What is Digg?135 Comments
- kickmenow, on 10/12/2007, -3/+37Including the above, some things a person ought to know before buying a tankless:
* They save gas, but instantaneous gas consumption is MUCH higher than a conventional water heater. In most houses, this means the gas supply needs to be upgraded, with a higher-capacity meter, larger pipe to the water heater, and possibly even other work on the street side of the supply. All at the purchaser's expense, of course.
* They all have a minimum flow at which they operate. This means that you cannot get a trickle of hot water, nor can you adjust the water temperature arbitrarily (at any given flow, there will be a point at which the water temperature drops from warm straight to cold)
* As the post by chembro84 points out, the tankless water heaters don't react to changes in water flow instantly, which means that any change in flow means a temporary change in water temperature (increase in flow causes temperature to drop momentarily, decrease in flow causes temperature to rise momentarily). These temperature changes can be large.
* There is still not very much expertise in the field with respect to maintaining these heaters. If something goes wrong with yours, be prepared to have very limited choice in service company. Too bad for you if that company has rude employees, or if they run into an issue that they don't know how to fix.
* You may even discover that your house's water pressure is not within the standard pressures required by code these days. If it's not, the tankless water heater may not operate correctly (failing to turn on at the designed minimum flow, for example).
I learned all of the above and more when I tried to replace our conventional water heater with a tankless. After four months of headaches, we finally gave up and switched back to a conventional water heater. - p9s50W5k4GUD2c6, on 10/12/2007, -2/+15These heaters can provided unlimited hot water on demand and changing to a tankless system generally results in savings of 15 - 20%
Water heating accounts for 20-25% of an average household's annual energy expenditures. The yearly operating costs for conventional gas or electric storage tank water heaters average $200 to $800, respectively. - Oxygen, on 10/12/2007, -1/+8We like instant gratification here in the states.
- tangledweb, on 10/12/2007, -3/+9If you dugg this story, be sure to check out http://www.horselesscarriage.net/ These things are wild!
As a side note, I have a tankless water heater, and I hate it and would never buy another. It is fine for showers, and other bulk uses, but it really annoys me for small tasks.
Imagine you are cleaning kitchen benches and will want to rinse a sponge out 5 or six times under a hot tap between wiping sections. Each time you need to turn the hot tap on, wait 30 seconds while cold water comes out, then rinse.
Oh god, that story sounds even more boring writen than it did in my head. Why did I bother peplying to this topic. I am going to go and kill myself now. - kickmenow, on 10/12/2007, -1/+7I also forgot to point out:
As chembro84 also says, you get to wait for the hot water always. To elaborate: with a conventional water heater, once you've gotten hot water to the faucet, the water in the pipe stays reasonably hot at least for a few minutes, if not longer. You can turn the water on and off repeatedly without too much change in temperature. A tankless water heater takes a few seconds to turn on, so every time you turn the water off and back on again, you get a few seconds of cold water in the pipe. When exactly you get the cold water depends on the length of the pipe, but the bottom line is that the water temperature drops drastically and then comes back up for each time you turn the water off and on again.
...and the above post reminds me: conventional water heaters often use a pilot light, so they work without electricity. But even a gas tankless usually depends on electronic ignition. So even though it's gas, it won't work without electricity. - glaive, on 10/12/2007, -0/+6Doesn't look like the link mentions microwave water heaters. For more info, check this out: http://www.theglobeandmail.com/servlet/story/RTGAM.20051122.gthotwater1122/BNStory/Technology
- CaptHarlock, on 10/12/2007, -1/+6-digg
We had one in a apartment... Brand new...
In the dead of winter the cold water would cause it to over compensate and either scald you (grandparents had to visit the hospital..) or get frost bitten by the damn freezing cold water because the auto-regulator kicked on to keep it from overloading/melting.
Bottomline is you never had a steady comfortable temperature, you had to juggle the faucet handles the entire damn time. - chembro84, on 10/12/2007, -3/+8my parents have one, and it's pretty cool but it has it's downsides. Firstly it takes a long time for hot water to come out, and when you try to take a shower on the end of the water line and someone else is using water, you get burned and then frozen pretty quick, but everywhere else in the house doesn't really have that problem.
