Howdy Readers-
Another month has passed (roughly) since my last post. Time sure flies by doesn't it? Well, it's been a COLD spring so far down in the Southeast US. Only in the past week has it finally been above 60F consistently. I say this as I glance outside where its supposed to be a high of 48F, gloomy, and rainy all day. *UGH*
Although the forecast does call for sun this weekend with temperatures in the high 60s. Yippie!
So...let's see where we ended up this month, shall we?
April 2012
Total Energy Consumption: 704 kWh
Number of Days: 32
Average Daily Consumption: 22.0 kWh/day
Heating Degree Days: 117 (note: only 14 days actual had HDDs)
Energy Consumption per HDD: 2.63 kWh/HDD (based on 14 days)
April 2013 (Mar 4 - Apr 2)
Total Energy Consumption: 737 kWh
Number of Days: 29
Average Daily Consumption: 25.41 kWh/day
Changed versus previous year: -15.5%
Bill Savings vs 2012 Consumption: -$0.52
Heating Degree Days: 444 (note: 28 days actual had HDDs)
Energy Consumption per HDD: 1.60 kWh/HDD
kWh/HDD Savings vs 2012: 39.1%
OK...so at first glance, I did worse than last year. I used about 16% MORE energy, but luckily it only cost me a whopping $0.52 more. I think I can deal. However, when you factor how cold it was this year as opposed to last year, then I'm doing just fine. If I include the HDDs, I was roughly 39% MORE EFFICIENT than last year.
I will say that this was tricky to look at because I had to make an "executive decision" on how to quantify days that had zero HDDs. For the month of April 2012, if I included all 32 days in my calculation, then it would have said I used ~6 kWh/HDD. Yes, that's a valid number, but its highly skewed because for nearly most of the month had no heating was needed so it's only looking at my "base" consumption at the time. So that doesn't give a good indication. So instead I only used the number of days an actual HDD was recorded. I did the same for my 2013 values. This brought the values more in line for as shown below:
2011-2012
12/2011 = 2.16 kWh/HDD
01/2012 = 2.45 kWh/HDD
02/2012 = 1.90 kWh/HDD
03/2012 = 2.14 kWh/HDD
04/2012 = 2.63 kWh/HDD
2012-2013
12/2012 = 1.82 kWh/HDD
01/2013 = 1.75 kWh/HDD
02/2013 = 1.73 kWh/HDD
03/2013 = 1.45 kWh/HDD
04/2013 = 1.60 kWh/HDD
OK...so this makes sense to me. I'm trending as expected. So I'm going to consider this a "minor" victory.
I really don't have any energy efficiency projects in the near future. Closest that once could even consider may be new window shades in the upstairs. As we prepare the nursery for the arrival of our twins, I would like to put in some nicer shades than the cheap versions (old school pull down things that I can never get it to stay when I pull it down). I was thinking about window films. I tossed in an example link. I get a little security benefit from it (you can't just smash a window anymore as the window film holds the glass in place...at least for a little while) not to mention some privacy too. An then there's the potential energy savings too. We'll see...I contacted my local firm to see how much it would cost. I'm just curious right now...but if the price is right, I may do it. I'll let y'all know...
I have a geothermal system just like yours with a desuperheater that connects to a single electric hot water heater. I too am looking to upgrade to a GE hybrid water heater. What kind of savings do you think I could expect by doing what you did and using the old water heater as a pre-heating tank (non-powered) and adding the GE hybrid? I love this blog so far ... very informative.
ReplyDeleteHi Mark-
ReplyDeleteI've seen substantial savings...somewhere around 200 kWh/month. That's roughly $20/mo at $0.10/kWh. And I haven't even used it during the 'Cooling' season (i.e. summer) yet to see the benefit of the preheat tank.
