[jtwrace]

Who has one and what do you like and dislike? 

Please mention the brand. 

[ArthurDent]

I've got a Rinnai 'on-demand' gas unit. Had it installed 3 years ago along with a direct vent gas fireplace insert. I had a major roof remod at the same time so with the added insulation it's a bit difficult to address the exact cost savings. Given my place was previously all electric with baseboard heat (not the most efficient), initially I saw a roughly 25-30% monthly reduction in the electric usage portion of my bill for the first year. The combined bill was still a little smaller than the prior electric only. That year there was a 15% increase in the gas charges, and there have been a couple of additional increases since in both electric & gas rates. The bill has remained pretty stable, and I have no doubt I'm saving over what it would have been without the changes.

Up front cost is a lot bit more than sticking with a tank, and it's definitely not for everyone. A Mech Engineer friend ran a cost analysis on his family/house, and figured for a family of 2-3 it would take at least 10 years to recoup the cost difference.  So if you are looking short term it's not cost effective. 'On demand' is also a very relative term. It takes probably at least twice as long to get hot water to the spout as it does with a tank. However, once it's there you can take all day showers without fear.

Other factors in play are your geographical location, which dictates the base temp of the water you are pulling thru the supply system. Tankless units are sized based on rate-of-rise/flow temps, so the colder the start temp the longer it takes to heat and the lower the top temp it can raise things. Configuration of your house also enters, with regards to how far from the unit to the farthest bath. There are small auxiliary units that can be added under the sink if you really want hot water right now.

Negatives - up front cost, the added wait for hot water, though I'm single so don't mind washing my hands with cold water most of the time.

Positives - I do like that I don't have to worry about running out of hot water, flushing the tank each year or so, and replacing a tank every 5-10 years. Which is probably above average due to single usage. In my case I also think there is enough savings to justify the up front expense since I'm most likely stuck for the long haul.

You might do a search of the archives here as there was another thread on the topic a couple of years back with a fair cross section of opinions & information. Note that this is for a gas unit, with electric YMMV. Hope this helps.

[jtwrace]

It takes probably at least twice as long to get hot water to the spout as it does with a tank.

A tank or a tankless still has to travel the same length of pipe from where it is mounted to the water outlet that you are standing at waiting for the hot water. If that run is 75 feet, then you are going to have to wait for 75 feet of water to clear out the faucet for the hot water to get to you.

[Steidl Guitars]

I have a Bosch tankless, gas.  I love it, but it's not for everyone.

And Arthur is right -- you do have to wait a bit longer for hot water than with a tank.  The tankless sends water right away, but it takes a few seconds to fire, so that's the difference.  Like him I am happy to use cold water for short-duration tasks.

I just installed an efficient dishwasher that doesn't draw enough to kick the unit on.  To get around that, I run the hot water in the sink for a minute or so (so much for high water-use efficiency!).

Still, I love not having 40 gallons of water sitting there being heated and not used.  So it takes more effort to use than a tank, but it's efficient and almost zero maintenance. 

[ArthurDent]

A tank or a tankless still has to travel the same length of pipe from where it is mounted to the water outlet that you are standing at waiting for the hot water. If that run is 75 feet, then you are going to have to wait for 75 feet of water to clear out the faucet for the hot water to get to you.

True, but with a tank the water flowing comes from the stored already heated supply. With the tankless unit (as I understand it) there is a control valve that slows or restricts the 'hot' water flow until the water is brought up to a certain temperature before it allows a full 'hot' flow. Hence the added delay. As noted the twice as long is in my location, outside Seattle. It would probably be much less in more southern locations, or possibly longer in colder climes. When doing my initial research I was told for places like Colorado it generally takes more than 1 unit to get the job done (2 units in series) as the temp range the water must be raised is quite a bit more.

And 'no', you don't see a reduced flow at the faucet, I believe there is a by-pass that sends make-up flow until the unit reaches temp, then the by-pass shuts down.

[jackman]

When I needed to replace my hot water heaters, I looked into tankless but it was not a good option in Chicago.  Three different companies said they would install them but cautioned about what to expect in the winter months.  It gets extremely cold in Chicago during the winter (it's 19F now but will be in single digits next week) and tankless heaters will not give sufficient water flow (or amount of hot water) in this climate.  There are other options (new efficient tank systems) you can look at if you are in cold climates but I don't think tankless will work for most people in this area.

Just wondering.  My info is about three years old.  Has anything changed?  The guys I consulted would have gladly installed the new tankless heaters.  In fact, they would have made much more on the deal but they said they were tired of complaints.  Plus, if you have mineral deposits in your local water supply, tankless systems are prone to clogging.  Is this something any of the tankless system owners have experienced?  I was disappointed but feel good about my decision.  Were there options I did not consider? 

Thanks!

