Is there a source of information for comparing the operating costs of traditional water heaters to those of tankless water heaters? If there is , could you point me in the right direction?
Thanks,
Matt
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Sorry, don't have a comparison website at my fingertips (CaseyR is the hotshot for obscure URL's). I would caution, though, that any such comparison is easy to be biased one way or other. Presumably biased towards tankless heaters because tanked HWHs are still the norm and tankless are trying to justify their higher prices to eat into that market. Usage patterns, fuel costs, amount of time on vacation, whether you set your tanked HWH on "vacation" when away, etc.
Rather than take a manufacturer's word for it, I'd suggest you figure about a 20% savings for the tankless units. Multiply by your energy cost and water useage.
Or try a natural gas utility website as a less biased source of info.
So once you have a annual savings amount (e.g. $80/year) just look at the present worth of that future savings for, say, 15 years. And compare it to the added capital and installation cost. If the higher cost is recouped (in today's dollars), go for it.
Matt,
I've been researching the same thing, and it turns out that the further south you live, the smaller the savings will be.
The most attractive thing about the tankless is the availability of continuous hot water, no matter how long it runs.
If you're gonna use gas (LP) you must have a dedicated line from your tank, not a branch off of the line in the house. Also you will need a minimum of a 5" exhaust stack over the heater to take care of the increased heat from the 150,000 btu burner. You'll also need a good supply of vented air for the burner. More than what a tank variety needs.
Talked to plumbers down here in Texas, and very few have installed them in either new or remodels.
HD sells one brand, and they have some literature available.
Hope this helps.
Tom,
The International Fuel Gas Code does not require a separate line from the LP tank, nor does any Mecahnical Code, that I know of. Where did you find this requirement?
Also, my Aquastar (Bosch) has an input rating of 217,000 btuh. It does have an induced draft fan and a 4" flue (all per manufacturer's installation spec's), though I increased it to 5" because of the specifics of the installation.
Bottom line here is that the installation of any gas (or other fuel burning) appliance needs to performed by a knowlwedgeble mechanic/plumber, per the applicable code.
Matt, one source for items like this is plumbingsupply.com, they sell various makes and types. Another limitation to tankless, though they supply an "endless" volume of hot water, most (not all) can only supply a single fixture at a time.
Tim,
It's been a while since I looked at that option, but I think it was with the literature on the heater that HD sells. It may have been on the spec sheet on-line too. It was very specific about the dedicated line if you are running propane, as it would lower pressure in you CH and cook stove when the WH was being used. The 5" vent stack was also a requirement. I'll look around and see if I can come up with it.
We're not gonna go with that option, as our savings wouldn't be worth it down here in Texas.
What's the feeling about indirect fired water heaters?
Double check the requirement about a separate line from the tank. Considering how LP supplies are usually setup, that requirement seems unreasonable. My LP tank is underground, with a buried supply that goes though a regulator/vent outside before entering the house. Under that "requirement", I would have to adapt at the tank to branch a second line off of the single supply vavle, trench in that new line, get a second regulator and punch another hole though the siding and rim joist, then run a new, separate pipe inside, to supply a single domestic water heater!? Well to say the least, I'm skeptical.
BTW, I sized the LP supply for my house, feed the Aquastar off of that line and never have any trouble operating the other DWH, gas furnace, gas dryer or the garage unit heater, in any combination or all at once. Based on the length and layout and demands, the supply is a 1" until a few loads drop off.
A properly sized fuel supply, whether natural gas or LP, will not have an unacceptable pressure drop due to its design supply to any or all of the appliances. Though, properly sized means actually doing a piping plan, calculation of the equivalent length, assigning all the correct demands along the line and picking the minimum pipe size required for each section of the run, based on a maximum acceptable pressure drop. With the tables available in the Internation Fuel Gas Code or previous Mechanical Codes, its almost as easy to do it right as it to do it wrong.
Edited 7/25/2002 7:50:01 AM ET by Tim
Tim,
Here's the site for Aquastar, and the info about the vent and lines.
http://www.cetsolar.com/instal125.htm
I've got a 5/8" feed to the house, with the tank 85' to the heater location.
Check the vent requirements too.
From the site you listed:
"Install the provided gas regulator with its directional arrow facing the gas flow path (also be sure to properly regulate Liquid Propane or Natural Gas at source when supplying AquaStar), this small regulator that is provided is NOT to be used on a high pressure"
Nothing about a separate supply from the tank. 5" flue for the gravity vent, if you get the power vent option, you can use a 4", for a reasonable distance. I was mistaken on the rating, 117 MBH input. I have the Aquastar 125LX with the power vent option.
