Aosmith hybrid water heaters wasted $

[Delmar]

My existing water heater is in an attic space. I'd rather not put a regular heat pump water heater in there.

Even though it would be a PITA to install, the attic would be an ideal location. All the waste heat from the house rises to the attic and would make the HPWH operate more efficient.

There are good and garbage appliances no different than refrigerators or HVAC. Unfortunately nobody posts about good experiences, only when things go wrong.

 

[jberger]

I'd suggest anyone looking at the Rheem HP Water Heaters read this thread over at GBA before you purchase.

Noisy Rheem Hybrid Water Heater - GreenBuildingAdvisor

Does anyone have a Rheem hybrid water heater and is the noise excessive? We just had a 65 gallon unit installed in our new house and whether it is in […]

www.greenbuildingadvisor.com

To be clear, I'll probably get one of these myself, but I just wanted to pass along the thread so you know what you might be getting into .

 

[timselectric]

Even though it would be a PITA to install, the attic would be an ideal location. All the waste heat from the house rises to the attic and would make the HPWH operate more efficient.

I've replaced that water heater twice, it's not that bad. (Horizontal access from top floor)
Temperature wise, it's only ideal in the summer.
My concern is humidity and winter freezing.

 

[timselectric]

I'd suggest anyone looking at the Rheem HP Water Heaters read this thread over at GBA before you purchase.

Noisy Rheem Hybrid Water Heater - GreenBuildingAdvisor

Does anyone have a Rheem hybrid water heater and is the noise excessive? We just had a 65 gallon unit installed in our new house and whether it is in […]

www.greenbuildingadvisor.com

To be clear, I'll probably get one of these myself, but I just wanted to pass along the thread so you know what you might be getting into .

Another reason why I want my unit outside.

 

[NEpowerandlight]

My gas bill is $8/month. That's water heater and stove. Of course, we don't have kids taking lots of showers and getting lots of clothes dirt.
(Calculate savings compared to THAT!)

My last Kenmore gas water heater came with the house, lasted an additional 21 years.
I blame its demise on a braided hose I installed, which rusted at the crimp, leaked and dripped water over outside of tank.
I'm using bendable stainless now.

"Lasts years" sounds like a fluke, failure of planned obsolescence.
Some compressor based systems do last decades (some of my refrigerators), but I don't think most consumer products today can.

On a lifetime 'per kWh of delivered heat' basis, heat pumps are about as carbon intensive as natural gas or LPG in heating.

Also hydrofluorocarbon (HFC) gases are as much as 2,000 times more potent in heating the atmosphere than garden variety carbon dioxide. At least six published studies, including one from a heat pump and refrigeration centre in Germany way back in 1994, have pointed out that HFCs leak from heat pumps both during their typical 15-18 years of operation and upon decommissioning.

 

[bones1]

I'd suggest anyone looking at the Rheem HP Water Heaters read this thread over at GBA before you purchase.

Noisy Rheem Hybrid Water Heater - GreenBuildingAdvisor

Does anyone have a Rheem hybrid water heater and is the noise excessive? We just had a 65 gallon unit installed in our new house and whether it is in […]

www.greenbuildingadvisor.com

To be clear, I'll probably get one of these myself, but I just wanted to pass along the thread so you know what you might be getting into .

I believe that was the case for the 240volt models that are available now. Supposedly the new 120v models are better in that regard but too
new to tell. Only available in Calif so far.

 

[soylentgreen]

As a counterpoint, I’ve had an A.O. Smith hybrid, heat pump water heater for four years, and I’ve been perfectly happy with it. Maybe I got lucky? Maybe you got un lucky?

 

[OzSolar]

I believe that was the case for the 240volt models that are available now. Supposedly the new 120v models are better in that regard but too
new to tell. Only available in Calif so far.

Oh my..

Something else that may not be immediately obvious about these HP water heaters is that they will cool the area around them. If it's in that little closet in a garage in Texas common to many spec homes no big deal.

However if it's in the middle of house in MN with 5 kids then you're dumping a lot cold air into conditioned space that needs to be heated back up.

I think most of these allow you to select HP or straight resistance mode so you'd want to actively manage that when needed.

 

[soylentgreen]

On a lifetime 'per kWh of delivered heat' basis, heat pumps are about as carbon intensive as natural gas or LPG in heating.

Do you have a citation for that? I find it hard to believe, because it takes about 2 kg of CO2 to make a kilogram of steel.

