Off-peak elec storage hot water?

Drake · 03-13-13, 10:27 PM

This is an option being promoted by elec coop where I am building retirement home. I understand how it works I just am not confident that water usage wouldn't quickly mix lower tank temp between off-peak heating periods. As my wife and I will be working to adopt a water and energy conservative lifestyle with just the two of us I am exploring whether a smaller whole house elec tankless water heater might be a better direction. Heat pump H2O heaters look interesting but our heating season is as long as our cooling season so finding the interior heat for the pump to collect without paying for it has to be considered. Summer cooling would be a plus though.

stevehull · 03-14-13, 10:12 AM

Drake,

First, what is the differential between the peak and off peak rate? Also look at the availability of natural gas as that option is almost always cheaper that using electricity to heat water.

I have a client that does not have access to natural gas, but very inexpensive off peak electricity cost ($0.03) vs almost triple on peak. We suggested two tanks with one tank just for preheating water at night.

Even if you have one tank, there is not much mixing between the top of the tank and the lower part.

Does this help?

Steve

Drake · 03-14-13, 01:51 PM

No natural gas available and LP expensive and going up. Off-peak rate(.04/Kw) slightly less than half regular rate. And your input does help never had experience with bigger than 40 gal tank. Coop have good incentives for off-peak consumption to consider. Also see more possibliities in self elec generation. No indoor combustion either.

NiHaoMike · 03-15-13, 09:35 PM

If you already have an electric water heater, all you need to do is add a timer.

Ryland · 03-16-13, 08:37 AM

The mixing of the hot and cold water is pretty slow, you should drain the sediment off your current water heater every few months as it is if you want it to keep it's warranty and in doing so you will notice that you can pull cold water out of the bottom of your hot water heater tank pretty easily.

Question is, do you want to use LESS energy or CHEAPER energy.
I like your idea of an off peek tempering tank then a small 3 to 5 gallon hot water tank that you super insulate and you could even have that small tank super close to your point of use for instant hot water.

Like has bee suggested already, a timer that you install, while it might not be connected to the off peek meter (if you have two meters) it will cut your KWH use by not allowing your water heater to reheat water at 2am from standby heat loss.

Xringer · 03-16-13, 09:54 AM

Being retired means less hotwater use in my house. We are using the Airtap A7
and it works okay down to 44F in the basement.
AirTap: A Heat Pump For Your Hot Water Heater: Hot or Not? : TreeHugger
It's not UL listed..

You might like one of the new Hybrid DHW heater.. A lot of folks use these in ASHP mode only..
Water Heater FAQs, Hot Water Heaters | GE Appliances

Drake · 03-20-13, 11:14 AM

Here a separate meter is needed for off peak pricing and a minimum # of gals to off peak heat tank storage to get into program. I did find out that A HP DHWH could be part of that storage system. If I find one for a bargain price I think the summer savings,cooling and dehumidification a potential positive. I know summer solar water heating is at its peak but going to be grid-tied so I favor collector space for PV, which is less potential trouble in long winter area IMO.

Drake · 03-20-13, 11:16 AM

Some good deals on HP DHWHs on Ebay but most won't ship. Too bad.

jeff5may · 03-20-13, 04:55 PM

With an 80 gallon tank connected to an A7 operating off-peak only, you should never have to worry about running out of hot water. Your electric bill should feel a stiff one-two punch, saving you thousands of dollars over time.

Daox · 03-22-13, 08:54 AM

That sounds like a good idea Jeff5may.

03-13-13, 10:27 PM	#1
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	Off-peak elec storage hot water? This is an option being promoted by elec coop where I am building retirement home. I understand how it works I just am not confident that water usage wouldn't quickly mix lower tank temp between off-peak heating periods. As my wife and I will be working to adopt a water and energy conservative lifestyle with just the two of us I am exploring whether a smaller whole house elec tankless water heater might be a better direction. Heat pump H2O heaters look interesting but our heating season is as long as our cooling season so finding the interior heat for the pump to collect without paying for it has to be considered. Summer cooling would be a plus though.

03-14-13, 10:12 AM	#2
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	Drake, First, what is the differential between the peak and off peak rate? Also look at the availability of natural gas as that option is almost always cheaper that using electricity to heat water. I have a client that does not have access to natural gas, but very inexpensive off peak electricity cost ($0.03) vs almost triple on peak. We suggested two tanks with one tank just for preheating water at night. Even if you have one tank, there is not much mixing between the top of the tank and the lower part. Does this help? Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990

03-15-13, 09:35 PM	#4
NiHaoMike Supreme EcoRenovator Join Date: Oct 2008 Location: Austin, TX Posts: 1,154 Thanks: 14 Thanked 257 Times in 241 Posts	If you already have an electric water heater, all you need to do is add a timer. __________________ To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...

03-16-13, 09:54 AM	#6
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Being retired means less hotwater use in my house. We are using the Airtap A7 and it works okay down to 44F in the basement. AirTap: A Heat Pump For Your Hot Water Heater: Hot or Not? : TreeHugger It's not UL listed.. You might like one of the new Hybrid DHW heater.. A lot of folks use these in ASHP mode only.. Water Heater FAQs, Hot Water Heaters \| GE Appliances __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..

03-22-13, 08:54 AM	#10
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	That sounds like a good idea Jeff5may. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

03-14-13, 01:51 PM	#3
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	No natural gas available and LP expensive and going up. Off-peak rate(.04/Kw) slightly less than half regular rate. And your input does help never had experience with bigger than 40 gal tank. Coop have good incentives for off-peak consumption to consider. Also see more possibliities in self elec generation. No indoor combustion either.

03-16-13, 08:37 AM	#5
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	The mixing of the hot and cold water is pretty slow, you should drain the sediment off your current water heater every few months as it is if you want it to keep it's warranty and in doing so you will notice that you can pull cold water out of the bottom of your hot water heater tank pretty easily. Question is, do you want to use LESS energy or CHEAPER energy. I like your idea of an off peek tempering tank then a small 3 to 5 gallon hot water tank that you super insulate and you could even have that small tank super close to your point of use for instant hot water. Like has bee suggested already, a timer that you install, while it might not be connected to the off peek meter (if you have two meters) it will cut your KWH use by not allowing your water heater to reheat water at 2am from standby heat loss.

03-20-13, 11:14 AM	#7
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	Here a separate meter is needed for off peak pricing and a minimum # of gals to off peak heat tank storage to get into program. I did find out that A HP DHWH could be part of that storage system. If I find one for a bargain price I think the summer savings,cooling and dehumidification a potential positive. I know summer solar water heating is at its peak but going to be grid-tied so I favor collector space for PV, which is less potential trouble in long winter area IMO.

03-20-13, 11:16 AM	#8
Drake DIY Guy Join Date: Jan 2011 Location: Mpls,MN Posts: 315 Thanks: 2 Thanked 17 Times in 17 Posts	Some good deals on HP DHWHs on Ebay but most won't ship. Too bad.

03-20-13, 04:55 PM	#9
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	With an 80 gallon tank connected to an A7 operating off-peak only, you should never have to worry about running out of hot water. Your electric bill should feel a stiff one-two punch, saving you thousands of dollars over time.