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I need to update my home hot water heater. I'd like a tankless instant hot water heater. Despite wanting to do my part for climate change, all indications poi

I need to update my home hot water heater. I'd like a tankless instant hot water heater. Despite wanting to do my part for climate change, all indications point me towards getting as natural gas unit instead of electric.

conk 5y ago
I’m curious why your preference is for tankless?
- Maximus9000 5y ago
  * Saves space in utility room * uses less energy * never run out of hot water * units are longer lasting
  - conk 5y ago
    I’ve had tankless and now have a rheem heat pump water heater. The rheem uses far less energy (~60 kWh/mo) then the instant water heater. Lifespan I’m not so sure about. I know depending on the water quality they can have issues. I’ve seen many tank water heaters still working after 30 years with little to no service. Tankless are smaller and it’s true they won’t run out of hot water so they do have that going for them.
  - ip26 5y ago
    An idea for you - consider an electric tanked with a drain water heat recovery unit. Even lower energy usage than a tankless, and while you can still run out of hot water the DWHR significantly accelerates the re-heating. The DWHR unit should last basically forever. This is what I did, been very happy. Total cost wasn't more than $1,600 (DIY). Tankless is a nice idea but was just too complicated to ever pay for itself as a retrofit.
    - ip26 5y ago
      Just to be explicit on the cost, it was something like: Electric Tanked WH: $600 DWHR: $800 Parts, pipe, new electrical circuit, new breaker, etc: $200
jjtheblunt 5y ago
I propose that you're improving things with tankless, regardless of heating technology. We just did the same on our 2014 house, which had a builder supplied 50gallon natural gas water heater. Those continually burn natural gas in varying amounts to keep the tank's water heated. In contrast, the tankless natural gas is a massive win just wrt natural gas, as it's only running when hot water flow is required.
- djrogers 5y ago
  > Those continually burn natural gas Not really - they're very well insulated, so they do a burn/coast/burn cycle where they are off far more than they are on. That said - I'm a big fan of tankless, however in a big family with typical loads, the savings in gas alone aren't as much as you'd think.
- danans 5y ago
  Tankless gas water heaters have been demonstrated to not be very efficient, and also require a great deal of maintenance due to the very high BTU burner they require. Here's Matt Risinger's take: https://www.youtube.com/watch?v=8RFuFBI3r2c https://www.youtube.com/watch?v=8RFuFBI3r2c
  - jessaustin 5y ago
    Risinger is entertaining, and is rarely afraid to spend more on construction, but in general his opinions seem to conform very closely to the commercial interests of his biggest sponsors. The biggest objection at your link seems to be that tankless allows long showers? What kind of ridiculous objection is that? There are big yellow efficiency tags on the front of every appliance for sale in USA. The content of those tags is closely regulated by the government. If there is some reason to believe that they are inaccurate for tankless water heaters, please link to that.
    - danans 5y ago
      Let me rephrase: Tankless gas water heaters (90-97% efficient) aren't anywhere near as efficient as more modern alternatives, specifically heat pump water heaters, which are 300-400% efficient. They are are marginally more efficient than condensing storage gas water heaters, which are 89% efficient. Given the gulf in efficiency between tankless gas and heat pump water heaters, tankless gas shouldn't really be promoted as examples of high efficiency. https://www.energystar.gov/productfinder/product/certified-water-heaters/?formId=8423992-4636-4-89-377412206&scrollTo=141&search_text=&type_filter=&fuel_filter=&brand_name_isopen=0&input_rate_thousand_btu_per_hour_isopen=0&markets_filter=United+States&zip_code_filter=&product_types=Select+a+Product+Category&sort_by=brand_name&sort_direction=desc&currentZipCode=94604&page_number=0&lastpage=0 https://www.energystar.gov/productfinder/product/certified-w...
lastofthemojito 5y ago
I went from a traditional (tank) gas water heater to a tankless gas water heater in my townhouse. I don't have any complaints about the performance of the water heater itself, but the process was a pain and I have had complaints from my neighbors about the gas smell when the water heater kicks on. Your mileage will almost certainly vary, but in my case the upgrade to a tankless water heater meant that the max gas draw for my house (if the water heater, furnace, stove and gas fireplace were all firing at once) would exceed the existing gas service to my house. So I had to get the gas company out to upgrade my service, which meant having the existing utility lines located multiple times (as the first markings washed away by the time the gas company came out), and I had bits of my yard dug up, etc. I also had to have county inspection folks come visit, and coordinate that with the plumber, etc. The exhaust for my water heater is right next to the border with my neighbor's townhouse, and they've got a deck at right about that level. And it turns out when a tankless water heater kicks on, the gas comes on for a second and then it ignites, pushing a small amount of unburned gas out the exhaust. My neighbors occasionally catch a whiff of that, and I've had to have the installer visit and get on the phone with the water heater manufacturer (Rinnai) to reassure them that everything is safe and working correctly. All told, if I knew then what I know now, I would have just gotten a new tank water heater - and I'm sure the entire process would have been over and done in a day, with no damage to the lawn or skittish neighbors. The guy who installed my water heater was a nice guy but I would have been happier meeting him once rather than a half dozen times. But if you wouldn't have to have upgrade your gas service or aren't worried about the exhaust location - by all means, join me in having infinite hot water!
- jhallenworld 5y ago
  Interesting, some of those older tank-less systems only kicked in if the flow rate was high enough. I used to have a really old tank-less system from the 1940s, it was just a heat exchanger in my oil heating steam boiler. This was massively inefficient, but it did provide infinite hot water.. My only complaint with my new (2013) tank gas hot water, is that the tank already cracked and had to be replaced. It was not cheap: $2200. This is a rip-off, but contractors are expensive. I think the new tank-less systems are supposed to be more reliable than traditional tank heaters.
sokoloff 5y ago
Consider also a heat pump water heater (often called “hybrid” as a category label even when some are not). Allows you to stay/switch to electric without the massive instant demand that a tankless instant requires. Dehumidifies and cools the utility area as well, which is helpful for some cases.
eyelovewe 5y ago
A rooftop solar heater 200 liters, plus an electric supplemental water heater plus the requisite control system runs about 2000 euros here, INSTALLED (Portugal)

