Tankless hot water heaters

[Big Country]

A friend at work mentioned these to me the other day. So I go to the big store and see they have one for the whole house that is electric. I hear the idea is like this, you only heat the water as you turn on the faucet (instant electric heat) and thus save money in the long run because of not heating then cooling then reheating. I also have issues of when someone is in the shower you can't turn any other hot water fixture on as the shower person get's a shot of freezing water. Anyone out there ever use the instant, tankless heaters? I am looking for opinions as we may go that route next year. Thanks! BC

[CAMAN]

Tankless water heaters are great, never used an electric one but can't be too much different than gas.

It isn't going to get rid of the cold shot of water you experience, that is caused by the length of run. I'm going to guess that the shower line is one of the longest/highest in the house? Water takes the path of least resistance, so when the faucet is opened on a shorter/lower line it will take that instead.

Just so you know, you get a pretty dang good energy tax rebate for installing one, so you may want to install it this year. I would recommend going through your local energy company and see what their prices are. Most of the time they are better units than the ones sold in the bigbox stores, and will last longer and hopefully cause less problems.

[Redlantern]

Big Country, you must have an older shower valve? Current code calls for what is called an anti-scald or pressure balanced valve. If someone flushes the toilet, you will get a reduced flow out of the valve but not a shot of hot water. Same goes for if someone is using hot water somewhere else in the house.

[krinkle]

A decent tankless water heater will give a reduction in the amount of water it lets threw rather than let cold water threw. This is how it is supposed to work.

If you are looking at cost savings look at the energy ratings on the heaters. There should be a year cost prediction on any of them. Makes it pretty easy to do a side by side with any type of tankless or even to solar or conventional tank heaters.

I would look carefully at who you by the heater from. There are a lot of components to them and you want to make sure your supplier will offer support for it. Last thing you need is to have your supplier say yes its under warranty just take the part out, send it in and we will send you a new one in a few weeks. Or pull the unit out and send it to the manufacture. Those are great warranties.

You will also want to make sure who ever puts it in is very knowledgeable about what they are doing. Yea, anyone can slap one in but there is a lot more to it. Is you well pressure properly cycling so that the heater can keep up with it? Is your water conditioned well enough to not calcium up the heater. Are you pipes properly sized and insulated in order to eliminate delays in getting hot water at the fixture. Is the heater sized to meet your household needs. In our cold climate sometimes it may take more than one heater to meet the needs. Are there issues with you current piping that may need to be updated to get the new heater to work at its best.

I installed a Navien gas tankless in my house last summer. The install at my house was pretty simple and about 3/4 of a day. It included adjusting the well pressure tank, installing a pressure reducing valve before the heater, adjusting a hot water pipe size and adding some insulation to the hot water pipes. I have done estimates as high as 9k that include new softeners, well tanks, re piping of water lines, and adding recirculating lines, updating gas services and gas lines.

Make sure who ever you are dealing with on this knows what they are doing or you will have a expensive heater that does not work well. Talk to the people they have installed for to double check because most plumber I know will say no problem, I can put that in. The reason I installed one in my own house was to get very familiar with them before ever thinking about selling one to my customers.

[swamptiger]

I don't have one, but I've read about them, and the general consensus is that most of them won't save you any money unless you can get some rebates or special electric rates for using them. There are also what is called "point of use" tankless heaters. These are installed near the kitchen sink, shower stall, etc. - close to where you will actually be using the water so it reduces the length of the run.

You might want to take a look at some of the higher end storage water heaters like the Marathon. These are well insulated units that have very little heat loss. Some of the utilities offer a reduced off-peak rate if you install a large unit and meter it seperately so you are heating the water in the off-peak time.

I am doing some upgrades in my house, and I have a hot water boiler, so I decided the best option for me is to go with a modulating boiler and an indirect fired water heating tank for domestic water. That way I can take advantage of the efficiency of the boiler to heat my domestic water.

[fishinchicks]

We love our tankless gas hot water heater. We have three daughters, and all like to shower in the mornings. Our family of five can all shower, and I can run the dishwasher and washing machine and not run out of hot water.

I would recommend insulating the water lines, especially on the longer runs.

[backlash 1]

In my opinion, they are a complete waste of money. Look at the energy guides compared to a normal heater. Plus the initial cost plus installation. You are never going to recover your investment. Pull the front cover off of one and look at it, looks real similar to under the dash of a 747, more boards than you can shake a stick at. I guarentee you this will need service down the road, and your $100. hr plumber will be standing there on hold for 45 min waiting in line to talk to a tech at the factory, and then the wait for parts to be sent to you.

Also, some of the box store gas tankless heaters are only warrenteed for up to 20 below 0. Well guess what, a few weeks ago it got to -30 here and I know of one that froze and broke spraying water all over. It happened to 3 others in Minnesota that I heard of.