Jack

[ArthurDent]

From what little follow-up on the technology I've done I don't think anything much has changed jackman. Good point on the composition of the water as well. I'd forgotten about how 'hard' the water I grew up with in Indy was. So far no problems with that after my 3 years. Not 'soft' by any stretch, but not nearly as bad out here. Sounds like you talked to the right folks for your situation.

Since you mention it I'll check with my installer on whether we need to do a maintenace check on mine. Thanks for the reminder.
JD

[bacobits1]

I looked into it last year. They wanted $5k !!!!!!!!!!!!!!
Now the heater itself is about $900- $1200 on average.
Where is the rest of the money going? An extended warranty etc.
I already had gas. What BS!

The only way this may be viable is an install when the house is built.
It can get a bit fussy on venting too.

Read below what consumer reports says.

http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm

When they asked me why I decided against it I just told them to read the above article.


D

[jackman]

Thanks Arthur.  I'm far from an expert and really wanted to go with the greener system but the drawbacks related to geography put me off.  The plumber said in areas where the water had high amount of sediment (like my area), the small arteries or tubes (don't know tech term) in the tankless heater could get clogged and restrict water flow.  The whole house tankless systems (in my layman understanding) work by sifting water into small tubes, creating more surface are that can be warmed up quickly.  These tubes (according to the guy - he may be wrong!) are susceptible to clogging over time if your water has sediment.  Also, if water entering the system is too cold, it takes longer to heat it up and the flow is much slower than comparable tank systems. 

I hope someone has a different experience because I like the idea of tankless and the savings they generate! 

Cheers,

Jack

[Carlman]

Do you really think a hot water heater has a tankless job? 
I know I appreciate what my water heater does... 

[ArthurDent]

Thanks for the link bacobits, good & definitely valid info (particularly the life-cycle costing numbers). And yes, sounds like someone was looking to stick you pretty good. My local utility supplies both electric & gas service. I got the gas service for free since they have been pushing that for some time to reduce the electron usage. That was dependent on doing both the heater & insert, as the insert qualifies as a heating device (& does the job very well). I barely use the baseboard any more, and not at all in the living/dining/kitchen area.

Since my HVAC folks ran the gas line from the service on one end of the house to the other thru the crawlspace for the insert, with a feed to the heater, and another capped for future gas stove I can't break down the individual run costs. But even with the '0' clearance vent thru the roof installation it wasn't anything close to what you were quoted for just the tank. A buyer beware situation to be sure. Also as you note the vent can be tricky due to code requirements for clearance to any air intake, or window.

Note that I'm no expert either, just been in one end of construction for close to 40 years and have access to some honest knowledgeable folks. I did a reasonable amount of homework back when I made the decision, and since I had changed my own tanks out twice didn't want to be bothered again now that I'm over 60.

Do you really think a hot water heater has a tankless job? 
I know I appreciate what my hot heater does... 

good one Carlman   

[srb]

I also had looked into a tankless unit, but the extra installation expenses made me go with a conventional tank in the end.  The gas tankless heaters require a higher volume of gas flow and my 3/4" gas pipe run would have had to been replaced with 1" piping.  The hotter venting also required an expensive triple-wall stainless steel vent.
 
Electric tankless heaters also require a proportionate increase in energy for on-demand heating, and one I was looking at required two 240V 50A circuits.
 
Both types have an electronic control module, which for some has been a costly replacement when out of warranty.  They also require a minimum flow to kick in, so often a trickle situation like a tiny stream of hot water for shaving is often not enough to trigger heating.
 
So I ended up with a conventional tank and spent an extra hundred dollars for the best premium internal insulation option I could find.
 
Steve

[jriggy]

Hi,

 Sorry for not reading all the posts here in deatail but... We have a Rinnai R85. Have had it  for a few years now and I did not notice any performance changes at all. There are only two of us here w/ 1 kitchen 1 full bath and one half bath. In our home, if the water takes longer to get hot at the source location, it is by seconds. No noticeable change to either of us. Also no flow change at all...

We have the exact same water 'performance' and our gas bill went down! Ill havta ask the wife how much if anyone is interested. But I believe our budget went down 15 or 20 a month.

[ArthurDent]

More good info Steve. I looked up my original exchange with my ME friend and have corrected that post, his findings were for 2-3 people payback was 10 years not 5. (memory just isn't what it once was, sorry for the mis-information)

It was also mentioned in my friend's comments that whether the installation is on an inside or exterior wall is a factor due to the need for combustion air. The possible need for additional ducting or an extended vent will add costs as in the '0' clearance vent you note.

