Recent Experiences with a Tankless Gas Water Heater?
September 13, 2018 9:55 AM   Subscribe

Our hot water heater is old and we’ve decided to replace it. We’re trying to decide between swapping it out for an updated version of what we have or replace it with a more efficient (and more expensive) tankless water heater. Our plumber recommends a Navien NPE-A series heater.

I’m very curious to hear people’s recent experience with these sorts of gas tankless heaters. We’re most concerned with whether we’ll be able to take fewer hot showers at the same time with the new technology vs. the regular old heater, and whether the utility bill savings is enough to be noticeable.

There's a lot of information pointing in both directions online, so we're hoping to hear some personal experiences to help us make our decision.
posted by thursdaystoo to Home & Garden (14 answers total) 4 users marked this as a favorite
With the tankless heater, it heats it on demand, so you can take infinite hot showers. Long, hot showers is really what the tankless technology shines at.

The places where a tankless heater sucks, is they take a few seconds to turn on and require a certain flow of water to turn on, and they take a non-zero time to warm up (5-10 seconds). So, some efficient front-loading washers will not trigger the tankless heater to start. And they are a PITA to use in a kitchen.

The warm-up time means that if in the morning at a certain tap in your house if it takes 10 seconds to get hot water, it now takes 15-20 seconds. If it takes 50 seconds (upstairs opposite end of house, it now takes 55-60 seconds. The fact that it turns off when the water turns off means that kitchen hand washing in winter sucks. One turns on mixed water, waits 15-20 seconds to get warm water and washes ones hands. Then one turns it off. Then 60 seconds later when you need to wash your hands again, you turn it on and you get 10 seconds of warm water, followed by 5-10 seconds of cold water, to be replaced by warm water. And that burst of cold water will happen every time you turn off the water flow for a bit.

If you're the sort of person who washes their hands 5 times in an entire day this might not be annoying to you. If you're the sort of person who can easily end up washing their hands 5-15 times just while making dinner/baking, then this really gets annoying.

I might be part raccoon in my need of hand washing... I found it *really* annoying.

There are fixes; one can get a 1-5 Gallon tank in the pipes after the tankless heater, but 1) that's now adding still more cost, and 2) there's now another element of something that can go wrong. 3) If that tank is passive, that adds that much more time in the morning after over-night cooling until one gets actual hot water.

While my wife really loved not having to worry about getting hot water in the shower; even if all three kids just showered before her, I couldn't stand it was so happy to move out of that house. I'd much rather spend money on a larger capacity standard heater than deal with the annoyance of a tankless heater again.

When we upgraded the water heater, we also upgraded the furnace. This was in the fall when we first upgraded, so the furnace wasn't on. As a family (now) of 4, our city utility says that we use less water than the typical household of 2. And our dryer was a gas dryer. So any savings from the small amount of water heating was obscured by the gas clothes drying.
posted by nobeagle at 10:20 AM on September 13, 2018 [3 favorites]

Another, possibly minor, factor to consider is that the tankless won't work in a power failure. I've had a couple of instances where my conventional water heater kept my house tolerably warm (at least warm enough to keep the pipes from freezing) by running hot water in the sinks and tub. No cold showers even if the power is off.
posted by H21 at 10:33 AM on September 13, 2018 [3 favorites]

We have a single, whole-house, gas powered, tankless water heater. Pro: you never run out of hot water. When we had seven houseguests for Christmas everybody could take hot showers with no waiting. If this is regularly an issue for you, go for it.

Cons: the installation was really disruptive due to gas supply and venting requirements. We needed a new internal gas line to supply it and they cut a bunch of holes in the ceiling in our basement to run the new line. For venting it needs to be installed on an exterior wall. We were having a new furnace put in at the same time so the overall disruption to our lives was minimized (everything happened in one long day) but both the new water heater and the new furnace required new vents in an exterior wall. Also, it's a little bit slower to provide hot water in our house. For us it's only a little bit slower, and we have never had the extreme problems nobeagle had. I think this varies a lot on your water supply (temperature and pressure) and the diameter and length of the pipes in your house. The single slowest tap to heat up in our house is the kitchen sink, which is annoying, but it was also really slow to heat up when we still had a tank. Honestly I feel like the tub upstairs is faster to heat up than it was before.

It neither raised nor lowered our gas bill appreciably. If you can swing having smaller heaters installed in each bathroom (the way they do it in Europe) you'll completely eliminate the wait for hot water and you'll probably reduce your gas bill a bit by reducing the loss caused by long pipe runs. You'll pay more for both parts and installation though, since you'd need new gas lines run to every bathroom. I thought our installation was disruptive, but that would be a whole lot worse.
posted by fedward at 10:40 AM on September 13, 2018 [1 favorite]

When we moved, we went from a tank gas water heater to a tankless.
Yes, it can take a little longer for the hot water to reach, say, the upstairs, but I've yet to have a complaint when I kick on a load of laundry while my wife showers.
I've had no issues with it in 6 years of use.
posted by plinth at 11:00 AM on September 13, 2018

We have the same, or a similar, Navien model like the one your plumber recommended. Our 1925 home used to have an oil-fueled furnace, and we replaced all of it when we had our two-zone HVAC system shoehorned into this house, which really wasn't built for such technology (duct work takes up a lot of precious closet space now.)

