Tankless Water heaters, yeah or nah?

[joseywales]

We have natural gas and a contractor wants to replace out 50 gallon water heater with a Navien tankless unit. $800 total cost more than a traditional heater. I'm not concerned about the $800, more the wife and two teen girls I live with. We've never run out of hot water with a 50 gallon tank, but I have no experience with a tankless unit.

If electric goes out, does a NG water heater still provide hot water?

How well do these tankless unit handle hard water?

Thoughts?

 

[Sixfeet4]

I’ve had one for 5 years with no issues. Only drawback is its not instant on hot water. You have to run the hot for a bit for it to warm up and the farther away you are from the heater, the longer it takes. Is annoying at my kitchen sink.

 

[dw1]

We have natural gas and a contractor wants to replace out 50 gallon water heater with a Navien tankless unit. $800 total cost more than a traditional heater. I'm not concerned about the $800, more the wife and two teen girls I live with. We've never run out of hot water with a 50 gallon tank, but I have no experience with a tankless unit.

If electric goes out, does a NG water heater still provide hot water? YES

How well do these tankless unit handle hard water?

Thoughts?

Not sure about hard water? could you put a filter inline with the water supply to the WH? I just put a tankless water heater in my barn bathroom, after a few minor adjustments it is working very well. I don't have natural gas in my barn so I had to go electric, but you are not paying to heat up a 50 gallon tank of water so that should save a few $$ and definitely be more efficient, doesn't matter if you have 2 teen girls or 10, they all would have hot water. Once it senses water flow, it starts heating. Any rebates from your utilty company for installing one of these?

 

[pepi]

Read the install requirement for them...... they appear to be energy hogs in spite of the hype. The gas line will be increased to something like 1 inch. I was contemplating the switch, decided it was not for me.

Think about how it works, your current heater, maintains a water temp. The tank less sits, water becomes room temp.

You want hot water, it ignites the burner like a rocket motor, bring the water to temp, and continues. To fulfill the demand at the moment.

After all the tank less has no storage or volume. How much water do they hold in reserve?

Think multi- hot water request and a rocket motor as a heat source, how will that be energy cost effective?

That cycle is repeated with every hot water demand...

The theory that 50 gal of water cost more to heat is not completely accurate. That 50 gals does not drop to room temp, because of the volume. It is heated with short blast, where as the tank less, because of the low volume. Must run at full blast at every cycle, for as long as the hot water is in demand...

Greg

 

[joseywales]

Not sure about hard water? could you put a filter inline with the water supply to the WH? I just put a tankless water heater in my barn bathroom, after a few minor adjustments it is working very well. I don't have natural gas in my barn so I had to go electric, but you are not paying to heat up a 50 gallon tank of water so that should save a few $$ and definitely be more efficient, doesn't matter if you have 2 teen girls or 10, they all would have hot water. Once it senses water flow, it starts heating. Any rebates from your utilty company for installing one of these?

Thanks guys.

Yes, there will be rebates.

We household softener, but I still worry about it. My dishwasher and coffee maker still have white residue.

 

[joseywales]

Read the install requirement for them...... they appear to be energy hogs in spite of the hype. The gas line will be increased to something like 1 inch. I was contemplating the switch, decided it was not for me.

Think about how it works, your current heater, maintains a water temp. The tank less sits, water becomes room temp.

You want hot water, it ignites the burner like a rocket motor, bring the water to temp, and continues. To fulfill the demand at the moment.

After all the tank less has no storage or volume. How much water do they hold in reserve?

Think multi- hot water request and a rocket motor as a heat source, how will that be energy cost effective?

That cycle is repeated with every hot water demand...

Greg

Thanks Greg. I just had my gas line increased for a pool heater and I have something like 800K BTUs capacity. To be honest, I don't care if the energy costs are a push (the same). If the unit lasts and works as advertised, I save a decent amount of space with it, so we'll see.

Rocket motors? Well now I really want one!

 

[TTA89]

We are a little past 2 years with our Rheem. No issues for us and I would 100% do it again. It's just my wife and I so it made a lot of sense for us. We have a weekend house and travel pretty frequently so it seemed like a waste to have a water heater sitting idle heating water a lot of the time we weren't home.

