Mine is not installed yet but I reviewed this and also spoke to several friends who have this. We are going with either Takagi or Navien (has a built in re-circulating pump)

Lalitha

We put one in about three years ago. Our hot water tank was getting old and would have needed to be replaced so we went tankless with a Rennai as part of our new furnace work. It's been so long that I can't remember what our old bills were, but I know we pay less now. I do remember when making the decision that it would take some time for it to pay off. Plus, we've put all that freed up space to use in the garage!

When we finally get the new master bath done, I'm going to enjoy being able to fill my gigantic tub full of hot water for a loooong soak. :)

we've had the navien for abt. 1.5 yrs. it was between $1,000-$2,000 more than a reg. water tank. we got it along with a new hvac system, so i'm not sure how much of our monthly savings is attributable to the tankless water tank.

upside: the ability to take nice and long warm showers even if the other shower is running or if you are the last one to take shower in the morning.
downside: waiting the min. for the water to heat up if you are the first person to use the hot water in the morning (then the recirc. pump kicks in).

Uh oh. I just read an article at consumer reports and it says that it takes about 20 years to pay off the difference in price, and by then they need to be replaced. But more than that, even the gas ones have to have an electric control and you lose hot water when you lose power. We lose power a lot in winter, and I wouldn't want to lose hot water on top of everything else.

I would to more research. We were planning on going tankless. We spoke to the place we thought we would purchase it from. They honestly told us the pros and cons and we decided not to do it. I also have a friend who had a tankless installed and now regrets it.

The cons for us were that we are planning to get a front loader washer. Apparently we would have to run the hot water in the nearest sink until it gets hot. Then turn on the washer. Because front loaders use less water we were told by the time the hot water started to come into the washer it would be filled. Hope that makes sense.

Also concerned with how long we would have to run the water (and waste) in order to get warm water just to wash your hands.

Our friend hates how long she has to wait for hot water.

I know that some people like it but just wanted to share some of the cons with you.

We ended up with a double tank system that we love and never run out of hot water.

We have a gas tankless for half the house, plus an electric tankless dedicated to the prep sink (which was a retrofit and therefore couldn't be tied into the kitchen tank water heater).

As long as you get a solid brand (do your research--there's a difference), I think the pros outweigh the cons and I wouldn't go back.

We put a tankless in the house we're helping my parents build, too.

The hot water is consistent and limitless, no concerns about laming tanks or tanks taking up space (our one tank is in the pantry).

One con is the need to flush out theo wrap buildup every year or so. Also, we had a relay switch go bad on a very cheap, chintzy electric tankless. Had I not been home, the entire house would've flooded (rarely, an equipment failure can cause insanely high pressures of steam to build up in the unit, and the unit can basically "blow." Ours did, and the steam obliterated the plastic pieces of the faucet in the under sink cabinet, causing a water to spray out everywhere.

This is a concern with an interior unit (and again, it's really rare that it happens at all according to the engineers from the various tankless conpanies i spoke with). We replaced it with a very reputable brand, and I'm comfortable with it now and have no regrets.

Our gas tankless is on the exterior of our house.

Hope that's somewhat helpful.

We converted to a tankless 2 years ago. Our lower level has a pool table and an antique billiard table and we didn't want to go through another busted water heater.

I had not anticipated that the water needs to run a bit before it is hot at a tap. Seems a waste of water.

And what idiot designs these things with air intake holes at ground level for snow country?? Worse, we also had a little varmint work its way into the air intake and set up house leading to an ugly early death by fan. Had to repair and retrofit with a pricey raised snorkle intake. Which we do not need to shovel out so that part is better. The 'snorkle' is one ugly looking contraption though...

Other than those surprises I am happy with it.

Our unit is exterior mounted on the wall. For washer, I anyway prefer a front-load washer with an internal water heater. For us in CA, this was a a good decision.