They took the oil furnace, the oil tank and the water heater out of our basement, and now there's this backpack-sized thing down there that lets us have everlasting hot showers. It's like magic.
posted by emelenjr at 11:02 AM on September 13, 2018

Point of use hot water heaters are the jam. I’ve used and maintained both tankless and little 2.5gal hot water heaters that are used under sink (if you work in a modernish office building take a peek under the sink; they’re everywhere!). We plan to go tankless when we redo a couple key parts of our house, because we’ve already installed point of use hot water in or kitchen; it was far enough away from the traditional hot water heater that it took forever to warm up anyway.
posted by furnace.heart at 11:30 AM on September 13, 2018

Unless you're in a area where the cost of gas is extraordinarily high, the payback period for a tankless is essentially the First of Never. Example: our non-heating season gas bill is something like $20-35/mo. That includes hot water for three (including an epic length shower taking child, a ton of dish washing and laundry), gas for cooking, gas for a clothes dryer shared by five people. So, only a portion of that already low bill is due to hot water demand. Let's generously assume that 70% of the bill is due to hot water heating and that a tankless could reduce our consumption by a whopping 50% (no way...I would be amazed at a 25% reduction.) The savings would be roughly $10 a month.
posted by Larry David Syndrome at 11:44 AM on September 13, 2018 [1 favorite]

Modern tankless water heaters come with a buffer and recirculation pump to eliminate the start time for hot water flow.
Navien calls is "Comfortflow".
Basically, it involves having a very small holding tank that operates much like a standard hot water heater. This water is then recirculated through the pipes for instant hot water at the tap.
In practice, what you mostly get is warm water, depending on how far you are from the water heater itself, but they do eliminate the hot water delay you get with older tankless systems.

Personally, unless you are a large family taking back to back showers, I'm not sure a tankless is worth the cost.
They are expensive up front and can be very costly to repair. There's a lot of stuff to go wrong, unlike your basic standard water tank.
The jury is still out on how much an average household will save over a conventional modern heater.
Also, older construction in the US often has gas lines that are too small for a tankless heater, meaning you'll need to have bigger lines installed.

Modern tank water heaters are very efficient. If you want "instant" hot water, installing a recirculating pump with return line can be much cheaper than a tankless install, and gets you 95% of the benefit for much less cost.

Of course, usage factors hugely into the convenience of a tankless.
If you typically have people taking back to back showers, then a child taking a bath, then running a dishwasher, the always available hot water of a tankless might be worth the investment.
posted by madajb at 11:45 AM on September 13, 2018 [1 favorite]

We're thinking about getting a tankless because our tank takes up an entire closet in our 1,004 square foot, 1920s house. Which has two closets.
posted by kirkaracha at 11:57 AM on September 13, 2018 [2 favorites]

I got a tankless Rheem installed last January when I needed a new heater, and it's been fine. I can think of only one time when I noticed I had less water than I wanted, and that was when I was in the shower and someone in another bathroom was running a bath (and even that wasn't bad). My gas bills have gone down about five bucks a month, but I also have a gas stove, fireplace, and furnace.
posted by The corpse in the library at 1:44 PM on September 13, 2018

In my old system, the oil fired furnace provided both heat and hot water. This was not the optimal system, as the furnace would run all summer. I replaced the furnace with gas, and added a tankless water heater. It's a small house, so the delay for hot water is about 10 seconds, the old system was about 5. I love taking a long shower!

It's true there's no hot water when the power is out, but the fix a made was simple. I wired the heater to an outlet via a plug. I bought a medium sized UPS box, and ran the heater of of it. The heater doesn't really draw that much power, and I bring the UPS into work to recharge. We lost power for eight days a couple of years ago, this system worked fine. No lights, but hot showers... yea!
posted by Marky at 2:26 PM on September 13, 2018

We have an instant gas hot water system.

Pros -
It never runs out
We only heat up water we use
You can set the temp on ours

Cons -
It takes a long time to heat up
On ours, the ppe the water goes through to heat up is narrow - if two people are using hot water at once, the temperature drops noticeably
Gas is not very good for the environment, if you care about that kind of thing, whereas buying 100% renewable electricity is very easy where I am

The system is fine, but in our next house, I'm going to be installing a heat pump hot water system like a Sanden, which is very efficient, and great for the environment.
posted by smoke at 3:34 PM on September 13, 2018

Bit of a curveball, but have you heard of heat pump water heaters? They operate on the same principle as a mini-split, but they just draw heat from your basement rather than from outdoors, so there's no exterior component. They are tank-based, and electric, but they are very efficient; several times more efficient than an old-fashioned resistive electric water heater. And depending on what state you live in, they may be eligible for substantial rebates. Possibly worth considering?
posted by Anticipation Of A New Lover's Arrival, The at 4:12 PM on September 13, 2018

I am late to this question, sorry, but I have to say I love tankless water heaters and I put one in every house I have lived in (3). I also put one in a cottage this year, and I have never regretted any of them. I saw significant savings the first one I put in, my gas bill dropped by 10-12%, but since then I haven't really paid much attention.

I have full house heaters, and we can do two things at once, like a shower and run the dishwasher. It does take longer for the water to get to the second floor bathrooms, but I really don't care because taking a shower and never running out of hot water is so wonderful.

We have one in a kitchen for a sink and dishwasher and they heat up immediately, so if that is important then consider getting one for each site.

They are initially expensive to install, and do need new vents and gas lines, but really, they are wonderful to have.
posted by chocolatetiara at 12:33 PM on September 14, 2018

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