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aschweitzer
Tankless Water Heater?
aschweitzer

I am trying to decide whether to go with a tankless water heater and would like some input from people that have used them. I have a large family and like the idea of continuous hot water. What do you like about these sytems? Are there any drawbacks? Any regrets with going tankless? My existing tank water heater is in my garage. Would it be ok to put it in the same place or is it best to move it indoors? Any idea on installation costs/difficulty? Any recommendations on brands? These units are quite a bit more expensive than a tank water heater and I am trying to rationalize whether it is worth the extra money. Any input is appreciated.

JacktheShack
Re: Tankless Water Heater?
JacktheShack

There's been a lot written both pro & con about this type of water heater.

They are popular in other parts of the world where HW use patterns are much less than people in the U.S. are accustomed to.

They have also found popularity in a number of small commercial venues like shops & motels, etc. where HW usage is low & limited to 1 or 2 people.

In a large family, there have been problems with recovery rates---if a large # of HW gallons is needed for a washer or showers, many IHWHs can't keep up & you get lukewarm, then cold water, wheras a tank heater has HW stored & can recover more quickly from high usage.

There have also been problems in northern parts of the country in winter when the ambient temp of the incoming water is near freezing.

What type of heating system do you have???

If you have hot water heat, consider an indirect HW heater as a more sensible alternative.

You should first calculate your PEAK USAGE, which is how many gallons you use during the busiest part of the day---several of the sites have a calculator for this.

Google some brand names & models, like Takagi T-K2 Flash, Bosh Aquastar, Paloma Pak, Rheem RTG-42PV, Bradford-White, Steibel.

At the "water heater rescue" site, click onto "choosing a hot water heater, then scroll down to read about instantaneous heaters.

http://www.tanklesswaterheaterguide.com/
http://www.aceee.org/consumerguide/waterheating.htm
http://www.encyclopedia.com/doc/1g1-106514058.html
http://waterheaterrescue.com
http://www.propane.ca/cleantruth/residential/waterheating.asp

misfitter
Re: Tankless Water Heater?
misfitter

I disagree with JacktheShack on the idea that a tank water heater is better than a tankless. I have installed over 50 of them. 40 of them outside Denver, Colorado for multiuse family types. the other 10 in Wilmington, NC for high end homes. Oh, and one for my middle class ranch home. I highly suggest them.

And you are correct they are more expensive to replace or install. But, every month after that the cost of the energy and the cost of water is less. Except if people take longer Hot water showers. As far as the hot water running out, YOU MUST MAKE SURE IT IS PROPERLY SIZED.

JacktheShack gave great weblinks. I like Tagaki and Rannai the Best. A well educated customer is one who is less likely to maon about the cost or the problems associated wtih something. You will need to make sure your have either gas or propane. I do not recommend electric.

To go Tankless is to Go Green.

Dobbs
Re: Tankless Water Heater?
Dobbs

I take strong exception to misfitter's post.

Shack nailed it! the links Jack provided clearly demonstrate the many problems large family customers are having with these tankless systems.

Apparently misfitter didn't bother to read the links. I've worked for the same co. for the past 10 years. we've stopped doing installs on them due to the complaints we were getting.

NashuaTech
Re: Tankless Water Heater?
NashuaTech

I also agree with the comments in shack's post.

He gives a balanced view that favors a tankless in small family units but not for high volume usage.

I can't see an install in the OP's situation.

Sherry
Re: Tankless Water Heater?
Sherry

To aschweitzer:

I researched tankless water heaters extensively earlier this year for a presentation I did for my home improvement club at work. Here’s some information from it.

Advantages of Tankless Units

  • Lower operating costs.
  • More energy efficient[LIST]
  • 24-34% more efficient in low (<41 gal.) use
  • 8-14% more efficient in high use (86+ gal)
  • Greatest energy savings if you install a demand heater at every hot water outlet (but not the greatest cost savings).
  • Elimination of standby losses.
  • Unlimited supply of hot water.
  • Longer heater life (expected 20 years heater life versus 10-15 for a tank). They also have replaceable parts.
  • Small size – space saving (26”x15”x7”)
  • Convenience[/LIST]
  • Disadvantages of Tankless Units

    • Units are more expensive in this part of the world where they are not dominant.
    • Unit draws a large amount of energy when they are running – up to 5 times (or more) the energy of a tank model.
    • Higher installation cost (probably not DIY)
    • Tankless unit might not be able to handle simultaneous use.
    • Electric units are not as environmentally friendly as they appear due to electricity production requirements.
    • Delay between turning unit on and burner turning on leads to slugs of cold water in between slugs of hot water. So tankless units are not well suited to frequent on-off use of hot water.
    • Minimum flow requirement might prevent low flow warm water (shaving, rinsing dishes). This could also give you a warmer minimum water temperature than you wanted.
    • If you have electronic ignition without battery backup you have no hot water when there is a power outage.