Ours runs on propane and I haven't noticed a difference in our usage patterns but our electric bill went down $100 bucks a month. (80 Gallon was in place for some reason)

Rheem by MikeTTA89, on Flickr

As stated above, the faucets that are far from the heater need to draw all the cold water out before they get warm. Our master bath takes 30 seconds or so to get hot water as it's on the opposite side of the house. It's not a big deal to us but it might be for you.

We put a "Blue filter" and a water softener in at the same time and that fixed a lot of the hard water issues for us.

 

[PsRumors]

We have had two tankless water heaters in our home for the last 20 years and could not imagine going back to tanked. With 6 in the household it was not unusual on a school morning to run out of hot water. After the install, never out of hot water, even have a hot water spigot plumbed outside for the pressure water.

As for energy efficiency, we saw a significant decline in our LP usage, went from 350 gallons a year to 230.

Yes tankless are not instant on but neither are tanked. You have to wait for the hot water to get to the fixture but we saw no noticeable time difference between the tanked and tankless. The biggest thing is to make sure the heater is sized properly for what is trying to be accomplished, number / type of fixtures, quantity being used at the same time, etc.

Now, the new tankless water heaters I am not quite as impressed with due to the technology they've had to take on due to government regulations. Our's have standing pilot lights and a simple flow valve that senses water flow and opens the gas valve, very simple design and user repairable if you are willing (have had to replace one flow valve in 20 years). The new heaters require electricity as they are not allowed to have standing pilot lights, so if the power goes out no hot water unless your heater has a battery backup. My parents had one of these installed and it works, but I like simplicity.

I love the tankless water heaters but they can be expensive.

 

[jacks2000]

Read the install requirement for them...... they appear to be energy hogs in spite of the hype. The gas line will be increased to something like 1 inch. I was contemplating the switch, decided it was not for me.

Think about how it works, your current heater, maintains a water temp. The tank less sits, water becomes room temp.

You want hot water, it ignites the burner like a rocket motor, bring the water to temp, and continues. To fulfill the demand at the moment.

After all the tank less has no storage or volume. How much water do they hold in reserve?

Think multi- hot water request and a rocket motor as a heat source, how will that be energy cost effective?

That cycle is repeated with every hot water demand...

The theory that 50 gal of water cost more to heat is not completely accurate. That 50 gals does not drop to room temp, because of the volume. It is heated with short blast, where as the tank less, because of the low volume. Must run at full blast at every cycle, for as long as the hot water is in demand...

Greg

When we installed our Rheem tankless our gas usage went down by half. I installed it in June so there would be no other usage other than heating the water. Most tankless heaters have multi-stage burners so they only use the amount of energy necessary to satisfy the demand called for. If you stand by the heater you can hear the burner ramp up as additional faucets/shower/washer calls for more hot water.

 

[joseywales]

Ok. I 'm warming up the idea. We already wait about 30 seconds in the master bath anyway. The only faucet that really has on-demand hot water is our powder room, directly about the hot water heater. So the delay isn't much to be worried about.

My real concern is the loss of electric. No, it doesn't happen often. But I was wanting a battery backup for our sump pump anyway, so perhaps there's a tie in. Again, if we lose electric for a day or so, no big deal, but extended could be an issue. The last storm that hit us, our development all lost power. We are only tied to about 800 customers on the grid, so not much of a priority, even with a school tied into the mix.

 

[jacks2000]

Read the install requirement for them...... they appear to be energy hogs in spite of the hype. The gas line will be increased to something like 1 inch. I was contemplating the switch, decided it was not for me.

Think about how it works, your current heater, maintains a water temp. The tank less sits, water becomes room temp.

You want hot water, it ignites the burner like a rocket motor, bring the water to temp, and continues. To fulfill the demand at the moment.

After all the tank less has no storage or volume. How much water do they hold in reserve?

Think multi- hot water request and a rocket motor as a heat source, how will that be energy cost effective?

That cycle is repeated with every hot water demand...

The theory that 50 gal of water cost more to heat is not completely accurate. That 50 gals does not drop to room temp, because of the volume. It is heated with short blast, where as the tank less, because of the low volume. Must run at full blast at every cycle, for as long as the hot water is in demand...

