ISO Recommendations RHEEM ELECTRIC Tankless Hot Water Heater

LightRoasted

If I may ...
If I may ...

That is not entirely true. I installed an electric tankless and have been pleased with the performance and savings.
Please provide the numbers. Total costs=Cost of heater, installation costs, material costs etc. vs electrical costs savings per month or annualized. Please.
 

Goldenhawk

Well-Known Member
Please provide the numbers. Total costs=Cost of heater, installation costs, material costs etc. vs electrical costs savings per month or annualized. Please.
I'd also be curious about the numbers, but it's not necessarily relevant. Total costs are not always the defining factor for "pleased with the savings". He may never reach payback - but he can still be pleased with a lower monthly bill, as well as being pleased with the unlimited hot water.

For example, I'm considering installing in-floor heating when we replace carpet with tile in a large room. I expect to be pleased with the warm floor, period. I also expect to be pleased that it will cost less to heat that room - while I'm also fully aware that the monthly cost decrease will NEVER pay for the cost of installation. I consider it an acceptable tradeoff for the luxury.
 

Chris0nllyn

Well-Known Member
I'd also be curious about the numbers, but it's not necessarily relevant. Total costs are not always the defining factor for "pleased with the savings". He may never reach payback - but he can still be pleased with a lower monthly bill, as well as being pleased with the unlimited hot water.

For example, I'm considering installing in-floor heating when we replace carpet with tile in a large room. I expect to be pleased with the warm floor, period. I also expect to be pleased that it will cost less to heat that room - while I'm also fully aware that the monthly cost decrease will NEVER pay for the cost of installation. I consider it an acceptable tradeoff for the luxury.
What's more relevant is the number of users.

If it's one person who works a ton, it may cost more to heat the water and not use it (in a traditional tank heater) vs. on demand heating (even though extended on demand use would drive up the electricity costs).
 

Goldenhawk

Well-Known Member
This calculator
https://ouc.bizenergyadvisor.com/BEA1/PA/PA_WaterHeating/PA-23_calc
(assuming $0.13/kWh and $3.25/gallon of propane)

implies that if you use 100 gallons of hot water a day, you'd save about $30/year (~3%) switching from an efficient standard electric water heater to a tankless heater; propane-fueled would be rather more expensive right now.

Not a huge savings.

A MUCH bigger savings would come from installing a heat-pump water heater (~$300-400/year, or 50%-75% savings).
https://smud-heatpumph2o.org/calc.php

However, I consider that a questionable savings since it's rather cheap to fix a standard electric resistance heater (often a $15 part), compared to fixing a heat pump (hundreds of dollars for most repairs).
 

JEFF69Z28

Active Member
What's more relevant is the number of users.

If it's one person who works a ton, it may cost more to heat the water and not use it (in a traditional tank heater) vs. on demand heating (even though extended on demand use would drive up the electricity costs).
Im not truly convinced that you will save a bunch of money with a tankless system as to me you use more electric on demand to heat the water than you will with it sitting in a tank at 120* waiting to be used It would seem that on demand would draw far more amps that a water heater but I do see other peoples points also..its like the set back thermostat why would you have your home at lets say 63* when your not home and then an hour before you get home your furnace comes on and runs for maybe an hour or more to to heat your home up to what ever temp you have it set to its to me anyways you would use more electric to do it that way...maybe some one can convince me otherwise...jmo
 

black dog

Free America
Im not truly convinced that you will save a bunch of money with a tankless system as to me you use more electric on demand to heat the water than you will with it sitting in a tank at 120* waiting to be used It would seem that on demand would draw far more amps that a water heater but I do see other peoples points also..its like the set back thermostat why would you have your home at lets say 63* when your not home and then an hour before you get home your furnace comes on and runs for maybe an hour or more to to heat your home up to what ever temp you have it set to its to me anyways you would use more electric to do it that way...maybe some one can convince me otherwise...jmo
Totally incorrect... I have two NG Renni tankless heaters and I easily save 40 to 60 bucks a month on not having 50 gallons of hot water sitting there doing nothing.
I easily have 120° hot water out of 4+ fixtures for as long as I wish and when I shut off the fixture the gas meter stops spinning.. I would never install an electric tankless.. NG or LP....
 

Goldenhawk

Well-Known Member
Im not truly convinced that you will save a bunch of money with a tankless system ... maybe some one can convince me otherwise...jmo
It has everything to do with imperfect insulation.

Fact 1. It costs a certain amount of energy to raise the temperature of water a certain amount. That's extremely well-established physics. In this area, ground water temperature averages 55 deg F. If you have 40 gallons to heat up from 55 deg ground temperature to 120 deg, a difference of 65 deg F, that takes 22,888,271 joules, or 5449588 calories, or 6.36Wh, or 21,694 BTU, depending on your unit system. That number is fixed - it's pure science. At roughly $0.13/KWh, the local SMECO rate, that is about $0.83 in electricity.