If we assume the hybrid, hot water heater is made of solid steel, then the break even point would be at about 200 kg of natural gas saved,
At 13.6 kilowatt hours per kilogram, this would happen for most people within 3 to 4 months? (I’m on mobile right now, so someone please check my math )

edit to add:
My calculations are assuming that the electricity is 100% renewable. That is obviously optimistic in some locations.

however, I also forgot to divide by 2.75 because each kilogram of natural gas burned releases that much CO2. If you account for this, the payback-time is even shorter.

 

[Nobodybusiness]

You scoundrel! Look at my Home Depot shopping cart. Literally seconds away from pulling the trigger on a HP water heater. I bet I have had one these in my shopping cart 10 times in the last 4 years but I keep seeing stories like yours and get cold feet.

Thanks for sharing and sorry about your luck.

View attachment 124200

Rheem isn’t AO smith. I have personally never heard anyone had any problems with Rheem although they may have and I’m just out of the loop.

 

[Rocksnsalt]

Wow we pretty much have a (civil) dumpster fire conversation over heat pump H2O heaters.
Which imho confirms they are a complex solution to a simple task.
And 4 years of trouble free service so far? ?
I think my grandparents natural gas water heater was over 30 years old when it was replaced.
Seems challenging to find one that’ll last over 5 or 6 years now. Engineered failure clock.

 

[timselectric]

Generating repeat business is not a new concept.
But, it's definitely more widely adopted now.

 

[Supervstech]

Wow we pretty much have a (civil) dumpster fire conversation over heat pump H2O heaters.
Which imho confirms they are a complex solution to a simple task.
And 4 years of trouble free service so far? ?
I think my grandparents natural gas water heater was over 30 years old when it was replaced.
Seems challenging to find one that’ll last over 5 or 6 years now. Engineered failure clock.
View attachment 124254

I am certain the product has its place in conserving energy, but yeah... at what cost?
My electric water heater was 20 years old when I bought my condo, it has served me over 10 years now, and is still going strong.
With me and three women in the house, it has had a workout...
I am sure I could have lowered my electric bill over the years if I'd installed one... but longevity seems questionable.

 

[Hedges]

 

[Nobodybusiness]

With me and three women in the house

You poor soul. ?

 

[RV10flyer]

My plan as soon as I get some free time (hvac pro) is to take a used 14 SEER 1.5 or 2 ton split heat pump outdoor section. Pull compressor and controls except defrost thermostat. Install in crawl space where existing 80 gal electric resides. Install a 100 or 150 gallon aluminum diesel tank, lying horizontal with large access door on top. Install the AH’s indoor coil (now a condenser except during defrost) inside the “pre-heat” tank. TXV inside and out. Install outdoor coil, fan and defrost tstat inside a small greenhouse facing south for higher ambient temperature/efficiency. I will have on a timer, to go kick on at 2 pm and off at 7 pm, set to maintain 120F pre-heat water temp. My existing 80 gal electric wh is on a timer. My 1” copper cold water line will go through preheat tank before going to existing reg water heater. Insulating everything well. We will see how it turns out. I’m figuring on about 1/3 the current with nearly the same 15000 btu output as my 4.5kW resistive element.

 

[robby]

I have no personal experience with them but I was ready to pull the Trigger but then I read the 1-3 Star reviews on the Rheem models and I backed out. A lot of common descriptions of the issues people had got me spooked.

Noise and Breakdowns seem to be common.

 

[djnorth]

Until they come with a 10+ year parts & labor warranty, they seem like a complex solution to a problem while there are proven quiet & reliable, albeit less efficient, products on the market. I don’t need any more headaches.

 

[robby]

My plan as soon as I get some free time (hvac pro) is to take a used 14 SEER 1.5 or 2 ton split heat pump outdoor section. Pull compressor and controls except defrost thermostat. Install in crawl space where existing 80 gal electric resides. Install a 100 or 150 gallon aluminum diesel tank, lying horizontal with large access door on top. Install the AH’s indoor coil (now a condenser except during defrost) inside the “pre-heat” tank. TXV inside and out. Install outdoor coil, fan and defrost tstat inside a small greenhouse facing south for higher ambient temperature/efficiency. I will have on a timer, to go kick on at 2 pm and off at 7 pm, set to maintain 120F pre-heat water temp. My existing 80 gal electric wh is on a timer. My 1” copper cold water line will go through preheat tank before going to existing reg water heater. Insulating everything well. We will see how it turns out. I’m figuring on about 1/3 the current with nearly the same 15000 btu output.