Greg

When we installed our Rheem tankless our gas usage went down by half. I installed it in June so there would be no other usage other than heating the water. Most tankless heaters have multi-stage burners so they only use the amount of energy necessary to satisfy the demand called for. If you stand by the heater you can hear the burner ramp up as additional faucets/shower/washer calls for more hot water.

 

[TTA89]

My real concern is the loss of electric. No, it doesn't happen often. But I was wanting a battery backup for our sump pump anyway, so perhaps there's a tie in. Again, if we lose electric for a day or so, no big deal, but extended could be an issue. The last storm that hit us, our development all lost power. We are only tied to about 800 customers on the grid, so not much of a priority, even with a school tied into the mix.

What about your fridge and other things if you lost power now? If you think this is really an issue then buy a portable generator. They aren't that expensive...

 

[59 wagon man]

most of the tankless require a 110v outlet to plug into. the fan purges the boiler of any residual gas before it will start. in the past power outages during the hurricanes, we just run an extension cord to the heater and it works. just has a small squirrel cage type fan in it. there used to be a unit which had a water turbine to produce its own electric but I do not know if it is still made. Higher end models modulate the btu's depending on the water flow so gas consumption will vary

 

[joseywales]

What about your fridge and other things if you lost power now? If you think this is really an issue then buy a portable generator. They aren't that expensive...

Yeah, I've been pondering a generator for years. Actually bought a tri-fuel unit. I was planning on running it on NG, but it was a new unit that when delivered appeared used, so I returned it. They stopped making them and that was the last one.

As you point out, I'm not sure how much hot water really helps, if all other power is out. I can take a hot shower I guess, but everything else is down. I have gas heat, but no fan to move the heated air.

 

[scheu]

I have a Navien Tankless. Had it installed about 2 years ago, not one problem. Sixfeet4 is correct, you have to wait just a little at the far end on the run to get hot water. But it's never bothered me.
As far as power outage, I have a small generator and a transfer switch. Enough to run the tankless, furnace, sump pump, and a few lights.
If I was to do it over I would have had it installed when I built the house.

 

[joseywales]

I have a Navien Tankless. Had it installed about 2 years ago, not one problem. Sixfeet4 is correct, you have to wait just a little at the far end on the run to get hot water. But it's never bothered me.
As far as power outage, I have a small generator and a transfer switch. Enough to run the tankless, furnace, sump pump, and a few lights.
If I was to do it over I would have had it installed when I built the house.

Thanks. My guess is that's exactly what this plumber has in mind. Change out my sump pump, hook up battery backup, and tie it in to the water heater. I'm meeting him today, so we'll see.

 

[jives]

Don't the tankless units also need electricity to spark the gas on demand?

We have a Baxi Luna dual unit -- hydronic radiant floor heat and domestic hot water. It can be fickle at times, needing yearly adjustment so that it does not vent propane out the exhaust.

 

[yeldogt]

Question: What are you trying to do ? What's wrong with the current set up?

You are not gaining anything going with the tankless -- I find a high recovery 40g tank to be the best fit for a few people when the house has NG.

The tankless are great when you need endless hot water -- or don't have NG. Someone going from electric tank to tankless will love the savings ... but they would get a huge saving going to a gas tank unit (not as large)

They also can make sense for a house that's infrequently used that needs a big tank due to many people -- no stand by loss.

I'm building a new vacation house -- no NG. I'm not using a tankless. I use $15 bucks a month w/ HW/range/dryer. How much can you save ?

 

[joseywales]

Question: What are you trying to do ? What's wrong with the current set up?

You are not gaining anything going with the tankless -- I find a high recovery 40g tank to be the best fit for a few people when the house has NG.

The tankless are great when you need endless hot water -- or don't have NG. Someone going from electric tank to tankless will love the savings ... but they would get a huge saving going to a gas tank unit (not as large)

They also can make sense for a house that's infrequently used that needs a big tank due to many people -- no stand by loss.

I'm building a new vacation house -- no NG. I'm not using a tankless. I use $15 bucks a month w/ HW/range/dryer. How much can you save ?

