Existing tanked one appear to be leaking; therefore, I need to buy a new one.
Are tankless ones worth it? I know they cost more upfront & have lower operating costs. How long (# of years) until break-even? I understand that they produce hot water all day but I’ve heard that there can be an issue with running multiple things at once; ie. they can’t produce enough hot water if you take a shower at the same time the washer is running. Is this true?
I’ve got gas if that matters.
If you’ve got gas, tankless will almost certainly be more cost effective than tanked. Electric models may depend upon local electrical rates. Payback time is commonly several years, but I’m sure your local installer will be able to provide some figures as part of the sales pitch.
As for capacity, that is governed by the size/capacity of your unit, and by the size of pipe carrying your heated water. If your existing tanked installation provides sufficient water for multiple uses at the same time, then your pipes are sufficiently large to accommodate that rate of flow. All you need do is purchase a tankless heater with an adequate flow rate (rather than a smaller, cheaper unit) and you’ll be golden.
I looked into it recently and found through several reliable websites that the monthly savings will never cover the much higher cost of parts plus installation verses a conventional hot water heater. Unless you have other specific reasons to go tankless, don’t do it because you think you’ll save money in the long run.
I want one, but not for the cost savings. A wall mounted gas tankless water heater mounted on my interior garage wall will open up a very useable area that is occupied by the tank style heater we have now. Another bonus: my wife’s marathon showers (:mad:) won’t leave me taking a lukewarm shower.
We don’t have one. But I’ve read up on them, and like anything else there are pros and cons to them.
Cons:
- Poor temperature regulation. Though I think modern units have improved in this area.
- If electric, you will need to run new wiring from your breaker box to the water heater.
- High unit cost and installation cost.
Pros:
- Depending on your water usage, you might save some money in the long run.
I’d say they make the most sense if:
- You already have a big enough gas line to the area, and either you are right on an exterior wall or already have a big enough vent. Both gas line and vent have to be larger than you would need for a tanked heater
- You want to use a lot of hot water sequentially in a short period of time. Perhaps you have 6 people that want to shower all in a row in the morning, and normally you have to wait in between showers or force someone to shower at night because you would run out of hot water
- You don’t live in the home 7 days a week- perhaps it is a weekend home in the mountains or at the beach.
I don’t think they make much sense if:
- You want to save money, because the extra initial cost + the extra installation costs for things like larger gas line or a new run of wire are usually pretty expensive.
- You don’t run out of hot water today and you don’t do anything special to make that happen.
We have one that we switched back on when our water heater rusted out a couple of years ago. It’s run off our oil burner. It’s “on demand”, meaning that if you want hot water, you have to run the tap a minute or two beforehand.
We can’t run multiple lines when the hot water is being used – i.e., you can’t do a hot-water wash when someone’s taking a shower or doing the dishes. Whatever regulates the temperature is set on the low side, which means you’ll only get extraordinarily hot water for a short period of time. That alone has taught us conservation (and thereby savings)!
I vote don’t do it unless you are 150% certain that your water pressure is sufficient during multiple streams, like three showers at the same time.
We got one, used it for a week, then returned it and got a regular one. Our water pressure, although it said it was sufficient on the box, wasn’t good enough. So you had to constantly adjust the faucet, which left you with either freezing cold water, or burning hot water.
This was about five years ago, so technology may be better now, but I wouldn’t ever put one in again. It was awful.
The solution is obvious…
We’ve had a gas one for 13 years and never a problem. If you make sure you get a big enough unit for your needs you should be fine.
Only down side is that ours is electrically primed - when the hot water tap is turned on, the flow triggers an electric spark powered by the mains to light the gas (there is no permanent pilot light). A consequence is that when there is a power outage, we have no hot water at all, which feels odd, given that it’s a gas system.
We used to have one and I hated it. First, it meant we had to run the dam oil burner all summer. Second, the process uses very thin pipes that clog up easily if the water has any calcium or other minerals in it. Every few months the thing needed to be disconnected and the water lines reamed out or you would get barely a trickle of hot water and eventually not even that. The “cure” for that is to get yet another machine, a water softener, which has its own maintenance issues.
Please pardon me if this is all just too obvious, but…
The inefficiency of a tanked water heater is that it must heat a large quantity of water (30, 50, or more gallons) and then maintain it at that temperature 24/7/365. Thermal loss of the water depends on surrounding ambient temperatures (cool basement versus warm utility room) and insulation of the tank. This loss is going to be pretty constant, although possibly with seasonal variation, regardless of hot water usage. The other energy consumption is heating replacement water for whatever you extract. This is entirely dependent on usage. These two together equal your energy bill. Regardless of ‘national averages’, this is highly individual for each home, in actual practice.
If you have a large family and people are at home possibly using hot water all day, most days, then the majority of your energy costs go to that initial heating of cold water, not maintaining it. In this situation, tanked heaters are as efficient as they will ever be, and savings with tankless are minimal. Not necessarily zero, but minimal. Of course, unless you have people showering in the middle of the night, even busy households typically have lengthy periods wherein no hot water is extracted and thermal loss to the environment predominates. But in an active household with people showering, dishes being washed for several meals, babies getting bathed, and so on, the waste loss of a tank is minimized. Average families with working parents and kids in school have less efficiency of use, with daily activity peaks and valleys.
This loss to the environment is totally avoided by tankless heaters, though. If you live alone, or perhaps just you and the SO, and you both work, then your hot water demands are probably concentrated in a couple of hours at the beginning and the end of each day. All the remainder of the time, your hot water tank is just maintaining temperature, burning energy, waiting for you. If you travel much, this waste is amplified. You could save some money by adding extra insulation to your tank. And you could switch it off (easy to install a switch for electric models, harder for gas) while you’re at work or traveling. You will need to remember to turn it back on though, and it may take an hour to heat up.