We have had one for 6 years now and it has worked perfectly. It is a 6.4 gpm gas and mounted outside up on the wall of the house. We started seeing gas savings immediately. The cost of water is so cheap that having to run the tap a few minutes is not a cost at all in our area. The constant hot water is lovely. We have a thermostat on ours and in the 6 months of warm weather it stays on 100 degrees so that our showers are not too hot. If I need hotter water, like when doing dishes by hand or running a once a week load of white clothes I bump it up to 140. In the winter it is set on 120-130 cause we like hotter showers then. Our DW has a heater so no need to have hot water from the water heater .

It is true that if your electric goes out you have no hot water. even though it is a gas water heater..so far in 6 yrs that hasn't been a problem here in AL. I wish we had the recirculating pump but didn't know about that ! That would be the only thing I would do differently. It is a great thing and I too love all the space we got when we got rid of the old water heater. c

i am doing tankless in my new build. i went with noritz. if you are doing a remodel and replacing an old water heater, sometimes the cost is not as high because there are lots of rebates (both federal and city) for energy star water heaters.

I've had one for almost 20 years now. It paid for itself by the first 3 years, but we DIYed the install, and it's a smaller model than most are putting in these days. If you want a larger model, the price and payback period starts to increase. If you have to pay labor, the payback period doubles as well.

It does NOT take any longer to get hot water to a fixture than it does with a conventional tanked heater. That has to do with the location of the heater, not how the water is produced. You might have a 1/4 second lag time for the pressure drop to trigger the burner, but that's it. If it takes 30 seconds to get hot water to a fixture, then it will take 30 seconds to get hot water to the fixture with a tanked or tankless.

As far as using a DW or clothes washer, yes, it's become second nature to only start either one of them after having used the hot water at the closest sink. However, I did that when I had a tanked heater as well because I rinsed the dishes for the DW, or usually was doing something or the other in the kitchen with hot water. It's is really not a big deal.

Because I have a smaller heater, I have learned how to use hot water serially rather than simultaneously. But again, it's not a big deal for a two person household to take showers one after the other rather than at the same time. Or to start the load of clothes after I've taken the shower. For someone with a larger household, that probably would be a big deal, and so they would want a larger model on the front end.

For the technical end, you will need to replace your current vent with a larger diameter double wall stainless steel vent, and that's pretty pricy. You'll also probably have to run a homerun gas supply line from the meter, as they take a LOT of gas when they light. It's the difference between a little bit of heat over time to get a pot of water boiling or putting the power boil on high to get it done faster. It's the same amount of gas, just delivered in a different time frame, so you need a larger line to get the larger amount for the tankless.

And the above is why the install of a tankless is pretty pricy. The black iron for the gas is pretty cheap, but the labor isn't. The stainless vent is pretty expensive, and so is the labor. The tankless itself is also more expensive than a tanked. Add all of the additional expense of the labor for all of those alterations, and you can see why the payback period is pretty long.

We have tankless in our new home. First time with one, but love it so far. We have a different situation than normal people as we have 6 showers and the house sleeps 26. It's great when there are a bunch of people in the house for unlimited hot water. It's also great when the house is not rented and we are not there because we don't pay to heat water we are not using. Ours is a propane Rinnai (no natural gas available where we are). We also have a central water manifold where the water heater is located. This gives us a direct line from the manifold to each of the water outlets, so the distance the hot water has to travel is the minimal possible. It does take a few seconds for the water to arrive, but not long.

We have one and love it. Individuals that complain about how long it takes to get hot water to the tap might forget it took that long with a tank hot water heater as well. That has to do with how far away the unit is not the unit itself.

We have a natural gas Rennai. We got it 2 yrs. ago to replace a dead standard gas hot water heater. We have been very happy with it. It is important you get one sized to your needs (how many faucets/appliances it can feed water to at a time). I don't think it really takes that much more time to get hot water then it did before. In my 2nd floor master bath, it was about the same. Slightly longer in my old kitchen. No time at all in the new kitchen (the sink is closer to the hot water heater.) Our gas bill went down significantly right away, I think DH said by about 25%.

