Tankless Hot Water Heaters

Bob Gagnon plumbing and heating

We have a lot of minerals in the water in my area. Would the minerals build up on a tankless heater , like we have on tankless coils inside of boilers? Bob Gagnon

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Dave_23

Tankless Hot Water Heaters

Folks,
My 50 gallon Richmond nat gas fired hot water heater is going on 20 years old. In anticipation of its failure, I'm considering a tankless system. I've looked at Rinnai, but am willing to consider others. What are your opinions on tankless systems? Or, would you simply replace the existing 50 gal conventional tank with a similar unit? (Note: I have steam heat, but would prefer not to run my boiler all Spring, Summer and Fall during the non-heating season.) Thanks, Dave

Dale

Deep question

Allot of variables, first find out how much you are paying for hot water, ie, how many therms of gas in the summer. Then, is your house set up to vent a tankless, mine isn't as I only have 6 inches between grade and siding and it's cold in Wisc. Next how much water in gpm at a given temp do you need? Go to the water heater web sites, like tagaki and see what you need, then what heater size. The Rinnnai and tagaki are really computers that heat water, don't expect to pay less than $2000 for a professional install for the 190,000 btu input type. They are a good choice for the right application but not for every house IMHO.

J.C.A._3

Another thing to consider.....

Length of run to the shower that "Mama uses". It takes a while for these things to respond to a call for hot water(or so it seems,) when the fixtures are far away. If they can be centrally located to appize all your requirements, go for it. They WILL save a lot of gas. Just remember the most important thing in the equation....If Mama ain't happy....no-ones happy. That my friend, turns into the bottom line.

Like Dale said, figure the max flow first, and size accordingly, but....Remember Mama. Chris

Dave_23

Point well taken

One of my biggest concerns is "shower quality." Our house, when it was built, included Sloan valve toilets. Therefore, we have very good water pressure throughout, which gives great showers (albeit more expensive...). My concern is that a tankless heater will reduce the hot water pressure to something similar to a cheap hotel.

Paul Pollets

Flows

Most instantaneous water tanks have a 4.5gpm flowrate. If you exceed that amount you will have lukewarm water coming out of the tap. A good showerhead uses 3-5gpm. Hotel showerheads are 2gpm.

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daniel ( doctors heating & cooling)

definitely go w/ a takagi, they're the best on the market w/a 35-50% savings compared to tanks. i've installed 100's & not 1 complaint!

daniel ( doctors heating & cooling)

your reply is brainless, takagi can be mounted outside, even in WI. plus there are other places to mount it to get the clearance you need

Timco

Sooo...

Does a tankless feed a 40 gallon WH, or vise-versa? I would think the WH would feed the tankless, so it would only fire up if the WH ran out of HW...

Tim

JackFre

Rinnai

www.foreverhotwater.com, www.rinnai.us, www.rinnaisolutions.com, www.tanklesstaxcredit.com
A lot of good info for you. Also, as freeze protection has been mentioned, Rinnai's are freeze protected to -30F.

Constantin

Hold on...

... first of all, personal attacks are not necessary. You can point out the error in the other persons post based on your experience, knowledge, etc. - that ought to be good enough.

Now, for the wisdom of installing a water heater outside, just because it can be done does not mean that it's a good idea. In cold weather, the standby losses will be significantly higher when the unit does not benefit from the thermal envelope of the home, so I'd install one outside only as a very last resort in places like WI. In warmer climates, this is not much of a concern and having the unit outside adds space inside, can be safer, and may make servicing easier.

Another issue in cold climates is power. The more remote the house, the more likely that an inopportune storm will wipe out power, causing equipment installed outside to freeze and fail. Installed indoors, the thermal flywheel, sheltering, etc. will give you at least some hours to get power going again before everything freezes up.

If hydronic heat is already in the house, I'd go with a indirect water heater. No moving parts, one less combustion appliance, and very low standby losses. Couple a indirect water heater with a modulating, condensing boiler and you have a pretty unbeatable combination of efficiency and comfort.

Dave Yates (PAH)

Daniel

Could you elaborate on the savings? I'm curious as to how you arrived at those efficiency numbers. Thanks

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daniel ( doctors heating & cooling)

mr. yates the numbers are listed in takagi literature. also comparisons from my own unit & numerous testomonies from my clientle

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daniel ( doctors heating & cooling)

the tankless eliminates the tank all together. the tankless is fed from the water main and only fires up when hot water is called for, there is no water stored in the unit.