Or get a tankless. It does not maintain a tank full of hot water. It waits, dead cold, for as long as necessary, even weeks at a time, until you open a hot water tap. Then it heats it immediately on demand, with very little lag time. And when you’re done, so is the heater. Temperature control problems as noted above indicate a faulty system or faulty installation. Today’s units are extremely good at providing unlimited quantities of consistently hot water, on demand, at any time. As I said earlier, the amount of water produced depends on the size/capacity of the tankless heater. Saving money by installing a smaller, cheaper unit will indeed limit the amount of hot water available at any particular time. Competing concurrent uses can produce temperature fluctuations. A competent plumber will be able to tell you just how large a unit you need for your expected demand. Don’t fib about the demand (“Oh, we never take showers at the same time, and we never run the dishwasher at the same time as drawing a bath.”) or you will be causing your own disappointment.
And the amount of water used cannot exceed the size/capacity of the pipes that carry it. If you presently have a tanked heater, and two people can take showers at the same time now, then your pipes are sufficient to carry tankless hot water for two showers too. Just make sure the unit is capable of heating and passing that much at the same time. If you can’t do that now, a tankless probably isn’t going to magically make it possible. But sequential showers will never be a problem again. With tankless, a whole SUV full of little ballerinas or soccer boys can take one bath after another with no one getting the ‘cold shower’ treatment. And you don’t have to curse that tank full of hot water sitting all alone in your freezing basement while your whole family is snowed in at Grandma’s house for the weekend.
I considered getting a tankless water heater, but there were three things that made me stick with a regular standing tank.
It needed a larger gas line, which would involve pricey upgrades to the line from the street.
It needed a larger vent, which would have been a bit of a pain as the existing vent went from the garage to the roof in a chase.
There’s still 200 feet or whatever of pipe between it and the shower. Sure, my shower will never run out of hot water, but it still takes a few minutes for the hot water to get there.
Going with smaller electric units at the point of use would give instant hot water, but I would have needed three units to supply the master bath, the kitchen and the guest bath and laundry.
Look at the vent requirements!
Others have hinted, but:
It requires a stainless vent (6" IIRC) with large clearances from combustible materials.
If you vent through a wall, you need the outlet to be 6’ from nearest door or openable window.
Basically, if it isn’t on an exterior wall or top floor, the vent requirement will kill the idea.
My contractor has suggested that I get a tankless water heater due to the fact that my funky old house has a non-conforming water heater that is basically sitting outside completely exposed to the elements. I’ve gotten away with it because that’s the way it was when I bought the house.
I’m a single guy with fairly low hot water demands. The beauty of the on demand water heater is that I can mount it in the attic without losing any valuable interior space. I’m raising the roof line any how, so I can design around the regulations. I think when I remodeled earlier I put in an adequate gas line, so that isn’t a problem.
I live in Thailand, and tankless ones are the most common. I am currently using a Toshiba 4kw model which is absolutely adequate, but they do go up to 6 kw or so.
The reports on gas ones that I have read indicate that they can produce as much hot water as required. I’d have used one myself, but they require a flue vent, and as I put mine in myself, I saved the problems of having to knock a hole in the wall by going electric.
I’d guess that the cost of the electrician/ gas fitter in the US would exceed the cost of the unit.
We turn our thermostat down to the lowest temperature possible during the summer. The burner only switches on we’re using hot water. It switches off the minute we turn off the tap. It’s certainly a lot cheaper than maintaining the temperature of a water heater 
(missed the edit window)
I was going to add, re CannyDan upthread, that tankless water heaters make sense if you have a small household with minimal hot water requirements. For instance, it didn’t make sense for us (SO, the dogs, and myself) to replace the water heater. We do the day’s dishes after dinner every night. Neither of us takes a shower every day. Most of our laundry is done with cold water. Why pay for a constant source of hot water [aka the heater] when you’re not using it?
Our water bill took a very pleasant nosedive when we switched the tankless heater back on. Ditto the oil bill – I’d wager to say that, when we had the heater, a good portion of the oil went to maintain the heater.
Its the on-demand and refresh rate of hot water convenience vs code costs. They’re pricey; where I used to work didn’t even have them as a flat price, just as an estimate given before install. Proper venting & a stand-alone interior wall for mounting were stated as requirements (but didn’t install them so there may have been some lee-way with that).
Slight highjack to prevent owners remorse
OK, so you don’t have a nice Navian. And your gas w/h has an expected life of 12 years. And you don’t want to pay $1500 every 12 years. What do you do? Well, I knew a handy gentleman who man an older one that wasn’t even as good as today’s models, and he made his last 25.
You see, there is a drain at the bottom of your gas water heater with a spigot and a threaded head just right for a section of garden hose… and every March he’d turn off the water & the gas and drain out water. The first few were grey buckets of sludge do to sediment
(thats what kills your w/h most times) and when the water got clear, he’d turn off the spigot, turn on the water valve and relight the unit.
'Course, he had to. He had 5 kids to feed including one who never seemed to listen. The one who carried those buckets upstairs and dumped them behind the garage wondering why we did this when none of the other neighbors did. 
Happy St Patrick’s Day & a slice of Soda Bread to you wherever you are, Dad. You Are Missed…
But if you make :mad: about your Wife, not viable. 
We replaced the gas WH with a fifty gallon. The only time I had a warm but not hot bath was when Mrs. Plant v.3.0 had a bath fist and I ran the dishwasher and laundry at more or less the same time.