- roeboedog, on 10/12/2007, -2/+6Um you have one for each functional groups you don't have one for each faucet. Put the kitchen on it's own with the laundry another for the bathroom. That way you can take a shower and do the dishes at the same time.
- roeboedog, on 10/12/2007, -0/+4The Penny Pincher inside of me goes crazy when I hear the Hot Water Heater Heating in the middle of the night - on a real cold night I will hear it four to five. (renter - Heater is outside in metal cabinet)
I do not understand, when something can save you money it has to cost twice as much up front. I checked these out awhile ago at Home Depot. They are twice as much as a Tank'd Heater.
WTF? - CanuckPlumber, on 10/12/2007, -0/+3Wow, a topic that I can say that I know a great deal about. Never thought I'd see this in here.
My opinion... Until North Americans learn to curb their over use of domestic water supplies, these won't work. If you only want to use one fixture at a time in your household and don't have a large bathtub, then they would work, but most households have a demand need greater than the 5.2 gpm flow rate provided by these system's.
Its good to see stuff that I can professionally provide an educated opinion on.
Dugg. - bacon_skoda, on 10/12/2007, -1/+4these don't get gov. subsidies, but solar water heaters do. what the hell.
- roeboedog, on 10/12/2007, -1/+4I have heard that it's just americans that want Hot Water Standing by. It used to be in europe if you wanted hot water you needed a least a half hour -
You go in the kitchen flip the switch to the boiler and wait a few - hot water when you need it seems better than having it stand by and wait for you to use it. - riskable, on 10/15/2007, -0/+3You've obviously never installed a whole-house tankless unit. They're installed in lieu of a tank in the garage/basement/wherever you'd normally put a tank. The more popular ones are propane and natural gas (no electricity needed).
-Riskable
http://riskable.com
"I have a license to kill -9" - tavisjohn, on 10/12/2007, -1/+4"Um you have one for each functional groups you don't have one for each faucet. Put the kitchen on it's own with the laundry another for the bathroom. That way you can take a shower and do the dishes at the same time."
Actually many of them can handle many appliances at once. My dad has one that allows for a shower, dishwasher, and washing machine all at the same time! And you still have hot water to wash your hands with!
It depends in the modle you get. If you are a heavy user of hot water, then get a unit that can handle your peak output! - Digg4all, on 10/12/2007, -0/+2Tankless water heaters are great. Many of you are complaining about how bad they are, but it is because many of the makes out there are junk. We sell Noritz where I work and they are awesome. They turn on at 0.5 gpm flow and have a digital thermostat to maintain the temp. We even sell them to larger industrial applications and they can also be used in a radiant heat application. Everyone mentions Bosch, well Bosch's top model in terms of gpm is the same as a low end Noritz. They have models that go up to 13 gpm which is enough for a large house running up to 6 showers at a time. In regards to everyone complaining about waiting for hot water, they make pumps which draw out of the hot line and recirculate the water into the cold line until the thermostat in the pump senses hot water. So you get hot water instantly even if your bathroom is far away from your heater. The key is to get a good plumber who knows what they are doing and knows their products. I hate to see everyone bashing a great idea because of lack of understanding, but in reality the only downside to a good tankless system is the initial cost.
- calgarian, on 10/12/2007, -0/+2I beg to differ with you. We moved to Europe 2 years ago and this is the common method of hot water supply in most of Europe. We have two bathrooms with showers, the kitchen, and our heating system running off one gas powered instant unit with great service and great efficiency.
- m85476585, on 10/12/2007, -0/+2Why not combine a tankless heater with a small tank (maybe 5 gal) to help even out the temperature and provide trickles of water. I'm not saying to just put a tank inline after a tankless heater. If it was built in, the heater could monitor tank temperature.
- mrASSMAN, on 10/12/2007, -0/+2sure, easy for you to say in FLORIDA. florida tap water is over 80 degrees. here in washington state, the tap water is around 60.
- m85476585, on 10/12/2007, -0/+2It will not be as warm. You have to buy one rated for the most GPM you think you will use.