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Timco

I understand this...but there have been several posts regarding a tankless either feeding or being fed by a 40 gal WH. Seemed to be a benifit, but I can never remember which comes first. Seems like the WH should feed the tankless, unless the tankless has no inlet temp sensor. Then it would run and heat hot water. If the tankless feeds the WH, it keeps the WH filled with HW and you have the exact same effect as no tankless at all, but endless HW without the issues of tankless only...

Tim

Bill_14

Sales of these products...

...should be based on factual performance and not based on advertising materials and website propaganda. Besides performance claims, there are numerous inept cost figures being thrown around by the public, by the Home Depot types and by contractors; none of which really understand how to design and install these system correctly.

Bill

Jerry_15

Yeah right - just don't ever lose power in the middle of winter. Sure it never happens where you live.

Plumdog_2

Literature to be taken with a grain of salt

For example; "your tank type heater runs 24 hours a day, even when your not home".

mp1969

Tankless

We are slowly getting involved with tankless heaters as we serve customers with large houses and therefore long runs.The wait for water is a concern and over cycling of the unit shortens life.
There are methods of recirc. that involve a small storage tank and an additional pump. I have installed both Takagi and Rinnai here in Wisconsin and find the venting package easier on the Rinnai.
Things to consider are gpm requirements, need for a recirc system, quality of water(tankless have narrow passages and lime up easily)complexity (relative to servicing) and overall cost effectiveness.
Even with global warming and our milder winters I would be very hard pressed to install any of these units outside in Wisconsin!

MP 1969

Greg_40

Tankless

Timco - to help answer your question. There are times in which a storage tank helps to be connected to a tankless water heater. The primary purpose here is to provide a quicker response to hot water needs, especially those times of small demand - ie- washing hands, shaving, etc. This can negate some of the savings advertised since tankless models do not maintain a tank of hot water 24/7. There are many times mating a tank to a tankless may pay dividends. If you have a need for this, the tank goes after the tankless heater. Assuming the tank is well insulated, such as a qualitiy indirect, standby losses could be minimal.

IMO, the jury is still out on the merits of tankless water heaters. Some will reap savings and enjoy bounties of hot water, while others will save little and may never get past the learning curve of waiting for hot water to arrive at a fixture. Remember, they are tankless, not instant water heaters as some believe. To me, the latter also negates much of the savings advertised of the tankless models. Now, if you have a means to capture and use the water which flows while waiting, this would be much better. I know a customer who turns on their laundry washer, which is located near their bathroom until the water is warm. Then he shuts off the washing machine and takes a shower. Eventually, they have a washing machine full of water for the next load and didn't just pour it down the drain. The washer may be full (of room temp water) when you are ready to do a load and the water emptied during the wait was not merely wasted. This takes a conscience effort to do, but there may be other effective ways to conserve. Pre heaters from waste water (Mr. Eatherton had plans for one on this site a couple of years back) may also help save water heating costs, for example.

Water quality will also be an issue. I'm sure some scale will build up, some tankless models talk of HX cleaning as part of routine maintenance. If you're having problems getting a standard low tech water heater to last due to water issues, you will likely have compounded problems with a tankless model. For those who use lots of hot water, I feel a tankless could be a wise choice, others may not benefit nearly as well.

Scott Denny

A few technical points

On line buildup, Webstone makes a valve package that facilitates relatively easy heat exchanger cleaning.

Scott Denny

A few technical points

On line buildup, Webstone makes a valve package that facilitates relatively easy heat exchanger cleaning.

Scott Denny

A few technical points

On lime buildup, Webstone makes a valve package that facilitates relatively easy heat exchanger cleaning.
http://www.webstonevalves.com/isolatorexp.html
A small pump, a pint of CLR, some connector hoses and you have a new occupation for the cabana boy. This maintenance cost should be factored into the calculations on the cost savings of these units, noting that with proper maintenance tankless heaters should last considerably longer than conventional water heaters.

As for pumped recirculation: care should be taken with the installation of these systems. Check valves and expansion tanks are often necessary. If a fast closing solinoid valve (washing machine) is located close to the discharge side of the heater, the shock caused when it shuts down may confuse the tankless onboard flowswitch, requiring an additional check valve on the hot discharge. Using a small electric water heater for recirculation purposes can absorb the 3/4" gallon plug of cold water discharging from the heater before the burners kick in, cut down on the heat exchanger wear, and decrease the size from a high head 1/12th hp pump to a smaller 25th hp unit. Bear in mind that this set up causes a 3/4" bottleneck (all hot water has to pass thru the electric heater)in the system. [see attachment] This can be a big problem in larger houses with multiple shower users.

