Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Plumbing

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-05-2012, 10:21 AM   #1
Member
 
Join Date: Nov 2011
Location: Raleigh, NC
Posts: 70
Share |
Default

Electric water heater suggestions


I'm replacing our electric water (we do not have gas).

Any experience with the Rheem EcoSense or GE GeoSpring hybird water heaters?

The water heater will be installed in our garage.

It seems like a good option for us. Only downside appears to be install price and some noise when the heat pump mode is used. We'll also have to run a line for the condensate but that's easy.

Main benefits should be cost dehumidifying our basement garage in the summer.

BTW, I've attached a picture of our existing 50 gallon water heater.

Nice, eh? It's lasted 14 years so far so we're pleased. Looks like a leak waiting to happen to me....
Attached Images
 
Rewound98 is offline   Reply With Quote
Old 02-05-2012, 10:38 AM   #2
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 3,973
Default

Electric water heater suggestions


I have a GE geospring. Very nice unit, as you say a bit noisy when the fan is running, but it is in the basement, so I don't mind. I was eligible for the tax credit for efficiency, so that offset part of the $1400 price. I installed it myself with no issues, it takes standard wiring and standard plumbing connections, but if you lack electrical and plumbing skills, you should of course hire a professional.

It is a bit difficult to directly compare the efficiency of a heat pump to a direct electric heater. The heat pump will get much of its energy from moisture in the air in the summer, and since we vent our dryer into the basement (using an appropriate lint trap arrangement) we have plenty of warm, moist air available all summer. As you surmised, the heat pump does a great job dehumidifying the basement all summer long, and makes hot water as it does so.

In the winter, there is no humidity available, so the heat pump uses the air to air mode, and the fan runs quite a bit, which I am sure is less efficient than summer mode, but still better than electric resistance heat. Out cost per kilowatt is about 19 cents, I think it is the highest in the lower 48, and we do not have gas available, so this was a good choice for us. Whether it is for you depends on your electric rate.
Daniel Holzman is offline   Reply With Quote
Old 02-05-2012, 11:36 AM   #3
Doing it myself
 
Alan's Avatar
 
Join Date: Apr 2006
Location: Crescent City, CA
Posts: 3,683
Send a message via AIM to Alan Send a message via MSN to Alan
Default

Electric water heater suggestions


Quote:
Originally Posted by Daniel Holzman View Post
I have a GE geospring. Very nice unit, as you say a bit noisy when the fan is running, but it is in the basement, so I don't mind. I was eligible for the tax credit for efficiency, so that offset part of the $1400 price. I installed it myself with no issues, it takes standard wiring and standard plumbing connections, but if you lack electrical and plumbing skills, you should of course hire a professional.

It is a bit difficult to directly compare the efficiency of a heat pump to a direct electric heater. The heat pump will get much of its energy from moisture in the air in the summer, and since we vent our dryer into the basement (using an appropriate lint trap arrangement) we have plenty of warm, moist air available all summer. As you surmised, the heat pump does a great job dehumidifying the basement all summer long, and makes hot water as it does so.

In the winter, there is no humidity available, so the heat pump uses the air to air mode, and the fan runs quite a bit, which I am sure is less efficient than summer mode, but still better than electric resistance heat. Out cost per kilowatt is about 19 cents, I think it is the highest in the lower 48, and we do not have gas available, so this was a good choice for us. Whether it is for you depends on your electric rate.
I've been looking at those and tossing around the idea of throwing one in my garage when my A.O. Smith electric finally goes out. I just keep going back to 50 gal electric = $250 Hybrid = $1200

It seems that they're both a steel tank so you get the same life out of the tank itself. Could I really save 900 dollars in energy over 8-12 years?

__________________
Journeyman Plumber
Alan is offline   Reply With Quote
Old 02-05-2012, 12:50 PM   #4
Member
 
Join Date: Nov 2011
Location: Raleigh, NC
Posts: 70
Default

Electric water heater suggestions


The adverts for these units tout a $300 / year savings but for me, electric costs about 6 cents/KWh (6.76 on peak/5.39 off peak).

Cost to operate standard 50 gallon electric / year: $293 (4879 kWh)

Cost to operate hydrid 50 gallon electric / year: $111 (1856 kWh)

So with $182 a year "savings" -- if i believe the cost estimates -- then after 5 years it'll be worth it.

Hmmm that's borderline but if it lasts another 14 years then I'd be pleased with it.
Rewound98 is offline   Reply With Quote
Old 02-05-2012, 02:19 PM   #5
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 3,973
Default

Electric water heater suggestions


I truly doubt you are going to recover your costs at 6 cents per KW. As I said, I live in the peoples republic of Massachusetts, and at 19 cents per kilowatt hour it wasn't a tough decision.
Daniel Holzman is offline   Reply With Quote
Old 02-06-2012, 08:56 AM   #6
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,781
Default

Electric water heater suggestions


When the temperature of its surroundings is low enough, the heat pump mechanism switches off and resistance heating elements take over.