- Murphys, on 10/12/2007, -0/+2I use the electric system. I put two in in parallel. That way I have plenty of hot water for showers AND since I have shut-offs on both sides of each, I have an easy way to take one out of service for repair with only minimal inconvenience. (ie only ONE shower at a time)
- riskable, on 10/12/2007, -0/+2I just installed a new water heater myself and did quite a bit of research which you can see here:
http://riskable.com/2006/02/12/new-water-heater/
Couple of things to note:
1. Propane tankless water heaters are at *most* 87% efficient (13% of your heat goes out the chimney/vent).
2. A high-efficiency electric water heater with R-24 foam insulation costs $200-300 (I paid $270 for a 50 gallon model).
3. At the current cost of propane (~$3/gallon--which will only go up), electric water heaters are cheaper to operate.
4. Tankless electrics take a while to "warm up" and can end up wasting a lot of water. They also cost a fortune and you will never make up the cost even with a 20-year life expectancy.
5. If you're *really* interested in saving on your energy bill, you'll invest in a solar hot water heater system. You can even add one to an existing tank-based system without much effort. It will take a couple years to make up the initial investment cost, but it is worth it. If you DIY you can make up the cost in no time at all!
I'll be updating my blog in a couple weeks with my DIY solar water heater system if my life lets me do it =). Estimated cost: $500.
-Riskable
http://riskable.com
"I have a license to kill -9" - nogami, on 10/12/2007, -1/+3My parents have one in their house as well (2 actually, one dedicated for bathrooms, and one for the rest of the house). It works pretty well, except theirs is an electrical version, and when the power went out on xmas morning, it meant no showers for anyone that day. At ~60 amps (I think), it's also not going to be able to run off of an emergency generator either.
I think I'd recommend looking at a gas-fired model (if gas is both available and cheap in your area). That way if there's a power outage, you can still power the heater with a generator to drive the minimal electrical needs of the thermostat and ignition system. - tomvendetta, on 10/12/2007, -0/+2But overtime, that pays off :)
- htsolutions, on 10/12/2007, -2/+4Again as everyone is saying these are used a lot in Europe and Asia because mainly of saving space and energy conservation. While I was in Spain shopping I found them more on the shelves than tanks. I have been looking into buying one for quite sometime and I found out some good information on them.
1. They last about twice as long as a tank. So this means that if you are going to stay in your house 20yrs you will save $. However, if you plan on moving in a couple of years you shouldn't bother. The reason that they last longer is because the water is not standing at long periods of time building up sediment in the bottom.
2. Tanks lose their energy efficiency over time. Again they build up sediment into the bottom and the tank.
3. Tanks heat and reheat water when you are not home. Where as tankless only heats the water when you are using it.
The two downside that I have heard about is that when doing dishes at a low output the tankless may not kick on. If you are like me I don't keep the water running when doing dishes so the tankless would shut off and turn on if I would do my dishes the normal way. The other downside is the fact that you have to wait for hot water. Well I have to wait for the hot water to get to my bathroom at the opposite end of the house.
Here in the US the biggest problem is that most contractors shy away from new technology. Setting up a tankless may require hardware firmware upgrades, circuit board configs, or jumper settings. This kind of technology does not aways go well with contractors. And contractors usually like to install items they are familiar with, which means that they get paid better rates when they get in and out of the job faster.
Lastly you can get a $300.00 tax credit this year and next due to the energy bill..(check with an accountant)
I'm looking into the Bosch 250SX NG. If anyone has more good information please post.
I'm a builder and I love tech but usually those two do not go hand in hand.... Cheers - friedmind, on 10/12/2007, -0/+2When I was researching tankless heaters one of the drawbacks I kept hearing about was that they aren't that great for sinks because you have to have a minimum flow rate for hot water to come out. So if you wanted a trickle of hot water you wouldn't get it because it wouldn't flow fast enough for the hot water to come out.
- error401, on 10/12/2007, -0/+2Because more efficient technology is newer, more complicated, and more costly to make?
- riskable, on 10/12/2007, -0/+1You're wrong on a number of points:
1. If you're using a propane or natural gas tankless water heater, most models come with pilot lights and/or mechanical lighting mechanisms. Some even come with electronic ignition systems that include battery backups. They will continue to operate when the power is out.
