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Tankless Water heaters

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Mar 31, 2012, 06:08 PM
Tankless Water heaters
We are considering replacing our 4 yr. 40 gallon hot water heater with a natural gas non-vented Tankless water heater. We have replaced most parts on the 40 gallon we have now with the manufacturer supplying us with new parts free of cost. (DUH!?) It won't stay lit. Not only replacing parts; sanded down the flame output.
The space gained by changing to Tankless would allow us to install a small water softener. We have read all information about Tankless but would like to read Pro's/Con's from actual users. Our home is a 1 Bath Ranch with only 2 people, dishwasher and washing machine. Only use water saver shower.
Mar 31, 2012, 10:12 PM
Overall, I am very disappointed in tankless water heaters. Not that they cannot work, then can, but the whole idea is to save energy and thus, save some money. From the manufacturers specs, the savings by using a gas tankless instead of your traditional gas water heater run about $50 per year. When you factor in the additional cost of the tankless unit (anywhere from $1,000 to $1,400 or so above a tank unit) it just doesn't make sense. And that's for a unit that continues to work efficiently.

Once you consider that hard water will reduce the efficiency of the tankless unit, the "savings' become even less. At it's rated flow rate, a tankless only has the ability to heat inlet water to 40 - 45 degrees above it's start point. With most ground water running about 65 degrees, that's giving you "hot" water that is only 105 to 110 degrees. Compared to the normal setting of 125 degrees for a tank unit. You are just not going to have as nice a shower as you are used to.

I started out being a big fan of tankless water heaters, but once I saw how poorly they perform in a whole-house function, I swung the other way. I would only recommend a tankless WH either for a remote part of the house for a single point of use or as a whole-house WH for a small vacation cabin that is frequently out of use.

Apr 01, 2012, 01:34 AM
From what I've read on line there are Tankless that will heat at a higher temps. If we were to install the tankless we would have space for a water softener which would alleviate the hard water issues. From what I read about the Rheem Brand, there is a way to override the unit so the temps can be raised higher. I have to wonder why the unit is manufactured to be set at a certain temperature yet the manufacture reveals the information on how to override the set temps. My first thought on this, is for safety purposes. We run our water heater higher in the winter due to the temp of the water that enters the house, it's Cold. I realize Tankless cost more but in the long run if we had a water softener we wouldn't go through water heaters every few years. Jaybee, since they are rated Energy Star, how can they receive the rating if they really aren't? Please don't think I'm arguing with you on this point, this is all new to us and we are checking all of our options. We go through water heaters too often and that's not cost effective. By having a water softener it would save us money in other areas. If there is more info you know about them, please forward it. Right now we are at the point we must make a decision soon. We couldn't leave on a planned outing today because we got up to no hot water. The darn pilot light went out again in the night, it does this randomly.
Apr 01, 2012, 03:07 AM
The darn pilot light went out again in the night, it does this randomly.

I'm presuming that the thermocouple or thermopile on that water heater has been replaced at least once already to stop that from happening.

Do you have room ANYWHERE in your house for a 40, 50 or 60 gallon hot water heater IF you don't need to supply gas or provide a flue vent to that location?

If so, there's system commonly called a "coil system" which is often used in hotels and apartment blocks where there's a HUGE demand for hot water first thing in the morning, but then virtually no demand for hot water until the following morning.

A coil system consists of a large insulated water storage tank (like you find inside your existing normal gas fired water heater), a SMALL water heater of any sort (including a tankless), a pump and a relay.

You connect the thermostat on the conventional water heater to a 24 volt transformer and the relay (instead of the water heater's gas valve). When the thermostat calls for heat, it completes a 24 volt circuit to the relay, and that relay completes two circuits; one 120 VAC circuit to turn on the pump and a 4 millivolt, 120 VAC or 220 VAC circuit to turn on or fire up the small water heater.

The pump then circulates water through the small water heater until all of the water is at the thermostat temperature setting of the conventional water heater, or about 130 deg. F.

That way, while you're at work, or sleeping, or sleeping at work, a small water heater (like a tankless) can slowly keep adding heat to the circulating water until you have 40 gallons (or more) of 130 degree F water available to you after work for cooking and cleaning or first thing in the morning for showering and bathing.

The advantage of this system is that it both provides the space you need for a water softener, and eliminates the principle problem with tankless heaters in that they can't heat water fast enough to allow for a hot shower or to wash clothes or dishes in truly "hot" water. That's because you're not using the water that comes out of the tankless heater, you're using the hot water that's coming out of storage.

