Water Heater T&P valve

[ronaldrc]

How important is your Water Heater T&P valve?

 

[walkerj]

I've seen that episode.

My favorite is the one where they blow up the cement truck full of hardened cement.

 

[brian john]

Or the non-dairy creamer.

 

[480sparky]

I'll leave the plumbing problems to the plumbers. :smile:

 

[mxslick]

Gotta love Mythbusters...

Gotta love Mythbusters...

I'll leave the plumbing problems to the plumbers. :smile:

But it's relevant here since it was an electric water heater.

To get that result they bypassed the thermostat, hi-temp cutoff, and plugged all the openings for the hot and cold water and T&P valve.

The heater in the video shown was 52 gallon capacity.

They also exploded a 30 gal. heater with no building around it...the explosion was still huge, the tank took a full 30 seconds to land, and the hi-speed camera playback showed an impressive arc as the wiring was torn away.

Thier tests were absolute worst-case scenario, as I think that in a normal house setup something in the downstream plumbing would also fail from the excess pressure, thus reducing the force of the explosion a small amount.

 

[480sparky]

But it's relevant here since it was an electric water heater.

It's still a plumbers' issue. I don't supply or install water heaters. It's just a piece of equipment I hook power to.

I'm not liable for damage a garage door operator causes if the safetys are bypassed. I'm not to blame if a furnace springs a gas leak. I can't be held accountable for someone sticking their hand into an garbage disposal while it's running. Don't sue me if someone climbs into an electric dryer and turns it on.

Are water heaters potentially dangerous? Absolutely! But my liability stops at the terminals in the equipment, or at the receptacle it's plugged in to.

 

[don_resqcapt19]

The real issue with the energy in this type of incident is the fact that the explosion is actually a BLEVE (boiling liquid expanding vapor explosion or as one of my hazmat instructors called it...blast leveling everything very effectively). The conditions for a BLEVE are very simple. You have a vessel that holds a liquid under pressure and you heat that liquid to a temperature above its normal boiling point. The pressure prevents the liquid from boiling, but as soon as you release the pressure the liquid vaporizes. The vapor (steam in this case) takes up much more space than does the liquid. One gallon of water will make 1700 gallons of steam. This happens instantaly and that expansion is the energy for the blast or rocket effect.

 

[brian john]

I'm not liable for damage a garage door operator causes if the safetys are bypassed. I'm not to blame if a furnace springs a gas leak. I can't be held accountable for someone sticking their hand into an garbage disposal while it's running. Don't sue me if someone climbs into an electric dryer and turns it on.

There was a case in Washing DC where a baby was left in a sink by the mother and grabbed the hot water lever severely burning the his/her self. The mother sued the plumber, electrician, the utility company, the Hot Water heater manufacture, the apartment complex owner and management company. I never did here the final outcome but I am sure most escaped liability but still a legal fee that has to be paid.

I think they should have strapped Buster to the water heater.

 

[Strahan]

Seal a container of water and add a small amount of electricity and bingo you made hydrogen very very very explosive. Yes speaking from experience. Sometimes you just have to find out for yourself even if it is completly stupid:grin:

 

[don_resqcapt19]

Seal a container of water and add a small amount of electricity and bingo you made hydrogen very very very explosive. Yes speaking from experience. Sometimes you just have to find out for yourself even if it is completly stupid:grin:

Yes, you can break water down to hydrogen and oxygen by flowing current through the water, but that is not what is happening in this case. In the example here you are simply creating a steam explosion (BLEVE).

 

[mxslick]

...BLEVE (boiling liquid expanding vapor explosion or as one of my hazmat instructors called it...blast leveling everything very effectively).

I like that...simple and effectively explains to the common folk what happens.

I think they should have strapped Buster to the water heater.

It would have been interesting to see the effect of that blast on Buster...I think the primary effects would have been from the steam and maybe the sheet metal shell of the water heater, as it looked like the tanks themselves lost the bottom and went straight up like a rocket.