I really wanted tankless - but our delta temp was too great and house a bit too large to make it work without an industrial model.
In the winter, our water enters the house at 37 degrees - so we would have needed a massive unit.
Make sure you know you delta temperature - and if you live up north - check the temp in the winter.

We ended up going with a hybrid - and it does make a difference in our gas bill. In the summer, our gas bill is almost non-existent. (.6-.8 per month) - and we have a gas dryer which DH washes and dries clothes constantly

I put one in about 7 years ago. One very nice thing I was able to do was to move the location of the unit. The old tanked heater was the side of the house where the chimney was. Because tankless units are so small and vent through the wall, I moved it to the other side of the house, just under the kitchen and lines to all the bathrooms. Instead of increasing the time to hot water, it decreased it. I had calculated that the money I would save just from the decreased time to hot water would pay for the unit in about 7 years.

Here is one thing I don't like. Say I am doing the dishes. I run the hot water and get hot water at the tap, fill a vessel, then turn off the water. After doing the dishes, I turn on the hot for rinsing. Fine, there is hot water there, because it was in the pipes already. However, there is a 3- to 6-second slug of cold water in that line somewhere!!

Overall, I am happy with it

Yes, yes, yes and no.

The water heater for two and a half bathrooms failed. It was an inside water heater in a closet and decades old. A modern efficient water heater has much more insulation so one that fit would have been a lot lower capacity. Even a less efficiently insulated one would have to be smaller because the old one didn't sit in a drain pan and didn't have an air intake vent. With the vent and drain pan required by current code, the water heater capacity would have to go down.

That's why we looked at a tankless.

It cost a good bit more than a tank one, but we were concerned that the capacity of a tank wouldn't be enough. We put in one with direct venting that pulls intake air from a vent pipe that goes to the roof which added some cost but that we we didn't have to put a vent in the floor of the closet.

So it was worth it because we get plenty of capacity and the bonus of recovering much of the water heater closet for storage.

Payback is probably better than Consumer reports calculated because we would have either had a less fully insulated tank water heater or had to run the small well insulated water heater at a higher temp to make up for the lack of capacity (which would also be a safety concern with our grandchildren using one of the bathrooms).

I don't find that it takes any longer for hot water to arrive at our bathroom. We didn't have a recirculating pump with the old water heater and most of the time is emptying the pipes from the cold water that's been sitting in them and getting the hot water to arrive.

It is important to get a tankless heater that's correctly sized. The larger the maximum flow rate, the larger the minimum flow required to get the heater to kick on so if you get too large a one, you may not get hot water when you just turn on a sink faucet at a low rate.

Our master bedroom has a large sunken tiled tub which with the old water heater could only just barely be filled to a good level. Mostly we use it as a shower, but it's nice that when I want a soak, the water heater can now fill the tub generously and supply plenty more if someone else wants a shower.

We are able to run it at a lower temperature than the old water heater - I think we have it set at 110 or 115 degrees which is better for safety.

As far as not having hot water when the electricity is out, isn't that true with a tank water heater now too? I thought that they all have to use electronic ignition now because pilot lights aren't allowed.

"As far as not having hot water when the electricity is out, isn't that true with a tank water heater now too? I thought that they all have to use electronic ignition now because pilot lights aren't allowed."

Nope not true, at least in Calif.

I wanted a pilotless one but in my area of S. Calif, we are required to have a "Low Nox" water heater, and at least at the time I bought mine, about 2 years ago, all the low Nox models still used a pilot.

Gary

I considered it.

My MBR shower is about 75' from the water heater.
I have a solar water system that constantly heats. Obviously. I kept the old water heater (new from a BG&E audit) as a back-up.

It would take between 10-15 minutes for the hot water to reach the shower. Now, I'm on well and septic and not in a drought zone, so only the electricity and water softener salt was an issue. I'm in a watershed, so it would go right back to nature.

I considered the tankless, but electrical ones are horribly inefficient and I didn't want to introduce another power source into the house, which would have to be propane. We're not on regular utilities in the country. Plus, I'm afraid of propane.