As you noted, one key will be to make sure you keep your existing water heater (disconnected) and then connect the GE Geospring in SERIES. Your old tank, which I bet has the desuperheater hooked up to it, will become a preheat tank. Even though most geothermal MFRs say that a one tank installation is OK, there's lots of talk on the Green Building Forum that says it isn't and to get the desired performance you NEED two tanks in series: http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/79200/afv/topic/afpg/1/Default.aspx
It makes perfect sense to me...the water heater turns on/off trying to maintain a desired temperature in the tank (it typically has a ~2F 'dead-band'...so it allows the water temp to drop from, say, 120F --> 117F, before reheating the water). Well, the desuperheater doesn't run if it detects that the water heater is already at temperature. So the only way the desuperheater actually adds heat to the tank is IF your HVAC system in running coinciding with the water heater at the low end of its temperature 'dead-band'...or if you happen to be using hot water at the same time.
I'm excited to see what happens this summer when I will finally start using A/C and turn on the desuperheater so I can see the benefit of the preheat tank. Yes, I turn off my desuperheater during the winter.
Check out my previous blog postings to see my thoughts:
http://homeenergyefficient.blogspot.com/2012/09/new-ge-geospring-hot-water-heater.html
http://homeenergyefficient.blogspot.com/2012/09/new-hot-water-heater-preliminary-results.html
http://homeenergyefficient.blogspot.com/2012/10/october-bill-lowest-month-ever-39.html
http://homeenergyefficient.blogspot.com/2012/11/november-2012-energy-billsecond-lowest.html
Good luck on your project! I installed the water heater myself...it was pretty easy.
Thanks Tommy,
ReplyDeleteResearching on greenbuildingtalk.com about the one vs. two tank issue is actually how I found your blog. I agree that 2 tanks makes more sense. My geothermal guy recommended 2 tanks when it was installed, but never explained why. I just assumed he thought I needed the extra capacity of 2 heated water heaters, so I turned it down.
I'd never considered turning off my desuperheater during winter as the manual doesn't mention anything about it. It makes sense that it would work against the heating of the house when on, but I'm not sure it is significant enough to make any real difference. I'm a contractor so I will be installing the GE hybrid water heater myself, I can get it for $900 (GE discount through my wife's work) and I can get a $300 federal rebate. Unfortunately I have no state rebates or utility rebates, so at the $600 cost it would take me around 2.5 years for my ROI (using your $20 a month savings calculation). However in the summer my utility bill is tiered. I pay double the standard rate if I go over a certain kwh amount. If this water heater helps me stay below that rate it will save me significantly more than $20 a month. I'm in MI and have consumers energy, and they have a monopoly on this area so I can't switch power companies (I've checked).
I am also considering adding a hot water re-circulator pump to my system. I have a kitchen sink at the very end of my plumbing run that takes a minute and a half to get hot water (I timed it). I think I am going to run a hot water return line from my sink into the bottom of the desuperheater mixing tank. That way I can push a botton on my sink, wait a few seconds for the pump to run, and have hot water. I recently read a review that said adding a re-circulator pump can save you energy consumption costs (of about $120 a year) over just running the water until it gets hot. Plus it's just a lot more convenient than waiting for hot water, and a lot less wasteful. What do you think?
Have fun with those twin girls coming! I have two girls myself ages 1 and 3. You will love how it changes your life.
It sounds like you have a fun upcoming project! If I would have known about the 2 tanks myself when I got my geothermal, I would have done it too. However, I'm sure I would have ended up with a cheap tank instead of the Geospring, so I'm OK. It's nice that you can get a nice rebate. I couldn't get one. My monopoly is Duke Energy and they don't give rebates for water heaters.
ReplyDeleteI've looked into recirulation pumps. However, I would say that it doesn't save you energy. It saves you water: 1.5 min x 2.5 gpm (faucet) = 3.75 gallons of water wasted. If you need to run the water 2x/day thats 2,738 gallons wasted per year. For me, I pay $2.15/CCF or $2.15/748 gallons. That's $7.89 in water bill per year. I've never bought the whole "it saves energy". Maybe it does save the energy that is lost that now needs to be replenished. But if that heat goes into conditioned space, I would say its not wasted.
One thing that I did which you may or may not have, is that I insulated all my HW lines. Mine are located in my crawl space. I insulated the desuperheater lines and all HW lines. That helped a good amount for me. If I could get them in my walls, I'd do it there to, but alas they are unaccesssible unless I start tearning down drywall. In deep winter, it stil can take about 30s to get hot water to my farthest fixture (Master bathroom), but it's not too bad.
