyle's Law. Crystal clear, but I wanted physical proof. So I set up my Dr. Demento lab in the driveway and used my digital refrigerant scale to test the 2-gallon and 4.4 gallon models. (We eventually used that 2-gallon model in a mall store that had a 6-gallon water heater. I had to get rid of it - all the guys at the shop were making fun of my having one in stock.) But I had a problem - only 95 PSI water delivery at my faucets. That's another story, but let's just say I'm testing the endurance of products at those pressures. So I rigged up an air compressor to pump additional water into the tanks. 150 PSI ain't exactly the norm for bicycle tire 12-volt pumps & I burned up two in the process. (Our industrial shop compressor doesn't hit those high numbers.) The digital scale allowed me to accurately determine acceptance volumes and confirm theoretical thermal expansion volumes/pressures once injected.

For about $5 bucks more, anyone can install the right size or they can keep on installing the undersized model. Pretty cheap insurance & protects the HO's investment.

Don't forget to adequately support those installations where the tank is installed on the horizontal! Think fulcrum. It's a **** responding to a flood at 2 AM!

BTW, Watts makes a flow-through TXT for those concerned about bacterial growth in stagnant potable water.

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Scott Toenniessen_2

Watts toilet pressure control valve

Check this out - a toilet fill valve that doubles as a thermal expansion relief valve.

https://www.wattsind.com/watts/index.cfm?ncp=yes&DID=9

Jack_15

presure

I had the same call on a oil fired Bock heater. The customer called for a smell, they did not notice when the pipes criss crossed it lifted the smoke pipe off causing the smell.
The water company installed a new water meter with a built in ckeck. We replaced the 32e and installed a st12.
From Jack..li