So. and this next thought is important to you who are unhappy with your wait, or whose water takes forever to get from the source to the outlet. I installed a recirculating pump in my MBR bath. With the switch integrated into the light/outlet box. If I want hot water quickly in at the other end of the house, I turn it on and in about a minute or less, it's there. I usually turn it on, comb out my hair, shoo the cats, and get into the shower.

Had I lost power with Sandy, I was gonna run an extension cord from my generator to the recirculating pump to see if I could get water that way. Couldn't flush, but with a 200 gallon water tank, I could do a lot. (DH had a need for bigger and therefore, in his mind, better.)

I didn't want electric, because I have 32 solar panels that keep me pretty much bill-free. The electric tankless models were equated with a self-cleaning oven: Huge, instant demands. Evidently the source of most every oven blow-out just before Thanksgiving when someone decides to clean their oven! I digress. Every little bit of electricity I don't use comes back to me as a credit on my bill. And, my meter runs backwards.

You're talking to the first, licensed and registered residential solar power plant in Maryland. and I got the license to prove it! :)

I'm really happy with the decision to put this pump in. I don't feel so wasteful and my impatient self doesn't have to wait. With my solar water heater, it's pretty much just like having a tankless, only better!

We converted from a gas forced air furnace to a boiler system with our energy audit work last year. The boiler we chose also acts like a hot water heater and the entire system is compatible with solar panels for down the road.

The financial savings has just been incredible - and so is the space savings. Our furnace was stuck in a small closet - and our water heater was in the kitchen. This in a 1,000 SF home. What a nightmare. Now, we regained that lost space in the kitchen and furnace closet is now freed up to be used as a kitty litter area or a spot for the vacuum as the boiler and piles are up off of the floor suspended from the walls. We also invested in smart thermostats and are cutting energy waste that way, too.

And I don't even have words for how nice it is to be able to seal up those gross floor vents cut into the concrete slab that have been blowing gods-knows-what in the dry air they blew out with the heat. Gross me out.

The unlimited hot water is a bonus - as is the fact that the house is consistently warm now. It used to be loud and noisy when the heat was on - then slowly get cold until the heat kicked back on. Which reminds me how quiet the new system is without that furnace rumbling like chitty-chitty-bang-bang and the hurricane force hot wind blowing through the vents.

I guess you can tell I am pretty happy with this change! My partner is a licensed plumber, which made this all affordable. I think this would have cost upward of 20K if I had contracted it out. I think we got it done for about $3,000.

Wanted to add, as for brands, our gas exterior is Rinnai, our electric interior is Stiebel TemperaPlus.

Really, really happy with the quality of both.

We're about to replace a 60-year-old boiler with a new high efficiency Viessmann with the on-demand water heating. Anyone have experience with Viessmann in particular?

We're a wee bit concerned about the cold 'drops' in the system and about the length of time to wait for the hot water to come. For those with a recirculating pump, does that solve the problem, and is it another huge expense? Could a smaller storage tank help in addition to the on-demand?

I live in a high-rise in a small one bedroom with a standard tank and I have to run the tap to flush out the cold water in the pipes - that isn't something that is only necessary with tankless. Looked into tankless but I don't have enough electrical service to run one (no gas in the building). Hoping the new microwave tankless thats in development will be the answer.

I don't have enough electrical service to run one ... Hoping the new microwave tankless thats in development will be the answer.

I think if you don't have enough amps to heat the water through I^2R, you won't have enough to heat it with microwaves, which is a far-less-efficient way of heating water.

We're a wee bit concerned about the cold 'drops' in the system and about the length of time to wait for the hot water to come. For those with a recirculating pump, does that solve the problem, and is it another huge expense? Could a smaller storage tank help in addition to the on-demand?

