natural gas tankless water heater use experience?

4 Comments

1. Paul in San Diego says:

   September 9, 2009 at 1:50 pm

   I bought a house a few years ago that had a gas tankless water heater. Here’s what my experience has been:

   Tankless water heaters are awesome, if you get the right size for the house. You truly get an endless supply of hot water (I even filled a 250-gallon jacuzzi with piping hot water all at one shot by using the hot water spigot for the washing machine). The problem is when you get one that is too small for your house.

   The existing water heater was a 3.2 gallon-per-minute (GPM) unit that would not provide enough flow to have multiple appliances (like clothes washer and dishwasher) going and have enough pressure to even wash the dishes at the kitchen sink. The way these things work is that they are rated at a certain flow rate (3.2 GPM for this one) over a nominal temperature change (usually 55 degrees F).

   So, let’s say your cold water (in summer) is 65 degrees and you set the water heater to 120 degrees. That’s an increase of 55 degrees, so you get the rated flow of the unit. But, when it’s colder and the cold water input is now 55 degrees, you still get 120-degree water out of it. But, now it’s at some flowrate that’s less than the rated GPM. That’s because a temperature sensor monitors the output temperature and, if it’s lower than the set temperature, it reduces the flow of water through the heater, so it has more time to heat to the correct temperature.

   Last year I remodeled the house and replaced the 3.2 GPM unit with a new 7 GPM unit. At one point, I turned on every hot water spigot in the house (two showers, three bathroom sinks, a bathrub, and the kitchen sink), and got decent flow out of each spigot. So, I knew that I wouldn’t ever have a situation where there wasn’t enough flow to run multiple appliances, have two people take a shower, etc.

   I got the unit on eBay, delivered, for about $1000. It then required a couple hundred more in ducting and other hardware to hook up (I don’t know what the installation labor was – it was part of the plumbing scope of work for the remodel). Also consider that, by code, you have to have 3/4-inch water supply and gas lines going to it. And, if you have an electric start burner, you have to have a 110-volt outlet handy (or have it installed) at the water heater location.

   Like I said, this was all done during a remodel, so everything was done as part of the electrical and gas line scope of work. But, I am absolutely pleased with this tankless water heater and would never want a tank water heater again.
2. Packrat 666 says:

   September 9, 2009 at 1:50 pm

   Installed properly the tankless system work great. My friend has one in a 3000 sqf house. never runs out.
3. banjoman says:

   September 9, 2009 at 1:50 pm

   I’ve had tankless water heaters in a rental I once had and also when traveling in the UK. I never really got good, hot water, just warmer than lukewarm. For that reason, I prefer a hot water tank. I always get hot water.
4. oil field trash says:

   September 9, 2009 at 1:50 pm

   A tankless heater if done properly will work just fine. We actually lived in a house in New Orleans in the 1940’s and 1950’s that had one and it served us very well. They have become much better now.