This wasn't my idea, so I'll see what the plumber has to say about what the proposed gain is. I suggested replacing my 13 year old water heater, as part of a basement finishing project. Regardless of any energy savings, I was thinking maybe the plumber feels we could use the added space. This Navien unit looks like it will fit in a "nook" in our poured basement. If that's the case, I save the entire space of a water heater in the finished area of my basement. Big deal? Nah. But it would be a much cleaner look for that part of the room.

 

[ddawg16]

I did a lot of research into it when I was doing my 2-story addition.

A couple of factors determine if tankless is a 'reasonable' modification

1. Can the tankless be put in a central location thus making for a much shorter run of the hot water? This would give you a savings in water (of course, a hot water recirc system would also solve that problem)

2. Is your water usage just a short time in the morning and in the evening?

If yes to those 2, then 'maybe' tankless is the best way to go

Energy wise, you save very little to no energy. With modern tank units and a proper blanket, it would take a LONG time to save $800 in energy.

If you use hot water all day long.....no energy savings.

We have a 50 gal gas unit.....we have NEVER ran out of hot water...family of 5

So, unless you have issues with running out of hot water, you will never see the savings of $800 more.

One side note...frequently overlooked is the advantage of an emergency water supply. If for someone you loose your water for a day or two, you now have 50 gal of water ready for use.. Kinda hard to get that from a tankless.

 

[Dagny]

If you have lots of iron or or other things in your water don't do it.

 

[elvee]

There are strong opinions on both sides, for sure. I'm surprised your plumber is recommending it, as most of them seem to think tankless units are some kind of black magic voodoo.

I have a Rinnai that we put in our house during a renovation five years ago. The house already had a 1" gas supply line so there were no issues on the supply side. It allowed me to stick the heater in the attic and save a bunch of floor space. The savings on my gas bill were a bonus. You should service them once a year to descale the heat exchanger. That is a matter of hooking up a cheap sump pump and running vinegar through it for an hour. I did it for the first time ever last month, and it did make a difference in operation.

I put a Navien condensing unit on my rental property about a year ago, mostly for space savings. It is installed on the outside of the house, and gave me the room I needed to fit a stacker washer and dryer in the house. That unit was great because it was able to use the 1/2" service line that was already in place for the tank water heater - no service upgrade, and incredibly fast ramp up time. My tenants love it, and I haven't had any issues with it.

The new units do need power for the igniter. As someone else said, if your power goes out then use a battery backup or just run a cord from a generator. That is what I did a few weeks ago when Irma knocked our power out for a few days.

If you really want instant hot water, you can add a small (2.5gal) electric water heater and a circulator pump on a timer. This can be set up to run just when you have a lot of usage (morning showers, dinner time, etc). This approach gives you hot water as soon as you open the valve.

 

[Showkey]

Most people with NG hot water pay $7-$15 per month to run a conventional tank unit.
So this is no return on investment on $800 up charge never ever happens. Some on forum report $1000-$3000 install up charge when they need upsize NG pipe and meter etc.

Tank models rarely if ever need any service. Not true with tankless, they are better than a few years back but still far from trouble free.

Waiting for hot water in distant faucets is a real deal killer.
Descale and cleaning maintenance depends on water quality and can be required every 6 months.
Some do not agree but witha family water and sewer charges and fuel cost often go up with the added use.

I have an electric tankless ( yes not the same as NG) in a vacation home it works but has all the issues mentioned like very very very slow hot water to distant shower, cost a small fortune to run but its a vacation home so liveable, needed descale twice even with low use. Small foot print and instant hot on are good features vacation home.

 

[yeldogt]

This wasn't my idea, so I'll see what the plumber has to say about what the proposed gain is. I suggested replacing my 13 year old water heater, as part of a basement finishing project. Regardless of any energy savings, I was thinking maybe the plumber feels we could use the added space. This Navien unit looks like it will fit in a "nook" in our poured basement. If that's the case, I save the entire space of a water heater in the finished area of my basement. Big deal? Nah. But it would be a much cleaner look for that part of the room.

Remember -- we are heating water. The goal is hot water.

