Electric tankless water heaters question

[427 S/O]

Anyone have one or know of someone who does?. Before purchasing I would like to hear the pros and cons.

Thanks in advance.

[olddog]

I assumed you were talking about the small units that you locate near the ussage rather than one that supplied the entire house. I have only seen whole house units that were gas fired.

Pros
You only need to run cold water lines - saves half the plumbing cost for new installations.

Near instant hot water - no running water until you flush the lines from the tank.

No water tank to rust out.

No heat loss from a tank of hot water that is constantly kept hot.

Never run out of hot water, as it is heated as you use it.

One unit fails in one bathroom and the rest of the house and 2nd bathroom still function.

Cons
Takes a fairly large breaker and wire to supply the power. Todays wire cost could offset any savings in plumbing cost.

Takes a minimum water flow to turn it on, so you cannot trickle hot water slowly.

You need to install several units at different locations; kitchen, bath, washer.

Opinion:
We have a few at work in the mens room. I am so used to turning water on full hot everwhere else that I jump from the hot water hitting so fast. Other than that I like them. Europe almost exclusively has used them for decades. When I was there back in 1985, a lot of them would scald you, if you were not careful. I was there several times since, and never noticed any problems in the later years. I like them, and think they generally make good economic and enviromental since. Once you get used to the instant heat, you will like them.

[J. T. Toad]

I have one.

It's a SETS.

http://www.sets-systems.com/

Email me if you have questions, I will be happy to share what I have learned.

[tcrist]

You can get one that runs the whole house but you need to watch what size you get because of what "olddog" mentioned about min waterflow.
We have family in Europe and they have smaller ones that service single uses/areas. They do not understand why we do not have them here. Saves on gas/elec trying to keep the water hot as in our water heaters that are normally in the garage way away from the water usage areas. Also there is the instant hot water idea. You are not waisting water waiting for your water to get hot.

Terry

[Smokingcobra2]

just priced out a Rinia unit for a 2100 sq ft house. runs around 4000.00
joeg

[J. T. Toad]

Originally Posted by Smokingcobra2

just priced out a Rinia unit for a 2100 sq ft house. runs around 4000.00
joeg

The size of unit should be based on projected use in GPM at peak usage and water inlet low temperature.... IOW, how much use at one time @ what temp.

$798 for 27KW - bear in mind, this is a huge supply of hot water... that's right 27KW! which means whilst it is on max draw, your meter will be spinning at cobra speeds!

It is funny, I never thought about the 'trickle' issue. I never use hot water in a 'trickle' mode, but, alas he is right. The difference between trickle and low flow is hardly noticeable.

[427 S/O]

Sorry, I should have been more detailed... I'm looking for the single unit to serve the entire house, no way can I run wire to each outlet without ripping out walls. I have a 3/2 1800 sq. feet. In the little research I've done, the Stiebel Eltron Tempra 29 seems to be a good choice?, $750. There three positive reviews.

http://www.plumbersurplus.com/Prod/S...at/479#Reviews

[427 S/O]

joeg, what do you get for $4000?.

[4RE KLR]

They work great, they are very durable and are energy efficient.

The whole house unit is the way to go if you can get the plumbing to work for you. They are easy to change when they go out. (hardly ever, but I have seen it happen)

If possible you may choose to go with a gas version as opposed to electric. The gas models are much more energy efficient and last many times longer than the electric ones do.

The gas ones come on heat the water and then turn off. No waste of energy.

I have put them in recirculating systems very successfully in many homes. The units come on and heat the water in the lines until it reaches a predetermined temp then it turns off. When you turn on a faucet you have instant hot water and the system resupplies the lines before the water gets cool again.

It is a win/win.

[Smokingcobra2]

427 it was the complete system ground up build have not bought it yet researching it to see wheter it is worth doing. would be all the plumbing etc in the house included, plus bigger service to accomidate it.
joe

[chopper]

I have a Rinnai unit which was installed about 8 months ago. Total cost with installation was about $3300. That included the heater (about $1600 for the 9.4 gal/min unit, the biggest one they make for residential use), the intake/exhaust vent system (about $400), an upgrade to the gas line from 3/4 inch to 1 inch, and all installation. The unit works very well, is significantly more energy efficient than the 50-gal tank it replaced, and provides an endless supply of hot water. I have a 4-bedroom, 2-bath house and it will supply all the hot water for everything in the house at one time.

