Water heater is starting to leak. Should I stay traditional or look to tankless? 2500sq ft house, going to be here 7-10 more years. I'm guessing they've been around long enough to be a stable technology now but I know nothing about it.
Water heater is starting to leak. Should I stay traditional or look to tankless? 2500sq ft house, going to be here 7-10 more years. I'm guessing they've been around long enough to be a stable technology now but I know nothing about it.
What does your usage look like?
Natural gas or electric? If you don't have gas, the electrical load for these can be substantial.
We have a gas-fired Rennai that is currently... 16? years old and has performed flawlessly 24/7/365 that entire time.
We love ours. Not only will it never rust out, but you can take a 3-hour shower if you want. It will handle a load of laundry and a shower at the same time with no problem.
When we put it in, there were 4 of us in the house - DW and I plus DDs aged about 14 and 10. As she got older, DD#2 in particular used to go in for 45-minute showers. It was really nice to be able to hop right in once she finally relinquished the bathroom without having to wait for recovery.
I can't say for sure whether or not it is more energy efficient than a tanked heater, because we replaced our gas-fired furnace at the same time, so there is no easy way to tease that data out. But looking at our summer gas bills I would say it is probably 10%-15% more efficient. But again, the real advantage is limitless hot water supply with no recovery period.
Because of the way they operate they take a small amount of getting used to. They're programmed to ignore small or very short demands for hot water, so if you're running it, you need to run it, or it will go to sleep. But that's not really an issue.
I'm not much of a technical guy, so I can't help from that standpoint. However, from a day to day living standpoint, I will NEVER go back to a regular tank. I've been tankless since 2015 (2 different houses) and swear by it. I haven't noticed any increase in energy costs...in fact I suspect it's lower. Endless hot water is just marvelous. When you've got a full house, you never have to worry about "scheduling" who gets in the shower when. It can even handle multiple showers at once. My master shower has two separate heads with separate controls and we can run both of them endlessly with no issue....while running the dishwasher.
Do it. You'll love it.
They are neat. As stated above, electric units take a fair bit of juice. Gas units can also be an issue depending on where they are and your exhaust capacity. You'll make more exhaust, though for shorter periods, and that can be an issue depending on where the unit is located and how/when the house was built. I don't remember any specs off the top, just something to be aware of.
I looked into them a year or so ago. If we had gas service I'd have bought one.
The electric versions have widely varied reviews. Water too hot, too cold, back and forth between hot and cold. I decided to pass on them. They may be better now.
The electric versions also require an enormous amount of juice. A unit sized for my house was going to require 3 - 60 amp breakers to be added to the panel.
In reply to Duke :
Duke, when you upgraded, did you also have to upgrade the gas line? Our current water heater is almost 5 years old and with how hard the water is here I suspect it will need to be replaced in 2-3 years. I guess I just need to get our plumber over here and have him check and see.
They are awesome, Do it.
We have been using one for the past 10 years or so. Never a problem with failures or flow to keep up with 2 showers and dishwasher..
The one issue we saw was "cold slugs", where if someone rinses a few dishes in short spurts, the water heater doesn't turn on and a slug of cold water enters the hot water line. If someone then showers, there is a surprise waiting for them a minute or two into the shower.....warm....COLD....warm again. We fixed this by installing a small 5 gallon electric just after the tankless as a mixer tank. I don't think it ever turns on since it is hot water in/hot water out, but we have never again seen cold slugs.
I also plugged the tankless into a computer battery backup so the electronics stay alive during power outages and we have hot water.
z31maniac said:In reply to Duke :
Duke, when you upgraded, did you also have to upgrade the gas line? Our current water heater is almost 5 years old and with how hard the water is here I suspect it will need to be replaced in 2-3 years. I guess I just need to get our plumber over here and have him check and see.
We already had city gas to the house. I'm honestly not sure how big our incoming service from the street is. But everything we did during the replacement was inside the basement, downstream of the gas meter.
The only gripe I have with tankless, and part of the reason I didn't go with one when my hot water heater died, was because I couldn't really install it myself.
I think in another 5-10 years they'll be like tanks and Mr. Cool mini-splits, you'll be able to install them yourself and the manufacturer will guide you through the process.
We had a tankless in the previous house, but when moving to the new one a few years ago (which needed a water heater) we went back to a tank-based one. Why? Mainly it had to do with the potential repair needs. Tankless systems aren't necessarily any less reliable, but when they do break down they are harder to diagnose and the parts are usually not available locally. So in the event of a breakdown you're looking at a longer time without hot water.
