OT: Tankless Water Heaters

[NHAero]

Despite the power of TV, physics will prevail. You can calculate the energy required at 100% efficiency to raise a gallon of water 70F, and that's what determines the power in kW required.

I wonder if what you refer to is about the switch from electric resistance tank-type water heaters to heat pump water heaters (both with tanks, both not instantaneous.) Heat pump water heaters are our "go-to" strategy and they save 2/3 of the cost of heating water with an electric water heater, and here where there is no natural gas they are much cheaper to run than propane.

Originally Posted by alancw3

on a recent episode of "this old house" they addressed the new generation of tankless electric whole house water heaters. from what i gathered the manufacturers have eliminated the problems of prior electric tankless heaters. you might want to do a search of "this old house" episodes.

[General69]

I installed one myself 5 years ago. Took about 16 hours with the copper sweating, gas line configuration, and new exhaust. I can install a tank heater in 30 minutes! You can find 1 year old tank units for $100 (I use them for my rental units) on the secondary market. Even with a self install, this unit was double what a tank cost. The return on investment is non-existent. Throw in the yearly maintenance and I would not recommend one unless you have space issues.

I have been having issues with the hot water sometimes not turning on. I will have to turn off the faucet and the second time the hot water will flow. This issue is only on the kitchen sink. The bathroom, bar, shower all turn on every time. Weird.

You also have to flush it with vinegar once a year. Turn off the bypass valves, fill a bucket with vinegar, then use a sump pump and hose to run the vinegar through the lines.

[Elefantino]

We have a Rinnai as well but the water, at the manufacturer limited maximum of 120 degrees, was not warm enough. We hacked the board and now it pumps out at 135, much better.

[El Chaba]

Originally Posted by General69

I installed one myself 5 years ago. Took about 16 hours with the copper sweating, gas line configuration, and new exhaust. I can install a tank heater in 30 minutes! You can find 1 year old tank units for $100 (I use them for my rental units) on the secondary market. Even with a self install, this unit was double what a tank cost. The return on investment is non-existent. Throw in the yearly maintenance and I would not recommend one unless you have space issues.

I have been having issues with the hot water sometimes not turning on. I will have to turn off the faucet and the second time the hot water will flow. This issue is only on the kitchen sink. The bathroom, bar, shower all turn on every time. Weird.

You also have to flush it with vinegar once a year. Turn off the bypass valves, fill a bucket with vinegar, then use a sump pump and hose to run the vinegar through the lines.

This. We have natural gas which is very economical. The plumbing/installation cost of installing a tankless heater would push the point of positive return WAY into the future. FWIW, we have hot water heat and shut off the water heater in the winter and use hot water from the boiler which eliminates the redundancy of the extra boiler running (the water heater).

[buddybikes]

We were in situation where our gas boiler over 40 years old, but water tank about 7 years. We cut out the whole thing, Much more space and cleaner!, as well as new piping in basement with duo heating/water.

Again - look at energy rebates in your area this could turn financial decisions around, we got 1,300 back from national grid.

[Tony Edwards]

I asked my plumber (a master plumber who also happens to be an electrical engineer) about tankless a few years ago and he strongly discouraged it. He said his company's customers who'd gone tankless tended to be unsatisfied and frustrated by the maintenance costs and the fact that (according to him) they are not well suited to a cold climate like ours. Given that he could have billed me a substantial amount to do an install I took him at his word that it wasn't a good idea.

[alancw3]

Originally Posted by NHAero

Despite the power of TV, physics will prevail. You can calculate the energy required at 100% efficiency to raise a gallon of water 70F, and that's what determines the power in kW required.

I wonder if what you refer to is about the switch from electric resistance tank-type water heaters to heat pump water heaters (both with tanks, both not instantaneous.) Heat pump water heaters are our "go-to" strategy and they save 2/3 of the cost of heating water with an electric water heater, and here where there is no natural gas they are much cheaper to run than propane.

i am far from an expert on tankless water heater but in this episode it was definitely
a new generation of electric tankless water heaters. emphasized because of all the prior problems with electric tankless. don't hold me to this because it was awhile ago but something about amperage possibly? the way rich tutuiy said it this was something completely new.

[PSJoyce]

We installed a Navien NCB combo boiler - hot water two years ago. It saves a lot of space, has not really saved on energy costs.

The thing that has caused the most grief is the acidic waste water condensate. We've got a neutralizing pump to pump the waste water up and out through the basement wall. Problem here is Massachusetts is that it gets cold outside in winter, and we've had several episodes of the water drain freezing outside, leading to overflows of the neutralizing pump if we're away. We've gone through several configurations of the outside drain and will find out this winter if it's finally solved.

[NHAero]

Don't know. One consistent issue of tankless water heaters is that you have to look at the minimum flow rate needed to get a unit to start. In some of the larger gas units, it can be over 1/2 gallon per minute, which can annoy people who dribble the faucet while brushing their teeth

Originally Posted by alancw3

i am far from an expert on tankless water heater but in this episode it was definitely
a new generation of electric tankless water heaters. emphasized because of all the prior problems with electric tankless. don't hold me to this because it was awhile ago but something about amperage possibly? the way rich tutuiy said it this was something completely new.

[Louis]

Originally Posted by NHAero

In some of the larger gas units, it can be over 1/2 gallon per minute, which can annoy people who dribble the faucet while brushing their teeth

But who in the world needs hot, warm, or even lukewarm water to brush their teeth? "Cold" works fine for me. I put it in quotes because it's actually room temp, since brushing your teeth uses next to zero water, so I just use what's in the pipe that has been warmed to room temperature. (plus I don't "dribble")

Edit: I know, I'm a real hard man!

[greenlawnracing]

Did not read all four pages, but my last two houses have been builder grade spec houses with low end tankless water heaters.

Love them

Was relocated for a few years in between houses and rented homes with conventional water heaters.

Hated them

It's just myself, my wife, and a baby, but if you have any need for an endless supply of hot water this is the only way to roll.

Only downside is that it feels like it takes longer to get hot water once you turn the faucet or shower on.

[joosttx]

Update: The tankless water heater was installed last week. Its a Navien NPE240A. It heats up super quick and I need maintenance once a year which costs $100. Satisfied with it thus far.

I am interested to see if there are any energy savings.

[pasadena]

Have had tankless for 10 yrs
Takaga is one of the best units.

It's far safer, far more energy efficient and just makes economical sense.
I change the filter a couple times a year and that's all the maintenance it's needed.

[donevwil]

Originally Posted by joosttx

Update: The tankless water heater was installed last week. Its a Navien NPE240A. It heats up super quick and I need maintenance once a year which costs $100. Satisfied with it thus far.

I am interested to see if there are any energy savings.

What's included in the maintenance that will be provided ?

Although they are relatively easy to service I can appreciate an inexpensive option to one more yearly task that will inevitably get postponed.

Sent from my LM-X410UM using Tapatalk

[joosttx]

Originally Posted by donevwil

What's included in the maintenance that will be provided ?

Although they are relatively easy to service I can appreciate an inexpensive option to one more yearly task that will inevitably get postponed.

Sent from my LM-X410UM using Tapatalk

descaling and inspection. its kinda how I see it too.