For most people using a house every day --- standby loss of of the 40/50 gallons of water sitting in the tank is not great .. and the 10-12% efficiency gain amounts to what? Even taking my whole gas bill in May (no heat -- no pool) I'm saving 2 or 3 dollars .. call it $5 = $60 a year.

I have two gas tankless at my beach house -- one for the outdoor shower and one for a master bedroom/bath addition. The outdoor shower is an obvious perfect use of a tankless -- it feeds just that shower ... sized just for that. The master bath -- it's in a side closet -- we had no space for the WH .. again it's about 5' away and sized for a single shower/ faucet. We don't use the place in the winter. The outdoor shower unit lasted 12 years with only one issue -- the master bath has been a bit of a pain at times... it's now about 10 years old.

If I had the space I would switch the master to a tank -- the outdoor shower is great with the tankless ....nothing else would work when 10 people need to shower coming back from the beach. The outdoor shower gets all the use.

I can only think of one issue I have ever had with a tank water heater. They are so simple -- and if properly plumbed in .. very easy to switch out. I buy the better Bradford White model with the larger burner/ faster recovery ....

I'm the same with boilers. In my new house I have to go with a condensing boiler -- due to size and location issues. But, my other places are simple atmospheric boilers. It takes a long time to make up 5-6k difference in price + the added cost of maintenance with more complicated equipment.

 

[ArmyVW_GuyInTX]

M

Tank models rarely if ever need any service. Not true with tankless, they are better than a few years back but still far from trouble free.

My tankless gas has been trouble free.

I installed my tankless Rheem 12 years ago - and have never had an issue. Zero issues. Plus the wife likes the "new" linen closet that/ seasonal closet in the hallway where the 50 gallon water used to be housed (older home- yes it was in the hallway). I'll never go with a tank style water heater.

During the summer months - all 9 of them, our gas bill is less than the minimum monthly charge to have gas service - including the gas clothes dryer.

I am not a plumber

 

[Randy in Maine]

I also have had zero issues with my propane fired tankless heater over about 10 years. I have good city water if that makes a difference.

In the interest of full disclosure my first one as a Rinnai that I sold to a friend about 5 years ago and it still going strong with no issues. I replaced it with a Baxi condensing boiler when I converted everything to radiant floor heat (and I needed the radiant loop).

I would never go back to a tank.

 

[yeldogt]

The OP is in PA and has NG .. I don't know if on a well. We have minerals in PA -- lots.

I guess it's just me ... don't see the upside for the OP. I'm all for variable speed HVAC equipment love having a modulating furnace -- both get you comfort. I put radiant heat in all my projects.

I just want to open my tap and get 125 degree water to come out with the least amount of fuss and cost.

 

[joseywales]

I did a lot of research into it when I was doing my 2-story addition.

A couple of factors determine if tankless is a 'reasonable' modification

1. Can the tankless be put in a central location thus making for a much shorter run of the hot water? This would give you a savings in water (of course, a hot water recirc system would also solve that problem)

2. Is your water usage just a short time in the morning and in the evening?

If yes to those 2, then 'maybe' tankless is the best way to go

Energy wise, you save very little to no energy. With modern tank units and a proper blanket, it would take a LONG time to save $800 in energy.

If you use hot water all day long.....no energy savings.

We have a 50 gal gas unit.....we have NEVER ran out of hot water...family of 5

So, unless you have issues with running out of hot water, you will never see the savings of $800 more.

One side note...frequently overlooked is the advantage of an emergency water supply. If for someone you loose your water for a day or two, you now have 50 gal of water ready for use.. Kinda hard to get that from a tankless.

Walking the basement, i think i'm looking more for disadvantage, rather than advantage. In other words, why not to do it. Here's the reason to do it and maybe it isn't enough

I found a spot, a nook if you will, at the bottom of our steps, opposite wall, where I can place the tankless water heater, my current water softener and the slat tub, and cover with bypass doors. By doing this, I "clean" up one wall a but, but I also open space in my other room, where an 8' pool table could now go without the previous challenges.

I hear you on the emergency water. I have 7,600 gallons at the ready, whenever I need it, maybe half that in the winter. I have an above ground pool and I ONLY treat it with bleach. If I need drinkable water, one or two days in the sun and it's better than your tap water!