FYI, in the heating mode, the desuperheater takes 5% of the heat from heating. It's not huge, but I figure I know heating is my highest bill, so I'd rather have it go to heating, not hot water.
BTW...where is your water heater located? If you're in MI, I'm guessing its indoors...basement perhaps? Just remember that the Geospring is essentially an air conditioner. It might be useful for dehumidifying (great for me!), but if its indoors, during the winter it will 'steal' heat from your house for the HW. Give you have a geothermal system I'd say that's an OK tradeoff...
Yeah I did some additional reading on re-circulation pumps last night and I think the general consensus is they do not really save you any energy. I have a well water with a 1hp pump running it. I was thinking that a 1/8 hp recirculation pump running for a few seconds each day might save some power over cycling the 1hp well pump. The circulation pump and all the plumbing parts wil cost me around $700, which is a high price to pay for an added convenience that doesn't really save energy. I have insulated all my hot water lines. When I built my house 6 years ago I took a lot of extra steps to really seal the house tight.
ReplyDeleteMy water heater will be going into my mechanical room in my basement (which is large enough for the water heater requirements) I have been looking into ducting kits to vent the water heater outside in the winter, and inside in the summer. I found that GE has a patent out for a ducting kit, but I don't see one on the market yet. Several other manufactures have ducting kits that I could buy and adapt to my system, or I could just build my own. Venting outside does create another challenge of where does the make up air come from. Having a tight house means I can't just vent outside without also introducing some kind of air intake to the house. I still need to work these details out. I may end up putting a wood stove down there at some point too, but that's up in the air right now. I have 6 acres with tons of trees, it seems a wood-stove would be a logical choice to reduce my electric bill even further, however I'm not convinced I want the additional insurance costs and maintenance of running one. But then again ... my hybrid water heater would work a lot better with a wood-stove supplying the heat. As you can probably tell I haven't made up my mind yet.
Mark-
ReplyDeleteImpressive stuff. I know what it's like looking into all this stuff and trying to figure out what's best. I did a LOT of research before I made a decision. I hope it all works out!
Ok so I received my water heater today, and I'm ready to install it. So I was looking though my geothermal manual when I discovered that my desuperheater has been hooked up BACKWARDS from day one. Ugh! Not only did my geothermal guy not explain why two tanks was better than one ... he hooked it up backwards! No wonder my electric bill seems high! The water heater probably had to run every time the geothermal kicked on. I'd call him up and give him a piece of my mind, but I know his company went bankrupt a few years ago. Oh well ... that's the end of my rant.
ReplyDeleteHave you looked into GE's Nucleus energy management system for your water heater? http://www.geappliances.com/home-energy-manager/ It looks pretty interesting as it communicates with your smart meter. Currently it is only available through your utility company, and my utility company doesn't offer it. But hopefully shortly it will be available to everyone. I've considered getting your TED system, but consider the cost to be a little high.
Excellent. It's fairy easy to hook up. One extra thing that I had to do to meet code was install a small pressure tank upstream in my cold water line. Hopefully you don't need to do that. I still have the scars on my arm from soldering the tee into the copper pipe and getting some of that molten tin on my arm.
ReplyDeleteBummer about the desuperheater installed backwards. Make sure you double check it. I thought the same thing at first too. But then I had to look closer and found out it was installed properly after all. For some reason the desuperheater install feels like it's installed backwards...it's been awhile and I'd have to look it up to make sure what it was that felt incorrect.
I did check out the GE Nucleus system a while ago. I've got the giant monopoly known as Duke Energy which means that the term 'smart meter' is pretty much unknown around here, otherwise I wouldn't need a TED unit. If the TED is too expensive, check out the efergy unit. I installed a couple of those for friends. It's much easier to install and cheaper too. The couple things I didn't like was the battery changing and you had to buy their 'special router' in order to get your data online. I was lucky enough to get the TED when it was still available at Lowe's...and I had a gift certificate so it wasn't all that bad.
Good luck!