2. A fairly new water heater tank will have an insulation rating of AT LEAST R-19 with some units coming in at R-24 (what I recently purchased). On these systems, your power can be out for DAYS and you'll still have hot water. Insulate your pipes for even longer lasting hot water.
3. The bigger the tank, the longer it's hot water will last with the power out.
-Riskable
http://riskable.com
"I have a license to kill -9" - Otto, on 10/12/2007, -0/+1"Why would you want a microwave water heater? If the power goes out, it won't work, and in 10-20 years they will probably discover that microwaves cause some strange disease or mutate bacteria in water. And microwaves interfere with WiFi networks."
If the power goes out, that electric inline heater won't work either, and most likely neither will the inline gas heater since it uses an electric solenoid to control gas flow.
And what they discover in 10-20 years is irrelevant... because what they know RIGHT NOW is that microwaves KILL bacteria in water. No mutations, just death. Also, microwaves could be a much more efficent way to transfer the power to the water than a conventional electric heating element would be. Yeah, you could immerse the heating element for 100% efficency, but that makes the element hard to service as well as putting thermal stress on it which may lead to eventual breakdown. But with microwaves, you can put the magnetron outside the water and still get 100% power transfer to the water, simplifying the process.
As for interference with WiFi, that is true, however it's also easily solved. You encase the whole thing in a metal box. Microwaves don't pass through metal. You'd want to do this anyway, so as to make sure that all microwaves were absorbed by the water, to increase efficency.
Short version: it's a damn good idea. - Tmack0, on 10/12/2007, -0/+1This is what I was thinking of doing for my own home. Put a 5Gal standard water heater after the tankless one, so for short demands, the water is already there and warm, there's a buffer to keep the temperature more constant, etc, but doesnt leak heat as bad as a full sized tank would. When you use enough hot water to trigger the tankless (same ammount as would without the tank), the tankless simply pre-heats the water that goes into the tank, so the tank itself doesnt actually turn on. The only time the tank heater would operate is when idle, and since it takes alot less energy to keep 5 gallons hot than 40+, the energy savings would still be realized.
- bshankle, on 10/12/2007, -0/+1I installed that Bosch model you mentioned. See here:
http://bruceshankle.blogspot.com/
I'm loving it. - nattybohman, on 10/12/2007, -0/+1I use one of these several times a year when I go to Europe and they are TERRIBLE. The amount of water that can pass through these systems is a trickle compared to American hot water tanks. I've tried them in several houses and all are the same.
There's no substitute for a shower from a hot water tank. When I build my house in Europe, I'm going to bring over an American hot water tank for the sake of comfort. Why live in misery to save a few cents on electricity? - kickmenow, on 10/12/2007, -0/+1They use way more on a per-time-unit basis than a storage water heater would (a whole-house heater is about 150,000 BTU/min or more, compared to around 25,000 to 50,000 BTU/min for a storage water heater). But the total energy usage is basically the same (ignoring, of course, the lack of a need to keep reheating the water).
For a given temperature and volume of water (which are constant), it takes the same BTUs to heat that volume to that temperature. Whether you put the BTUs in all at once, or over 10-20 minutes doesn't matter as far as your gas bill is concerned. - wb9dgo, on 10/12/2007, -0/+1We have had one for about 6 years. When we go on vacation we don't heat water we aren't using. I can fill our Hot Tub full with hot water in just over an hour. Only problem is we have to cool it down with cold water before we can use it! It does take about 2 seconds for the water to get hot initially. Just check Bosch's web site for spec's.
- freestyle, on 10/12/2007, -1/+2Very cool but what happens when you use water faster than the heater can supply?
PS this site is probably going to go down soon because of the digg effect so here's a cahced link:
http://www.tanklesswaterheaterguide.com.nyud.net:8080 - Silencer7, on 10/12/2007, -0/+1Here in Japan, they're pretty convenient, at least for places like my apartment. The best part is the button that will fill your bath for you at a preset temperature and volume. For bigger houses? Yeah, you might want a tank. But if you're living alone or as a couple, and don't mind waiting 5-20 seconds for hot water, these heaters are pretty nice.