Better to train your family members to take a normal length shower.

[kstruck]

Just to throw in my two cents...

I have a buddy who lives in northern MN and he also looked at going the tankless route, however he was told by someone that in his particular situation that the water coming up from the well was initially too cold for the heater to adequately heat the water to a useable temperature for the volume he would need. Apparently this might not be an issue in a city where maybe the temp of the water is a little bit higher.

[krinkle]

Mn water is not to cold for a tankless heater. It will just limit the amount of hot water that the heater is able to produce. A heater installed in warmer climates may be able to produce upwards of 10 GPM of 120 degree water. That same heater here in MN in the middle of winter may only produce 6GPM. The heater needs to be sized and matched to its intended use.

Even with tankless heaters being some of the most efficient heaters on the market they may not be the cheapest to install and run. Just like hybrid cars are the most fuel efficient to run but are not the cheapest to buy.

[Big Country]

Wow. A variety of responses. Good. That is what I needed. Thanks to all who put their two cents in. We are putting in an outdoor wood boiler this summer and I will also be looking into heating water with that. I will need to determine which route will work best for our family. The house is old, 1954. All of the plumbing is mostly original. I know down the line we need to convert, but until summer these are just options to look at. The electric tankless I was looking at had said that calcium build up is not a problem as the water flows through to quick to build. But then again, we do have a well and live in the country. A water softener system is something that I don't want. Our water tastes excellent and I am not a fan of the softener taste. Any of you that responded positively about owning one use well water? BC

[spearchucker]

I don't know how you can go without a softener for washing clothes, showering, and dishes. You don't have to drink it. I have separate hard water faucets for drinking.

[swamptiger]

Quote:

Even with tankless heaters being some of the most efficient heaters on the market they may not be the cheapest to install and run. Just like hybrid cars are the most fuel efficient to run but are not the cheapest to buy.

I think the "hybrid car" is a good comparison - this is a high tech piece of equipment, and I for sure wouldn't buy one if I didn't have softened water...

[BobT]

Just to throw in my two cents...

I have a buddy who lives in northern MN and he also looked at going the tankless route, however he was told by someone that in his particular situation that the water coming up from the well was initially too cold for the heater to adequately heat the water to a useable temperature for the volume he would need. Apparently this might not be an issue in a city where maybe the temp of the water is a little bit higher.

Tankless water heaters come in all sizes and flow rates so this should be able to be overcome.

I looked into it when our last water heater failed and I found it didn't pencil out. I chose to install a Marathon and take advantage of our power company's off-peak electric program. The water heater is poly and will never rust, guaranteed for life not to crack, and is very efficient. The monthly cost to heat our water went from about $35.00 down to about $10.00. The operating cost difference between using the Marathon this way and the tankless water heater wouldn't pay for the tankless in my life time.

[MARINERMAGNUM]

This is something I have recently upgraded to so I can tell you some facts.

The cost savings on operation are dependent on your rates-which vary greatly. Our electric company has pretty steep rates. We run alot of laundry and alot of hot water. Luckily,we are in the country so we use propane-a traded commodity. It goes up,it goes down,we contract an amount every fall for a set price-electric rates never go down,only up. Last year it cost $1500 to heat the house,this year it will cost $800-but the electric bills stayed the same . We averaged about 1800 KW hours a month,then we got rid of the electric clothes dryer-bam!,saved $45 a month. Most dryers,water heaters,and ovens are gonna pull around 4500 watts each-that's alot of juice. Anything with a 50-60 amp breaker is gonna cost you. Last month we got a new gas range and got rid of the electric,also last month a nationwide retailer was selling Paloma/Rheem tankless units for $520 which is about half price. This was enough for me to try one,and I can tell you now it was the best money I've ever spent. I installed mine myself and used the best stuff I could find-CSST,stainless venting,etc. All in all I got about $800 total in it. As you can see,I have a 105 gallon Marathon also,and no matter what anyone tells you,they are a juice hog if you run lots of gallons a day. 4500 watts is 4500 watts-if that sucker is cycling,it's costing you money.

After installing it,I turned on both showers and 4 hot water faucets and they were all rippin hot. The things need to be sized proper to work proper-get the biggest one they make and you can't go wrong. The bigger ones just decrease the burner and use less gas when only 1 faucet is running anyway-so it's a wash.

I plumbed around the marathon with valves so if something went wrong with the tankless,I still have the electric for backup. [not sure whether I should drain it or not?]

Like I said we used to run about 1800KW a month. Now? about 900-and we are living exactly the same. Replacing those 3 electric major appliances took the elect. bill from $180/mo down to about $80-$95/mo. So yes,it will pay for itself-in about 10 months to a year. We've penciled out the propane averages and it was beyond a no brainer.

