THIS IS CARRYING "INSTANT HOT WATER" TO THE MAX!

I recently wrote a blog entitled “Why is my hot water tank leaking?” and at that time I thought I had pretty much covered the basics of what to expect from a malfunctioning Hot water heater. Over this past weekend I ran across a thread on the DIYChatroom.com discussion group which not only has reminded me of additional dangerous possibilities of a hot water heater malfunction but gives me reason to reemphasize the importance of the T&P valve as well as the need for you to know how much potential damage an out of control HWH can cause. Reference http://www.diychatroom.com/f7/hot-water-coming-out-all-pipes-help-44137/ to read and understand how this situation started and the many postings in response to the thread that were made, including mine.
This homeowner comes home to find that hot water is coming from all faucets hot or cold and even in the toilet. What would your first thought be? Somehow the pipes have gotten crossed? Somebody has turned on a valve somewhere in the house blocking the cold water?(no such valve exists), It’s all in your mind, the days have become hot and the water must be heating in the pipes?.....NONE OF THE ABOVE. This homeowner has an out of control hot water heater with either no T&P valve or one that is stuck and not opening. As the thread continues we find that there apparently isn’t one at all. He posted his thread at about 7:30 Saturday morning and I saw it about 1 hour later along with another reader and I was afraid at that point that neither could have gotten back to him in time. If you read my response you will see that I am trying to give him some information but more importantly I am urging him to turn the darn HWH off then worry about why it’s doing it. It is also important to note that in today’s economy we all have to make decisions about what we can and cannot afford. I for one am disabled and have limited financial resources and have to make day to day decisions as to what I can spend money on just basic necessities. With that said the homeowner states he can’t afford a plumber and the reality is this is one of those things that he will have to afford and can surely afford a plumber more than to have to replace the house or pay for a funeral.
Now what happened? As I said in my opinion, and the opinion of all but one of the posters to the thread, is that for some as yet undetermined reason the HWH has over heated to the MAX and a malfunctioning or non-existent T&P valve has allowed so much pressure from this overheating to cause the boiling hot water to force its way through the plumbing system and seek an outlet to relieve the pressure. If the valve had been working the pressure would have been relieved by the valve opening and draining pressure and water out. In most cases the plumbing would not hold and the HWH tank would literally explode. One of the posters relates a story of HWH actually blowing out through the roof of the house and in this case had the HWH exploded it is gas fired and so a resulting fire and explosion would have probably occurred. CAN YOU NOW SEE WHY I WAS IN SUCH A PANIC WHEN I READ IT? We still don’t know the final outcome of this particular situation but we do know that he turned the HWH off in time and hopefully is addressing getting the problem repaired by a licensed plumber today.
The last posting (#20) sums up the things that some folks will do to save money and yet endanger their families (not aimed at this homeowner) plug up the hole where the T&P valve was supposed to be, or allow a non-functioning T&P valve to remain in place, unchecked and not replaced. Don’t wait for hot water to fill up your toilet. Read up on how to do a regular maintenance on your HWH or call a good plumber and ask that he come out and check yours at least on an annual basis. There are many other things that can cause problems with a HWH, stuck or malfunctioning thermostats, heating elements shorting out in an electrical heater, in the event of a gas fired heater faulty pilot lights and deteriorating burners. All of these as well as the general condition of the tank should be inspected and respected.