Circus: I should say first that I know little about the Viessman furnace in particular or even boiler-loop hot water systems in general. However, here are my thoughts:

Even though I cited them as a disadvantage upthread, the cold drops are not that bad. I am often the "second one to use the shower." Therefore, the hot water is already there in the pipes for me, but there will be a 3-6 second cold drop coming down the pipe (literally). I typically just get in and start using the shower at my preferred temperature. After a few minutes, the water temp will drop, but it doesn't fall below what is comfortable. (If it does, I just step out for a minute.) The temperature quickly starts rising again, until it is fully back to preferred temp after about 10 sec. The temperature does not drop that much because the warm pipes help heat the cold slug of water.

The cold drops are a bit more of a problem with hand-washing dishes, where I would prefer to be able to turn the hot water on and off more frequently to rinse things as I wash them. What I do instead is to fill a vessel with hot water to wash everything (as I would do under any circumstances), then I wash everything before doing any rinsing, setting it all off to the side. I then turn on the hot water and rinse everything sequentially.

I have toyed with the idea of adding a smaller storage tank. I was thinking of adding about 6 sec. of supply. Since showers are limited to about 2.5 gpm, that would mean a storage tank of about 1 quart. The effect of this tank would be to add about 6 sec until full temp was reached after initial demand, and to moderate temp rises and falls with a 6 sec. time constant. Still toying with the idea, but probably won't bother.

As for recirculating pumps, I don't see this as a good idea (except perhaps in areas where water is EXTREMELY scarce). For a tanked system, it seems to me that you are greatly increasing stand-by heat losses (by using your hot-water supply lines as a radiator inside your walls!). For a tankless system, you are effectively turning your hot water lines into a storage tank, and are thereby CREATING standby losses (where none existed before). I don't believe it is physically possible to save a single BTU of energy using them (although they provide convenience and save water).

As caryscott pointed out, on-demand systems do not really cause much additional time to get hot water. It takes my system 3-6 sec. to get the water up to temp. (In my particular case, all of that time and then some was eliminated by relocating the heater to a spot closer to the hot water runs). If I understand how your proposed boiler-loop systems work, I would think that they do not take ANY additional time to get the water up to temperature.

What model furnace were you thinking of?

Circus, a standing water heating tank defeats the whole point of an on-demand. To me, that's a HUGE waste of money and effort.

I am so pleased with my recirculating pump. It was roughly $540 including the installation. It pays for itself with the electricity and water, and salt (on this mineral-heavy well) I won't use.

Keeping in mind that my pump is turned on, on demand itself. Before I shower. I do use cold water for almost everything else except the DW I run about 1ce a month. I am not using the pump as an inadvertent radiator.

It uses my cold lines to return the water back to the solar water tank, so those warm up. The second the pump is turned off, it begins to cool. I could leave it on all the time, but to me that's pointless.

I did consider a marine water heater. But I just didn't want to devote the electricity to another appliance.

C.

steph2000,

more info about your system would be most appreciated..we have gas forced air and i hate it for the same reasons you listed..

my BIL fixed our heater last winter and told us to start saving for a new heater..we will need one in about 3 yrs, it will be 20+ yrs old by then.

he will be able to get the system at cost, so this will be a significant savings for us..any info as far as brands etc would be great.

TIA

Do most of you with gas have yours installed on the outside of the house next to the gas meter? It seems like that's where I've heard they normally put them, but my gas meter is near the front of the house and I'm afraid a tankless water heater on the outside wall of the house would be so ugly. I have an HOA and I would also worry about them not liking it. The gas meter is low to the ground, so that can be hid with shrubs, but the water heater would be higher up.

Do most of you with gas have yours installed on the outside of the house next to the gas meter?

Certainly not those of us who live where we have winter!

We are in central AL and we do get many days below or at freezing. Our tankless is mounted on the side of our home right next to the gas meter. It is hidden by shrubs up midway on the wall so it isn't an eye sore.

The cold was a problem the first winter, 6 yrs ago and we solved it by placing insulation batting inside the case. It is easy to open the front and just tuck a batt inside. It remedied the problem immediately and we have had no other worries with the unit. Ours is a Noritz .