 

[tdott]

Ran the numbers, didn't make sense for any of my houses so far.

 

[deljaso]

Do the tankless water heaters have "power vents"?
I have two water heaters that are power vented, and had to replace one of them a couple of years ago... I had no idea how much these things cost.
I am wondering if the tankless have the fan on them already and I can get one installed cheaper than a power vented tank water heater when my other one goes out.

 

[yeldogt]

Do the tankless water heaters have "power vents"?
I have two water heaters that are power vented, and had to replace one of them a couple of years ago... I had no idea how much these things cost.
I am wondering if the tankless have the fan on them already and I can get one installed cheaper than a power vented tank water heater when my other one goes out.

Two? Why two? what do you use for heat? Builders like the power vent because they are easy to install .. be glad you don't have two electric.

The power vents can be as expensive -- it's all a question of size and quality of each product

 

[alexb2000]

I have a Rinnai NG fired tankless. Hands down the best appliance I have ever bought. The wife takes baths in a big tub and the bitching about running out of water was endless until I installed the tankless.

The other thing to consider is if a bunch of people have to get ready at the same time, not an issue with tankless, but can easily be even with a big water heater.

I am even considering putting one in the fifth wheel, once you have one it is really hard to go back.

 

[deljaso]

Two? Why two? what do you use for heat? Builders like the power vent because they are easy to install .. be glad you don't have two electric.

The power vents can be as expensive -- it's all a question of size and quality of each product

I have two because my house has 8 bathrooms. One for each half of the house.
I was just wondering if the costs of a tankless vs. a power vent are comparable. I know when it goes out is not the time to comparison shop and wanted to get an idea before the next one floods my basement. My thought is that conventional vs. tankless might be a significant cost difference, but power vent "tank" vs tankless might be a much smaller $ gap.
When the last one went out, I went through a couple of plumbers before one knew where in my area to get a power vented model installed. And when that company installed it, the plumber didn't know how much it would cost - he said "I have no idea, you will get a bill in the mail".

 

[yeldogt]

I have two because my house has 8 bathrooms. One for each half of the house.
I was just wondering if the costs of a tankless vs. a power vent are comparable. I know when it goes out is not the time to comparison shop and wanted to get an idea before the next one floods my basement. My thought is that conventional vs. tankless might be a significant cost difference, but power vent "tank" vs tankless might be a much smaller $ gap.
When the last one went out, I went through a couple of plumbers before one knew where in my area to get a power vented model installed. And when that company installed it, the plumber didn't know how much it would cost - he said "I have no idea, you will get a bill in the mail".

Feel for you .. don't miss my big house !

 

[Showkey]

]

My thought is that conventional vs. tankless might be a significant cost difference, but power vent "tank" vs tankless might be a much smaller $ gap.
When the last one went out, I went through a couple of plumbers before one knew where in my area to get a power vented model installed. And when that company installed it, the plumber didn't know how much it would cost - he said "I have no idea, you will get a bill in the mail".

Tank power vents are ball park $600-900 depending size and brand.

Big ball park, Tankless rinnai brand can run $1200-$1800. Lesser brands $1000-$1500. But many report high cost for NG line upsize for large units.

Menards

 

[rsanter]

I love mine. Never going back
We have hard water in our area. Has not been a problem yet

Bob

 

[LS6 Tommy]

A natural gas water heater may not operate without electricity unless it has a standing pilot, which is not too common anymore with high efficiency water heaters.

Tommy

 

[Stuff]

In SW PA I find that tankless gas works fine in the summer but in the winter when groundwater temps dip there are problems. Showers are OK but wide open like filling the bathtub or the washing machine just gives lukewarm water.

 

[bruincounselor]

But many report high cost for NG line upsize for large units.

Why a larger line? I had my pressure upped for free. Love my tankless.

 

[yeldogt]

Why a larger line? I had my pressure upped for free. Love my tankless.

Problem if you have low pressure gas service -- many older areas use low pressure. Think my gas line is almost 2" to the meter -- required for a 400k pool heater. This can be done with 3/4 high pressure.