In lots of apartment blocks and hotels they have one, two or three 500 gallon insulated water storage tanks, and only a relatively small 60 gallon water heater. A pump circulates water through a loop that includes the insulated storage tanks plumbed in series and the small water heater. That small water heater heats up all of the water during office hours and overnight so that everyone can have a hot shower at about the same time each morning.

I'm wondering if a coil water heating system would work in your situation if you could replace your existing water heater with a tankless heater and use your existing water heater just as a hot water storage tank?

PS: Instead of using a gas fired non-vented tankless water heater, you could buy a tiny 5 gallon conventional gas fired vented water heater to serve as the small water heater. That would be small enough to hang on a wall, and would work better because it would allow the H2O produced by burning natural gas to be vented to the outdoors instead of accumulating inside your house as humidity.

This message has been edited. Last edited by: Nestor,
Apr 01, 2012, 08:46 AM
Nestor, thank you for the suggestion, the water heater that's failing indeed has had the Thermocouple replaced with parts supplied by the manufacturer, hubby took care of replacement and sanded the gas output area. We don't have room for any other tanks in our home. This is why we thought the Tankless would be great. Install the Tankless and then have space for a small water softener. We are both home all day due to being disabled. We don't have a vented water heater now, that is another reason for wanting the Tankless. We live in an area where our water is extremely hard and we imagine this to be the reason we burn out water heaters so frequently. The Tankless seems to be the perfect solution for being able to free up space for a small water softener. With the information I'm receiving, going Tankless is not worth the money spent. Our utility closet is large enough to hold our furnace, water heater, a small 4 shelving unit for storage which hangs above a 2 1/2 x 2 1/2 hatch in the floor for entering the crawl space. Unfortunately we do not have more space within our home for any other form of plumbing and heating. I've received 2 good responses and views on the Tankless and I hope to receive more before we reach the point of being completely stranded without hot water.
Apr 01, 2012, 11:32 PM
Misc. comments:

1. A traditional gas water heater as well as a gas fired tankless can both be energy star rated. In fact, the efficiency of a gas tank water heater is one reason why the tankless is not that great of a deal. Now, compared to an electric WH, the gas tankless will cost much less to run. It's just not that much better than a regular gas WH.

2. Tankless WH's increase their temperature by restricting the flow rate. This keeps the water within the coils longer and makes for hotter water - just less of it. A whole-house tankless may have a rated flow rate of around 7 GPM while giving you 105 degree water. Restrict the flow so that you get 125 or 130 degrees like a tanked WH, and your flow rate will drop to the 4.5 - 5 GPM range. While this may still work for you, you need to calculate how many fixtures may be in use at any time to see if it's enough.

3. Hard water has nothing to do with your gas WH failing. Your gas WH has a burner on the bottom and a central chimney that heats the water. The gas and the water never mix - it's a heat exchange system. If your flame is going out (and since you have already replaced the thermocouple) then I would check two areas:

A. Make sure that the pilot light flame is hitting the thermocouple probe. The flame should go around the tip on both sides. If the flame is not making good contact, then the thermocouple is too cool and shuts off the gas. The simple fix is to bend the thermocouple end so that it sits inside the pilot flame.

B. Check your chimney. It could be located in such a way on your roof that it's getting a draft that blows out the pilot flame. While hard to see something obvious with this, you can troubleshoot by adding a wind deflector to one side of the chimney or by adding a chimney section to make it taller.

4. Finally, call a couple of plumbers in your area and get their opinion of tankless. I would trust an experienced plumbers opinion much more than a likely biased tankless WH sales company. I work with several plumbers and none recommend tankless WH's except in similar cases mentioned in my earlier posts above.

5. For me, I would rank them this way for whole house use:

#1 - Gas fired traditional tank water heater. Reasonably inexpensive to install (provided you have gas service), very fast recovery time and fairly economical to run.

#2 - Traditional electric WH. While much more expensive to operate, there is a very low install cost. Plus, an electric WH is very flexible as to install location. This in itself can make it a good choice for a smaller home. Other than an operating cost that is three times that of gas, cons are a long recovery time and elements that can be degraded by contact with hard water.

#3 - Gas fired tankless. If you do not have hard water and do not have very high GPM usage of hot water, then these can work well. Other than cabin usage mentioned above, a gas tankless can fill a very large tub with hot water. A 100 to 140 gallon tub would tax even a large gas tank WH. Downsides are the high install cost, lower hot water temperatures and reduced efficiency over time - moreso in hard water areas.

