tankless

Dan_18

Dose a tank less water heater really save money as apposed to a 40 gallon gas with normal usage?

Unknown

Tough call,,,,,

My opinion is this,,, "tankless on demand" fire-up whenever the HW tap is opened and heats the incoming water as quick as its passing through(at a GIVEN RATE pertaining to temp rise),,,, if your "raw cold water" is from a well this temp is usually constant year round. (forget about any impurities for a minute).



If  on a municipal supply, if pumped from a river or lake, the "raw cold water" temp will vary depending on the season,,, ever try peeling potatoes in Feb?  This WILL effect the water temp you shower-in using tankless and lessen its output.



Savings?,,,, perhaps, at "given" times of the year,,,,, for me, I`d rather a storage tank and get HW anytime I may want. :-)



I see some of my competition "giving them away" in free draws,,,, even if I had-one I know what I would do with-it  :-)

mjcromp

minus the BS

I have installed many Rinnai heaters. Very rarely do I have a customer complain of water problems, not enough, fluctuations ....

It looks as pretty near every heating guy in this place has a problem with them (i guess they are just too smart for a tankless)

I don't have problems with them. They are reliable. Don't burn gas when they are  not being used...

All my customers are happy with how they operate and their gas bills. Sometimes a gas bill will go up because they know they can't run the tank out of water and take longer showers.

I have installed over 100 tankless heaters (majority Rinnai and some Noritz)

I have a good idea of what is working well. I contact customers after a few weeks and also about a year later just to make sure everything is good and they are still happy and have yet to have a customer that want's a tanked heater again!



As for you people that don't like the tankless. Opinions are like you know what!!!! and you know the rest of it.

If your opinion is constantly going to be against tankless just get over yourself and don't feel compelled to give your stinkin' opinion!

(I tried to say this as nicely as I could! You should have seen my rough draft!!)

Steve_210

data

can anyone provide any data for comparision

Wayco Wayne_2

Be aware

tankless heater need annual maintenance, depending on the type of water you have. In our area we have a lot of minerals in the water. It looks like Luray Caverns in our humidifiers in no time flat. Tankless heaters in our are must be flushed out with white vinegar or something similar or they will lose efficiency and evetually stop working well.  Tankled water heater should be flushed out bi annually to remove settiment from the bottom of the tank, but no one does that. The only problem you experience is a shorter tank life span.  WW

Mark Eatherton

The answer is.....

It depends! But you probably already knew that.



The manufacturers claim 20 to 30% reductions. That is for a gas fired tank versus tankless. A comparison of electric tank to electric tankless is around 2 to 3 % savings.



mjcromp is of the attitude that everyone here on the wall HATES tankless heaters, which is not quite true, but the ill will toward thankless water heaters comes from negative experiences that have been relayed here on the wall.



For example, people (including the manufacturers) like to think of them as "miniature boilers". They then misapply them in space heating applications, and then due to a lack of flow and temperature differential, the appliance rots off the wall due to short cycling.



Another scenario is where the manufacturer tells people that it is OK to have a potable water heating system that can also be used for doing space heating with a RFH system without the use of a heat exchanger to isolate the two fluids, thereby creating a Legionella magnification farm. Again, the appliance will rot off the wall due to short cycling, because it never gets hot enough to dry out the exchanger on the fire side.



Then there are the WILD claims made by the manufacturer as it pertains to the gallons per hour of hot water produced. THe problem is, they don't have to use a particular "temperature rise", so you get some manufacturers making what appears to be exhorbitant claims, when in reality, their production is really no better than their competitors, but the consumer doesn't have the where with all to sit down and perform their own analysis to see exactly what it is that is going on inside the "Magic Box".



These products were designed for a specific purpose. Raising the temperature of a fixed stream of water a certain degree rise, and under THOSE conditions, the average efficiency is around 80%. Yes, there are some more efficient units out there (mod cons), but they are also more expensive, and less applied.



The other thing the manufacturers forget to mention is that the output of the appliance decreases when used at altitude. Like by 1/5th here in Denver...



They also don't mention that in some cases, only one person or one appliance can be calling for hot water, or everyone gets a lot of luke warm water.



With having said all that, I will say that when I had one, I LOVED it, because I had a virtual endless supply of hot water, so long as I was the only one using it. The biggest problem was, that my tee aged daughter also discovered the endless stream of hot water, so my fuel consumption only dropped 10% versus the tank type heater.



Then, I replaced that unit with a reverse indirect, coupled to a 80K btuH modcon boiler, and my fuel consumption dropped to 30% of the previous tank type heater. I have the same limitations as it pertains to compounded loading, but the whole family is aware of that, and works around it nicely.