This won't make a big difference if you live alone or it's just you and the wife,or if you're older,but if you run a ton of hot water like we do,and you're electric rates are high,it will save you money-we're living proof. Man did it feel good to shut that breaker off!!

The love of my life........

[The_Duckslayer]

To drain or not to drain... If you leave it full the water wil rust and turn brackish. Drain it and it might rust and then make the water red when you re-fill it. If the marathon is that well insulated could you run the output of the tankless heater into the marathon? Not sure how that would work if the marathon were not turned on at all... how cold would the water get and how long would you have to let the water run through it to warm it back up. That would only work out well if you had constant use maybe... I dunno just a thought that went through the old noggen. Take care and N Joy the Hunt././Jimbo

[MARINERMAGNUM]

The marathon is all plastic,so nothing would rust. It is well insulated. We got it they year we had the big ice storm and it was without power for 3 days and the water in it was still quite warm. I don't think it would be practical to use it as a reservoir. The hot from the tankless would mix with water in the tank and end up luke warm. I was concerned about mold forming in the tank,so I didn't know if it should be drained,or left full for storage.

[icerube]

Thats a great idea!!!!! The marathon would have to run a little because you would get a shot of cold water into it every time you called for hot water.

[BobT]

It doesn't matter what the wattage of the heaters are in the tank or the tankless. What does matter is the amount of water you need to heat over a given time period.

If you still use the same amount of hot water in a given day, then you require the same amount of power to heat it from ground temperature.

The only thing you save between using tankless vs stored is the heat loss from the system. There is no such thing as a perfect insulator that human kind is aware of. Therefore, the water in your stored tank will lose some heat and so you need to reheat the water to get it back up to your setpoint.

Heating water using electric heat is 100% efficient. That is, all the heat energy generated is transferred to the water. It takes a constant BTU/hour of heat to accomplish this task and it doesn't matter whether your heaters output 450w, 4500, watts or 45,000 watts. The only difference will be in the time it takes to heat the water up to your setpoint.

In a tankless system you are not storing hot water but you still have to heat the water from ground temperature. Remember, it takes the same BTU/hour to accomplish this task. The only savings between the two comes from not having to pay for the heat loss during storage.

Heat loss is only a factor to consider if you don't use much hot water and you have an over-sized storage tank. If you use a lot of hot water and you tank is not larger than necessary then you won't realize any significant cost savings by using tankless.

If you using your tankless water heater to heat the water for your Marathon, you aren't saving a dime in heating cost and in fact you spent a lot of money to install it for nothing.

Edit:

One thing I forgot to mention. If your water heater circuit is using a 50-60 amp circuit breaker I'd have it looked at. A 4500w load only requires a 30A circuit. If your water heater was wired professionally it was most likely done using 10awg wire and a 50 or 60 amp breaker is way over the rating of the wire. In other words, in the event of a short circuit your house would likely be on fire before that breaker would trip.

[swamptiger]

Quote:

Thats a great idea!!!!! The marathon would have to run a little because you would get a shot of cold water into it every time you called for hot water.

A better way to do it would be to use the Marathon for a tempering tank in the off-heating season. Run the cold well water into the tank first to allow it to warm up some before it hits the tankless unit. You wouldn't gain anything in the heating season this way, however, because it would be taking the heat out of the air in the house, so you would be paying for it anyway. Probably really not a very effective tempering tank either, because it is a very well insulated tank, so the gain would be minimal.

[MARINERMAGNUM]

Quote:

A 4500w load only requires a 30A circuit.

Correct,but in case you didn't know,most elect. water heaters have dual 4500 watt elements one at the top and one at the bottom-thats 9000 watts churning if you run it out completely,thus you need the heavier breaker when they both kick in. So Bob,if your marathon has 2 4500w elements and it's on a 30 amp breaker,you should have your's looked at. Mine is wired with #6awg copper.

BobT,the common denominator you are forgetting is the cost of a KW hour vs the cost of a gallon of propane.

"If you using your tankless water heater to heat the water for your Marathon, you aren't saving a dime in heating cost and in fact you spent a lot of money to install it for nothing."

I'm not doing what you describe,I think you got confused.

"Heating water using electric heat is 100% efficient."

I would say this depends on the wiring,a longer run and undersized wire will create more draw thus killing efficiency.

"If you use a lot of hot water and you tank is not larger than necessary then you won't realize any significant cost savings by using tankless."

I would argue this point but the more important aspect of it is,if you use alot of hot water and your tank is not too big-you're gonna run out of hot water pretty darn fast!

"The only savings between the two comes from not having to pay for the heat loss during storage.

This is not quite accurate. You're not considering the savings of using propane over electric when the rates favor propane.

