Tankless Water Heaters - Yes/No?


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Old 03-26-12, 12:41 PM
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Question Tankless Water Heaters - Yes/No?

I need to replace my gas water heater and I'm thinking about the new tankless water heaters, but I have a few questions.

Will hot water get to the first floor bathroom and kitchen sooner. and the same for getting hot water up to the second floor bathrooms. Right now I'm wasting quite a bit of water just waiting for it to get hot, and the water rates are not cheap where I live. Would I need some sort of "circulation" pump to get the hot water to these rooms faster?

What brands are out there? Which ones do I consider and, more importantly, which should I stay away from.

What do I look for in a tankless heater? Gallons produced, temperature settings for water, amount of savings, energy credits, etc? Will the savings on gas be offset by an increase in electricity?

I'm really in the dark about these heaters and before I go out searching for one I'd like to have some basic knowledge about them.
 
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Old 03-26-12, 03:25 PM
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I think that for every plumber, in the US anyway, that advocates tankless you will find five (or more) that advocate against it. Where tankless really shines is when you have a need for continuous, or almost continuous, hot water. If you have several people taking back-to-back showers you will likely love tankless but if your water usage is fairly typical then at best the tankless might be adequate.

The time to get hot water to the fixtures is a function of the length and size of the piping between the source and the point of usage. Tankless won't make this any better and under some circumstances it will be worse. Most tankless heaters do not accept the use of a recirculating pump, at least not without an additional storage tank. Those that do, such as the Navian, are often very high priced and if it has a continuous recirculation then the cost of heating this water will likely be considerable, especially if the intervening piping is not thoroughly insulated.

There is more.
 
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Old 03-26-12, 03:34 PM
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It is the hidden cost of installation that may get you. Your current venting for a storage type WH will need to be replaced with more expensive high temperature venting. The gas line to you current WH may not be sufficient requiring new gas piping. Your current gas meter may are may not have the necessary flow to support an IWH. The gas company may charge to upgrade your meter.
 
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Old 03-26-12, 03:42 PM
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So far you have been given good information to digest. Aside from the technical part, think about your present water heater situation. You go to work for 8 hours and are constantly heating water that has gone colder. You go for a two day weekend to mom's house. You are heating water constantly. Pretty pricey considering the price of gas nowadays. I am sure you don't turn the water heater off every time you leave for a slightly extended time period. With the newer gas tankless units you heat the water you need and like Furd said I believe the Navian is the only one that is adaptable for recirculation. As Ray said, the exhaust piping is about $60 per 2 ft section, so it can be really expensive unless you are on an outside wall. It will also take 1/2" gas line, and you may not have that large if you are on propane.
 
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Old 03-26-12, 04:33 PM
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Oh, come on, Chandler, you do NOT "continuously" heat the water in a storage tank type water heater. I have a 12 year-old el cheapo atmospheric burner tank type and it doesn't fire but maybe once or twice for only a few minutes every 24 hours to maintain the temperature if I don't use any hot water. Newer gas-fired tank type water heaters lose less heat than mine so would likely fire even less.

Almost all but the smallest of the gas-fired tankless have burners rated about 198,000 BTUs/hour and you would be hard-pressed to fire that with a 1/2 inch natural gas pipe of any length. Most tankless installations require a dedicated pipe from the meter of no less than 3/4 inch nominal size and depending on the piping run a 1 inch pipe may be necessary.

The Navian is a "condensing" water heater and advertises an efficiency of around 98%. BUT, it only achieves that efficiency when it it is continuously burning. For an average over 24 hours the "efficiency" will be far less. Add to that the cost of the Navian (better than $2,000 last I checked) AND the cost of larger gas piping and you can buy several tank type heaters AND the gas to run them for the expected lifetime of the Navian. One very good thing about the Navian is that being a condensing unit it can use PVC piping for the air supply and exhaust rather than the high temperature (generally stainless steel) required by most tankless heaters. One last thing about the Navian: When I looked into them about a year or so ago I found they had an abnormally high record of trouble and a fairly poor record of customer service. It's a shame because I really like the concept. Maybe they have improved their failure rate and there customer service since then.

Another thing that is generic with tankless is that if you have "hard" water you WILL need to "descale" the unit periodically. This may be only every couple of years or maybe a couple of time every year. This descaling requires taking the unit out of service and connecting a pump and hoses and circulating a cleaning solution through the heater for a period of time, maybe an hour, maybe more. It can be a DIY job (if you don't mind purchasing and storing the pump, hoses and buckets) or you can contract it out at an additional cost. Tank type heaters should be flushed at least yearly and maybe twice yearly in cases of less-than-pristine water but doing so is only attaching a garden hose and opening the drain valve.
 
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Old 03-26-12, 05:18 PM
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Not to say the burner is running constantly. But the burner does activate when you aren't home or on a road trip, whereas the tankless heaters work on demand. You know that. Yeah, the descaling is a problem, especially on wells with hard water. That's sad to hear about the Navian. I, like you, was impressed with the concept, but concepts don't prove out all the time.
 
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Old 03-26-12, 06:32 PM
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Hey tranch, hows it going. I bought a Navien tankless for my house about two years ago, Paid 1500.00 dollars for it. It is a bit pricey but if you have a family they work very well. It has a recirculating system to keep hot water close to whichever tap you wish to use. It can also be set to recirculate only at the most used times with the remote keypad, so it not recirculating all the time, therefore not running the burner and wasting gas. I had to install a loop water line to all the fixtures so the circulating feature would work, this may get pricey if you have to have a plumber come in to do it. Overall though, I really like the Navien, have had no trouble, installed it myself with a little advice, and do not have an elevtric heater taking up space and electricity. Also on a loop systen, there should not be any noticeable difference in the time it takes hot water to reach the second floor fixtures. Hope this helps in your decision, there are many different brands out there, I just picked Navien for all the features It had
 
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Old 03-26-12, 08:34 PM
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Stateofone, how many years will be your pay back on that before you start saving money over a conventional water heater? What were your installation costs?
 
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Old 03-27-12, 12:44 PM
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I have a 50 gal GE conventional that runs for about $15/month. The trend in nat gas prices has been down in recent years.
 
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Old 03-27-12, 06:36 PM
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Hi ray2047, I installed it myself, with a little advice from a plumber friend of mine. PEX tubing is the only way to go, haha. I paid about 1500. 00 for the unit, about 250.00 for the gas lines, PEX tube and miscellaneous valves and fittings. I do not know what a conventional electric costs, I suppose around 300 to 400.00 for a really good one. I figure that my electric bill has dropped between 15 and 20.00 per month without the electric heater. The propane costs are minimal, I have not noticed much difference in my propane use. I figure between six to eight years for being paid for, but that is a calculated guess. The best part is being able to take 20 minute hot showers without running out of hot water, to each their own.
 
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Old 04-04-12, 04:49 PM
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I have a 50Gal NG water heater. Only two of us in the house, but our gas bill is usually $27 per month. $10 of that is taxes. Fireplace is the only other Gas appliance in the house. Payback for a tankless would be so long, just pointless to do it.
 
 

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