Tankless water heaters

[skyking1]

Old is electric. I'd need two 40 amp 2-pole breakers in place of the one I currently have. Electrician does not think it should be a problem but will look at existing setup (load center) tomorrow. Most of the additional cost is running the additional wires from the panel to the heater about 5 feet away.

My biggest concern is that I have 100 amp service. 2x40 means the water heater would use 80 meaning anytime I use the stove and the water heater kicks on I could be tripping the main. I know there are solutions but they could start getting expensive. We'll see what the electrician says tomorrow.

that is a red flag for me. This is the corner people will back into that requires upgrading that 100 amp service. I emphatically suggest not going tankless with that service in place.

Edit: as suggested by flyfish above, look at the hybrids, electric heat pump water heaters. They are on my house design for earning energy credits, I can go several ways to get the required 6 credits on the new build and a hybrid gets 1 of them.

 

[badatmath]

The plumber told me I'd have to run electrical to the spot where my gas water heater sits now. . . which is in a fairly crappy location anyway. IDK. I didn't have a lot of faith in him really but no specific reason.

 

[euro]

Our beach home in New Jersey has a bit more of a temperature drop than Hawaii has. The tankless gas water heater is in an unheated basement/crawlspace and the home is unused during the winter months. We turn off the water and power down the water heater when we winterize the home. We’ve never had a problem.

Here in North Carolina climate, we can (and do) mount tankless heaters on the outside wall of the house. Makes venting much easier for gas fired versions. In fact, for one of my rental properties, this was the main driver for going tankless because it freed up a lot of pantry space inside the house where the old water heater used to reside.

 

[Music Lover]

that is a red flag for me. This is the corner people will back into that requires upgrading that 100 amp service. I emphatically suggest not going tankless with that service in place.

We don't need unlimited hot water so there are no benefits to tankless because a regular tank meets 100% of our requirements. Add in the cost of replacing a breaker panel (if not required anyway) and the math makes no sense at all. No matter what the tankless fans claim, the energy savings will be negligible.

 

[retire48in2018]

A possible concern

We’re told - that the water here is hard, and a tankless needs to have a water softener.

Don’t know the veracity. Have not checked options, yet - and whether water is so hard that needs softener regardless

 

[COcheesehead]

We don't need unlimited hot water so there are no benefits to tankless because a regular tank meets 100% of our requirements. Add in the cost of replacing a breaker panel (if not required anyway) and the math makes no sense at all. No matter what the tankless fans claim, the energy savings will be negligible.

Dept of Energy claims a 24%-34% energy savings of tankless vs tank. I suspect adding the app like we have which allows you to shut it off completely for hours at night helps too.

 

[Out-to-Lunch]

The plumber told me I'd have to run electrical to the spot where my gas water heater sits now. . . which is in a fairly crappy location anyway. IDK. I didn't have a lot of faith in him really but no specific reason.

One of the driving factors for me was the possibility of moving the water heater from one side of the house to the other. The previous location was dictated by the flue, which was far from the runs to hot water usage. I moved the tankless heater to the other side of the house, which is right near the hot water outlets.

 

[Affinity4Investing]

Old is electric. I'd need two 40 amp 2-pole breakers in place of the one I currently have. Electrician does not think it should be a problem but will look at existing setup (load center) tomorrow. Most of the additional cost is running the additional wires from the panel to the heater about 5 feet away.

My biggest concern is that I have 100 amp service. 2x40 means the water heater would use 80 meaning anytime I use the stove and the water heater kicks on I could be tripping the main. I know there are solutions but they could start getting expensive. We'll see what the electrician says tomorrow.

You are receiving completely incorrect information. Most 30, 40, or 50 gallon electric water heaters require (1) 30amp dual pole circuit breaker. No residential water heaters require (2) breakers - ever (unless you actually have 2 different physical water heaters in a very large home). The size of the breaker and the size of the electrical wire are determined by the watts drawn by the heater elements. The size of the tank is irrelevant in determining breaker and wire size. 100amp rated panels are completely fine for feeding water heaters up to 50 gallons. 99% of the heaters I've installed or seen, operate on 30amp breakers and 10-2 Romex wiring. Consider the information in the following for detailed explanations or PM me. Happy to help you make sense of this:


https://www.usawaterquality.org/what-size-breaker-do-i-need-for-a-water-heater/

 

[braumeister]

You are receiving completely incorrect information. Most 30, 40, or 50 gallon electric water heaters require (1) 30amp dual pole circuit breaker. No residential water heaters require (2) breakers - ever (unless you actually have 2 different physical water heaters in a very large home).

Not true.
My residential water heater is on two 30 amp breakers.

 

[Music Lover]

You are receiving completely incorrect information. Most 30, 40, or 50 gallon electric water heaters require (1) 30amp dual pole circuit breaker.

I think they were referring to the requirements to upgrade to a tankless.