I am in central Florida and when I built my home I put 4 tankless water heaters in. I believe the first brand was Watts. Their systems kept failing. One actually turned on by itself while we were away and caused a pipe to burst flooding my home. I have replaced all of the original units and find them quite nice. My home is spread out and large, so tank heaters would take forever to reach the farthest rooms in the house. I have one in the master, one in the kitchen and two in the garage. Two are 80 amp and two are 60 amp. If I were to do it over, I would have at least 120 amp for the baths and 80 amp for the other areas. The 80 amp unit gets warm enough for me in the shower, but my wife is always complaining that it is not hot enough. So... lesson learned.

@sprtphntc - Sorry it took me some time to find this again! Glad to share any information I can.

My partner did a great deal of research on this and became sold on an Italian company named Embassy Onex.

We ran the pipes (they seem more like hoses to me, but technically flexible pipe) down through the existing ductwork in the cement, snaking it through. That was remarkably easy - and just required the smallest of drywall/floor work.

We were going to go with very high end, expensive baseboard because I cannot stand baseboard. It was sooo spendy, though, and then my partner got access to unlimited free commercial stainless baseboard and sits higher up off the floor kinda like a floating shelf. I wasn't sure I could afford the space, but it seems like no big deal at this point and how do you argue with free? We still might splurge down the road on some baseboard for the public areas, but so far, I'm content despite my anticipatory anxiety. (The only down side is my partner treats every horizontal surface as a place to put crap - lol)

The unit is totally quiet. The MOST you hear is an occasional click.

Let me know if you want more information and I'd be glad to get it for you.

Here is a link that might be useful: Embassy Onex

steph,

thanks for getting back to me...the info was great and i am going to show it toDH to see if its feasible.

i like that this company has some options, so that's always good.

i agree, iwouldn't argue with anything that;s free, i would make it work also...

thanks again!!

We did since our old one was in the kitchen and we needed the space. So we put the tankless outside and it's been great. Though we did pay extra for the circulating pump and that was worth it too.

Angie: our on-demand water heater will be part of a new boiler system that sends hot water circulating through our 100-yr-old radiators. It will be run on natural gas. I think the boiler model we contracted for is either the Vitodens 100 or 200.

Angie, I am also amused by the thought of an outdoors water heater. Really? Here in Maine, you'd have to light a fire under the tank to liquify the ice first before even attempting to heat it up .. ;-)

Christine & Cary, & all -- thanks for the additional input! Every morsel of actual user experience makes it so much easier to make these decisions.

Because it's a direct-vent unit, we're going to have to locate the boiler/water heater along an exterior wall, further away from the kitchen sink, so I'm a little concerned about that. Hmm.

Belladom -- what do you like most about the recirculating pump, & how do you notice its effect? Thanks!

Do most of you with gas have yours installed on the outside of the house next to the gas meter?

Msrose, ours is installed inside almost exactly in the center of the house. We put it up high on the wall inside a closet above the hanging rod. Not so much for winter reasons as the house is in NC. Our house is on the coast, so very corrosive environment for anything outside. In fact most people have to replace their HVAC units about every 5 years. Eeek! Not looking forward to that.

Oh, to answer the original question ... at our primary residence, we have a fairly new gas hot water heater that we got about 2-3 years ago. In the summer the water is the only thing running on gas and it takes about $20/month. It makes sense it would be higher over the winter, but assuming if it is the same cost over the winter that is about $240/yr for hot water. There are 2 of us. We have gas heat in the winter, so iI am not sure exactly how much just the hot water costs.

At the other house, we have the propane Rinnai tankless and the gas logs fireplace (which are not run too often). We have filled the propane a few times since June 2011. I think it is averaging out to about $500-600/yr which includes the gas logs AND it's hot water for about 10-12 times the number of people.

Jeez, I can't remember to answer all the questions at one time. It was new construction. $690 for rough in gas lines for Rinnai and fireplace, $350 for the vent pipe - not sure if that was for fire or Rinnai, $515 for the gas lines and our propane tank, $1575 for the Rinnai and final installation.