Demand water heater question

[Anna]

We're planning to replace our tank water heater with a tankless one sometime this summer or so. I have no idea where to start researching this. Anybody have any recommendations and/or suggestions as to what features to look for? Are there brands that are reliable?

Thanks.

Anna

[wbsettle]

Lowes/Home Depot usually have flyers from various manufacturers in the store. It was actually one of those flyers that steered me away from going tankless when the time comes to replace my current heater. I can't remember the brand, but they're own published annual fuel savings numbers showed it would take me close to 10 years to recapture the price difference between tankless and traditional gas fired, assuming $0 maintenance costs on the tankless unit.

Googling tankless water heaters should turn up a number of sites, as well.

Don't overlook supply requirements in your installation cost. To get the BTUs needed for the tankless, I would have to install a larger gas line from the meter to the water heater, assuming the street to house service was up to the load. In my case, that's 70' as the crow flies.

-Brent

[Anna]

Brent, thanks for the advice. I have been to some of the big box stores, and I got overwhelmed by the information. I naturally distrust them because they tend to push products they don't know much about.

Our tank water heater is 8 years old, just like our house. I think their expected lifetime is 10 to 15 years, and the warranty is only for 5 year. I'm a little nervous about the tank leaking. We are also a two-person household, and it doesn't make sense to keep 80 gallons or so of water in the tank kept heated all the time.

Utilities here in the People's Republic of California can get pretty expensive, and our ROI might look a little rosier than yours. I'll eventually talk to some of the installer guys, but I really want to be armed with information when I can.

Thanks again.

[cgallery]

Brendt's experience is the same as mine. I'd have to install a new gas line, and it was going to become a reasonably large expense.

However, I saw on some home improvement show that they were using an electric tankless. They (electric units) are less expensive, and wouldn't require running an expensive new gas line. They also don't require venting.

So the question becomes whether an electric tankless can supply enough hot water (we are not big hot water users--only 1.5 baths in the house, and we can manage not running washing machine/dishwasher/shower at the same time), and whether it would cost more/less/same as gas tank unit to run.

I did some research and didn't come up w/ an answer (but lots of biased opinions), so I wouldn't mind hearing other people's opinions here.

[Uncle Cracker]

A well-insulated water tank does not require a whole lot of runtime to keep water at temperature, similar to a thermos. It's the marginal ones that can getcha. Look at the energy numbers posted on the units for comparison. Consider also a tank "blanket" for additional heat retention. The earlier suggestions are spot-on. It will take a looong time for a break-even, given today's prices for tankless units.

[Slik Geek]

My only experience with tankless water heaters is at work (for sinks, not tubs, showers or washers). They are electric and installed with a plumbing distance of between five feet and fifteen feet.

You would think that you would get hot water sooner than at home where you have multiple tens-of-feet distance to the centralized hot water tank, but my impression is that the delay is similar. This may be due to the fact that my experience is with electric heaters - they may have a slower response time (electricity has to heat the coils, which in turn heat the boiler instead of flames directly heating the boiler).

Hence, my very limited experience says to get a gas-fired heater if possible.

I would suggest getting units with heating capacity on the high side (ie higher flow ratings / greater heat rise). (Especially with an electric-powered heater). Otherwise, if you don't get enough heat to be comfortable, you'll despise your expensive water heater purchase every time you use hot water.

I wonder about the energy savings claims for tankless models when your household includes teenagers. If I had a endless flow of hot water (ie a tankless heater) in my household, I fear that my gas and water bill would be higher due to endless showers by the kids. I like the fact that the tank empties and it falls behind - that gets them out of the shower!

[Slik Geek]

In addition to Cracker's suggestion, insulating the hot water pipes wherever possible can also be helpful. It's very cheap, relatively easy.

[KenBurris]

got a new 50-gal Rheem (gas) Tuesday - it looks like they make most other "brands" - energy sticker says avg $315 per year - it was $649.99 installed (including $50 permit) Quote from same company for tankless was $2350 - assuming no change in gas pipe size, wiring, etc. I'm not sure how much an on-demand might save in the long run
P.S. I bought my house in 1999, the inspector said the warranty expired on my water heater in 1979, so I've been waiting... i finally had leakage starting a couple of months ago - just enough to dampen the floor - maybe a quart - finally gave in when the pilot went out, and I's rather buy a new one than light the old - new one has electronic pilot lighting.

[iceman61]

If you Google tankless water heaters or on-demand water heaters you will hit some sites with calculators that will suggest sizes with the factors you supply. As previously suggested I would probably go to a gas-fired heater also for the speed.

