Info and Advice on Tankless Water Heaters

[W.J.Christy]

My last two houses have rinnai tankless heaters. My biggest complaint is the amount of time it takes to get hot water to the location its needed. Tank water heaters are always hot and provide some heat into the lines always so the water at the tap increases in temp far quicker than the tankless. If you can install a recirc loop on the tankless, that should solve that problem. Something to think about, 1.5 GPM faucets, shower heads, etc... do not work well with tankless heaters (well mine at least) the flow out of them was too low to keep the heater running and would shut off mid shower which was not awesome. Scale build up is a thing here too. Some thought needs to be given to the hardness level of the water. A water softener may be required to keep the exchanger scale free and the other internal bits working well.

 

[markayash]

These water tanks are original to the home construction so 2005/06. And you can be assured that the cheap home builder probably got all these heaters for the homes in my association at some discount fire sale for old products that are obsolete. So they lived and functioned for 17 years. I suppose that’s a good run.

Still got one in the garage so, depending on what my plumber comes back with on a quote, I might bite the bullet and replace both of them at the same time.

As for alarms, any good recommendations there? Again, I’m a simple guy so I don’t need fancy. The utility closet is only accessible from outside so even though it shares a wall with the master bedroom closet, it could go unheard unless it’s a real screamer. I’m not a huge fan of WiFi IOT junk so I’d rather keep it as low tech as possible.

I have the wyze home alarm and it has water sensors. Isn’t a lot per year and l can monitor it when we are at the beach along with doors etc.
I really want a Wi-Fi water shutoff so if I did spring a leak I could at least kill the water to the house. Plan B is call my neighbor to go shut off the water

 

[tgrinchy]

Do all tankless water heaters require electricity? In the time we‘ve had extended outages, I was always thankful to have hot water. Mine are at the 7-8 yr mark so hopefully have a few years before i need to replace

 

[JoyfulNoise]

Side note - I do have fully softened water in the house so any heater will be fed with soft water.

 

[Texas Splash]

Interesting topic. Since our home was built in 2006 (with softener), I've gone through THREE 50-gal Rheem water heaters. They lasted 8 yrs (unknown internal fault), 6 yrs (bottom seam tank leak) , and 2 yrs (upper section galvanic corrosion resulting in leak) respectively. Fortunately for me the leaks were handled by the drip tray which took the water from the garage to where I park the cars to get my attention. Other than the inconvenience of exchanging the heaters, they were DIY and all under warranty, so Rheem was good about the exchange. But still on my mind. At work we have two small tankless heaters for the bathroom sinks. One works great but the other is very sensitive to water flow and never seems to come on. I have an almost 3K sq ft home (single level) and the heated water travels anywhere from 10ft to almost 100 ft which has me concerned if a tankless system can handle the demands across the home. Good thread to get smart on.

 

[JoyfulNoise]

Do all tankless water heaters require electricity? In the time we‘ve had extended outages, I was always thankful to have hot water. Mine are at the 7-8 yr mark so hopefully have a few years before i need to replace

Yes. Either they are electric heated which requires a pretty big service hook up OR they need a nearby 120V outlet to run the onboard electronics. Thankfully my outdoor utility closet has a light fixture I can scavenge for power. There’s a plug in there but it’s an fused SRU that powers the furnace/air-handler. Code requires that the furnace be on an SRU with a fuse so I can’t convert that to regular two plug outlet.

I suppose hot water for an outage is important but we rarely have outages (once a year event maybe) and then in that case it might be preferable to stick with a tank heater in the garage so that there is some limited access to hot water

 

[mknauss]

If I was building this house again, I would consider small on demand tankless for the bathroom and kitchen faucets separate from the overall tankless for large uses like showers, clothes washing, dishwasher, etc.

It does take time to get the hot water to the faucets. And since most water use at sinks is short term (hand washing, etc) a small, electric, on demand would make more sense at those spots.

 

[Mdragger88]

Noritz here, too. N-0751M, which is the older model of what you have (200000BTU, 9.8GPM, etc.). Ours was installed in 2008 and needed its first repair earlier this year -- I replaced the igniter, around $50 and about an hour to diagnose and R&R. I expect it to last at least another decade.


It's hard to get lower tech than this. I have one behind every toilet, under every sink, and in the tray around the clothes washer:

View attachment 455111
https://www.amazon.com/Glentronics-Inc-BWD-HWA-00895001498-Basement/dp/B000JOK11K

A tip, if you decide to buy these: Fold a section of paper towel over the sensor, so even a slow drip will soak the paper towel and close the contacts. Otherwise they won't close until they're in at least 1/32" of standing water.

Great idea doing the paper towel thing today!

 

[Mdragger88]

I have the wyze home alarm and it has water sensors. Isn’t a lot per year and l can monitor it when we are at the beach along with doors etc.
I really want a Wi-Fi water shutoff so if I did spring a leak I could at least kill the water to the house. Plan B is call my neighbor to go shut off the water

I didn’t want to have to have the wyze hub so I just went with some hubless ones on Amazon but it would be nicer to have them all in 1 app

 

[wireform]

Do all tankless water heaters require electricity? In the time we‘ve had extended outages, I was always thankful to have hot water. Mine are at the 7-8 yr mark so hopefully have a few years before i need to replace

Good point, I always had a whole house standby automatic generator so it wasn't an issue but can see that being a problem.