Other pros and cons: the tankless systems take up a lot less space, and you can even mount them outside if you live somewhere that it doesn't freeze much. They're more expensive to buy and while they do use a little less energy to run they'll never pay it back. You need to do annual maintenance to descale the heat exchanger (basically pump white vinegar through them for an hour). Compared to a tank system you get less hot water all at once (size the unit properly for your needs), but you'll get it for as long as you want (the 3 hour showers). And yes, it increases the wait til until you get hot water because the heat exchanger needs to heat up. Another minor point is that it needs electricity to run the logic board and fan, so a gas unit won't work during an power outage unless you have a UPS for it.
Our house is electric, in FL. Right now just the two of us since the kids grew up and moved out, but there are 4 BR of potential use. Most days it's just 2 people and the washing machine.
Duke said:z31maniac said:In reply to Duke :
Duke, when you upgraded, did you also have to upgrade the gas line? Our current water heater is almost 5 years old and with how hard the water is here I suspect it will need to be replaced in 2-3 years. I guess I just need to get our plumber over here and have him check and see.
We already had city gas to the house. I'm honestly not sure how big our incoming service from the street is. But everything we did during the replacement was inside the basement, downstream of the gas meter.
Yeah, we already have a gas water heater and gas furnace. I just remember reading in previous threads here that sometimes the current supply line isn't large enough.
I considered upgrading our very small hot water tank for a tankless but a lot of them I saw would only raise the temp of the water a fairly low amount, like 50 degrees. This is less than adequate when your well water comes out the faucet at 34 degrees. This was a few years ago though, it might have changed.
What I did was turn my hot water up to the other extreme that's a bit over 200 degrees coming out of the faucet. Mix that with 34 degree cold water and you have a good amount of hot-ish water
glueguy (Forum Supporter) said:Our house is electric, in FL.
Electric units can require 120 amps or more, depending on their capacity. You may need to upgrade the electrical service to your house to accommodate one.
Another thing is depending on the quality of your water, they may require regular maintenance to clean out calcium deposits.
z31maniac said:Duke said:z31maniac said:In reply to Duke :
Duke, when you upgraded, did you also have to upgrade the gas line? Our current water heater is almost 5 years old and with how hard the water is here I suspect it will need to be replaced in 2-3 years. I guess I just need to get our plumber over here and have him check and see.
We already had city gas to the house. I'm honestly not sure how big our incoming service from the street is. But everything we did during the replacement was inside the basement, downstream of the gas meter.
Yeah, we already have a gas water heater and gas furnace. I just remember reading in previous threads here that sometimes the current supply line isn't large enough.
That's what we had, and our existing gas supply was plenty.
Antihero (Forum Supporter) said:I considered upgrading our very small hot water tank for a tankless but a lot of them I saw would only raise the temp of the water a fairly low amount, like 50 degrees. This is less than adequate when your well water comes out the faucet at 34 degrees. This was a few years ago though, it might have changed.
What I did was turn my hot water up to the other extreme that's a bit over 200 degrees coming out of the faucet. Mix that with 34 degree cold water and you have a good amount of hot-ish water
200dF?! That's incredibly dangerous and a real scalding hazard. You absolutely shouldn't have that over 140dF and even that requires care in use. Normal 'hot' tap water is 110dF.
My tankless is set to 130dF and it can make that temperature in 90 seconds in the dead of winter when the water temp is 50dF. Unless you live in Canuckistan, your ground water isn't going to get much colder than that.
In reply to Duke :
Thanks, good to know!
In reply to glueguy (Forum Supporter) :
We had one small under-sink electric Bosch unit at our old place that was junk. Our current house has a lager electric unit in the master bath that we don't like, but have learned to live with its shortcomings.
It basically has 2 heat levels, which are triggered by flow rate, but turning the cold water up/down can impact the hot flow rate, which makes it tricky to get the temp perfect. After 6-years I've figured out how to get it set ok, but it took a while.
Also, here on the coast with our pipes only about a foot underground, the outdoor temps have a big impact on water temps, which also complicates the issue.
I have heard here & from others that the tankless gas units are much better. The POs could have easily ran gas to this new addition, but for whatever reason didn't.
I wouldn't touch an all-electric one. The exception might be one of the fancy-pants hybrid air heater/water heater heat pumps, but I don't know enough about them to recommend.
