1. The Bomb in Your Home Needs Your Attention!
By Stephen Ruback, Professional Inspector [TREC license 6030] page 1 of 2
Not the icon of doom that shows A common water heater tank size blow, they will be spewing boiling
up on your computer at the worst is 50 gallons, so the pressure in that water full blast. As the water heater
possible time – this is the real thing. one gallon air space, at boiling, keeps heating, they will keep
You just haven’t recognized it would rise to more than 900,000 psi, spewing. Wouldn’t it be handy if
because it’s been disguised as a if the tank were strong enough. It that boiling water was directed
water heater. would have to be a really super outside to a visible location that
Remember that cylindrical thing strong tank to hold that kind of didn’t cause damage? Well, they are
hidden away in some corner, closet pressure. Better than that – there’s supposed to be, but not all are. You
or attic that magically converts the no air space at all in your water may wish to check yours.
cool, incoming water to a nice hot heater. That means the pressure The valve is sized to discharge
bath or shower? That’s it. Some potential is infinite, but lets just say enough hot water from the tank, to
folks even have two of them. that it’s greater than trillions of keep the tank from overheating by
Let’s think a little smaller for a pounds per square inch! No tank in pulling in cool water from the
moment. When you heat a few cups the known universe could hold back supply line. If the pipe is blocked,
of water in a pot, or teakettle. Once that kind of pressure. In short, if the restricted or too small, we’re back to
that water is boiling, what could thermostat gets tired, falls asleep, the bomb. The discharge pipe for the
happen if it spilled? Could that be quits or dies on the job, your water PT valve is not supposed to be
dangerous or harmful? Of course. heater will keep on heating – smaller than the size of the opening
Now, enlarge the picture. Water without other intervention – quickly on the valve [typically 3/4 copper or
is rather compact, weighing in at becoming a 300 - 400 pound bomb. galvanized pipe]. If it is, your flow
about 8.2 pounds per gallon. If you Water heaters do blow up – is restricted. Elbows restrict flow.
convert that measly single gallon of spectacularly! They can make like a More than four, and you and your
water to a gas [steam], it will insist rocket and land down the street. family are definitely at risk. Uphill
on taking up more than 1250 gallons They can level a house. It’s flow allows water to collect in the
of space. Your water heater tank happened a lot. The death toll is pipe. When it blows, that water can
doesn’t have anywhere near that real. It’s not a pretty thought. That’s act like a plug – kaboom. Keep that
kind of room inside, and it’s already why an enterprising fellow, back in drain line running down, all the way
busy, holding 40 or 50 gallons of the 40’s invented a low cost device to the end.
water. Turning all 40 gallons into to prevent these catastrophes. It’s Your PT valve should have a
steam would demand more than called a Temperature & Pressure [or dedicated drain line. That is a line
50,000 gallons of space. This could Pressure/Temperature] relief valve. not connected to the drip pan or any
be a problem. That’s your T&P or PT valve for other line, and going directly to a
What would happen if the short. If your thermostat fails and safe and visible location [preferably
thermostat died and the heater went the PT valve doesn’t do its job or is outside]. Any deviation from this
into full-time on mode? A typical improperly installed, we are back to can cause serious problems.
electric water heater would reach square one with a very real, live For it to work, the temperature
full boiling temperature in little bomb in the house. It’s because of sensor inside must extend into the
more than two hours. A typical gas the PT valves, and short water tank several inches. When it is
heater would reach boiling heater life spans, that we don’t hear installed in a pipe outside of the
temperature in less than an hour. much in the news about water heater tank, it won’t work. Be sure yours is
Let’s look briefly at how big a explosions these days. installed in the right place for your
problem that might be. Just for Thermostats are sealed units with tank. That’s directly on top, or on
illustration, consider one gallon of no user serviceable parts inside. We the side of the water tank. If your
water in a two gallon super strong, are at their mercy, but PT valves are water heater is so old it doesn’t have
sealed tank. That gives a whole a slightly different story. They can a PT valve port, replace it, real soon.
gallon of air space to play with. be checked for proper installation PT valves get old and die,
Converting that gallon of water into and routinely checked for operation sometimes before the water heater
steam, will raise the pressure in that A PT valve is required for each dies. The only way to know if one
tank to more than 18 thousand psi. water heater, but they are not always works is to test it. That's why there’s
[pounds per square inch]. installed properly, and they can die a little lever on top, so you can open
Typical water heater tanks are too. Yours is calling to you at this it briefly to verify it is not stuck.
claimed to withstand as much as very moment. The valve manufacturer suggests,
150 psi. A significant portion of that Their function is to automatically in rather large print, the valve
pressure allowance is taken up with open and relieve the temperature should be tested at least once a year.
normal water pressure which and pressure in an overheat It’s a simple thing to do. Be sure the
typically runs more than 50 psi, but situation, thus avoiding an drain line for your PT valve is
it gets even more interesting. explosion. directed to a safe place, and lift the
That means, in an emergency lever for a few seconds.