You could always install a smaller unit under whichever sink in your house uses the most hot water to kind of give it a test run. True, you would still be purchasing it but it will save you a considerable amount if you decide it's not what you want it to be. Last time I checked (couple of years ago) they were about $150 as opposed to the $900 it would take for my needs.

These prices are without installation.

[Tom Slick]

I looked into tankless a couple of years ago. Rinnai are common and highly recommended, they are really neat systems. after weighing the pros and cons I had a 40 gal bradford white installed. Qualified service and parts availability are still an issue with tankless. ground water temperature is also an issue, the unit can only heat the water so much as it passes though. they function best in series with a solar water heater.

[unclecritic]

Its been my expierence with a few manufactures that they are vague on warranty issues. A proper install requires flush valves installed into the water piping to isolate the heater so you can put the unit into "flush" mode to remove any scale and build up from the heat exchanger. From what I understand it involves an external pump and an acidic solution... more costs...

No big deal other than cost of the extra valves and I am lead to beleive that there is a memory unit in some of these models that keeps track of when its been flushed, and if you fail to meet their requirements (i.e. too much time betwwen or lack of flushing at all) the wont honor the warranty if the heat exchanger goes bad.

And if you find a good deal on a unit, make sure you price out all of the venting parts as well. These are really easy units to install, but the price for the venting materials is ridiculous... like $89 just for the termination cap...eeesh.

Ive gas piped a few of these, and after all is said and done, the home owners have been pretty happy with them. But this has been in $1mil+ homes so cost probably wasnt a huge factor.

They are a really good idea IMHO, but they are just too new to be excuted well. The prices are still a little high for the long run payback.

But having endless hot water is pretty nice. Plus when the 200,000 btu flame fires up when water is needed, its probably pretty fun to watch the meter spin around like crazy

[Anna]

Thanks for the comments and suggestions, guys. At least now I know a few things:

- For one, I didn't know that the gas line capacity could be an issue. I'll see tomorrow what our current capacity is.

- The energy efficiency of the current heater is in the low end, which also makes me think I'll have to replace it one way or the other anyway. Our rating is 80 AFUE. The least efficient rating is a 78, and the most efficient is a 96.6.

- I also made a calculation, and I need at least 5 or 6 gallons per minute. We had a family of 5 staying with us a couple weeks ago, and they really stretched our current set up to the limit. I hate not having enough hot water when it's my turn to get in the shower.

- Thankfully, we don't have teenagers who are more prone to waste water/have longer showers.

- It will have to be gas-fired because an electric heater costs twice as much to operate.

- I'm going to research more about the Rinnai. My husband just mentioned that one of our friends is having two of these installed at his new house, and I'll give him a call and find out what he thinks/how much it costs. Also, this maintenance issue that UncleCritic mentioned.

- Lastly, I hate that big ugly tank in the garage. Would be nice to get rid of it and build more cabinets/storage in its place.

(I just remembered: When we were living in a place with a much smaller tank, when I got pissed off with my husband, I'd turn the dishwasher on when he went in for his shower. He never could figure out why he didn't get hot water sometimes. It defeated the purpose of "punishing" him, but it's still funny whenever I remember it. I hope he doesn't read this thread.)

[Tom Slick]

On any unit you buy make sure that you have a local dealer and a local service person, more than a day without hot water is miserable.

I have heard that bosch units don't perform as well as advertised, my local pumber claims he has replaced a few of them because their units were too small for an average house.

rinnai makes a system with point of use temperature control panels. that means if you like a 103* shower you dial in 103* at the shower. If you like 120* for washing dishes then you dial in 120* at the sink control. it heats the water to your desired temp so that you are using hot water only, not 140* water mixed with 70* water like a tradional water heater system.

[Anna]

rinnai makes a system with point of use temperature control panels. that means if you like a 103* shower you dial in 103* at the shower. If you like 120* for washing dishes then you dial in 120* at the sink control. it heats the water to your desired temp so that you are using hot water only, not 140* water mixed with 70* water like a tradional water heater system.

The installation is going to be much more complicated than just taking down the old heater then because of the dials at each point? Or are we talking about a heater for each location?

[Tom Slick]

it is an accessory ($$$) that you add on to the main water heating unit, it is not mandatory. I just think it's a slick system.

you also have to have all new exhaust ducting installed. tankless require specific exhaust duct materials and sizes due to their large, efficient burners.