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I am looking to switch our regular ole propane 30 gallon hot water tank with a propane on-demand hot water tank. Thoughts? Does anyone have any experience with this type of hot water heater in our area? I was wondering if the minerals in the water would build up and become bad news. Any advice on these on-demand units in general?

gracias.

I've been using Paloma on-demand, tankless water heaters in 2 houses since the late 80's and just love them. Any brand is probably just as good. Even though they are more expensive to buy, the savings are so great that the payback is rapid. As in any water heater there is a buildup of calcium which, in the case of tankless heater, begins to restrict the water flow. When this happens, every 3 or so years depending on the hardness of your water, simply hook up a water fountain submersible pump and run vinegar through the heater.

The only drawback that I have ever found is that the hot water never runs out so you could spend all day in the shower no problem.

If you don't have much water pressure the water travels through too slowly and can be too hot (scalding). I knew someone who had the opposite problem, the water traveled through too quickly and didn't get hot enough. I think if you can regulate the pressure you can avoid this problem.

The right tankless water heater for a given application is determined by two criteria. (1) the POSSIBLE peak demand determined by the number of shower heads/bath tubs, the clothes washer and the dishwasher, and (2) the temperature of the water arriving at the water heater at the coldest time of the year. The reason - tankless water heaters are sized by flow rate (gpm) and its capacity to increase the temperature of water X degrees. Example - if the inbound water is 35F and you want 120F water (the maximum for personal safety) the heater will have to raise the temperature 85F at its maximum flow rate.

Use the web to learn more. There is A LOT of information NOT provided by the manufacturers. A good place to start is:
http://www.tanklesswaterheaterguide.com/ and http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=12820

All brand names are NOT created equal. Stick with the established brands like (but not limited to) Paloma, Rheem, Rinnai etc. Go for pilotless ignition but beware of units that tout self-generating electrical energy to spark the pilot. Read PLENTY of product reviews before you make your final decision. Check Consumer Reports ratings - not the best but a good place to check your decision.

Tankless, pilotless waterheaters are one of the best ways to reduce individual consumption of non-renewable resources and conserve energy. Good luck....

_________________
geo
www.Axle Canyon Preserve.com

I had a tankless water heater in Colorado with very hard water. I used a Hardness Master. It breaks down the hardness with a very low electric currant. Very inexpensive and easy to install in minutes.

on demand water heaters are great.
also great is solar pre heating by using used water heaters (gas, electric not leaking) under glass tilted 45 degrees and oriented south, with insulation on the back, sides and bottom and connected into the cold water supply of the regular water heater.
depending on the care , insulation, number of tanks and lack of shade this solution can provide 100% of hot water needs, certainly 50% in this sunny climate.
there are several in this area that have been in service for 2 or more decades including mine.
call five 3 eight- 522 nine for info.

Are the perfect answer for some situations, but not the cure-all which many would have you believe. A series of poorly-designed studies over the past fifteen years or so did not help. The report below is quite technical, but far more comprehensive than previous studies I have read.
http://www.state.mn.us/mn/externalDocs/ ... Report.pdf

If your eyes start to glaze over, skip to page 60 (and to page 83 if it happens again.)

Note that they are using $1.20 per Therm for NG and $0.12 per kWH for electricity, so we would see paybacks roughly twice as long here.


Two standouts:

The simple payback calculation showed that at current installed costs and energy prices 20 to 40 years would be necessary for a TWH to pay for itself, as shown in Table 23. The economics would be improved for TWHs on a life cycle basis if, as some TWH manufacturer’s claim the lifetime of a TWH is significantly longer than the StWH.

and

The findings from this study strongly suggest that the DOE Energy Factor needs to be modified. This report shows that it does not accurately predict installed performance or provide a non-biased metric for comparison between technologies. Comparing measured daily efficiencies versus rated EFs showed that EF over-predicted efficiency by 14 percentage points (23%) for StWHs compared to 9 percentage points (10%)for TWHs.

"CONCLUSIONS
Tankless water heaters can be successfully installed and operated in Northern Midwest
climates. TWHs can be used in residential applications with only moderate changes in
qualitative aspects of water heating performance, with some attributes rated better and some
worse than for StWHs. TWHs save a considerable amount of energy over natural draft StWHs.
TWHs saved an average of 37% of site energy consumed for water heating at ten sites in the
Minneapolis/St Paul area, which was about 6000 kBtu per home per year. TWHs provided this
energy savings with no significant change in hot water consumption. Even with these positives
of tankless water heaters the low cost of natural gas and the high installed cost of TWHs limits
their feasibility. Without considerable rebates the simple paybacks for these heaters were 20 to
40 years, making widespread installations seem unlikely. " (StWHs standard water heaters, TWHs tankless water heaters )

yes, from that same study, page 83
except for the "handy" and the well to do, anyone hooked to the natural gas supply pipeline the easiest cheapest is the std 40 gallon, natural draft water heater.
for those not so lucky and who use propane or electricity for waterheating, the preheater (self-installed) is a likely good option.
for the "environmentally committed" do whatever your heart and head desires, remembering that your efforts will have uncertain benefit because of first costs, iffy technology, and unknowable complexities. but, if you share your experiences perhaps there'll be social and environmental benefits.