Replies

1. 
   peteshlagor | May 01, 2009 06:57pm | #1

   Based upon my experience with two houses and 10 years of running these things, with that usage, you'd be better off with a tank model. 

   I'm serious.

    

1. 
   Matt | May 02, 2009 02:10pm | #4

   Do you want to expand on that a bit?

1. 
   peteshlagor | May 02, 2009 05:58pm | #5

   Well, I have in the past and it, plus far more can be found with the "search" feature.

   But since you asked nice,

   Consumers Reports did a study on tankless vs tanked last summer.  Without stealing their thunder, their studies found nineteen to be the average number of times hot water is turned (or called for) on daily within the average household.

   Tankless models are marvels of engineering.  The gas flow modulates according to the water flow asked - and it adjusts upon demand.  A tankless model has the equivilant of a blowtorch for a heat source compared to a mild flame for a tanked model.  Recognize the blowtorch is being modulated.

   It's design and the inherent transfers of heat along the way, plus programmed assurances/measurements create (more of) a delay in delivering the hot water, thus causing the flame and water to run longer.  And the length of runs compound that.

   A full appreciation for how these things operate is needed by all within the household.  They all must understand the little "characteristics" the system puts out and how to live with them. 

   You mention 3 people in your house.  I got two in mine.  Now really, do you think you can get them to reduce the number of times they need HW to below 19 per day?  And shorten the length of use?  Or maybe at best, run multiple HW appliances at the same time to maximize efficiency?  Or to avoid another bolus of cold water coming thru the lines?

   I have a hellof a time getting the wife to even think of using the HW faucet differently than at her work.  Guests or kids, forget it.  They'll simply complain about how long it takes to get hot water, or that the hot water "runs out" if they slow the stream down to below the minimum rate for the heater (don't think that's not important). 

   And if you start on the path to "educating"everyone, you'll come across as a big dork.

   The last thing they'll think is, "Gee, Matt's so smart for putting in this HW system that's 10 times as expensive as ours at home that works better."

   Or maybe they would.  I find people around me like sarcasm.

    

1. 
   popawheelie | May 02, 2009 06:14pm | #6

   Sometimes more complicated just doesn't pay.

   It's like cars that cost so much these days. With all the technology in cars today, you'd think they would get better millage.

   Most of the gadgets they put on cars I dont' like or want.

   I think tank water heaters work fine.

    "There are three kinds of men: The one that learns by reading, the few who learn by observation and the rest of them have to pee on the electric fence for themselves."Will Rogers

2. 
   Matt | May 06, 2009 05:50am | #12

   Thanks for your thoughts and experiences....

   I think that is one reason we come here - to get the straight poop - not the marketing literature version....

2. 
   peteshlagor | May 02, 2009 10:43pm | #9

   To clarify,  I love mine too!

   When questioned by my buds or guests, I got all kinds of nice things to say about them.  The space created by hanging a small unit on the wall is incredible.  I replaced two 50 gallon tanks with mine.  I now got a huge utility room that allows me to iinstall a sink, urinal, and a communications distribution panel where I didn't have that choice before.

   They offer me a decent means of lowering my energy efficiency score towards a Five Star rated house.

   We travel a fair amount.  That's when the tanks keep on pumping out the heat.  A tankless won't.

   I can fill the big Jacuzzi, take a shower, and wash both dishes and clothes at the same time without running out of HW.   That's why there were two 50 galloners in the first place.

    

   But trying to prove to my DW that spending $3200 was a good financial decision, I'm having a tough time with that.

   One gets these things for reasons other than saving money.  And don't let a plumber or salesman blow smoke up your vent about you needing to cover three showers and the washing machine at the same time.  A Tagaki TK-3 will do you just fine.  High and low flow rates.

1. 
   davidmeiland | May 02, 2009 10:56pm | #10

   Like you are saying, the space savings is a HUGE plus. My gain in that area was similar to yours. My install cost was about half of yours. I had to extend the gas ten feet, no need to upsize it, same with the water, all DIY, one day's labor. I have seen other situations where the gas line upsizing would be very expensive, in fact I've done a couple over the years where a lot of new gas line was run. Also did one where the venting was stupidly difficult.

2. 
   sledgehammer | May 02, 2009 05:13am | #2

   Tankless is usually used as the primary with solar as a backup.

    

    

3. 
   rez | May 02, 2009 05:28am | #3

   Greetings scorch, here's a link to mucha data, some along the lines of which you question.

   http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

    

    

   Cheers

    

4. 
   davidmeiland | May 02, 2009 06:16pm | #7

   We have a Takagi tankless and it works fine, has for several years.

   If you want to use a tankless with solar, one of the questions you ask the tankless dealer is, what is the max incoming water temperature I can run with this heater? Assuming you have a solar storage tank ahead of the tankless, you may be running warm water thru the heater. You may need a tempering valve or some other semi-smart setup to make sure the temperature of the stored water is taken into account.