So, as long as all occupants are aware of the limitations, and don't increase their shower times you can expect a net savings of around 20 to 30%. Just don't be oversold on its capacity, and don't try and use it as a space heating appliance unless is it specifically designed for that purpose and you should get along just fine.



To each, is own. For me, mod con and reverse indirects are where it's at.



HTH



ME

gerry gill

The savings will also only be

on the PORTION of the gas bill that pertains to domestic water heater production, not the entire gas bill..that portion is usually very small to start with in the northern states..just wanted to clarify that as when people hear of 10 % savings or more they think of the entire gas bill..

EricAune

I agree with Mark E.

.The majority of opinions expressed are negative, due to bad experiences.  This in my opinion is a result of improper application of a tankless water heater. 



Sizing the heater (any heater) for the demand is imperative to its performance and the owners overall satisfaction.  Flow rates of different faucets installed throughout the same home are often overlooked, as are water consuming appliances such as dishwashers and clothes washers.



Careful consideration of laundry habits and dishwashing have to be taken into account.  When do you do your laundry and how much?  The same for washing dishes....How often do you take a shower/bath and does this occur at the same time as your laundry usage?  Does everyone hop in a shower at the same time or is your schedule staggered?



These are questions that are not significant only to tankless water heaters; they should be asked about a tank type too if proper sizing of storage/recovery is desired.



I have installed Rinnai and Navien.  Only about a dozen of each.  In all cases the owners have been satisfied with their performance initially and throughout time.  Some installations called for two units rather than just one, this was easy to figure after accessing the owners usage and demand. 



IMOP, I like the Rinnai product....hate the venting.  Switched to the Navien because of the standard PVC venting and have become partial to the buffer tank and its abitlity to eliminate sandwiching.

TonyS

I installed a Navien

in my own home 1 year and 4 months ago. It has performed flawlessly. It operates at 98% efficiency, making just the amount of hot water you need at exactly the temperature you desire only at the time you want it, Go away for ten years and come home home......you didn't use one cent of gas. Maybe you could get the other 2 percent of heat if you really tried. Maybe you could use an atomic reactor and split the gas atoms to obtain more heat. As far as cleaning the units once a year if you have hard water...that's a plus, that you actually have the ability to do it. Tank type water heaters may not be susceptible to pressure drop in hard water conditions but you can bet their efficiency is just slowly dropping away with basically no way to clean them out. 2 inches of concrete on the bottom of a water heater does not improve efficiency. Check stack temperature on a tank type water heater after a couple years in hard water. I don't know about 40 or 50% percent savings, that's all a bunch a crap, totally dependent on how you make hot water now and how big your family is. But I do know there is no better way to make hot water.

EricAune

Tony

"But I do know there is no better way to make hot water."



Three words, Solar.

HDE_2

Mark

"They also don't mention that in some cases, only one person or one appliance can be calling for hot water, or everyone gets a lot of luke warm water."

ME,

Not too bad of a take on tankless with exception to your one comment above and it happens to be the most misunderstood misconception.

With exception to the units 8-12 years ago and a few still available that start with a B in the home stores, all quality units don't work that way.

Inside the units are water control valves that regulate flow to control output at a preset temp desired with a given temp rise. The purpose of that valve is to regulate flow to give near outlet set point temp. So, you cant overdraw a quality tankless and get luke warm water, it just cuts back flow which is felt as reduced pressure and volume but the temp is still at near set point.

All fixtures share the output that it is capable of at the given temp setting/temp rise/BTU input.

It's not too hard to properly install a tankless with a heat exchanger for heating or combi and if done right hitting temps or concerns of condensation wont be the problem, however the reality of the efficiency and life expectnancy are a whole different issue. My take is perhaps a small rec room or such that needs some auxillary heat but not as the main source.

Mark Eatherton

Hence, my use of the term...

SOME cases....To their credit, tankless water heaters have come a LONG way since the days of old, when you had to light the pilot before you could use it. Much more intelligent control logics. More efficient heat exchangers. More intelligent CONSUMERS. Education of the consumer is key and important to success. I think everyone posting on this thread will agree with that statement...Bottom line, tankless is not for every one, and reverse indirects with mod cons are not for everyone. Each has its time and place. Just make certain that the application is appropriate for the setting.ME

TonyS

Yes Eric, I meant

with gas. I agree with you on solar. I have 2-20 tube panels on a drainback for over a year now.I have to say I have been really impressed.

EricAune

Getting away from the original question a bit, but

Mark,



"Bottom line, tankless is not for every one, and reverse indirects with

mod cons are not for everyone. Each has its time and place. Just make

certain that the application is appropriate for the setting.ME"



This is exactly what I have been trying to tell other contractors in my area.  Some seem to pin fault on the appliance (in some cases, make/models this might be right.  see Home Depot above) but the real fault is probably due the salesman/installer.