[hometheaterdoc]

I have a natural gas fired 50 gallon tank in a now 2 year old house... it's not in any need of replacement, but I've been considering tankless for the sole reason that taking a shower after the better half means cold water thanks to high flow heads in the master bathroom shower and her penchance for taking her good sweet time in there in the mornings...  it would almost be worth the cost just for that reason alone... I've been tempted to look into it but was concerned about the timeframe to recoup the upfront costs.  Thanks to everyone for the info... I'll look into it a bit more and see if it makes any kind of sense....

[Steidl Guitars]

If you don't want to be inconvenienced, a tankless is probably not for you. 

My tankless cost me about $600 a few years ago, and I did the installation -- I am no plumber. 

I hung it on the wall (~20 lbs.?), extended the gas line that was in place for the heater it replaced (screw fittings), added a few feet of copper pipe to connect with the existing inflow and outflow pipes, and enlarged the roof vent from 4" to 6" to handle the larger pipe (double walled spec'd). 

The unit I have requires no electricity at all; it has a wee turbine that creates the spark to fire the burners. 

Seems that electric units make the most sense only when located at the point of use, say under a sink, where you only need small amounts of hot water.  To run a whole house unit, we want fire and want it now. 

[twitch54]

having hot water baseboard heat (oil fired boiler) the domestic hot water coil is incorporated within. IMO, it works superb and it's one less item (hot water tank) that I have to deal with. I'm on well water and my original coil and boiler (builders grade) lasted almost thirty years.

[borism]

We installed a Takagi - Japanese tankless water heater ~ 10 years ago. It was about $ 1000. Fortunately, a friend installed it for free. I think Takagi is now sold under the Bosch brand through home depot. The greatest benefit is continuous hot water. We are a household of 4 and occasionally have a few guests stay over. In the past, with a hot water tank, we would routinely run out of hot water. I live in Connecticut and it gets very cold here in the Winter and so far there have been no issues related to flow-through water heating. Finally, the unit has performed without glitches so far. Only minor issue is that you can not run two showers in separate bathrooms at the same time. There is not enough hot water flow.

[chrisw]

We had a Noritz 751 model installed in January of 2008 here in the North Texas area and we've been very happy with it.

The up-front installation costs and requirements (large enough gas lines) are definitely a negative, but it allowed us to relocate the water heater from the attic (in the center of the house) into the garage - the city inspector explained they require a certain amount of space in the garage for a water heater, and our garage was 18" shy of meeting the requirements, but a tankless model was acceptable since it's a much smaller unit. I feel much better knowing if the water heater begins to leak, it would leak in the garage instead of into the ceilings!

When they installed the unit, they routed the controller into the master bathroom so we could set the water temp to say 105-110 and just turn on straight hot to fill up our jetted tub. One really cool feature it has is a flow alarm, so I set it to 30 gallons, turn the hot water on, and walk away. When I hear it beeping, I know the bath is ready. Also, setting it to 30 gallons reminds me that I've lost of track of time in the warm shower.

Hard water is definitely a concern, and I have to connect a bilge pump to the tankless unit and cycle 5 gallons of vinegar through it once every year to help dissolve some of the build up. Since the unit is in the garage now, this isn't a big deal for me.. when I had to climb up in the attic and connect a garden hose to flush the previous water heater, that wasn't much fun.

One thing I learned this week with all of the ice and snow in the Dallas area is if the gas supply pressure drops low enough (due to the high demand on the utilities), the unit will give up and throw an error code. Once I set it to a lower temperature and reduced the flow, it was able to keep up to provide me with 100 degree warm water.

Since we had additional piping added to relocate the water heater into the garage, it actually takes longer for the warm water to reach the faucets, and I've considered an under-sink electrical water heater just for the master bath since it takes about two to three minutes for the warm water to get to the faucet, but it hasn't bothered me enough to do anything about it quite yet.

Last year as part of remodeling the house, I started doing reading on shower heads and switched to shower heads made by a company who has been getting a lot of attention from major resorts for their low flow shower heads, Bricor (www.bricor.com) We switched to a 1.5 gpm shower head in the guest bath, and a 2.0 gpm shower head in the master bath, and those have really paid for themselves in water savings.. the previous shower head was delivering close to 5.0 gpm and while it gave a good drenching shower experience, I can honestly say that the new shower heads deliver a solid "high pressure" shower experience.

Anyway, good luck with your decision! 

[Phil A]

I replaced mine with a conventional one 3 years back.  Someone I work with is about to do the same now.  They have become more commonplace than they were 3 years back but not as common as conventional hot water heaters.  There are still many reports of maintenance on some units costing more than conventional units.  When the A/C compressor went last year I bit the bullet and just got whole new furnace too as I figured I would have to do that 6-8 years down the road anyway.  I replaced the windows a year and half back from the builder's grade crap to something decent and that made a difference.  I also could have waited but figured I'd just grab the energy credit and bite the bullet since I had saved to so it and interest rates were low and I'd get a better return on energy savings.