Help me keep my hot water heater from exploding

May 6, 2008 8:57 PM

What do I need to know to check my temperature and pressure release valve of my electric water heater? I just got a home maintenance book that says hot water heaters can explode if the pressure release valve becomes inoperable.

I check one website and it says to check it every 6 months. Talk to another person and they say I'm about to make a huge mistake by checking it at all.

I've owned my home for 3 years and the TPV has never been checked and I don't know if it was ever checked by the previous owners. The hot water heater (around 15 years old probably) is in the attic right above my daughter's bedroom. Therefore I'd rather end up with a leak into her bedroom versus a huge explosion above her bedroom.

So hivemind, what do I need to know in order to do this properly...especially if there is anything you learned about doing this that might be skipped over in home maintenance books and diy websites?

Bonus points for anyone that has stories of an explosion or near explosion that happened to them or someone they know. (Mostly so I can show this person that told me not to check it because they never explode that yes, sometimes they do)

Thanks for your help :)

posted by GlowWyrm to home & garden (11 comments total)

Boom.

According to these guys, both your thermostats and your pressure valve would have to fail to make it explode. You can check your valve just by slightly pulling it up, and see if water comes out. If it does, your valve's fine. That's how I do it anyway. And it might be a good time to check the overall state of your heater, considering that it is in the attic.
posted by ddaavviidd at 9:18 PM on May 6, 2008

You won't blow up your heater by checking that the PTR valve works. You might blow up your heater by continuing not to check that the PTR valve works. So, check the valve. The valve will be mounted right on the tank, quite near where the main hot water pipe comes out but on its own dedicated pipe, and it will have a little lever sticking out. All you need to do is move the little lever and see if you hear water rushing through the valve. It's really no big deal.
posted by flabdablet at 9:43 PM on May 6, 2008

The issue with checking the relief valve is that if it's sufficiently old and mineralized, it may not close all the way after being checked, resulting in an annoying leak until you change the valve out for a new one. If this happens, you can stop the leak by turning off the water to the heater, and it's pretty easy to change the valve yourself, just pick a new one up at a hardware store along with a pipe wrench (old one could need some leverage to get off!) and some of that thread sealant tape.
posted by trevyn at 10:01 PM on May 6, 2008

If you change the PTR be sure to re-install the down tube. It is there to prevent scalding in case the valve activates while someone is near the tank and to make it possible to approach the tank to turn the water off.
posted by Mitheral at 5:28 AM on May 7, 2008

What would be the harm in simply checking an appliance, whether it's a water heater, toaster oven, TV, or something else? If you check it, and all's good, then all's good. If you check it and find a problem, well, you've nipped it in the bud.
posted by scottso17 at 6:34 AM on May 7, 2008

A 15 year old water heater is at the end of its expected lifespan. You might consider just replacing it before it dumps many, many gallons of free-flowing city water into your daughter's bedroom. I don't think it's going to explode but I do think the tank is going to disintegrate when you start messing with it.

/voice of experience
posted by acorncup at 7:34 AM on May 7, 2008

I had a water heater that needed to use its release valve -- somehow the water pressure coming into the house became increased, and as I passed through the kitchen one night I heard a sound like raining in the basement. The release valve was doing its job, spraying water sideways from the unit all over the basement. So if the alternative that night was explosion, I am really, really glad that the release valve worked. Let's all check them regularly!

BTW, the city had to come and install a pressure-limiter on the water main that entered the house because it was way, way too pressure-full for the appliances.
posted by xo at 9:19 AM on May 7, 2008

Your water heater is in the *attic*? And it's *15* years old? I second replacing the whole water heater, with a nice new high-efficiency one. You (and your daughter) will sleep easier.

Another thought: Wouldn't it make sense to install a drain line from the pressure/temperature relief valve down to a drain? Just so it wouldn't totally *ruin* the bedroom ceiling if it ever did cut loose?
posted by exphysicist345 at 6:32 PM on May 7, 2008

Thanks for all your responses. I think you're right, we should just replace it given it's age. I've had this house almost 3 years but it was built in 1994. So I'm assuming that it's almost 15 years old. I looked around yesterday and could not see any sort of label or anything else indicating how old it was. However, there was a leaflet sitting on top of it that was covered in dust and almost crunchy from age. That alone tells me it's probably the original water heater.

Thanks again for everyone's response. Now to scrape my pennies together for a replacement.
posted by GlowWyrm at 10:14 AM on May 8, 2008

You know you can always get one of those new fancy Tankless Water Heaters they're better for the environment and they don't have a tank to explode! They also save space.
posted by Lisin at 7:48 AM on June 6, 2008

I looked into the tankless water heaters several months ago. They are ideal for new houses but my house would have to be re-plumbed in order to work with a tankless heater. :(
posted by GlowWyrm at 8:14 PM on June 8, 2008