5. 
   PedroTheMule | May 02, 2009 07:57pm | #8

   Hi scorch,

   I am doing an addition to my house (after a lifetime of doing other people's additions) and need a recommendation for a tankless water heater. The house will be 1700 sq ft., 3Bed/2Bath and a family of 3 and occasional house guests. I need the water heater to be either direct vented from the crawl space (preferred), or an outdoor unit. And the catch is that I'd like to add solar water heating a little ways down the line, so ideally the tankless heater would be a unit that I could keep in place and use as a back-up. Does anybody have a recommendation of a model that would be good for me? And also, do you have any other general recommendations about pre-planning and/or pre-plumbing for a future solar system?

   I started out with a Paloma externally mounted tankless and absolutely love it and not a single regret.

   They do make an "inwall" casing that somewhat recesses the unit now, but I'm not going to retrofit a finished, working unit; however, I would do the flush mount if I were starting from scratch rather than an inside model. Personal choice and my location isn't prone to long term hard freezing, but my unit does include an electric heat strip to protect it during mild freezing. I also like that all combustion takes place outside which means no risk of carbon monoxide and no need to make up for intake air.

   Now to solar.....I'm working on a unit in my shop that should be in place.....oh you know how us gadget freaks are....probably won't be completed 'til next spring but I hope to be finished in a couple of months.

   My ground/low wall mounted solar collector will be piped as a closed loop system incorporating an antifreeze type solution so it'll stay active year round. A very tiny pump will circulate the water from the heat exchanger coils within a superinsulated holding tank. The street water enters the holding tank and is warmed by the heat exchanger coils circulating from the solar panel. The water will then feed to the input of the paloma tankless. When hot water is needed the solar preheated water will feed the tankless, if temps are high enough then the water will pass right on through with no adjustment, if the water is too cool, the gas tankless will fire and do it's job, even if the solar water isn't bath temp, it will require less gas to heat to the desired temps.

   The worst thing I'm dealing with is the tankless and the solar are on opposite corners of the house. I'll change this arrangement in my retirement home where I'll be preheating with a wood fired boiler in winter and solar in summer with the same gas tankless year round.

   Concerning preplanning with a tankless style of use and not having to explain it to every person that crosses the threshold.....we put two handled faucets at every location.....if someone is doing a general hand washing.....they're rarely going to flip on both handles....turning on cold gets them cold water......turning on hot they realize it's a big house and may take a moment to get the hot water....if they're too dumb to figure this out, let 'em ask and I'll give 'em the "you're stupid" look......for us we chose to put the tankless at the master bath wall where the majority of our hot water needs are. Any time I think an explaination is necessary....to our overnight guests who are upstairs.....hey when you get your shower....don't forget you're on the top floor and it might take about 30 seconds until the hot water reaches you.......

   Simple as that.

   Pedro the Mule - Now if I could only find a way to recycle "my" gas....

6. 
   djthx | May 03, 2009 03:03am | #11

   I installed the Paloma (Rheem) PV74 unit about a year ago. 

   Pros:  You never run out of hot water.  With my wife, one teenager, and one 9 year old princess in my household, this is a major plus - since I'm usually the last one to take a shower in the mornings.

              I installed the unit myself.  The instructions are straight forward, but you do     need to know plumbing, electricity, and venting.  And the venting requirements are somewhat demanding.  It also needed a water filter.

              The unit looks modern and neat.  And it takes up much less space than a tank water heater.

              In theory, it's an energy saver (since you don't have to heat the water continuosly).

   Cons:  I find that there really isn't a noticeable energy savings now that the hot water never runs out.  Everyone - myself sometimes included - takes a much longer shower, and this defeats the energy conservation objective.

              Once the water in the lines get cold - especially in the colder seasons, it takes a long time for the hot water to reach the faucet.  The time it takes will be less if you install a branch piping/manifold system, with each faucet having its own 1/2" line.  But installing this setup is time consuming and/or costly.

              Even if the water in the lines are still hot, the water in the unit's copper tubing is cold.  And I've heard my wife scream many times after getting hit with this cold water sandwich effect.

              The heater will not activate unless you have sufficient flow. 

   To combat this last two cons, you can install a small electric tank water heater, and a recirculating system (and I believe also an expansion tank).  However, I never sought to do this, because after a while, just like we got used to not taking long showers, and/or using the washing machine simultaneously, when we had the hot water tank, we got used to these "nuisances".

   In conclusion, just based on the fact that you'll never run out of hot water, I recommend this system.

     

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   Edited 5/2/2009 8:04 pm ET by djthx

   
   

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   Edited 5/3/2009 9:49 am ET by djthx