#4 - ELectric tankless. As a whole house unit, practically worthless. Very high install cost, usually requiring upgrading to more than a standard 200 amp service. A whole-house electric tankless will require three 220v circuits at 40 to 50 amps each. So in addition to the WH install you have several thousand dollars to spend to upgrade your electric. As a single remote point of use WH, they work fine but that's about it.

Dec 03, 2012, 08:13 AM
Hallo everyone.
You share very nice points so i think A good tankless unit requires also a good installation in order for it to work reliably. A good installation must take into account the required size of the unit, proper gas supply and venting into account. With the new condensing tankless unit the venting has become much easier with use of PVC.

This message has been edited. Last edited by: stover8924,
Dec 03, 2012, 11:29 AM
jaybee, when I thought our water heater was leaking, we checked electric tankless. spec on the Richmond (aka Rheem, the OEM, aka GE, probably aka everbody except A.O. Smith, another water heater company that actually runs their own plant) requires 4 40-amp circuits.

the house has a 150 amp main breaker, and I frankly think the drop from the power company is only a 100.

even with the temp rise only 40 degrees (and in the dead of winter, that's' 80-90 degree "hot" water) it's a no-go.


question on why you can raise the dial but water heaters are shipped at 105-110 degrees: meddlers and babies is why.

there have been many babies scalded to death because momma left them in the bathtub "for just a minute" with the water running. start the water, adjust it, put in the baby, run to the phone, bring it back, and you have a little lobster that can't even cry any more.

this of course is because all the cold water in the lines has to purge before the full heat of your hot water tank comes out. that takes a minute or so in most houses. by that time, an 80 degree stream could have risen to over 120.

that's why the meddlers, your government in action, stepped in and first recommended, then mandated, that nothing ships that can go higher than 115 degrees.

your big strong manly men used to burning off the barnacles every morning raised a giant stink. so the plumbing industry manufacturers, who hadn't changed much of anything except ship their products temp-restricted, publish the override instructions. with the usual "you do this at your own risk" statement and a page in the instructions putting forth the good news of the anti-scald regulations.

This message has been edited. Last edited by: swschrad,

sig: if this is a new economy, how come they still want my old-fashioned money?
Dec 05, 2012, 11:01 PM
i installed a tankless water heater in my new house
5 years old now
i was not impressed, i installed a 50 gal heater next to the tankless heater, and turned it off
i am on propane and the tankless was costing to much. i save nothing
as far as your heater that goes out all the time
have you checked the flue? I have seen water heaters pilots that were "blown" out by wind or a draft coming down the flue pipe
ck and see if your draft diverter is installed correctly on the top of the heater
also ck that you have a vent cap on the roof at the termination of the vent
also, ck that the top of vent is not above the highest peak of the roof, it could be acting like when you blow into the top of a coke bottle
the whistle..will stop the flow of air, and cause a backdraft situation, blowing out the pilot*****?v=vn7bkncf1_E
Dec 07, 2012, 01:18 PM
all heating vents/chimneys have to be installed above the roof line... code varies, some say a foot, some say more. you need to get away from swirling winds and have clear access to open sky to vent correctly.

sig: if this is a new economy, how come they still want my old-fashioned money?
Dec 07, 2012, 04:13 PM
swschrad, Smile your correct in the vent being 12 in above roof line. but.. sometimes, due to trade winds, and just where you live.
it can be lowered when your pilot light gets blown out constantly
if the op wants to involve the inspectors. Roll Eyes
after it is determined that was the problem.
a variance can be applied for
the "rule" of 12in above roof line, is usually pretty much ignored, when its a 12-12 pitch and the heater is installed on the lower end. if not a guy wire and 20ft of vent pipe would have to be installed.
lets face it, a home owner will not stand for a vent sticking up 10 ft in the air, the builders either
and the inspectors know it
it could be different up north, but down here. they let it slide Cool*****?v=vn7bkncf1_E
Dec 18, 2012, 08:20 AM
Here are a few links on tankless water heaters that may help you in your decision making process.

First is an article that is several years old from Consumer Reports on installing tankless water heaters. That you might find useful if trying to decide on tank v tankless. I doubt the economics have shifted much since the article was written 4 years ago.

Tankless water heaters
They're efficient but not necessarily economical

Tankless water heaters
All videos
Heating water accounts for up to 30 percent of the average home's energy budget. Some makers of gas-fired tankless water heaters claim their products can cut your energy costs up to half over regular storage heaters. So is it time to switch?

