Greening Your Home - Tankless Hot Water Heaters Experiences

I'm inventistigating tankless hot water heaters and would appreciate experiences from foflks who have them.

We had quotes from two separate firms for a Rinnai natural gas tankless model but both were expensive to install, even after government rebates; financial payback was more than 7 years for each.

And they need special venting requiring the location from both firms to be 30 feet away from current hot water tank location which would result in wasted water and wasted heating of the water with the extra distance travelled.

I came across an electric tankless firm who's products are used in PATH concept and demonstration homes (and elsewhere) that are less expensive to install but not sure about the operating costs.

Thanks for your experiences,
Dan

I had a Rinnai installed a year ago and can attest that the operating costs are less than half of that of my old tank heater.

Unfortunately, the installation business is a racket. Rinnai requires certified installers, or their warranty is void. (So much for DIY, unless you pay them to get certified, so the advantage is...?).

Also, the government rebate yields nothing for the consumer, as the retailers mark up the cost of the unit by the amount of the rebate. Rebates are market distortions, and should not be necessary if the efficiency gain were sufficient. By offering rebates, the implication is that there are economic disadvantages to overcome (which therefore become automatic).

Special venting is required for interior gas installations only. The gas tankless units put out a lot more combustion byproducts than conventional gas units. (Installers love to install interior units. Ca-ching.)

Never heard of the 30-ft separation requirement. Sounds fishy. Get another estimate.

My questions are is the water heater you have now not capable of the hot water that you need? Is the unit under sized. Only seen the need for extra hot water heater in restaurants. If you go with the tank-less id remove the old water heater and size the tank-less to the load needed.

You don't say where you are or where the water heater is located in the house, but in many cases, tankless does not provide the savings people are led to believe. If your tank heater is sitting in a garage or attic and you're in an area that routinely reaches temps over 100, tankless would probably have a payback period that's considerably longer than is advantageous.

Electric units may not actually have lower installation costs depending on your house. Because of their extremely high amperage requirement, they often require an electrical service upgrade which would make the installation costs of a gas unit look like peanuts. You need 200amp service or better and space in the panel for a new 220V circuit. Be sure to calculate the cost of circuit installation as part of the install.

All that being said, tankless units can provide a great benefit in many parts of the country. Consider that they usually have a life of around 20 years so a 10 year or less payback period is not unreasonable. Make sure you do all your math and good luck.

Doug M.

Most tankless water heater literature talks all the wasted energy used in a tank type water heater, but fails to ever mention how much. No costs comparisons of therm usage. In the house that I used to live in I had a gas water heater, a gas clothing dryer, a gas stove and gas oven and we were a family of four. During the summer months the gas portion of our utility bill averaged $25. So how much can you really save?

Some time ago I did some calculations and found out that the savings were not very significant. Turns out todays tank water heaters are fairly efficient and well insulated. I don't remember the exact figures but they typically loose less than half a degree an hour of temperature. I live in a mild climate and my water heater is in the garage. I assume if you live in Minnesota and it's in an outside shed it would be more. So I came up that my gas savings on my house would be $36 bucks a year or $3 a month.

Here's an article that confirms similiar savings.

http://www.pmengineer.com/CDA/Archives/8cf9e86f7c298010VgnVCM100000f932a8c0____

The house I live in now has a tankless heater. If anything I use more hot water now because I know that the hot water never runs out and allows me to take as long of a shower as I want.

kai455, Manufacturers can't give cost comparisons of therm usage due to the number of factors that influence it. The number is far too variable.

As you pointed out (good job), not everyone can benefit enough from tankless to make it worth the extra expense. Like you, I live in a moderate climate and for more than half the year my gas bill is under $20 a month. My water comes in off the street at nearly 90 degrees and dumps into a tank that's sitting in a 110 degree attic. There is virtually no heat loss to save and certainly not enough to justify spending more than twice as much on the water heater. Beyond that, I also have a hot water circulation system that runs at select times of the day to give us nearly instant hot water at the faucets so we don't have to dump several gallons down the drain waiting for it to get warm. Circulation is not compatible with tankless.