Japan still seemingly has no concept of home insulation. It boggles the mind. - Spec8472, on 10/12/2007, -0/+1Australia too -- We've had natural gas based ones for ... well, atleast 25 years. Not so sure about electric though.
The issue with the minimum flow-rate before it kicks in can be a little annoying, but I believe this can be adjusted (by a plumber, if not by the consumer).
As for needing to upgrade your gas supply - again, not sure the differences, but we never had a problem running a gas oven/stove, gas room heater, and the hot water at the same time.
Ofcourse, now we're using solar hot water (with electric booster for winter, since there's no mainline gas at the new place) - so we get better savings yet again. - Cyberdactyl, on 10/12/2007, -0/+1There's one thing that everyone's missing here.
If the power goes out. . .as it does quite often for some areas prone to ice storms or electrical storms. . . you're out of luck with instant units. A hot water tank serves as a hot water accumulator, allowing the family to have limited hot water for almost 12 hours if used conservatively. - CanuckPlumber, on 10/12/2007, -0/+1There is a vast difference between residential and commercial applications. ;)
- chiller2002, on 10/12/2007, -0/+1Not really the "How Stuff Works" article that I was expecting--it didn't really explain how these things work and really isn't as "magical" as the poster made it seem. And although Instant Hot Water is not an entirely new concept (in fact it has been around for quite some time), it is still a great solution that more people have yet to implement in their homes.
- kickmenow, on 10/12/2007, -0/+1Yup, buffering the output of the tankless water heater would work. As does using a constant-temperature mixer valve to control the final output (the tankless can fluctuate a bit, while the faster-responding valve keeps the tap temperature constant). There are a variety of ways to address the shortcomings of tankless water heaters.
Also, note that the various shortcomings of a tankless water heater may not be an issue for everyone. In many cases, a tankless water heater makes sense. I just think people considering buying one ought to know more than the pie-in-the-sky marketing chatter from the people selling them. - Flood_of_SYN, on 10/12/2007, -0/+1When I have a small hot water task to do, I use a bucket or other small container to hold enough water for the task.
- true, on 10/12/2007, -0/+1Your article on your website on installing an electric tank is very useful, specifically on how to compare the cost of propane gas vs. electricity.
How do you compare cost of Natural Gas vs. electricity? In my area natural gas has skyrocketed 3 times when electricity seems to be a stable .10 to .098 per kw. - CanuckPlumber, on 10/12/2007, -0/+1Actually, it moves out the flue and up the chimney. Very little heat is gained into your home via your exhaust.
Cheers - Wolfman~K, on 10/12/2007, -0/+1The company I work for sells these things, gas fired whole house, work very well.
Blatent plug
http://www.supply1.net - Cyberdactyl, on 10/12/2007, -0/+1@ riskable
DUHHH!
If you have gas heating your HWT, losing electrical power wouldn't be an issue...now would it? - CanuckPlumber, on 10/12/2007, -1/+2@ kickmenow
"* They save gas, but instantaneous gas consumption is MUCH higher than a conventional water heater. In most houses, this means the gas supply needs to be upgraded, with a higher-capacity meter, larger pipe to the water heater, and possibly even other work on the street side of the supply. All at the purchaser's expense, of course."
The gas line size is only marginally higher (increase from 1/2 inch to 3/4inch) and I doubt that the reg would have to be changed. I've installed more and more of these lately and the changes to the gas line and associated piping isn't all that much.
Cheers - bossm4n, on 10/12/2007, -0/+1I put one in last year and I love it. Less space, endless hot water, lower gas bill. Those three outway any negatives.
- CanuckPlumber, on 10/12/2007, -0/+1Its amazing how many plumbers and pseudo-plumbers there are out there.
- Woknblues, on 10/15/2007, -0/+1If your electricity goes out, I am not too sure if a bath or shower is the first thing to be concerned with. At least in my experience with power outages, (I had 7 days without in So Florida last year), a cold shower is not the worst thing in the world to happen, nor is it very uncommon to about 4 Billion people.
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