 

[Steeler75]

Two reasons for not switching to tankless are one I can still take a hot shower if the power goes out. Second, in a natural disaster (ie. earthquake) I have a 50 gal. emergency supply of drinking water.

+1

Just like having a gas stove. With unreliable utilities in California, I like having the ability to use my stove and have hot water in power outages.

 

[SecondAttempt]

So we settled on just replacing the tank heater. The electrician said my load center has plenty of excess capacity. But he agreed with me that we would be tripping the main circuit breaker anytime the stove or oven was on and someone tried to get hot water. He said he wouldn't do it.

Upgrading the service would be cost prohibitive since the house is about 200 feet from where the pole is and is underground from there. That would be a lot of trenching and probably larger conduit to hold the bigger feed wires. It might be something I'd consider if I add a whole house generator as mentioned in another thread since it could probably go in the same trench as the propane. Or maybe not depending on code.

ETA: He did bring up an interesting suggestion. He suggested a propane tankless. But then said then you have to deal with all the issues with propane around here. I had not mentioned my generator consideration. And by "the issues" he may have been referring to a recent propane drive strike the shut down a lot of restaurants and other businesses.

 

[old medic]

+1
Just like having a gas stove. With unreliable utilities in California, I like having the ability to use my stove and have hot water in power outages.

Our current water heater is only 11 gallons, runs on 110 single phase, or gas. in 5 years we ran out of hot water only one time. Living in a camper has its advantages during power failures...

 

[Affinity4Investing]

Not true.
My residential water heater is on two 30 amp breakers.

It is true for traditional/modern tank water heaters in the capacities mentioned. I am not referring to tankless heaters nor those exceeding capacities of 50gal. Not until you get up into silly large capacities and those that draw ~10kW -18kW, do you need to go to 2x30 or 2x40amp breakers. Some even require 4x40amp breakers, but again, never for traditional/modern 30-50g heaters. If you have something to the contrary, please state the make/model of the device. Would be interested in investigating this and learning more about it.

 

[bobandsherry]

Take a look at hybrid water heaters ...basically a heat pump approach. We no longer use propane to heat our water.

I'm in FL and last house had a Hybrid WH (electric) - it worked great and was very efficient. It was installed in the garage so lots of hot air to pull to heat the water and the garage was cooled a few degrees too. Now have a tankless as new home has gas. Hybrid would not be my choice for cooler climates.

 

[ERD50]

I'm in FL and last house had a Hybrid WH (electric) - it worked great and was very efficient. It was installed in the garage so lots of hot air to pull to heat the water and the garage was cooled a few degrees too. Now have a tankless as new home has gas. Hybrid would not be my choice for cooler climates.

Hybrid *might* make sense if you have no access to gas/propane. I don't think it can be cheaper to run than those, so you'd never payback for the higher initial cost.

And I really question the life of the heat pump in these. I had a dehumidifier (same technology) die before the end of the 2nd season.

And if you don't have a spot you want cooled, you'll end up paying to heat the cold air it kicks out. So pretty specific conditions, and I still worry about the lifespan, especially with the higher cost.

-ERD50

 

[JoeWras]

Agree ERD50.

A traditional electric WH is perhaps the simplest appliance one can think of. Simpler than a toaster.

A traditional gas WH is pretty simple too. Thermocouples have been used for over 100 years.

But the heat pump? Oh my. Cheap, thin refrigerant tubes that "can't be repaired" are only the beginning.

I still really like the concept, but if they are making a typical 5 to 7 year throw away appliance, they can keep it.

 

[bobandsherry]

Hybrid *might* make sense if you have no access to gas/propane. I don't think it can be cheaper to run than those, so you'd never payback for the higher initial cost.

And I really question the life of the heat pump in these. I had a dehumidifier (same technology) die before the end of the 2nd season.

And if you don't have a spot you want cooled, you'll end up paying to heat the cold air it kicks out. So pretty specific conditions, and I still worry about the lifespan, especially with the higher cost.

-ERD50

Most hybrid water heaters have a 10 year warranty. I had my last house for 8 years and had no problem with the hybrid. That house didn't have access to gas, so it was the best option. BTW, new owner hasn't had any issues. So that's 9 years. Compared to electric the payback is about 2 years so the savings has more than been covered by the higher cost of the hybrid. With gas at new home it was nice that builder included the tankless. The tankless has a bit more maintenance, needs to be flushed yearly and it's not as simple as a regular tank water heater to flush out. Fortunately a buddy of mine is a plumber and will do the job cheaply.

Also, my AC here is FL is also a heat pump, have had no issues so not sure of the concern of heat pump.

 

[bobandsherry]

Agree ERD50.

But the heat pump? Oh my. Cheap, thin refrigerant tubes that "can't be repaired" are only the beginning.

I still really like the concept, but if they are making a typical 5 to 7 year throw away appliance, they can keep it.