My company mainly installs furnaces and heat pumps, but we've probably installed 20 or 30 tankless water heaters. Rinnai is my favorite brand. They probably will require more attention over their lifetimes than an old-fashioned tank unit, but the endless hot water and compact size are very hard to beat. A few notes:
-They use a lot of gas in shorter bursts, so you're going to have to run a large gas line over, and some houses even require meter upgrades - In California, most gas meters are rated at roughly 250,000 btuh, and if you've got a 130k water heater, a couple of furnaces and a commercial style gas range, that won't be enough.
-If your climate is mild, I recommend hanging it outside
-The biggest complaints that I've seen have to do with flow rates. As has been noted, if you're trying to heat up a dribble of water it won't be enough to trigger the flow switch and will never warm. On the other end of the spectrum, some water heaters won't support much more than a single appliance or bath at a time. Sucks to feel your pressure drop every time the clothes washer wants hot water. So pay attention to that.
Duke said:Antihero (Forum Supporter) said:I considered upgrading our very small hot water tank for a tankless but a lot of them I saw would only raise the temp of the water a fairly low amount, like 50 degrees. This is less than adequate when your well water comes out the faucet at 34 degrees. This was a few years ago though, it might have changed.
What I did was turn my hot water up to the other extreme that's a bit over 200 degrees coming out of the faucet. Mix that with 34 degree cold water and you have a good amount of hot-ish water
200dF?! That's incredibly dangerous and a real scalding hazard. You absolutely shouldn't have that over 140dF and even that requires care in use. Normal 'hot' tap water is 110dF.
My tankless is set to 130dF and it can make that temperature in 90 seconds in the dead of winter when the water temp is 50dF. Unless you live in Canuckistan, your ground water isn't going to get much colder than that.
It is hot, you just never use it alone and it's less hot.
And I literally have 3 ft of snow on the ground now and a well that's many hundreds of feet down. 34 degrees give or take is what the water temps at coming from my faucet
Have your water tested first. Certain elements cause issues with scale on the heating element. Here in PA and on a well, we have a sediment filter, charcoal filter, softener and UV light for the domestic water supply. It's a pain, but we have really good water and when I de-scale the tankless hot water heater every year, I get ZERO scale from the flush. It's an upfront cost, but prolongs the life of the unit, so hopefully a trade-off in the long run.
If you don't have natural gas into the house, it might be worth looking into getting a propane tank set and plumbed into the area where the water heater will be mounted. Some units require a double-wall stainless steel exhaust while others only need a PVC pipe. Our Navien heater only uses a PVC pipe, so you can probably use the same vent as the tank heater you currently have. Personally, I will never go back to a tank HWH after having the tankless.
I did 2 electric tankless units on "flip houses" in Florida and both worked very well, but we had to shed some items in the electrical panel to make room for the breaker required to run the unit.
Just know going in, you are going to spend $3K to install one. Maybe more. Depends on several things. Where is the old one located? Is it close to an outside wall? These things direct vent with special plastic pipe fittings as of May 1st last year. The days of venting with regular sch 40 PVC are gone. Anybody that has one now vented with regular PVC will have to change the PVC out for the special vent piping when they change the water heater or any other direct vent appliance. Good luck with that if the old vent passes inside a finished wall. Is the gas pipe going to current water heater sized big enough? Old WH was sized for 40K BTU or so. Tankless are at least 120K and many are in the 200K range. Is the gas meter outside big enough for the increased BTUs? Is the line coming in from the street big enough? Is the gas company willing to give you more gas? Here in Mass, you can't install any appliance with extra BTU unless gas company approves it ahead of time. I can't tell you how many times, a heating company installs something and then tells the home owner to call a plumber to hook it up to the gas. Our first call is to the gas company. There have been many times the gas company says flat no. Homeowner is stuck with something they can't use and in many circumstances where converting from electric/oil to gas, no heat. Only quick solution is to convert to propane and sign a contract with a propane company. Just had to repipe a guys entire house because he paid an electrician to install a gas generator, then called me to "hook up the gas". Inspector had a field day. I ended up getting to replace the boiler and reline the chimney after the inspector got a look at what was going on. What started out as "I'm tired of filling my generator with gasoline whenever the power goes out" turned into a sizable home equity loan.
In reply to tr8todd :
My career in the engineering world started some 25+ years ago with me having to cold-call town inspectors and local utility companies to go over NG generator installations in new construction supermarkets. Then followed by a load-letter to the utility company. Someone from the plumbing design dept had to make the contact with the gas utility. Thanks for the trip on the way-back machine.
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