Is a tankless water heater good for my situation?


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Old 06-08-11, 03:21 AM
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Is a tankless water heater good for my situation?

I currently have an electric water heater. It's fairly expensive to operate.

I am on a natural gas line, which heats my new furnace (which I love).

I'm going to have a 2nd person living in my home next month (my gf) and the human activity in the house will obviously double. But even with the 2nd person living here, I KNOW that my hot water usage will be below 40 gallons a day.

My house is fairly small. 1000 square feet. I think I can easily have changes to the gas line done which enters into my basement. The electric modifications I'm not sure about.

I live in Iowa. Groundwater temps can be pretty cold for about 4-5 months of the year. I've never tested it however.

There's a lot of "hype" about these tankless heaters. But there's also a lot of people who swear by them. I'd never buy one from a big box store and try to cut corners on costs. I'd only have it done by an experienced, reputable company that stands by their work.

My question is, is my situation good for a tankless unit? Obviously groundwater temperature is a big consideration, but based on all the other factors, am I in a good situation for the benefits of a tankless unit?
 
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Old 06-08-11, 07:47 AM
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If gas is cheaper per BTU in your area then I'd suggest switching from a storage type electric you now have to a gas storage type heater. You haven't mentioned size of the existing water heater but a 50 gallon should be more than enough for just two people. Venting will need to be added but will probably be cheaper then for a instant heater.
 
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Old 06-08-11, 08:54 AM
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I've had a tankless now for nearly 2 years. My thoughts are (with a 2 person household) to go with a storage gas heater. The tankless would be great for several family members potentially using lots of hot water, in my opinion the benefit ends there. It takes twice as long running water in sink or shower for water to get hot as before with our gas storage heater, and small things, such as running small amount of warm water in bathroom sink, can't really be done without running sink faucet full flow for a while first. It takes a fairly large flow to 'trigger' the tankless to come on. Our overall water bill is around 30% more, just because of running extra to get hot water. All that, plus the expense of the tankless itself, I'd go back with a regular gas heater.
 
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Old 06-08-11, 09:38 AM
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Originally Posted by mwpayne
I've had a tankless now for nearly 2 years. My thoughts are (with a 2 person household) to go with a storage gas heater. The tankless would be great for several family members potentially using lots of hot water, in my opinion the benefit ends there. It takes twice as long running water in sink or shower for water to get hot as before with our gas storage heater, and small things, such as running small amount of warm water in bathroom sink, can't really be done without running sink faucet full flow for a while first. It takes a fairly large flow to 'trigger' the tankless to come on. Our overall water bill is around 30% more, just because of running extra to get hot water. All that, plus the expense of the tankless itself, I'd go back with a regular gas heater.
If you don't mind me asking, what kind of tankless do you have?

I've been reading a lot about these. The condensing tankless units have attempted to handle some of the complaints about cold water sandwiching. I don't know about the hot water wait after turning on the faucet.
 
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Old 06-08-11, 10:36 AM
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I agree with the others that tankless is probably not cost-effective for you. This is especially true if you are considering a condensing tankless.

With your water source being from wells (either your own or from a municipal source) you WILL have to deal with scaling issues and that will require at least yearly descaling of a tankless and it could be more often than once a year depending on the amount of water used and the scaling factor.

Tankless water heaters require a large gas pipe, often directly off of the gas meter. Non-condensing models require special high-temperature exhaust venting and considering both gas supply and venting the installation cost could exceed the cost of the heater itself. Condensing models don't have the need for the high-temperature venting but the capital cost of the heater itself is pretty steep, often $2,000 or more. The condensing models that I have read about don't have the best reviews and mostly it is control issues. While I like the concept of condensing tankless the reliability issues and capital cost stop me from considering them as a viable alternative to storage tank heaters.

Quite honestly, when a life cycle cost analysis is done a storage tank water heater almost always will beat a tankless of any design.
 
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Old 06-08-11, 11:40 AM
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I have a 40 gallon NG water heater and we never run out of hot water and as a result don't worry about who's using hot water at any time (2 adults, 1 child) - some tankless heaters will have trouble keeping up with significant demand
 
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Old 06-08-11, 12:54 PM
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Originally Posted by LesnarRules
If you don't mind me asking, what kind of tankless do you have?

I've been reading a lot about these. The condensing tankless units have attempted to handle some of the complaints about cold water sandwiching. I don't know about the hot water wait after turning on the faucet.
I have a renni tankless. Sandwiching really hasn't been that big of an issue, just bugs me to have to turn sink water full on to wet toothbrush or wash face/hands with warm water. Another issue is, if/when it breaks, who works on the thing? I can fix gas valves, solenoids, etc on my regular heaters, but when I opened the cabinet of this thing I may have well have opened the hood of the space shuttle. Having said all that, so far it works as it's supposed to, we've run two showers and dishwasher at the same time, it handled it no prob.
 
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Old 06-08-11, 08:09 PM
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Originally Posted by mwpayne
I have a renni tankless. Sandwiching really hasn't been that big of an issue, just bugs me to have to turn sink water full on to wet toothbrush or wash face/hands with warm water. Another issue is, if/when it breaks, who works on the thing? I can fix gas valves, solenoids, etc on my regular heaters, but when I opened the cabinet of this thing I may have well have opened the hood of the space shuttle. Having said all that, so far it works as it's supposed to, we've run two showers and dishwasher at the same time, it handled it no prob.
How is your gas bill since going tankless? Any savings at all?

There's a Navien condensing unit that I'm looking at. It has some kind of recirculating system so it limits the wait for hot water. It's also uses the exhaust from the burner to heat the water, making the outdoor exhaust much cooler, thus allowing for pvc venting.

My gas meter runs into my basement where I would install a tankless unit. I could put the unit very close to the gas meter.

I have a water softener so mineral buildup/scaling issues should be minimized.

And I'm on city water, not a well.

I don't wash my hands with hot water. I rarely wash my clothes, towels, sheets, etc with hot water. Mostly hot water is used for showers and the dishwasher.

The Navien unit I'm looking at claims to have a "no minimum flow rate" that can supply hot water as low as .1 gpm.

Sounds pretty good. Only concern I have is the incoming water temperature. And the lack of good reviews out there.
 
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Old 06-09-11, 08:05 AM
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We have a gas furnace and dryer, as well as water heater. If there's a gas bill savings I haven't noticed it. Bills are about the same as before.
 
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Old 06-09-11, 10:52 AM
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My opinion is (and it is shared by a large number of people) that retro-fitting tankless to save money is a mistake. Total life cycle costs are going to be such that you probably won't see any REAL savings until the second tankless is installed.

BTW, in Iowa you are using well water even if you get it from a municipal water utility. The softener will definitely help but there WILL be more maintenance on a tankless than a tank-type water heater. The Navian, although an excellent idea is NOT trouble free by any stretch of the imagination and neither does it attain that claimed 98% efficiency most of the time. For the cost of the Navian, something like $2500 plus installation, I can buy AND fuel tank type water heaters for the rest of my life.
 
 

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