Every appliance, method, idea or concept has its limitations.



Dan,  



In my opinion, look at the hot water demand, flow characteristics of the faucets and the incoming temperatures vs. the setpoint temp. needed at the faucets.  Take that info and compare the performance of any units that are available in your area.  This is definitely a case of "you get what you pay for" as this is a hot market for energy saving devices and the appliances with like features will most likely have like pricing.



Home Depot Employee,



Point well said.  Thermostatic sensing is a requirement in my book, not flow sensing as this can easily be fooled by low flow faucets/applications.

mjcromp

Thanks!

I appreciate people actually telling their stories, some good and some bad but this is good progress!

Now on many points I agree Tankless may not be for everyone.

a customer must be aware of the things that make "special"

In my area water quality is not a problem. We have awesome water here.

Now non-skilled people installing them is a problem sometimes.

I always tell a customer during the estimate process "you will get endless hot water but just not with every appliance in the house running". Here with a Rinnai a customer can run 2 showers at the same time and no problems. Some situations we install a 4 gallon electric tank to combat the "cold Water sandwich"

Thanks again for your honest thoughts not just numbers!

Unknown

mjcromp

ME says "Then there are the WILD claims made by the manufacturer as it pertains

to the gallons per hour of hot water produced. THe problem is, they

don't have to use a particular "temperature rise", so you get some

manufacturers making what appears to be exorbitant claims"



This is what I was trying to get-at!

HDE_2

Actually

I believe all manufacturers are very honest with their temp rise/GPM flow rate published that I am aware of. 

 You just need to look past the sales lit that tends to promote best performance and go right to specifications where you will find most published in 5 degree temp rise increments usually starting at 35 right up to 75 or 80 degrees Fahrenheit.

Mark Eatherton

Why not one standard???

And this standard doesn't just apply to tankless water heaters, but should also apply to indirect and reverse indirect water heaters as well. How about one standard against which to compare these technologies, and a set of parameters under which these standards are compared?



Let's pick a "middle of the road, happy medium", against which all tankless, and indirect and reverse indirect manufacturers must state their operating efficiencies and hourly capabilities.



Let's say a flow rate of 5 GPM for everyone. Lets say a thermal input of 100K btuH.



For indirects and reverse indirects, lets say 5 GPM flow rate with an entering water temperature of 50 (potable) and 160 (boiler) water.



This would then break down to a net instantaneous % efficiency number, and an hourly gallon capacity that the consumer could then sit down and do a direct and fair comparison on. WITHOUT having to delve into the O&M manuals, and burn up a lot of grey matter trying to do an apples to apples comparison.



I know I am leaving something out of the big picture, but I think you get my drift.



Our government SHOULD be taking the initiative to require this, but where to start?



THAT is what I am talking about :-)



ME

mjcromp

Take that

one step further (I realize it's just a sales pitch and needs to be almost like a MPG rating for a car but...) and lets say Boiler A has a 98% efficiency rating but boiler B has a 97% efficiency rating. Now manufacturers won't tell you that that is under certain conditions not just 100% of the time it will be that way. Buy a new t.v. and they will say it's the sharpest picture. then you get home and find out it's grainy because they want you to have a HD signal to it............ and on and on.  I would love it if in this world we could come up with some kind of standardization but this world is far from perfect and so "it is what it is!" (dang I've been hearing that a lot lately)

As backwards as it is you need to check the fine print as with anything else you do.

If you want a quality piece of equipment, do your homework.

If you want a quality job, do your homework.

Sorry for being all hmm like I was being before. As you can see this is a sore spot with me. I believe the biggest problem with Tankless are they are misunderstood.

M.E. and Dave Thanks for being nice while I ranted.

Larry Weingarten

About Marks' thoughts...

Some good people in ASHRAE are working on your idea right now!  I believe it would supersede Energy Factor as a better real world measure, taking all energy usage and different habits of use into account.  I really don't have any idea when this work will be done, but at least you can rest better!



One of my personal hobby horses is the concept of life cycle cost, which should be at the heart of the original question here.  What good is a more energy efficient appliance if you must spend all your savings and more with higher installation and maintenance costs?  Why bother spending those dollars on an efficient piece of equipment when the system you feed the hot water into is uninsulated and oversized?  How about the wasteful fixtures?  As Dan has advocated for years with steam, get out of the boiler room and look at the entire system.  Just as Affordable Comfort has been pushing house as a system, for its energy and environmental benefits, we in the trades could do a lot of good by thinking and teaching life cycle cost to our clients.  It's a slightly different perspective. There. I'll jump down off that particular hobby horse!