Home grade and water heater grade heat pumps can "suck heat out of" aka "air condition" exterior air incoming perhaps as low as 20-30 degrees F but at those temperatures their efficiency in terms of running cost versus BTU output (into the house or water tank) is about the same as or worse than resistance heat. Also at those temperatures what little moisture is in the air condenses out and freezes and the heat pump has to "take a rest" and warm up the coils every so often using additional resistance heating elements to melt off the ice deposits.
__________________
The average homeowner who lost his house in the Oklahoma tornadoes should move for good and not rebuild. Too much complexity watchdogging the contractor. Too much a chance to be defrauded.

Last edited by AllanJ; 02-06-2012 at 09:00 AM.
AllanJ is offline   Reply With Quote
Old 02-06-2012, 09:32 AM   #7
Member
 
Join Date: Nov 2011
Location: Raleigh, NC
Posts: 70
Default

Electric water heater suggestions


My garage never gets below 50F!

It's mostly below grade and underneath a living space.

I'm still on the fence about this but now leaning towards getting one.

If anyone has one of these I'd be curious to know how it's performed.
Rewound98 is offline   Reply With Quote
Old 02-06-2012, 10:27 AM   #8
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,781
Default

Electric water heater suggestions


Note that the water heater heat pump unit, installed inside the garage, will quickly pull the air temp in the garage down dozens of degrees. Then it might shut off and put the intra tank resistance elements on. It is up to the basement floor and below grade walls to warm the air back up to 50 degrees using ground ambient temperature and it is up to the garage ceiling to warm the air back up using heat from the house interior above (forcing your furnace or another heat pump to work harder). Or you will need to bring in outside air if that is at a higher temperature than what the heat pump did to the air originally inside the garage.

Or another way of saying it is that if the heat pump inside the garage can keep the temperature in there around 60 degrees when the temperature would otherwise hover around 80 in summer then that same heat pump will tend to keep the temperature around 30 if the temperature is normally around 50 in winter.

If my calculations are correct, it takes about 25000 BTU to heat up a 40 gallon tankful of water from 40 to 120 degrees (80 degree rise which is typical). Meanwhile a 20 x 20 x 7 foot garage has a volume of air (2800 cubic feet) that for each degree the heat pump sucks heat it gets a little over 50 BTU. If the heat pump were allowed to pull the temperature down 20 degrees (50 to 30 F) it would get about 4% of the BTU needed to heat the water before the air had to pick up heat from the floor, walls, and ceiling.

1 BTU will heat 1 lb water (about a pint) 1 degree F (a gallon weighs 8.3 lb)

50 cf of air whose temperature is lowered 1 degree F will yield up 1 BTU.
__________________
The average homeowner who lost his house in the Oklahoma tornadoes should move for good and not rebuild. Too much complexity watchdogging the contractor. Too much a chance to be defrauded.

Last edited by AllanJ; 02-06-2012 at 10:42 AM.
AllanJ is offline   Reply With Quote
Old 02-06-2012, 12:39 PM   #9
Civil Engineer
 
Join Date: Mar 2009
Location: Boston
Posts: 3,973
Default

Electric water heater suggestions


AllanJ, your computations are correct. And I believe your conclusion is also accurate, i.e. putting a heat pump water heater in an unheated garage would save no energy in the winter. It would still save energy in the summer, by essentially acting as a dehumidifier, and extracting energy from condensation of moisture.

However, I have my heat pump water heater in the basement, which never gets below about 55 degrees, even in the winter with the water heater heat pump going. The basement is not heated, however there are two sources of heat which contribute to maintaining air temperature. One is the boiler, which runs all winter, and which leaks heat into the basement. The other is the dryer, which is vented into the basement, so produces a fair amount of heat and moisture when we dry clothes.
Daniel Holzman is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to properly drain and flush a hot water heater? speedster1 Plumbing 9 04-17-2012 09:55 PM
electric versus propane water heater Jeremy Hillary Boob, PhD Appliances 7 01-30-2012 05:23 PM
Is my panel sufficient to add Electric water heater andy Electrical 16 04-21-2009 08:34 AM
Replacing a Water Heater with Electric One 2031pratt Plumbing 3 12-26-2008 09:17 AM
(Water Heater MYSTERY) Hot water out from dead tank with cold water in it? Inayity Plumbing 6 07-14-2008 08:36 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.