A few things to consider, however. (1) The actual quantity of hot water you will get from a particular unit is largely a function of the temperature of the incoming water. Mine will run everything in the house, but our incoming water temp, even in the winter, is usually above 55 degrees. If your supply temp is closer to 40 degrees, your output will go down. (2) As was pointed out above, the unit needs a minimum water flow to operate. Mine is 0.6 gal/min before it turns on. Most are about 0.5 gal/min. This isn't a problem in the cooler months (remember, I live in Arizona) but in the summer months, with the incoming water temp around 72 degrees, the unit cycles on and off during showers, resulting in some loud whining noises emanating from the bathroom. (3) If you put it in the garage or basement, in place of your old tanked unit, you will still have the same problem with time lag for getting the hot water to the outlet. (4) Tankless units are more sensitive to clogging up with calcium and magnesium deposits than a tank unit, so you should probably consider some form of water softener if you don't already have one. I installed an ionic softener during the summer to try to combat this problem; another $1500. You may or may not need this depending on the hardness of your water supply. If you don't have a softener, my installer recommended getting a small submersible pump to use in backflushing the unit every six months or so. (5) Most folks with tankless heaters and teenage daughters say they suffered from two big price shocks. The first was for the installation. The second was for the first month's gas bill when the teenage daughters discover that they can stand in the shower for literally hours since the heater doesn't "run out" like a tank heater will. (6) Once installed, the system is easy to use since the temperature output is controlled from a digital panel on the front of the heater. Adjusting the output temp is a matter of tapping on a keypad. (7) For the larger, whole-house units, you need to consider upgrading the gas supply to a 1-inch line. The 3/4 inch line will work reasonably well as long as you don't run the unit at max capacity. If you run it at max frequently, the unit has a hard time keeping up with the demand. One dealer to whom I spoke flatly refused to consider installating any unit in my house unless I agreed to the upgraded gas line. (8) Given the relatively high price compared with a replacement tank unit, breakeven payback time can be a matter of years rather than months. Consumer Reports ran an article on tankless heaters a couple of months back and recommended some things to consider when deciding whether this would be cost effective for you. Rinnai gives a 5-year, non-prorated warranty (and my installer increased this to 6 years total on the entire unit) with a 12-year factory warranty on the heat exchanger (the part which usually fails). (9) I opted for the bigger unit while the dealer actually recommended a smaller one. He said the 7.5 gal/min unit will supply adequate hot water for a family of 4 with very few limitations. This would have saved me about $150 but I went for the larger one on the theory that more is always better.

FWIW, this is what I got:

http://www.foreverhotwater.com/model-r94lsi.php

The ionic water softener I installed later:

http://www.easywater.com/EasyWater-W...r-Systems.aspx

This was long but I hope it helps.

[427 S/O]

Chopper, your talking about a NG unit, correct?.

[chopper]

Yes, it's natural gas. I don't know of anyone who makes an electric whole-house unit, although I suppose it's possible, but I was told it would take close to 100 amps of power to run it at the same capacity as a gas unit. Rinnai also makes a propane model, if you don't have a gas line to your house.

If you are looking at a point-of-use installation, such as for a dishwasher or upstairs shower, a smaller electric unit may fit the bill. A common installation these days seems to be for dishwasher replacements. The new dishwashers do not heat the same way the older models did. That is, the older models would take water in and heat it to a preset temperature, usually 145 degrees F. The newer units, to make the EnergyStar ratings, have smaller wattage heaters and will only heat up for a maximum of 20 minutes, with a temperature rise of about a degree per minute. Since the dishwasher needs a minimum water temp of 145 deg F to wash properly, that means the water in the bottom of the dishwasher at the start of the cycle has to be at least 125 deg F and is usually specified as such in the installation manual. Even if you have your water heater set to 140 deg F, the line temperature loss transporting the heated water to the dishwasher, plus the temperature loss from the water contacting the dishwasher pan upon entry, pretty much ensures the water temp in the dishwasher cycle will be insufficient to clean the dishes properly. As far as I know, only the Bosch units still use an internal heater that heats to a preset temp; mine heats to 151 deg F according to the literature. Anyway, some folks have taken to installing small electric under-the-sink tankless heaters to feed just the dishwasher and kitchen sink in order to alleviate the dishwasher problem. Bear in mind, however, that even a small under-the-sink electric unit may require 240 volts to operate.

[Cobrabill]

Hard water can ruin(as in complete junk) a tankless WH in as little as two years.