conk 5y ago

I’m curious why your preference is for tankless?

Maximus9000 5y ago
* Saves space in utility room * uses less energy * never run out of hot water * units are longer lasting
- conk 5y ago
  I’ve had tankless and now have a rheem heat pump water heater. The rheem uses far less energy (~60 kWh/mo) then the instant water heater. Lifespan I’m not so sure about. I know depending on the water quality they can have issues. I’ve seen many tank water heaters still working after 30 years with little to no service. Tankless are smaller and it’s true they won’t run out of hot water so they do have that going for them.
- ip26 5y ago
  An idea for you - consider an electric tanked with a drain water heat recovery unit. Even lower energy usage than a tankless, and while you can still run out of hot water the DWHR significantly accelerates the re-heating. The DWHR unit should last basically forever. This is what I did, been very happy. Total cost wasn't more than $1,600 (DIY). Tankless is a nice idea but was just too complicated to ever pay for itself as a retrofit.
  - ip26 5y ago
    Just to be explicit on the cost, it was something like: Electric Tanked WH: $600 DWHR: $800 Parts, pipe, new electrical circuit, new breaker, etc: $200

jjtheblunt 5y ago

I propose that you're improving things with tankless, regardless of heating technology. We just did the same on our 2014 house, which had a builder supplied 50gallon natural gas water heater. Those continually burn natural gas in varying amounts to keep the tank's water heated. In contrast, the tankless natural gas is a massive win just wrt natural gas, as it's only running when hot water flow is required.