It's not a cheap throw away, most hybrid water heaters have 10 year warranty. Mine was AO Smith brand, 10 year warranty. That's longer than any regular tank water heater I've owned.

 

[ERD50]

It's not a cheap throw away, most hybrid water heaters have 10 year warranty. Mine was AO Smith brand, 10 year warranty. That's longer than any regular tank water heater I've owned.

Well, the payback (compared to tank electric), is better than I would have thought. I'm seeing $489 vs $117 annual cost for the popular 50G versions at Home Depot. So that's about a 3 year payback ( $1466 purchase cost vs $409 - again, assuming you aren't needing to heat the cold output!), which is very good.

I still am concerned about the total environmental cost of these things leaking refrigerant over time, and all the embedded environmental cost of a compressor system vs a heating element (dead simple/cheap).

-ERD50

 

[bobandsherry]

Well, the payback (compared to tank electric), is better than I would have thought. I'm seeing $489 vs $117 annual cost for the popular 50G versions at Home Depot. So that's about a 3 year payback ( $1466 cost vs $409 - again, assuming you aren't needing to heat the cold output!), which is very good.



I still am concerned about the total environmental cost of these things leaking refrigerant over time, and all the embedded environmental cost of a compressor system vs a heating element (dead simple/cheap).



-ERD50

Which is why I started my original comment saying "I'm in FL and last house had a Hybrid WH (electric) - it worked great and was very efficient. It was installed in the garage so lots of hot air to pull to heat the water and the garage was cooled a few degrees too". So it was actually cooling a hot zone slightly, so I guess I can consider that an additional savings.

There is also an additional savings to be considered, with a tiered rate, the hybrid lowers the peak summer time use when rates at higher tier are 2x the base level, saves a few bucks more by lowering the kwh used at the higher tier.

I also mentioned that it probably wouldn't be a good option in cooler areas.

As for environmental concerns, lower energy use and therefore less pollutants being generated from electricity production over its lifetime may offset partially or fully the environmental impacts.

 

[ERD50]

....

As for environmental concerns, lower energy use and therefore less pollutants being generated from electricity production over its lifetime may offset partially or fully the environmental impacts.

I understand your other points, I was just pointing them out for the general case.

And the "may" offset is the question (and I don't know the answer).

-ERD50

 

[JoeWras]

It's not a cheap throw away, most hybrid water heaters have 10 year warranty. Mine was AO Smith brand, 10 year warranty. That's longer than any regular tank water heater I've owned.

That's great. But I would like to hear about how that 10 year warranty works out when there's a problem. Because some of the stories about long warranties on HVAC systems are legendary. And not good.

It usually revolves around the fact these are limited warranties that only include labor the first year. After that you get reamed by labor costs.

AO Smith is no different. From their Voltex hybrid warranty sheet: "For the first year only, warrantor will provide for onsite service or labor to replace a defective part or tank using a factory authorized service professional"

You can be sure that anything like a leaking evaporator is going to incur a huge labor charge. After all, that's one argument HVAC contractors use to replace instead of fix.

Just my opinion. Look I LIKE THE IDEA OF HEAT PUMP WATER HEATERS. What I don't like is the current state of affairs with our terrible refrigeration design and manufacturing, for all products.

 

[euro]

Well, the payback (compared to tank electric), is better than I would have thought. I'm seeing $489 vs $117 annual cost for the popular 50G versions at Home Depot. So that's about a 3 year payback ( $1466 purchase cost vs $409 - again, assuming you aren't needing to heat the cold output!), which is very good.

I still am concerned about the total environmental cost of these things leaking refrigerant over time, and all the embedded environmental cost of a compressor system vs a heating element (dead simple/cheap).

-ERD50

I'm not sure I really understand that assumption (of not needing to heat the cold output). These systems always use indoor air (and don't draw from outside), right? So, in the winter, clearly, you will have to somehow heat the air that then gets used by the water heater heat pump. Or are we assuming that there is actually an added benefit in the Summer in that the system actually provides extra air conditioning. And somehow the winter/Summer situations are a wash?

 

[JoeWras]

I'm not sure I really understand that assumption (of not needing to heat the cold output). These systems always use indoor air (and don't draw from outside), right? So, in the winter, clearly, you will have to somehow heat the air that then gets used by the water heater heat pump. Or are we assuming that there is actually an added benefit in the Summer in that the system actually provides extra air conditioning. And somehow the winter/Summer situations are a wash?

I think it is very situation dependent. It depends a lot on the location of the heater. Mine is in a basement garage, in the south USA. Garage water heaters are very common in the south. This is perhaps the ultimate location. In summer, it will cool off the garage, which I use as a workspace. I don't condition this space, so a little cool would be welcome. In the winter, the cars heat up this space some. A little cool won't matter. As a workshop, I'd just put on a sweat shirt. And our winters don't get too severe so the temperature rare gets to cold in this garage.

If the device is in a closet in the living space, it changes everything.

If the device is in a northern basement, it also can be an issue.