You have a 5/8" copper tube to the REGULATOR at the house. The fuel is at pressure upstream side of the regulator. Pipe sizing for an LP system begins at the regulator, where it becomes a low pressure gas. Typically, no greater than 11" wc. (The same is true for NG, except there is a meter involved with the regulator and supply pressure is different from that of LP.) Check out where the gas enters your house. Tell me if you don't have a copper tube coming out of the ground, into a regulator and a 3/4" steel (hopefully black) pipe supplying the house.
If you ever decide to change anything about the gas supply in you house, I would suggest that you hire a licensed plumber to do the work, they will understand.
You guys are scaring me. At least someone suggested calling someone who know what the heck is going on. Good move.
HAHAHAHATom
Thanks for your, .... help.
I most likely will be going tankless because of space saving and should last much longer than a tank type. JMHO, Roger
http://www.stateind.com/new/Tankless_WhitePaper.pdf
The attached paper is my attempt (as a knowledgable water heater person) to give an objective evaluation of tankless vs. storage type water heaters. As you can see, the energy savings are not really significant compared to the cost of the units. In addition, unlimited hot water works only if you use relatively small amounts of water. Remember, some of the modern shower heads can use 12 gpm of water...no tankless heater will keep up with that. On the other hand, they are entirely appropriate for some applications...limited use demands, etc.
I hope this helps!
Bill
After reading that article I think it is biased against tankless. So I recommend this article: http://www.eren.doe.gov/consumerinfo/refbriefs/bc1.html
JMHO, Roger
The article may be biased against tankless water heaters but... the other articles do not address the tankless weaknesses. They dismiss or ignore the flow limitations, costs, servicing and the installation issues. In addition, they over inflate the cost savings due to energy savings. You may be interested in investing an additional $400 or more in a heater to save $40 or $60/yr. but I am not. Furthermore, I was fascinated by their statement that the expected life of a tankless is 20 yrs. How do they come up with that? Most of the industries warrantees are five years or less! In any case, I can buy two storage water heaters to get more than 20 years of life and still put money in my pocket.
As I said in the article, if you have plenty of money and if you never need significant flow of hot water, tankless heaters may be a good option. However, most modern homes need more than 2.0 or 2.5 gpm of hot water.
Obviously, some homeowners are very pleased with their investment in tankless heaters. I think that is great but....don't let their pleasure translate into a blind purchase without considering the flow limitations, the high investment and installation costs and the maintanence costs.
Bill
Hi Bill, The costs of the Bosch tankless is 575.00. A name brand tank type close to the same efficiancy ratings and energy label costs and still not even close on the warrenty is 355.00. Thats about 200.00 Every part of the Bosch is replaceable not true on a tank which in this area last only about 15 years tops. I am a single person building a 2 bedroom house so flow is not a problem. Thanks Roger
Since the operating costs will be the same, the only difference is the warrantee. Read the Bosch warrantee very closely, the advertising says they are designed for 20 years but...the best warrantee I have found is for 15 yrs and that is only on the heat exchanger. If you are truely getting a 20 warrantee and not just a statement that it is designed for 20 years...great. You also need to consider that they recommend yearly service by a professional...what will that cost over 20 years. Finally, the average storage water heater in the US lasts 11.3 years. Depending on where you live, you could expect significant longer life...in Milwuakee the expected life is about 20 years.
Check your installation costs, the Bosch will require a 5 inch vent tube while your standard 40 gal. heater will have a 3" or a 4" vent. In any case, you will need a larger vent. Depending on your house, it could be easy or it could be difficult (expensive) to convert to the larger vent.
If the venting is not an issue and if you get a true 20 year warranty then I would say a tankless makes sense for you. As I stated in the while paper, tankless heaters do have their place. It is just necessary to sort thru all the issues to make sure you are not disappointed.
Bill
I was in Lowe's the other day and saw something very interesting, a tankless electric water heater! No vents, no airsupply problems, not much information either. But get this- a label on the unit said it was rated for 28 kilowatts! It was all contained in a box about 14" square ("That's a water heater?") Anybody had any experience with one of these?
The electric tankless heaters do not require a flue but one must be aware that they require high amperage electrical service. Before you get too excited about the ease of installation, check the electrical requirements.
Bill
I have one. Made by SEISCO, in Texas. Indeed does take 28KW. Some rather large wires, and close to the supply panel. Have not finished house yet, so it has not been run. Man who sold it to me has two - one at home and one in mtn cabin. He says it will take care of you in shower whiole dishwasher is running. Can't wait!
