“The Iron Giant’s” Back Story

By , December 15, 2018

We’re settling in to life with “The Iron Giant,” the home-built wood-fired hot water heater we recently installed in the cabin. It has an interesting history.

A good friend in town gave us the heater to use as long as we need it. He used it at his off-grid cabin long ago; it sat unused for about 25 years, so he’s glad someone can put it to use again.

Here’s its story, as he told it to me. I’ve edited it to preserve my friend’s privacy:

My friend used to sell a lot of Agua Heaters, the Mexican-made wood-fired water heater we’ve used since moving to the homestead in 2006 (see Keeping Clean on the Homestead). One day, a repeat customer came to him with a proposition: he’d grown tired of burning out Agua Heaters, and decided he could build a similar, better heater himself. He proposed that if my friend would pay to ship the stainless steel needed for the project, he would build two heaters, one for himself, and one for my friend.

wood-fired water heater

The heater, showing some of the original plumbing configuration (Photo: Mark A. Zeiger).

They struck the bargain, and the man built the heaters. I’m not entirely clear on the extent of construction—my friend may have taken his tank to a local welder to add a fire box and funnel into which he fit a 6″ stove pipe.

I asked at what rate the man had burned out his Agua Heaters. My friend guessed that they lasted a year or two on average. This astounded me—we’ve needed three of them in the past 12 years! Of course, we don’t heat water every day, so perhaps we don’t use them as much as this fellow did.

At any rate, my friend used it for a long time, then set it aside when municipal utilities reached his place.

Having used the Agua Heaters for some years, I can see that the improvements work well. Stainless steel construction, and thicker metal to boot, makes this heater long-lasting. It may be more than 30 years old now, and will most likely outlast us.

Also, the larger, square fire box allows bigger fires with larger wood. We’re still experimenting with the correct fire size, one that will evaporate the inevitable condensation formed by cold water and metal meeting the fire’s heat. We’ll get it eventually—we’ve had our current wood stove so long that I’ve forgotten that it takes a bit to learn how to use a new stove, including this one.

hearth extension

The new hearth extension, before painting to match the rest of the pad (Photo: Mark A. Zeiger).

We also appreciate how the tank holds heat! After we heat water for the day’s washing, we find we have warm water into the next day. Our cold tap gives us icy water at this time of year, so we appreciate the warmth when we can get it.

Finally, the inflow and outflow are oriented to North American plumbing. The Agua Heaters all seemed to be plumbed opposite of our standard, leading to weirdly crossed pipes to match shower and sink fittings.

When we returned “The Iron Giant” to service, I removed its old fittings for more modern ones, blacked the fire box, added a gasket to the door, and made other minor improvements, such as adding more fire brick in the back of the box, and adding a grate to help keep the fire from falling into the room. I also extended the fireproof pad it sits on to allow us to burn it more safely.

gluing gasket to fire box door

New gasket for the fire box door, held in place by high tech clamps (Photo: Mark A. Zeiger).

If we take good care of it, one day we may become part of “The Iron Giant’s” back story as well. Who knows where it might end up in the future?

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