Imput gas sizing is another issue on retrofits.

Catagory III venting requirements, often with condensate removal issues is a real headache, especially in retrofit.

In Japan they place these heaters in close proximity to the point of use. As such, energy savings probably can be quantified, depending on cost per cfh of gas provided.

Because there are so many variables involved (unit size, placement, cost of labor in a given location), I could not, without a sight visit, gave even a WAG (wild **** guess) as to how much an installation would cost.

Bill_14

Gas Service Sizing

Some of our local "competition" likes to sell and install these systems without any regard to proper gas service sizing. If this is not a part of their so-called bid proposal, the customer is faced with an extra charge.

Hopefully, our inspectors will start double-checking the entire gas piping system and be putting a stop to this practice. There are some guys that simply do not know how to size gas piping...most just want to get the job and get their foot in the door. Until these contractors do things the correct way, we will always be bidding apples-to-oranges.

Bill

Bill_14

Big Grains!!! (NM)

Dave_23

Location

I'm still not sure how I'm going to proceed. However, the plumbing contractor I spoke with was very frank and honest. I suggested that I might like to have any future tankless system located nearest the destination for hot water, which for the most part are all stacked at the back of my home. Whereas, the existing hot water heater is located at the front of my house near the chimney. Thus, a somewhat wasteful, long wait for HW. He prefers to run a 1 inch gas line from the meter inlet to the tankless, especially if it's a long run to the back of a house. He also suggested that a standard HW heater with a timed recirc loop my be a reasonable approach as well. He also discussed "cold spots" with tankless systems, when demand changes. Also mentioned was a learning curve in that the dynamics of a tankless, albeit more efficient, are different than conventional systems.

KAG

Freeze-up

Install an anti freeze valve, when you lose power valve opens up and drops water in unit. If you come home and see water flowing out of pipe you know you have no power. Go and turn off water and wait for power to return. Whether unit is inside or out no power no hot water and if power is out long enough unit will freeze inside home.

Scott Gregg

There is too much to type for this one

So go here:
www.tanklessva.com
Scroll to the bottom and click on the link to Tankless 101.

Paul is dead wrong on several counts. (Sorry)

My company is a Rep for Noritz. Noritz, Takagi and Rinnai are the BIG 3! It is my opinion that Rinnai and Noritz are ahead of Takagi on technology, performance and quality, although the Takagis do work well.

We have sold between 4000 and 5000 Noritz models. Guess what? NOT ONE COMPONENT FAILURE! Also, not one complaint of running out of hot water has got back to us. You know why? Because you can't. I have heard similar things about Rinnai.

Now yes, you can choose the wrong size and that would limit your flow, however that is very unlikely to be a concern in standard homes up to 3-1/2 baths with modern fixtures. Possibly in an older home, up north, with old 5GPM shower heads. (All Shower heads sold have had to be 2.5GPM for a very long time now.)

They work. I'm even putting one in my new home to work with a Geo system for maximum savings and comfort. www.vaenergyhouse.com

This will be the first public release of the this site. I will post another link on it's own post for input by the bretheren.

One last note Installation is very important and not a DIY'er project. Hire a pro that knows what he's (or she's) doing.

daniel ( doctors heating & cooling)

> ...should be based on factual performance and not

> based on advertising materials and website

> propaganda. Besides performance claims, there

> are numerous inept cost figures being thrown

> around by the public, by the Home Depot types and

> by contractors; none of which really understand

> how to design and install these system

> correctly.

>

> Bill



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daniel ( doctors heating & cooling)

where else do you get the basis of factual performance other than owning one and the feedback of satisfied customers. yes they are satisfied because i am a contractor who knows how to design and install. go build a birdhouse or something!

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Mark Hunt

You


should watch your mouth.

Mark H

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Bill_14

Scott Gregg

Maybe...

I've heard concerns about liming but never actually seen it hapen. Noritz has a "Scale Shield" that is a cartridge type filter to protect the tankless. It's a lot cheaper than a whole house softener too.

Treating the water is the best choice, but even if a tankless were to lime up, with the Webstone valve set, flushing is an easy task.

Dave Yates (GrandPAH)_1

Sprinkling a few grains of salt

Here are some facts to consider:

http://www.contractormag.com/articles/column.cfm?columnid=356

PS - Please ignore the weird typos that occured when the article was posted in the archives. Must be a Bill Gates glitch(G).