 

[guinness]

As for alarms, any good recommendations there? Again, I’m a simple guy so I don’t need fancy. The utility closet is only accessible from outside so even though it shares a wall with the master bedroom closet, it could go unheard unless it’s a real screamer. I’m not a huge fan of WiFi IOT junk so I’d rather keep it as low tech as possible.

I use a Govee Water Leak Detector, it's standalone with a loud alarm but it also transmits wirelessly on 433mhz. You can get their WiFi gateway to monitor this or go DIY and use rtl_433 project as they added Support for Govee Detectors.

Govee Water Sensor Review [Protecting Your Home]

At a system price of under $100 and the cost of internet service, the Govee Water Sensors provide peace of mind while your away from home.

snowbirdingcentral.com

 

[JoyfulNoise]

If I was building this house again, I would consider small on demand tankless for the bathroom and kitchen faucets separate from the overall tankless for large uses like showers, clothes washing, dishwasher, etc.

It does take time to get the hot water to the faucets. And since most water use at sinks is short term (hand washing, etc) a small, electric, on demand would make more sense at those spots.

The only place in our home where the time to heat is a major issue is the kitchen sink. The hot water is fed by the heater that died and it’s pretty much equidistant to either hot water heater. So it’s a run of about 50ft or more and thus takes several minutes before the water heats up. I typically just rinse dishes of any way and then make sure that the water from the faucet is nice and hot before running the dishwasher. It would be good to have a point of use heater under the sink BUT I already have the sink, the 5-stage RO and a garbage disposal crammed under there. No more room or electrical service under there. If I ever redid the kitchen, the cabinet space around the island sink would get a major overhaul to accommodate the space needed for all the stuff.

Eventually the interior design of the home just becomes outdated relative to the equipment and appliances available to the modern homeowner.

 

[kul]

Noritz here, too. N-0751M, which is the older model of what you have (200000BTU, 9.8GPM, etc.). Ours was installed in 2008 and needed its first repair earlier this year -- I replaced the igniter, around $50 and about an hour to diagnose and R&R. I expect it to last at least another decade.


It's hard to get lower tech than this. I have one behind every toilet, under every sink, and in the tray around the clothes washer:

View attachment 455111
https://www.amazon.com/Glentronics-Inc-BWD-HWA-00895001498-Basement/dp/B000JOK11K

A tip, if you decide to buy these: Fold a section of paper towel over the sensor, so even a slow drip will soak the paper towel and close the contacts. Otherwise they won't close until they're in at least 1/32" of standing water.

I can vouch for these water alarms. They have saved me a few times. I have one under every sink as well as washer/dryer area. They are super loud so can be heard throughout my home.

 

[JJ_Tex]

In our old house, we switched to tankless and were happy with it. There were some differences though:

• You do not run out of hot water, but you also have to consider how much hot water you will be using simultaneously. In our old house, it was fine with the exception of running the bathtub + someone else trying to take a shower. Rarely an issue, but one to think about especially if you have one parent trying to give the kids a bath and the other trying to shower.
• You need electricity to light the flame. We added a small battery backup to ensure we could have hot water even if the power went out.
• Our installer added a sediment filter before the tankless as he said it kept the tankless form getting caked up with sediment and requiring flushing. Never an issue and I was always amazed when I would clean out the sediment filter. I would recommend adding this if you go with tankless.
• Our natural gas bill was slightly less (~$25/month) with a tankless
• If you have a recirculating system that gives you instant hot water in the house, that will not work with a tankless. We have that in our current house and I love it, so when we replaced our 2 water heaters last year I went with the traditional water heaters so I could keep that functionality.

 

[JoyfulNoise]

No recirculate in the household plumbing (no ability to add that either). But I will say that I’m seeing higher end tankless units that come with kits that allow one to use a recirculate pump. So it seems like the manufacturers are adding that as an upgrade features.

 

[Saturn94]

Do all tankless water heaters require electricity? In the time we‘ve had extended outages, I was always thankful to have hot water. Mine are at the 7-8 yr mark so hopefully have a few years before i need to replace

We were very happy to have hot water (NG 40 gal tank) after our power was out 5 days after a hurricane.

 

[JoyfulNoise]

We were very happy to have hot water (NG 40 gal tank) after our power was out 5 days after a hurricane.

I was joking with someone today who has a trip next week to FL that she couldn’t have timed it any better with the tropical storm/hurricane predicted to hit the hour she is supposed to take off from Phoenix. We both agreed that, as Arizonans, we have no concept of weather interfering with life … there’s only one weather question to ask here every day - sun’s up, how hot is it outside?

 

[reggiehammond]

Re: leak monitoring

The house we bought 7 years ago had “FloodStop” sensors on all the hot water heaters (3 of them )

They work really well with both audible alarm and automotic water cutoff- there’s a sensor pad that sits in the drain pan under the heater that connects to a small control box. If the sensor is activated, a motorized valve cuts off the cold water supply. Your leak possibility would only be the size of the tank, provided there’s enough air leak to keep the leak continuous.

Because we have them installed; we have never had a leak. I only know they work because I tested them to see how fast it responds - it’s instant.

 

[Flying Tivo]

after our power was out 5 days after a hurricane.

You can probably use a no-break APC, since the consumption is very low. Or just an inverter with car battery.

 

[Saturn94]

You can probably use a no-break APC, since the consumption is very low. Or just an inverter with car battery.

Good to know for future reference.

Since then we bought a portable generator some years ago, and this year installed a transfer switch to make hookup to the generator easier. Of course since buying the generator, we’ve only needed it once (power out for a day), lol.