Thus, no matter which system you select, that cost of raising the temperature is an absolutely fixed number.

But...

Fact 2. No insulation is perfect. A higher difference in temperature leaks heat out faster than a small difference in temperature. Thus, hot water inside a tank gets cool faster than less-hot water inside the tank. If you heat up the water to 120 and let it sit... that heat leaks out over time, through the insulation. So keeping the water hot and ready has a certain cost to it.

And then there's the equipment cost...

Fact 3. Tankless systems cost more. This offsets some (maybe all) of the energy cost savings.
Fact 4. Your wiring must be able to support the power draw. You might need it upgraded. Or you might need a propane tank installed.

Good article:
https://www.digitaltrends.com/home/tank-vs-tankless-water-heaters/
 

JEFF69Z28

Active Member
Totally incorrect... I have two NG Renni tankless heaters and I easily save 40 to 60 bucks a month on not having 50 gallons of hot water sitting there doing nothing.
I easily have 120° hot water out of 4+ fixtures for as long as I wish and when I shut off the fixture the gas meter stops spinning.. I would never install an electric tankless.. NG or LP....
How about your bill for propane does it not more than cost of electricity just curious as I have a heat pump with propane back up for heat and my electric bill last month for my 3100 sq/ft home was 129.00 but then I had my 2 100 gallon tanks filled from about 45-50% full to 80% full and that was 268.00 if your wondering why 80% it is the law I think as there has to be room for expantion of the propane,now just for sh!ts and giggles my compressor took a dump on my 18 year old system so I turned the outdoor stat up to 60* so Iam now heating all the time with propane until it warms up and I can install my new outdoor system.I will now see what is cheaper buy the month heat pump and gas heat below 38* or straight up propane which I useing now.
 

nutz

Well-Known Member
If I may ...



Please provide the numbers. Total costs=Cost of heater, installation costs, material costs etc. vs electrical costs savings per month or annualized. Please.
My 50 gallon standard electric heater was due for change (tank leak) A new 50 gallon replacement was ~450.00. I purchased an eco smart tankless for $499.99, then purchased 3 CBS at ~25.00 each, I had #6 wire on hand from wiring barn. I needed 2-3/4” tees, 2-3/4” male adapters, and 2-3/4” caps so under 10.00, torch, solder, flux and rags on hand.
For the last year, my electric bill has averaged 13 dollars less per month, but I also changed 90 percent of lighting to LED.

And with all that, SMECO still says I am less efficient than my neighbors. Wish I knew which ones so I could ask what they’ve done.
 

BadGirl

I am so very blessed
We have 42 solar panels as well as a great tankless gas water heater. I am very pleased with our set up, and with our calculations, we will break even in our initial output in about seven years. We purchased the solar panels and water heater outright.
 

black dog

Free America
How about your bill for propane does it not more than cost of electricity just curious as I have a heat pump with propane back up for heat and my electric bill last month for my 3100 sq/ft home was 129.00 but then I had my 2 100 gallon tanks filled from about 45-50% full to 80% full and that was 268.00 if your wondering why 80% it is the law I think as there has to be room for expantion of the propane,now just for sh!ts and giggles my compressor took a dump on my 18 year old system so I turned the outdoor stat up to 60* so Iam now heating all the time with propane until it warms up and I can install my new outdoor system.I will now see what is cheaper buy the month heat pump and gas heat below 38* or straight up propane which I useing now.
I have a 500 gallon tank at the farm for the tankless, stove and dryer. I only have to fill it once every few years. The last fill was about 1.30? A gallon if I remember correctly.
I rotate between two homes and the tankless is the best bang for me. When I walk out it doesn't cost anything money and it's easy to drain if the house freezes.
If a few friends show up to hunt or good off it will provide you with endless in both bathrooms and kitchen at the same time for as long as needed.
Same with the house, she can fill up the bathtub while I do dishes and jump in the other shower and the hot water never been ends.

I have never done a true cost analysis, but I'm quite sure I save at least 20-50 bucks a month depending on what's going on at the time.
When I installed both of mine I installed the extra valves for draining and servicing convenience, I flush out the heat exchangers once a year with Renni's chemicals and I've never had any problems with them..
 

spr1975wshs

Mostly settled in...
PREMO Member
I need to get the flush valves for mine and do a good run through with a CLR type cleaning fluid.
 

DoWhat

Go Trump!!!!!
PREMO Member
I need to get the flush valves for mine and do a good run through with a CLR type cleaning fluid.
I use white vinegar. I would think CLR would be too harsh.

[video=youtube;T4FaqGod3VU]https://www.youtube.com/watch?v=T4FaqGod3VU[/video]
 
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