PPS - Want to determine how much hot water you'll really need to provide? Do the math ot take a bath (a cold one!).

Adjusted bathing temp minuis the coldest water seen during the year divided by the storage temp minus that same cold water temp. That yields the percentage of hot water in the mixed delivery. Time the time it takes to fill a bucket that has marks for gallon(s). From that you can easily determine the GPM of hot water and use the units net input to see if you can really meet the peak demand.

Hot water recirc is another issue. Both Fine Home Building and Contractor will have recirc columns in the coming issue. FHB will have a moderated BB to discuss the issues starting on the 16th. Join us for participation by signing up for "Breaktime".

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Bill_14

Link

Dave,

How do you retrieve that link within your article?

Bill

Bill_14

Link

Dave,

How do you retrieve that link within your article?

Bill

Bill_14

I may not be very smart Daniel, but I actually am good at building birdhouses...Bluebird houses are my specialty.

I want to also say that I erred in not being very clear with my previous statement. I meant no disrespect to you or anyone else that dares expose themselves on these threads. My words were taken incorrectly, but I could have done a better job.

However, I will stand by my intended comments that there are several customers (lay people), retail establishments (like Home Depot) AND "CONTRACTORS" in my area that spout off totally false information. I am sure some of the comments are what they have heard or from what advertising they have read.

This is just like anything else in our business. If someone wants to "lowball" a price to get in the door, I would compare that skill level to building birdhouses. However, if someone wants to be thorough and factual with their design of these individual systems, then I am all for a good sales contest.

{Customized Design + Materials & Equipment + Installation Costs + Markup = Sales Price}

Hopefully, the above formula applies to everything we do. We can even do this for more than one system in order to compare costs. To take it even further, we can now calculate (estimate) fuel costs based on the facts known and obtain a figure that justifies a solid recommendation for the customer.

Sure, our company would rather make a $4000 sale over a $1000 sale, but NOT at the expense of a customer who is uninformed on ALL the facts. {These dollar amounts are totally hypothetical}

Bill

Bill_14

Birdhouses...

I may not be very smart Daniel, but I actually am good at building birdhouses...Bluebird houses are my specialty.

I want to also say that I erred in not being very clear with my previous statement. I meant no disrespect to you or anyone else that dares to expose themselves on these threads. My words were taken incorrectly, but I could have done a better job of communicating.

However, I will stand by my intended comments that there are several customers (lay people), retail establishments (like Home Depot) AND "CONTRACTORS" in my area that spout off totally false information. I am sure some of the comments are what they have heard or from what advertising they have read.

This is just like anything else in our business. If someone wants to "lowball" a price to get in the door, I would compare that skill level to building birdhouses. However, if someone wants to be thorough and factual with their design of these individual systems, then I am all for a good sales contest.

{Customized Design + Materials & Equipment + Installation Costs + Markup = Sales Price}

Hopefully, the above formula applies to everything we do. We can even do this for more than one system in order to compare costs. To take it even further, we can now calculate (estimate) fuel costs based on the facts known and obtain a figure that justifies a solid recommendation for the customer.

Sure, our company would rather make a $4000 sale over a $1000 sale, but NOT at the expense of a customer who is uninformed on ALL the facts. {These dollar amounts are totally hypothetical}

Bill

Dave Yates (GrandPAH)_1

must be

A reference to an article I wrote that's no longer in the archives. I can pull it from my files (at home), but won't get back until late tonight due to a family/doctor conference regarding some parental health issues. As a result, I may not get an opportunity to post that for today.

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jackchips_2

Hi Tim,

> I understand this...but there have been several

> posts regarding a tankless either feeding or

> being fed by a 40 gal WH. Seemed to be a benifit,

> but I can never remember which comes first. Seems

> like the WH should feed the tankless, unless the

> tankless has no inlet temp sensor. Then it would

> run and heat hot water. If the tankless feeds the

> WH, it keeps the WH filled with HW and you have

> the exact same effect as no tankless at all, but

> endless HW without the issues of tankless

> only...

>

> Tim

jackchips_2

Tim, I have

a takagi 240 installed before my 50 gallon gas fired storage tank and we have not run out of hot water since it was installed about three and a half years ago.

It also heats my pool through a heat exchanger in the summer. It takes a few days to get up to temp but with a solar cover it maintains it with no problems.


Jack