DonThe GlassMasterworks - If it scratches, I etch it!
Been using the Aquastar 240FX in a 3600sf house with three showers and a whirpool. Wasn't concerned with operating costs as my main concern was not running out of hot water. Flow rate is +5gpm and I've had no problems with taking two showers at the same time. Most importantly, my wife doesn't complain anymore of no hot water for her whirlpool. The 240FX has a power vent and installing the vent was no problem except we had to change from a B vent to single wall vent after reading more closely the instructions. I have natural gas. The cost will turn some buyers off ($1,000) but as the TV add says, no complaining family; priceless.
I just installed an aquastar 240fx in my 2 family house a couple months ago, for my apartment. My apartment is about 2000sf, 4 bedroom, 2 bath. So far I love it, but it does have a couple of drawbacks. Of course tanks have drawbacks too, and I feel the tankless overall is better.
First of all, it isn't over $1000 (well I suppose it is if you buy it at the depot). I got mine brand new on ebay for $630 after bidding low on maybe 4 auctions. When I got mine there was approx. 1 240fx per day up for bid.
Installation was pretty straighforward; I did it in a weekend. You don't need bigger than a 4" vent unless you are going a long way with the vent horizontally or doing a bunch of elbows. Actually the hole in my chimney where the old 3" pipe went in was big enough to accomodate the new 4" pipe so that wasn't a problem. I did have to replace about 4' of gas pipe to upgrade the 1/2" line to 3/4", and I had to replace maybe 3' of cold water pipe to upgrade it to 3/4". Mainly all this was tricky because it was in a very congested area around the chimney with lots of other vents and pipes around.
So now we can run 2 showers at once with no problem, and never run out of hot water. The unit takes up less space and will last longer. Our house inspector said the best grade of tank heater will last around 10 years here.
Also we are now saving about $10/month on gas. Not a huge amount but over 20 years, it adds up to $2400 as well as the fact that I would have had to use up two tank heaters in the same period.
As everyone probably knows, tankless is big in japan and europe. Its really not a problem if you get the right unit(s) for your needs. You can get a bigger heater than the 240fx, or install two.
The one annoying thing is that we have a single basin kitchen sink, so I usually do the dishes with just a trickle of warm water running continuously. The amount of water I want to run is just at the threshold of the heater so it is either not on or goes on and off. All in all a minor complaint.
Has anyone bought the new design of tankless. Instead of using a battery to light the ignition it uses I guess a small water turbine to power the ignition, interesting??
Wow, that sounds cool. Have you got a make and model number for that?
-Holly
H, its the 125HX. Try this site: http://www.houseneeds.com/shop/HeatingProducts/WaterHeating/AquaStar1/AquaStar125.htm
Sounds like you're guessing that it has a small turbine to recharge the battery. I'd guess that a thermocouple pile is used. Since there is lots of waste heat, and only a small eletrical demand to recharge a battery enough a make a spark 20 times a day. And a thermocouple pile is cheap and has no moving parts. The ones on the Voyager space craft have functioned in a hostile environment for 20 years and 2 billion miles. I'm guessing, but that's how I'd design it.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
One of my goals is to eliminate the central brick utility chimney (about 18x24") and recover those cubic feet on all three floors. Currently I have a 50 gal electric which will likely fail in the next few years.
At a home/garden show I saw a new type of gas HWH that was higher efficiency (say 80 vs 70%) but was set up so that the flue could be vented out a side wall, and I have a great location for it in a back corner. This wasn't one of the super high efficiency fan driven models (95%) that used the huge coil in the tank to heat water. Does anyone know about this type? I failed to get the proper literature, or else promptly lost it, and I'd like to be prepared when/if the electric model goes out.
TIA
Bob
Controlled Energy Corp. They handel the Bosch, and Home Depot a the distributor. I'm about to install my second one (Owner/builder). One drawback, you need a two knob controll in your shower. If you try to take a warm (not hot) or cool shower, as you turn the watter cooler the flow thru the heater is slower, so it picks up more heat, untill you slow it down to the point of no flow, and it shuts off. With a two handled controll, turn the hot on, then adjust the temp by adding cold. Short term fix, run hot water in the sink while you shower.
Clint
Thanks. You are my new hero.
I have a Bosch Tankless HWH that I use at a cabin, and I've not had any problem with a single handle valve in the shower. The water temp seems to react the same way as it does with our normal HWH at home. The manufacturer recommends that you set the preferred hot water temperature to the max comfortable so you don't have to mix it with cold (and reduce its efficiency).
B Whiley