My Nissan Leaf Forum

Two adults in our home, natural gas, piping to shower, laundry and kitchen are less than 15 feet. Might put in solar water heating in the future. Tank heater is making noise and running short of heat, way past it's warranty.

Tankless heaters worth the expense?

Can water be preheated by solar before it gets to the tankless unit?

Any other thoughts? I have to do something TODAY! Thanks for any input!

-Harry in Fresno, CA

I don't have a tankless unit, but my understanding is that you need a larger gas pipe to accomodate the load and a larger vent pipe to carry out the exhaust.

In certain areas, though, I've heard there are incentives that might help ease the cost of installation...

yes and yes.
I like mine, and you could send the water through pre-heat. we have it in a shower and bath that is intermittently in use, so it is even better than having a tank hold water for a bathroom with sometime-demand

The only complaint I've heard about tankless water heaters (from a guy who installs them) is that a lot of times you also have to install a water softening system, otherwise mineral deposits build up in the tiny tubes that the water passes through (there are lots of them and they are very small to increase surface area) and they end up getting plugged.

I guess it all depends on how hard your water is though.

I have a tankless water heater that we installed when we modeled about 5 years ago. I love it! It didn't need a bigger gas line and the exhaust duct is the same size as the regular water heater it replaced. I noticed an immediate and ongoing reduction in our gas bill and never having to worry about running out of hot water is nice. There is a picture of it elsewhere on here in the thread on where to place your EVSE in the garage...

Regarding a water softener: Perhaps if you have really hard water it might be necessary but the unit I have will signal if it detects excessive mineral buildup in the heat exchanger, at which point a simple external decalcifying procedure will clean it. I have yet to have to do mine.

I installed one in my previous home, when there was still the energy savings tax break (30% off unit + installation).

there are 2 scenario where I think tankless is very useful:
- Low usage: very few people live in the home, so you basically use no hot water, hence no gas. this was my case, and I saw my gas bill drop to almost negligible sum. Of course, I wasn't paying much for hot water to start with. I probably save $10~$15/month.

- High usage: you have a lot of people and you really need a lot of hot water. Because it's tankless, you'll never run out of hot water. You won't same much money over a standard water heater in this high use scenario, however.

Keep in mind the installation cost may be much higher than just swapping out the old heater and installing a new one. My plumber had to run a whole new gas line from the meter to the tank because of the size requirement (tankless require much more gas when it's on). He also upgraded the exhaust because of the stricter code (a lot more heat is generated when a tankless is on).

I wouldn't have done it without the 30% tax break, however. it's a terrific upgrade, but don't do it expecting to get a ROI. I estimated my payback period to be about 8 years with the tax break, and 12 years without.

take a look at heat pump hybrid electric if carbon emissions are a concern. we just had one installed and are loving it. projections suggest it will cost about $10 a month in full heat pump mode, saving us $300-400 annually. we went with electric because we are working on going zero net energy/zero carbon. Eventually we want to replace our gas furnace with a heat pump as well. Our utility offers a $250 rebate, the feds offer a $300 rebate and then assess for a complete solar PV system to net zero our annual consumption, including the car... probably at least year or two down the line. Home depot had this heater on sale for $1,300. The install was easy!

In a warm climate and in the right place in your home the a heat pump water heater can be great but you do need to read up on it and make sure it is the right fit for your home http://www.geappliances.com/heat-pump-hot-water-heater/. the refresh rate is slow in full heat pump mode but it sips electrons, 500 watts per hour vs 4,500 an hour. the GE hybrid heat pump has three modes, heat pump only, hybrid mode (for higher demand where the resistive coils augment heating during peak use) and full resistive heater mode for very high output times. It also has a vacation setting where it drops the temp to 50 degrees or ambient and the day before you return it goes back up.

We added a Euro pro high performance/low flow shower head and sealed up the shower stall to retain heat and get plenty of long showers out of the hybrid/electric heater we put in. When it's convenient we time our clothes drying with showers and circulate the warm humid air from the dryer into the room with the hybrid heat pump, capturing the waste heat from the dryer... don't know how much this is saving us, but the heat pump is able to keep up with the dryer and it's at least fun.

We have yet to see the electric bill but we expect to be able to drive the leaf about 10,000 miles a year on the energy saved!

the upside of a tankless gas system is that gas prices should be low for a while and your water supply is virtually endless. The downside is that you are still relying on fossil fuel and emitting carbon into the atmosphere.

It takes lot of energy to heat water. If you're doing it in a short time then you need a lot of power.

I don't have one but you might look at something like this hybrid. It has a small tank so the standby losses are low but it is very efficient so it can provide hot water at a rate approaching what you'd get with a pure on-demand heater. No idea of how reliable these are. http://www.hotwater.com/water-heaters/r ... ybrid-gas/

The noise is likely due to accumulation of scale and/or sediment in the tank.

http://www.inspectapedia.com/plumbing/W ... ushout.htm

tankless systems, especially gas tankless work extremely well and are worth the cost. The heating is so fast, i doubt a solar water heater will make a difference. If cost is no option, obviously a solar water heater helps, but the cost of them is so expensive it takes usually about 15-20 years to get your cost back.