    Economic analysis
    I analyzed my gas usage and calculated my hot water costs. What I found was that the tankless heaters would definitely save money in operating costs due to their higher efficiency. My “efficient” tank heater is 59% efficient – 59% of the energy produced by burning gas actually gets converted into hot water. The rest goes out the flue. A tankless heater will be in the ballpark of 82% efficient. But for me – a single person – the savings I’d see due to the higher efficiency was only about $21 a year. A tankless heater also eliminates stand-by losses – the energy that is lost to the surroundings and then the water heater just has to heat the water back up again. I calculated my maximum annual standby losses at about $104 a year. But this is not all standby losses – it also includes the gas I used for my gas fireplace (not a lot) and cooking. Since I live in the frozen northland we have to have our water heaters inside. For me to install a tankless water heater would require a rework of my plumbing and ventilation. (Tankless units require a higher feed rate of gas and they require more venting capacity than a tank style heater.) The rework of the plumbing and venting can be costly. One source I had gave a rough estimate of $1200 (which I think might actually be low). One other point… looking at a year’s worth of gas bills shows me that here in Minnesota I was running my furnace 9 months out of the year. For me any heat that “leaks” out of my water heater leaks into my house and contributes to heating my house. So eliminating standby losses for me wasn’t a big selling point. Now, if you live in the south and can put your tankless unit outside the installation costs probably won’t be so high and eliminating stand-by losses carries more weight. But for me I figured I’d need at least 4 people in the household to justify a tankless water heater from an economic point of view.

    i.m.plummin
    Re: Tankless Water Heater?
    i.m.plummin
    Quote:

    YOU MUST MAKE SURE IT IS PROPERLY SIZED.

    I'll throw in with 'fitter I've installed a few of these and they are still working beautifully 6 years later and do not run out of hot water or get cold water sandwich or whatever.

    The thermal rise required and the desired max. and min. volume at that temp must be known when designing the system. For high demands, multiple units will likely need to be installed to accommodate the HW usage.

    The biggest problem I've seen with the on demand heaters is the ineptitude of the installers. They are no more complex than a furnace. Everything has to be properly sized.

    misfitter
    Re: Tankless Water Heater?
    misfitter

    Thanks to SherryH for a break down.

    If it isn't about the opinions, then what is it for?

    And if the customer isn't educated about the product, they may be just as uninformed about as some installers. And yes, just because the product is new doesn't automatically make it better. But, these are good products along with PEX pipe and Air Admittance Valves. Just not in every situation.

    Shubi
    Re: Tankless Water Heater?
    Shubi
    aschweitzer wrote:

    I am trying to decide whether to go with a tankless water heater and would like some input from people that have used them. I have a large family and like the idea of continuous hot water. What do you like about these sytems? Are there any drawbacks? Any regrets with going tankless? My existing tank water heater is in my garage. Would it be ok to put it in the same place or is it best to move it indoors? Any idea on installation costs/difficulty? Any recommendations on brands? These units are quite a bit more expensive than a tank water heater and I am trying to rationalize whether it is worth the extra money. Any input is appreciated.

    I have a Noritz in my home and I absolutely love it. The unit does not waste energy heat water when you're not using it, takes up very little space compared to a tanked unit, and is a sealed combustion unit so it has no chance of backdrafting. The unit is expected to last many times longer than a tanked unit, and I have run the dishwasher, washing machine and showered at the same time and never ran out of hot water. It's definately worth the extra money, but the manufacturer advises against installation with well water unless you have a water purification system. Drawbacks? If you lose electricity, you have no hot water at all, since none is stored. For the small amount of electricity that is needed to run it, a good uninteruptable power supply (UPS) may be all you need to provide hot water until the power comes back on. The only other drawback is you'll have more space to clutter up without that big, ugly tank in your basement.

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