That thought crossed my mind but I could see two main issues.

1) The condenser coils are typically made out of Aluminum which is IMHO is not going to hold up well submerged in water for a long period of time.

2) The slots between the Condenser coil are going to quickly get filled with Calcium and Chlorine deposits.

Let me know how it works out because it's not that hard to make and not that expensive but I do worry about those issues.
The last thing I need is another appliance that needs a lot of servicing.

 

[OT Ducati]

That thought crossed my mind but I could see two main issues.

1) The condenser coils are typically made out of Aluminum which is IMHO is not going to hold up well submerged in water for a long period of time.

2) The slots between the Condenser coil are going to quickly get filled with Calcium and Chlorine deposits.

Let me know how it works out because it's not that hard to make and not that expensive but I do worry about those issues.
The last thing I need is another appliance that needs a lot of servicing.

I think he just wants to pre heat his water supply to the water heater with a copper coil submerged, this should work fine.
" My 1” copper cold water line will go through preheat tank before going to existing reg water heater."
If he puts the condenser coil in, you are correct.

 

[RV10flyer]

That thought crossed my mind but I could see two main issues.

1) The condenser coils are typically made out of Aluminum which is IMHO is not going to hold up well submerged in water for a long period of time.

2) The slots between the Condenser coil are going to quickly get filled with Calcium and Chlorine deposits.

Let me know how it works out because it's not that hard to make and not that expensive but I do worry about those issues.
The last thing I need is another appliance that needs a lot of servicing.

I do have both aluminum and copper coils. I will add some water treatment to the pre-heat tank to prevent microbial growth. I also have a lot of copper tubing that I could form in to my own coil. I’ll try to make a nice gasketed hatch for the top to prevent as much evaporation and heat loss from the water. There’s going to be some experimenting to get the pressures correct and running smooth. Once I get it working correctly, I will share diy plans with anyone interested.

 

[RV10flyer]

I do have some coaxial heat exchangers that go in geothermal units. I was trying to keep from using pumps and consuming more electricity. This is why I just wanted to put the condenser coil in the preheat tank then have my 1” copper water heater inlet line passing through maybe two or three lengths and then back to the 80 gal electric water heater. Thank all of you for the advice and ideas.

 

[OzSolar]

At least the one you are looking at is..Rheem.

Good to know that you like Rheem.

My current H20 heater is going on 17 years old and a recent draining of ~5g produced an impressive amount of scale and black flakes. I fear the inner liner is now compromised. Previous dranings only produced small amount of scale.

 

[OzSolar]

I do have some coaxial heat exchangers that go in geothermal units. I was trying to keep from using pumps and consuming more electricity. This is why I just wanted to put the condenser coil in the preheat tank then have my 1” copper water heater inlet line passing through maybe two or three lengths and then back to the 80 gal electric water heater. Thank all of you for the advice and ideas.

I have a 1200 gallon atmospheric storage that I built out of ICF blocks into the corner of my basement. Two sides of that tank are the ICF basement walls so it doesn't take up that much space.

There are two heat exchangers the I hand made out of soft K copper coils in that tank. One set, near the bottom is for getting heat from the Tarm wood boiler. It is two 100' coils of 3/4" in parallel. My understanding is that with this sort of heat exchanger you're better off with more surface area than you are volume.

The other heat exchanger is near the top of the tank for preheating my domestic hot water and also delivers heat to the tank from my ground source heat pumps desuperheater in the summertime.

I'll send some pictures of my set up.

Edit: We're starting out 20th winter with this set up and it's been working flawlessly since I designed and built it.

 

[Rider]

I put in an AO Smith 40 gal last year to replace an electric heater that was in the house when I bought it in '94, and I suspect it was the original to the house when it was built in '70. Don't make them like that anymore.

I knew there were high failure rates on hybrid heaters when I bought it, but took a chance. So far, so good (jinx....) I keep mine on heat pump only mode all of the time and it provides all the hot water I need. Someone mentioned that the space it's in gets cooled. Sure does. I have mine in the basement and you can feel the coolness. However, it's also a dehumidifier, so it takes a significant amount of moisture out of the air, lessening the load on my standalone dehumidifier. My basement has never been drier or more comfortable.