Like I said earlier,it all boils down to how much continuous demand you have for hot water and what your utility rates are for gas vs electric. If you have an older couple who don't do much laundry,no kids,and only shower every couple days,forget it,it won't make a difference. That 105 gallon marathon would run out on us almost daily-then you have to wait.

There is a reason behind why tankless has been used in Europe for 40-50 years.

[backlash 1]

Marine mag

I see how much you saved on your electric bill, but I must be missing something, i'm not seeing how much it now costs you to operate the tankless, dryer, and range with propane.

Typically I believe propane has the highest cost, next to elec and nat gas.

[swamptiger]

Quote:

Typically I believe propane has the highest cost, next to elec and nat gas.

In the area I live, electricity is the most expensive, followed by propane, and natural gas is significantly less expensive than either electric or propane. NG is only available in certain areas, however. And again, when you are doing comparisons between propane and electric, you need to take into consideration there are special programs available for off-peak heating, dual-fuel, etc., from the electric companies.

It sounds like in MM's case, he may have been using more water than he could store at the off-peak rate, so he was paying the regular electric rate at least part of the time, so in that instance the LP would be less expensive - at least where I live.

[MARINERMAGNUM]

Quote:

Typically I believe propane has the highest cost, next to elec and nat gas.

I guess I'm not getting through.

As I've stated many,many times,it all depends on the given rate for each type of energy.

I am on one power company,and some that live only 2 miles from me are on another company's electric. Their KW/hr rate is 4 cents per kw/hr cheaper than our rate,doesn't seem like a big difference eh? Well,it is when you use 1500-2000 kw/hrs a month. Rates for each unit of energy vary to the extremes. I know some who pay 19 cents per kw/hr and I know some 35 miles away who pay 6 cents. Same for nat gas rates,and propane as well. Example:we contracted propane for $1.07/gal. I know some who are paying $1.50,$1.01,$1.80.

As for how much gas the propane appl. use,it's hard to explain,but if you've been in a routine for years like us,you know when you're going to need some gas put in the tank. The gauges run on a percent dial. I always have exactly 300 gallons put into our 500 gallon tank. [400 is max because they can only fill them to 80 percent] so I can keep better tabs on it.

Kinda hard to explain but we are getting the same amount as usual,put in at the same time as usual,so we don't even feel it.

Lol,when we thought our elect. bill was too high,the co. sent out an energy advisor. While he was here,I asked him about how much that elect clothes dryer was eating,to which he replied "they're not bad at all" Later,upon the advise of a neighbor who went thru the same ordeal,we replaced the dryer with the gas unit. Our meter socket is digital,and the company gets the usage piped into their computers direct,so no more meter readers. Anyway,a couple months after installing the gas dryer the co. sent out a dude who snooped around the barn,machine shed,and finally came to the house and asked my wife if we had "tampered" with anything. She asked,why?,he said that our kw/hr usage had dropped dramatically and they wanted to know the reason for it. I called the lying energy advisor and throughly chewed him out.

On a side note,you can ask any plumber,electric water heaters have the slowest recovery time of any type of water heater-no matter how efficient they are.

I'll re-iterate one more time,you need to evaluate your elec.,gas/propane btu/hr,kw/hr costs and pencil it out for your own location and your own rates,and figure in your usage requirements.

A decision like this is totally regional and dependent on all the above factors. What are your rates? Can you get a good price on a tankless?,Can you install it yourself and do it right? Is it practical for your usage? There are many specific questions that have different answers for different families.

What saves me money might cost someone else more who lives only 10 miles from me.

[MARINERMAGNUM]

Quote:

In the area I live, electricity is the most expensive, followed by propane, and natural gas is significantly less expensive than either electric or propane. NG is only available in certain areas, however.

Ditto here. This is exactly what I mean-it really,really varies.

Our elect. co. has it set up where the 1st 800kw per month is really pricey,and any usage over 800 the price drops 2 cents a kw/hr. [big whoop] They know everyone will use 800,so they nail them on that.

If they were really concerned about conservation as they claim to be,the deal would be reversed so when you got to using too much it gets more costly making you slow down and conserve-not cheaper.

[swamptiger]

Quote:

What saves me money might cost someone else more who lives only 10 miles from me.

That's true - prices for the various fuels differ dramatically depending on your location.

One thing that is seldom mentioned about electricity is the generating and transmission losses - they can amount to a large percentage of the price of a kilowatt. If you live in a sparcely populated area, electric rates are typically quite high - I think I've read 40-50% transmission losses from the generating plant to the outlet aren't uncommon in rural sparcely populated areas, so the "100% efficiency" of electricity is sort of a misnomer and only applies from the outlet to your appliance - assuming it is working correctly...