In regard to capacity, we have a 40 gallon tank in a 5 bedroom 3 bath house. When all 4 kids were home, we generally ran at least 4 showers back to back every morning, sometimes 5, and often had the washer going at the same time. We have NEVER run out of hot water (unless you count the time my wife accidentally filled the garden tub with all hot :rolleyes: ).

You have to do the math and look at all the details of your specific situation. You can't just believe the ads that say a tankless water heater saves, just like you can't believe that going on Nutri Systems allows everyone to loose 50 pounds in 30 days. Little in life is that simple.

Doug M.

Educator,

Here's what I've learned from my experience, both as a end user and home inspector:

Avoiding Tankless Water Heater Problems For Installers, Home Inspectors and Homeowners (http://paragoninspects.com/tankless-heater-home-inspection-evanston-chicago-il-faq.html)

Michael, Very nice! Let me know when you move to the Dallas area. I'm a real estate agent and am always very pleased to find an inspector who knows what he's doing.

We're seeing a lot of builders putting tankless units in new construction now and, IMHO, that's where they should be going. Retrofitting to an existing house that's set up for a tank unit often just doesn't make sense, as we've covered in previouse replies.

Doug M.

MT doesn't just talk the talk.......

Beyond that, I also have a hot water circulation system that runs at select times of the day to give us nearly instant hot water at the faucets so we don't have to dump several gallons down the drain waiting for it to get warm. Circulation is not compatible with tankless.
Doug M.

There is a pump that can work with tankless.
http://www.lainginc.com/
click on the autocirc

It is a circulation pump that does not require the use of a return line to the water heater. It pumps the cold water back through the cold water line. I have one in use with my tankless unit and it works somewhat (again was already installed when we moved in). It does make the cold water warm for a few seconds. Plus sometimes it comes out warm goes back to cold for a few seconds(longer than the fire up time of the tankless) and then back to warm/hot water. But when I unplugged the unit it does take a long time to get warm water at that faucet.

Just found one by same company that is made solely for tankless.

http://www.instanthotwaterpump.com/product/tankless/index.htm

Yes, these systems do work (I have a Laing pump that's run silently and flawlessly for almost 10 years now - great product), but please realize that using any type of recirculation with a tankless water heater greatly negates the savings gained by not having the tank. The heater has to run whenever the circulator is on. The pluming is taking the place of the tank.

Ideally, because of their small size, tankless units can be installed close to the areas where hot water is used so circulation isn't needed. In reality this is rarely the case unless they're put in during new construction.

If the overall goal of installing a tankless unit is to save enough on energy costs to make up the additional purchase and installation costs within a reasonable amount of time, using any type of recirculation pump with it is not viable.

Doug M.

Many thanks for all the input; very much appreciated.

After much constrination we've decided not to proceed.

Our current 80 gallon water heater is only costing $15 / month to rent + around $20 to heat the water / month.

But we would like to be as green as possible. We are going to investigate solar water heaters as there is a new program in our area where the cost for a solar water heater may be the same or slightly less than a tankless, all-in. Yes, gov't grants are involved.

We'll see how we go.

Thanks again,
Dan

Ok, I have to ask...you rent a WH? I've never heard of this. Is it through the utility company? I presume it includes free service and replacement if it fails? Just wondering....

Ok, I have to ask...you rent a WH? I've never heard of this. Is it through the utility company? I presume it includes free service and replacement if it fails? Just wondering....

Actually, the practice of renting a hot water tank is pretty common in these parts (Ontario). Yes, like any rented equipment, if anything goes wrong or if it starts to leak they just come to the house and put a new one in.

It used to be for years through the local utility, but they sold the hot water tank rental business to a private company. Hasn't been any change in service from what we have received.

Dan