Bubble, bubble, mostly trouble
Jan. 26th, 2005 02:47 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
jere7myI'm still in my nightshirt, waiting while a little gas flame heats 50 gallons of water to a reasonable temperature. Our water heater has just been repaired, you see. I imagine most of you don't care how a water heater works, but I puzzled it out last night, so for funsies I'll put it behind a cut.
Okay, I don't actually know how our water heater works, but this is what I deduced at 4AM, crawling around our freezing dirt-floored basement on my hands and knees, reading instructions with a penlight:
There is a gas flame beneath the tank, just like the one on a gas stove. The gas comes on when the water gets too cold, and goes off when it gets hot enough. This flame is lit by a pilot light, which is always on—unless it is not, which was the case last night. If it is not, there is a problem: the water gets cold, the main gas comes on, nothing ignites it, the water never gets hot, the main gas never shuts off, and soon your basement is full of natural gas.
Happily, there is a safety feature built-in: a little bit of metal called a thermocouple, which sits directly in the pilot flame, and is connected to the main gas valve. If the pilot light is on, the thermocouple is very hot, and tells the valve to stay open; if it goes out, the thermocouple gets cold, and shuts off the gas. Now, this creates a bootstrapping problem: the thermocouple starts out cold, so the gas is off, so there's no gas for the pilot light. You have to manually override the thermocouple by pushing a button, which allows a trickle of gas to the pilot light, so you can snake your hand into the rusty innards of the water tank to light it. Then you need to hold the button down, keeping the pilot lit, until the thermocouple gets hot enough to keep the valve open on its own—about a minute. At that point, you should be able to release the button and maintain a nice pilot.
Every time I released the button, the pilot went out, which told me something was broken. I guessed that our thermocouple was faulty; it looked a bit gungy while I was poking around in there, but I don't really know. Whatever the problem was, the repairman fixed it, we seem to have hot water, and I (theoretically) know how to light a water heater pilot light now. Go me.
Okay, I don't actually know how our water heater works, but this is what I deduced at 4AM, crawling around our freezing dirt-floored basement on my hands and knees, reading instructions with a penlight:
There is a gas flame beneath the tank, just like the one on a gas stove. The gas comes on when the water gets too cold, and goes off when it gets hot enough. This flame is lit by a pilot light, which is always on—unless it is not, which was the case last night. If it is not, there is a problem: the water gets cold, the main gas comes on, nothing ignites it, the water never gets hot, the main gas never shuts off, and soon your basement is full of natural gas.
Happily, there is a safety feature built-in: a little bit of metal called a thermocouple, which sits directly in the pilot flame, and is connected to the main gas valve. If the pilot light is on, the thermocouple is very hot, and tells the valve to stay open; if it goes out, the thermocouple gets cold, and shuts off the gas. Now, this creates a bootstrapping problem: the thermocouple starts out cold, so the gas is off, so there's no gas for the pilot light. You have to manually override the thermocouple by pushing a button, which allows a trickle of gas to the pilot light, so you can snake your hand into the rusty innards of the water tank to light it. Then you need to hold the button down, keeping the pilot lit, until the thermocouple gets hot enough to keep the valve open on its own—about a minute. At that point, you should be able to release the button and maintain a nice pilot.
Every time I released the button, the pilot went out, which told me something was broken. I guessed that our thermocouple was faulty; it looked a bit gungy while I was poking around in there, but I don't really know. Whatever the problem was, the repairman fixed it, we seem to have hot water, and I (theoretically) know how to light a water heater pilot light now. Go me.
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no subject
Date: 2005-01-26 08:01 pm (UTC)I wonder if modern gas heaters, like modern gas stoves, use an electric sparker to light the gas? Probably not -- the pilot-light-plus-thermocouple approach seems better.
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Date: 2005-01-26 08:43 pm (UTC)Fast Heaters
Date: 2005-01-26 10:36 pm (UTC)Re: Fast Heaters, from MelissaR
Date: 2005-01-30 05:06 am (UTC)