djrogers 5y ago
> Those continually burn natural gas Not really - they're very well insulated, so they do a burn/coast/burn cycle where they are off far more than they are on. That said - I'm a big fan of tankless, however in a big family with typical loads, the savings in gas alone aren't as much as you'd think.
danans 5y ago
Tankless gas water heaters have been demonstrated to not be very efficient, and also require a great deal of maintenance due to the very high BTU burner they require. Here's Matt Risinger's take: https://www.youtube.com/watch?v=8RFuFBI3r2c https://www.youtube.com/watch?v=8RFuFBI3r2c
- jessaustin 5y ago
  Risinger is entertaining, and is rarely afraid to spend more on construction, but in general his opinions seem to conform very closely to the commercial interests of his biggest sponsors. The biggest objection at your link seems to be that tankless allows long showers? What kind of ridiculous objection is that? There are big yellow efficiency tags on the front of every appliance for sale in USA. The content of those tags is closely regulated by the government. If there is some reason to believe that they are inaccurate for tankless water heaters, please link to that.
  - danans 5y ago
    Let me rephrase: Tankless gas water heaters (90-97% efficient) aren't anywhere near as efficient as more modern alternatives, specifically heat pump water heaters, which are 300-400% efficient. They are are marginally more efficient than condensing storage gas water heaters, which are 89% efficient. Given the gulf in efficiency between tankless gas and heat pump water heaters, tankless gas shouldn't really be promoted as examples of high efficiency. https://www.energystar.gov/productfinder/product/certified-water-heaters/?formId=8423992-4636-4-89-377412206&scrollTo=141&search_text=&type_filter=&fuel_filter=&brand_name_isopen=0&input_rate_thousand_btu_per_hour_isopen=0&markets_filter=United+States&zip_code_filter=&product_types=Select+a+Product+Category&sort_by=brand_name&sort_direction=desc&currentZipCode=94604&page_number=0&lastpage=0 https://www.energystar.gov/productfinder/product/certified-w...

lastofthemojito 5y ago

I went from a traditional (tank) gas water heater to a tankless gas water heater in my townhouse. I don't have any complaints about the performance of the water heater itself, but the process was a pain and I have had complaints from my neighbors about the gas smell when the water heater kicks on. Your mileage will almost certainly vary, but in my case the upgrade to a tankless water heater meant that the max gas draw for my house (if the water heater, furnace, stove and gas fireplace were all firing at once) would exceed the existing gas service to my house. So I had to get the gas company out to upgrade my service, which meant having the existing utility lines located multiple times (as the first markings washed away by the time the gas company came out), and I had bits of my yard dug up, etc. I also had to have county inspection folks come visit, and coordinate that with the plumber, etc. The exhaust for my water heater is right next to the border with my neighbor's townhouse, and they've got a deck at right about that level. And it turns out when a tankless water heater kicks on, the gas comes on for a second and then it ignites, pushing a small amount of unburned gas out the exhaust. My neighbors occasionally catch a whiff of that, and I've had to have the installer visit and get on the phone with the water heater manufacturer (Rinnai) to reassure them that everything is safe and working correctly. All told, if I knew then what I know now, I would have just gotten a new tank water heater - and I'm sure the entire process would have been over and done in a day, with no damage to the lawn or skittish neighbors. The guy who installed my water heater was a nice guy but I would have been happier meeting him once rather than a half dozen times. But if you wouldn't have to have upgrade your gas service or aren't worried about the exhaust location - by all means, join me in having infinite hot water!

jhallenworld 5y ago
Interesting, some of those older tank-less systems only kicked in if the flow rate was high enough. I used to have a really old tank-less system from the 1940s, it was just a heat exchanger in my oil heating steam boiler. This was massively inefficient, but it did provide infinite hot water.. My only complaint with my new (2013) tank gas hot water, is that the tank already cracked and had to be replaced. It was not cheap: $2200. This is a rip-off, but contractors are expensive. I think the new tank-less systems are supposed to be more reliable than traditional tank heaters.

sokoloff 5y ago

Consider also a heat pump water heater (often called “hybrid” as a category label even when some are not). Allows you to stay/switch to electric without the massive instant demand that a tankless instant requires. Dehumidifies and cools the utility area as well, which is helpful for some cases.

eyelovewe 5y ago

A rooftop solar heater 200 liters, plus an electric supplemental water heater plus the requisite control system runs about 2000 euros here, INSTALLED (Portugal)