Probably not. Gas tankless water heaters, which use high-powered burners to quickly heat water as it runs through a heat exchanger, were 22 percent more energy efficient on average than the gas-fired storage-tank models in our tests. That translates into a savings of around $70 to $80 per year, based on 2008 national energy costs. But because they cost much more than storage water heaters, it can take up to 22 years to break even—longer than the 20-year life of many models. Moreover, our online poll of 1,200 readers revealed wide variations in installation costs, energy savings, and satisfaction.

With the help of an outside lab, we pitted Takagi and Noritz gas-fired tankless water heaters against three storage water heaters. We didn't test electric tankless heaters because many can't deliver hot water fast enough to replace a conventional water heater if ground­water is cold. Even in areas with warm groundwater, most homeowners would need to upgrade their electrical service to power a whole-house tankless model.

Our tests simulated daily use of 76 to 78 gallons of hot water. That's the equivalent of taking three showers, washing one laun­dry load, running the dishwasher once (six cycles), and turning on the faucet nine times, for a total of 19 draws. While that's considered heavy use compared with the standard Department of Energy test, we think it more accurately represents an average family's habits. We also ran more than 45,000 gallons of very hard water through a tanked model and a Rinnai tankless model to simulate about 11 years of regular use.

Here's what else we found:

Water runs hot and cold
Manufacturers of tankless water heaters are fond of touting their products' ability to provide an endless amount of hot water. But inconsistent water temperatures were a common complaint among our poll respondents. When you turn on the faucet, tankless models feed in some cold water to gauge how big a temperature rise is needed. If there's cool water lingering in your pipes, you'll receive a momentary "cold-water sandwich" between the old and new hot water. And a tankless water heater's burner might not ignite when you try to get just a trickle of hot water for, say, shaving.

Nor do tankless water heaters deliver hot water instantaneously. It takes time to heat the water to the target temperature, and just like storage water heaters, any cold water in the pipes needs to be pushed out. And tankless models' electric controls mean you'll also lose hot water during a power outage.

Up-front costs are high
The tankless water heaters we tested cost $800 to $1,150, compared with $300 to $480 for the regular storage-tank types. Tankless models need electrical outlets for their fan and electronics, upgraded gas pipes, and a new ventilation system. That can bring average installation costs to $1,200, compared with $300 for storage-tank models.

Tankless units might need more care
During our long-term testing, an indicator on the tankless model warned of scale buildup. We paid $334 for special valves and a plumber to flush out the water heater with vinegar. Many industry pros recommend that tankless models be serviced once a year by a qualified technician. Calcium buildup can decrease efficiency, restrict water flow, and damage tankless models. Experts suggest installing a water softener if your water hardness is above 11 grains per gallon. Ignoring this advice can shorten your warranty.

Efficient storage models are pricey
We also tested the $1,400 Vertex, a high-efficiency storage water heater by A.O. Smith. The manufacturer claims its installation costs are similar to a regular storage model. But its high cost offsets much of the roughly $70 per year the Vertex will save you. Instead, we recommend buying a conventional storage water heater with a 9- or 12-year warranty. In previous tests, we found that those models generally had thicker insulation, bigger burners or larger heating elements, and better corrosion-fighting metal rods called anodes.

And a link to the Energy Department website on the subject:

And a buying guide on them:

And a tutorial on them:

An article talking about circulation pumps and standby loss. In my house I have option 2 a retrofit-by-pass system located in my master bathroom. For tankless systems option 3 is preferred. These are helpful when the unit is far away from the point of use. The entire article is worth reading and can be found at the link.


Homes that have a long run from the water heater to the farthest fixtures will experience a long wait for hot water. You turn on the faucet, wait for a minute, and the water is still running cold. Tighter restrictions on flow rates and “greener” fixtures make this problem even more annoying. It wastes water, energy, and is inconvenient.The solution to this problem is a hot water recirculation system. These systems overcome the problem by circulating hot water so it is available in the nearby supply pipes. The system is designed to provide hot water at the most distant fixture and every fixture in series or close to the main line. There are three basic types of recirculation systems:

1) Traditional: This system consists of an extra “return” pipe that allows water from the farthest fixture to be returned to the water heater. A pump is located near the water heater and when it is on water is pushed out of the heater and back through the return pipe. The pump can be outfitted with timers and thermostats to keep the running time down to a minimum.

