My abstract thinking about a tankless water heater became more concrete recently when we realized that our (25-year old) water heater was broken. Not just broken, in fact, it was actively spraying water all over the crawlspace. The bad news is that it took us several weeks to realize. The good news is that the crawlspace has excellent drainage, since the water didn’t seem to stay. According to the water company, we used 66,000 gallons of water (usually, we use 1-2 thousand), so we’re glad it didn’t back up! We’re also dreading our water bill.
In the meantime, we had a plumber come out and make a quick $100 fix to the leak. The water heater still didn’t work because of a broken temperature breaker, so Maggie short-circuited it. It works well enough now, we just have to keep the water heater off at the main breaker so that it doesn’t overheat. The part is relatively cheap and easy to replace, but since the current water heater is so old, we decided to see how much it would cost to have it replaced.
Two weeks of phone calls to the plumber later and we finally had an estimate. They said that it would cost $800 to replace the current one with a new electric tank and that there was no such thing as a whole-house electric tankless water heater. $800 seems like a lot and I was pretty sure I’d seen the apparently mythical electric tankless versions, so I did some digging.
It turns out that the natural gas tankless water heaters can give a much better flow rate than electric ones. I’ve seen natural gas tankless run up to 10 gallons per minute with a 55-degree temperature change. Electric ones seem to peak at around 4 gallons per minute.
Still, 4 gallons per minute seems reasonable to me, so I’m not sure why the plumber thought it was impossible. We only really use hot water for showers and doing dishes (and we rarely do those at the same time). A standard shower fixture uses 2.5 gpm and a sink uses about the same, so that would be pushing things somewhat. Of course, the result would just be slightly cooler water, which wouldn’t be terrible either.
And if we got a low-flow showerhead and a sink aerator, we could reduce that to 1.5 gpm and 0.5 gpm respectively. That’s only 2 gpm, which would only require a middle-of-the-road tankless water heater.
Even if we got a dishwasher, we’d only need 3 gpm to make sure it would get hot water. It doesn’t seem like it would be a big deal to avoid taking showers while washing dishes, especially since we only wash dishes once or twice a week.
Or maybe I’m deluding myself and it would it be unbearably annoying to start a shower and then have it get colder as Maggie starts up our (hypothetical) dishwasher. Guests might come over and be devastated that the water got colder when they took a shower at the same time (in different showers, for those of you with dirty minds).
Another possibility is that Maggie and I just don’t use as much hot water as a usual household, so an electric tankless would work perfectly for us. How much hot water do you all use at once? More than a shower and a faucet? I’d love to hear from you to see if our water usage is really that unusual.