Wednesday, September 30, 2009

The Peruvian Water Heater (Therma) Controversy

One of the major issues among Peruvian familes is the Water Heater or Therma controversy. According to common Peruvian belief, it is deplorably wasteful to keep your therma on all the time...NOPE...they say, you have to turn that OFF and the only time you're allowed to have it ON is 40 minutes before you want to take a shower. The reason for this is purportedly to save on energy bills. There are even ADS to this effect as if turning off your water heater is going to keep the rain forests from getting cut down.


So let me get this straight, if you work at 6, and you have to get up at 5 to get ready, you now have to get up at 4:20 and turn on your damn therma if you want to have a hot shower in the morning? That's frickin' absurd.

The other thing that drives me nuts is I don't think this "turn of the therma" campaign has any kind of basis in scientific reasoning.

Newsflash! The therma's got an AUTOMATIC-SWITCH on it! Reference the above picture in which the little red light right in the center is turned OFF, thus meaning that the therma is not pulling any juice!

Another newsflash! Water has a HIGH HEAT CAPACITY...what that means is that it takes a LOOOONG time to head up water, and once it's heated it stays hot for a looooong time (to understand what I'm talking about, try heating a knife with a cigarette lighter for 30 seconds, now touch the to compare, try heating some water with a cigarette lighter for 30 seconds and then touching the water...get back to me on how this experiment works out).

With minimal insulation, that water is going to stay hot with one heating until its next required use. If your therma is turned ON, it can kick on and "top off" the heat. If you're turning your therma off like a frickin' moron, the water heater has to heat that water from the bottom every...single...time...thus resulting in a HIGHER ENERGY USE...

Ok, Ok, actually I haven't verified that last statement with any kind of scientific experimentation. The way to do it would be to go a month with your therma on, taking note of your energy bill, and then go a month turning it off (and turning it on at 4:20 so you can have a shower before work) and then seeing how your bill is different at the end of the month.

Look, if you do this, and you prove that there are SIGNIFICANT savings (I will NOT wake up at 4:20 in the morning just to save 2 dollars a month), then send them to me and I will PUBLISH them on my web page and tell everyone I meet to turn off their therma. But until a SCIENTIFIC study is done with EVERY type of therma available in Peru, and done under controlled conditions, DO NOT fund televison ADS telling people to turn off their therma like that's the way to save the frickin' world....
Subscribe to "Streets of Lima" by Email


  1. We do it. But we turn ours off in the morning and then back on again about 3pm if we can remember to do it (have to give our daughter a bath at night). We haven't done it consistently enough to find out whether it will lower our electricity bill substantially but I bet it will. I don't trust the automatic off switches, especially because the insulation from thermas can well as the storage capacit of the therma. And you are right, the water stays hot for a while, but runs out faster. I did a quick search and this is a pretty nerdy but useful citizen science analysis: Heating water is one the biggest energy costs/uses in our homes though, so it is worth investigating. Nonetheless, any attempt to educate people about how to reduce their energy usuage should be viewed as a good thing. If only the U.S. were so progressive in that sense.

  2. I also have doubts about how necessary it is to manually control the therma. However, I decided this was not a battle worth picking and instead we just installed an instant water heater in one of the showers. For all I know, using this device takes more electricity than leaving the therma running, but it keeps the peace.

  3. I've noticed the same thing and it drives me crazy as well. I've also noticed that walking around Miraflores, there's an abundance of uninsulated water heaters mounted on the OUTSIDE of apartments!

  4. Thomas aka HombreOsoChanchoOctober 2, 2009 at 6:21 AM

    I keep mine on all day just to increase the chance of global warming. Since we've had 11 years of global cooling I feel I need to help out Al Gore so he can afford is private jet and the carbon factory he calls home.

    Actually, I keep it on simply because I want hot water need it. If it costs me and extra 20 soles a month so be it. If I get home from a bar late at night and want to wash the crusty smoke out of my hair I can do so with a nice hot shower at 3am.

    I wonder if I can hook up one of those instant gas heaters to where my therma currently connects to the central water system thereby instantly heating water for my entire apartment. The thing I don't like about instant hot water heaters is they only work at one source. I like hot water in every faucet.

  5. Lucky gringo, you have water heater. We're not quite so lucky in our apartment in Cusco...

  6. Hey Ward,
    Yup, I lived waterheaterless for the first 8 years I was helped me though because it got me off my fat butt and into the gym (where I could get a hot shower) on a regular basis. Makes me think I should pitch the "no water heater" diet plan.

  7. Just get solar panels and you do not have to worry if you waste a bit of energy.... sun is free for all!