2) Retrofit-By-Pass: This system utilizes the cold water line as the return line to the water heater. A pump (generally located on the top of the water heater) is used to create a slight pressure differential that allows the cool water in the hot water supply line to by-pass into the cold supply line. This is accomplished through a thermostatically controlled valve that is mounted at the furthest fixture from the water heater. The pump is equipped with a timer that allows the system to run whenever desired.

3) Demand: This system is similar to the retrofit system above because it also utilizes the cold water line as the return line to the water heater. The similarity ends there because this system requires that the pump be mounted at the farthest fixture. When hot water is “demanded” a wireless remote is pressed that will activate the pump. The pump will run until hot water reaches the sensors and then it automatically shuts down. In lieu of a remote, motion sensors may also be used. If you have a tankless water heater this is the system that generally works the best.We are familiar with all of these systems whether you want one installed or need your existing system repaired. They all have their advantages and their drawbacks, which is why you need to consult with us before making a decision. Remember, there is no substitute for experience.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Apr 21, 2013, 02:10 PM
I know this topic is fairly old, but to share my experience: We replaced a gas tank water heater with a tankless gas WH. The positive is that it produced as much hot water as we need. The tank we had was smaller than our bath tub, so we always ran out of hot water before it was filled. Now, there is an endless flow of hot water, enough to fill the tub. And we can have multiple users of the hot water without a problem.

The negative is that it takes longer for the hot water to start, so with the heater in the basement, but second floor shower has to be run for some minutes before the water is hot enough. A waste of water. I had read about that issue, but my installer said he did not experience it. Also, when I turn the water off and on to rinse dishes, it does not remain hot.

I think these tankless HW's might work better suited for small living units.

I am going to research hybrids, which have a small tank.
Apr 21, 2013, 05:52 PM
Your problem isn't so much the water heater but the standby loss in the pipes. Tankless work very well in a compact house where the water heater can be placed close to the point of use. Alternatively, a special circulating pump can help cut down on the wasted water without having the unit firing up all the time. You have to wait while the pump gets the water moving in the system, it send the cold water back towards the unit via the cold water line rather than down the drain. Once the water runs a loop and hot water is at the pump you can open the tap and get hot water.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Apr 27, 2013, 08:27 AM
good advice sparky, what you need is a 120 volt strap on aqua stat installed on the return line about 3 ft from the heater . set it at desired temp and it will tell pump to kick on /off to maintain temp in circ loop*****?v=vn7bkncf1_E
Apr 27, 2013, 10:26 AM
Originally posted by Frodo:
good advice sparky, what you need is a 120 volt strap on aqua stat installed on the return line about 3 ft from the heater . set it at desired temp and it will tell pump to kick on /off to maintain temp in circ loop

That set up defeats the savings realized in a tankless system. Your tankless water heater will be constantly kicking on and off heating water when there is no demand without the benefit of an insulated tank. A tanked gas water heater isn't one of the bigger users of gas in your house. Space heating uses much more gas than heating water. If you have gas the article I saw in Consumer Reports says you'll never reach payback from energy savings with a tankless especially when you throw in the extra maintenance the tankless water heaters require.

Tankless water heaters have their place, but I'm not convinced in many modern US homes with the spread out design with points of use for water spread out between floor and opposite sides of the home that they make any sense.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Apr 27, 2013, 04:46 PM
you are 100% correct i was thinking of a regular water heater or i wasnt thinking at all
either way. your right Smile

they do make a valve that is installed under the sink that connects the loop i'll see if i can find it

This message has been edited. Last edited by: Frodo,*****?v=vn7bkncf1_E
Apr 27, 2013, 04:56 PM

this will work it uses a timer, its like ron poppels cooker...set it an forget it!

This message has been edited. Last edited by: Frodo,*****?v=vn7bkncf1_E
Apr 27, 2013, 05:03 PM
john d...this is what i do. when i get ready to shower
i walk in the bathroom turn on the hot water at the sink. get undressed and the water is hot when i get into the shower. takes about 1 minute.*****?v=vn7bkncf1_E
Apr 28, 2013, 01:22 PM
Frodo is right. I just let the shower run and get ready. But it kind of wastes water. Plus, the other issue is on-demand for things like rinsing dishes or washing hands. Plus, not being in Southern MS, the pipes in our basement get really cold in the winter! Our delay is probably longer than yours.

I think Sparky617 nails it. After a couple of years with a tankless heater, I see why they are more popular in Europe (I think). They make more sense in small residences and with the WH on the same floor as the living quarters. However, I do have a better supply than I did with the tank. We never run out. I am actually thinking of doubling down on this idea and looking into a hybrid system -- just a small tank for storage.