Yours,  Larry

Bob1111

Tankless Efficiency / Smoke & Mirrors

The major issues I have with tankless heater efficiencies are that these companies use the term energy efficiency as if it somehow covers the full range of energy efficiency for the entire heating industry.  The fact is, under any top tier standard such as those published by GAMA or CSA, these tankless heaters for the most part are not very efficiency at all.  Secondly, they would have you believe that a traditional tank type heater is somehow non-efficient due to storing a volume of hot water.  The fact is, tank type heaters lose only a few cents per day in energy when built to the current standards.  

 

When you consider the cost of installing a tankless heater including the cost of the heater ($900 - $1,200), increased gas line size, new vent system and increased maintenance, you could install and operate a traditional tank type heater many times over for the life of any home. 

HDE_2

Times Change

Deja Vu

I remember all these objections to 90% + furnaces 30 years ago, then the same with 90%+ boilers 10 years ago.

With about 3-4 years to go will tankless be as widely accepted and part of the norm? Probably

Ponder this-

50 plumbing and heating professionals in a room, you could almost split the room in half, one side being pro-tankless, the other side being skeptical opponents.

How would I take a stab at separating them? By age.

EricAune

Age, probably

Hopefully not though.  I would like to think that there wouldn't be a pro/con crowd and that each would chose based on the application and the ability of each method.



Maybe this is where we will be in 3-4 years?......it shouldn't take that long.

gtrotta

Consumer Reports on tankless water heaters

We actually tested tankless water heaters and are in the process of testing solar water heaters. Stories can be read here.



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

http://blogs.consumerreports.org/home/2009/10/best-solar-water-heaters-eagle-sun-sunmaxx-hot2o-rheem-american-solar-energy-society.html



That said, we were recently on vacation at a B&B in New Hampshire where the owner had several Rinnai echeloned to provide water to the rooms. I asked him if he had any problems with maintenance, and he said:



"Nope! We're on the same aquifer that Poland Spring takes its water from!"



All best,

Mark Eatherton

Interesting reading....

However, if everyone on the face of this Earth based thier decisions purely on economics, NO conservation efforts of ay significance would ever get done.



Like solar, I think people do it because it is the "Right Thing" to do. That and the convenience of never running out of hot water again are appealing, but in some cases (teen aged chillun's) it MAY end up costing the consumer MORE energy due to the endless stream of hot water...



I would love to see a direct comparison of a reverse indirect coupled to a mod con boiler, compared to a conventional tank type heater...



Interesting stuff just the same.



Thanks for sharing.



You said "We actually tested". You work for the org. that did the testing?



ME

Paul Pollets

Tankless comments

I've enjoyed this thread and wish comparative testing and analysis was common in the US. Not to be. Same with mod-cons. On a certified bench test, we'd see the truth, not smoke and mirrors.

We get several calls per week from customers using tankless heaters with problems. The problems are: 1.They run out of HW whenever the 2nd person uses the HW. 2. The radiant heating system is using the same heater and they run out of HW. 3. The HW is lukewarm during heating season. 

The solution of these problems always results in significant cost.  It's disappointing to see so many heating contractors put in what doesn't work. I'm not condemning the tankless heaters for what they do. I will say they are a very poor choice as a heating source.  

Jean-David Beyer

What's a reverse-indirect hot water heater?

I know what an indirect--fired hot water heater is. I even have one on my mod|con boiler.



But I do not know what a reverse-indirect one would be. What is the difference between them and what might be the relative advantages of each?

Devan

Reverse indirect

Is using the inner coil of the tank for DHW, and have it surrounded by the boiler water. Reversed of how it's usually piped.One advantage is now having a larger buffer for the boiler, thereby less cycling of boiler and longer run times. Making boiler more efficient. Downside is no longer having a stored volume of water.

Jean-David Beyer

Let's see if I understand you.

It seems that a Utica Hot Line (domestic tank with a coil of boiler water inside it) is one we agree is a (normal) indirect hot water heater.

It seems that an Ergomax (tank with boiler hot water in it and a coil to

deliver domestic hot water) would be a reverse indirect hot water heater?



But which would my Weil McLain Ultra Plus indirect hot water heater (domestic tank inside an outer tank with boiler hot water in it) be? The inner tank holds about 38 gallons and the surrounding water jacket with the boiler water in it holds only 6 gallons.



I think that the distinction may not really matter all that much; it is a question of how much water is used to store the heat, and where it is stored. If the stored volume in three heaters is the same, and they are properly insulated, it may not matter even in theory. I do not suppose it really matters much in practice at this point, since mine is only 6 months old and working fine.