2. The Bomb in Your Home Needs Your Attention!
By Stephen Ruback, Professional Inspector [TREC license 6030] page 2 of 2
Observe the water flow and good to breathe, carbon monoxide adventures can be avoided with
return the lever to its original kills, quietly and without smell. proper preparation, vigilance and
position. If it works, you’re OK. If it Early trouble signs are nausea and timely maintenance. Leaks never
won’t open, or won’t close fully, headaches. Be sure your water really fix themselves in the long run.
you have a bomb waiting to happen. heater has a generous supply of That brings up a related question.
Any malfunction calls for outside air for combustion, and that Where is your main water shut off
replacement of the valve. the flue is fully vented to the valve? Can you quickly and easily
When you do your weekly or outside. Those water heaters tucked turn off your water supply before
monthly home maintenance survey into a closet or back room suck large your house is flooded, when you
– you do that, right? Every time you amounts of air from your living have an emergency leak? There is
walk by the PT valve outlet, notice space and depend on poorly sealed supposed to be a service supply
whether it is dribbling water. If it house construction for that air. In valve for every house, but a
does, it’s time for replacement, as newer, tighter, energy efficient surprisingly large number do not
your bomb is almost ready. construction, inside gas water have one. Just because you have one
heaters must have a dependable doesn’t mean it works. It’s simple to
Other Common Concerns source of combustion air from the test. Close the main service valve,
Water heaters in garages should outside. then open one faucet and see if the
be installed with their ignition Typical life expectancy for gas water stops flowing. If it doesn’t,
sources at least 18 inches above the water heaters is about ten years, a you have a problem.
floor. That’s because cars get little more for electric. The most If your only shutoff valve is at the
parked in garages. Cars carry common failure mode is a leak. meter in one of those cute plastic
gasoline, which is very flammable. When was the last time you even boxes near the curb, think about
Cars can leak gasoline. Gasoline looked at your water heater? Unless how much damage could be caused
vapors are heavier than air, so they it’s in the garage, it is supposed to by a runaway leak when it takes
would gather at floor level. Most have a drip pan under it, with at hours for the water department to
garages are open enough to allow least a 1 inch diameter drain line, respond to your call.
some of the vapor to escape [from a directed to a visible location In the case of water heaters, and
small leak], hence the 18 inch [preferably outside]. That way, plumbing in general, “out of sight is
height. Does this apply to electric when [not if] it leaks, you may have out of mind” may not be in your
heaters too? You bet. Switches a visible warning before the flood. Is best interest.
generate sparks, and the electric your drip pan bigger than the By the way, new homes always
thermostat operates a switch. diameter of the heater to catch all need an inspection too. Be sure of
Gas water heaters offer additional probable leaks? It is clear of what you are buying, and avoid ugly
dangers. The hot combustion gasses insulation and other debris that surprises with a thorough home
are supposed to be directed outside could plug the drain? Most are not. inspection, before you close the
by the flue pipe. Right on the side of If your water heater is in your deal. You will save money and
each section of the pipe it says keep garage and you have a bunch of trouble in the long run.
at least one inch space from stuff stored in your garage, you
flammable materials. Does wood might appreciate having a drip pan Stephen Ruback is a licensed
burn? Does plastic burn? Of course, under that water heater too. Professional Inspector; member of
so make sure nothing is too close to Where is your shut off valve? TAREI [Texas Association of Real
your flue pipe – like rafters, roofing When the water heater leaks, it Estate Inspectors] and HAR
materials, foam insulated pipes or would be handy to be able to shut [Houston Association of Realtors];
plastic ducts. off the hot water line and still be approved by TREC [Texas Real
If your flue pipe doesn’t specify a able to use the cold facilities. Be Estate Commission] as a
clearance distance, it is probably sure you can get to that valve. Not Professional Home Inspection
single wall type that gets even hotter all are accessible. Even worse, some Instructor.
and requires even more space. Such have been installed on the output In addition, he has earned a BS in
flue pipes are outmoded and side which turns off the hot water engineering from Trinity University,
considered unsafe. Schedule flow to the house, but does not stop is an author of several books and
replacement as soon as possible. the water coming into the water teaches a variety of self
Gas water heaters actually have a heater – oops. empowerment courses through
fire in the bottom to heat the water. Corroded fittings, valves and Leisure Learning. For more
This fire requires lots of air to joints indicate a problem waiting to information, he can be reached at
support the combustion. Inadequate happen. It’s usually more 832-489-1071.
combustion air causes generation of convenient to have these taken care
carbon monoxide. of before they spring into
While any exhaust fumes are not emergency mode. Most plumbing