Friday, July 06, 2007

Going Tankless

I've been collecting information on things I want to include in my dream home. I'm currently researching tankless water heaters.

I'm leaning toward electric over gas because of the solar panels, but I wondered if any of my readers have any experience with tankless or on demand water heaters. My brother in law said he looked into them and decided not to get one because of the yearly maintenance. I can't find anything that says they require yearly maintenance.

I like the idea of not keeping a tank of water constantly hot. I also like that if we have company staying with us, we won't run out of hot water. My concerns mostly center around what temperature the water will be heated to and how well the temperature will be regulated when the temperature of the incoming water changes throughout the year.


Tyler Farrer said...

My research into tankless heaters went like this.

Me: "Hello, I'd like a price quote on a tankless water-heater?"
Sales Guy: "How large is your home?"
Me: (I give him the figures)
Sales Guy: About $2,000 installed.
Me: -click-

masterplumber32 said...


I am a master plumber and have installed 100s of tankless heaters. There are only several minor drawbacks that I see with converting to tankless, which I'll mention later. Tankless heaters (gas) will provide up to 9.8 gallons of hot water per minute. This all depends on the incoming water temp and temperature setting. I live in the south so incoming water temps normall don't drop below 40 degrees or so.

I prefer the Rinnai R85i and Noritz 751M. The Noritz is a little more powerful and produces approx. 1 gallon more per minute than the Rinnai, but both are great heaters.

These heaters will produce (worse case scenario) enough hot water for 2 showers plus 1 additional fixture (dishwasher, washing machine, etc.) simultaneously. Again this is worse case scenario in the coldest months.

I prefer to set the heater at 110 degrees. This allows maximum water flow through the heater, but it takes some getting use to. You'll find that you'll be mixing less cold water than usual with showers.

A couple of drawbacks include the upfront cost of the job. Tankless installs (retro) typically cost between $2000-$3000 depending on the individual job. Seperate venting and gas line upgrades make the installation a bit tricky. Another drawback (in some cases) is that often times a tankless heater will need to be installed in a different location from the existing tank heater because of the venting requirements. This will make travel time to certain fixtures take longer than normal, and allow for quicker travel to some fixtures quicker, depending on how the home is layed out.

The last (minor) drawback on tankless comes when a consumer turns the hot water on and off repeatedly at a fixture. Since the tankless heater senses flow, and then fires the heater to heat water on demand, this often times allows a samll amount of cold water to pass through the heater and on to the fixture. This is referred to as "cold water sandwich" and exists with all tankless heaters. This is the most minor of the drawbacks in my opinion, as some customers never experience this because of their habits of using the fixture.

Please visit my blog at for more tankless discussion or questions.