So I was looking at the newspaper the other day and noticed that my local utility, Piedmont Natural Gas, has just asked the NC State Utilities Commission to lower their rates by 5%. This is after Duke Energy initially wanted a 17% hike in electricity rates...which the Utility Commission wants to limit them to 7%. Either way...Electricity Up...Natural gas down.
This has made me think about my stance on natural gas hot water. As I've written previously...I'd like to keep my future in my own hands. I can't make natural gas (ok...maybe a little after a nigh drinking microbrews or my wife's chili...) but I can make my own electricity via solar panels. And I hope to do so one day. However, the fact that natural gas is getting cheaper is intriguing.
As of now, I'm using my hot water heater roughly 0.75 hrs per day....note that it is winter here. So that's equal to ~3.6 kWh/d or $0.306/day @ $0.085/kWh (note...this rate is current and doesn't include the projected increase).
Natural gas has a heating value of 1000 BTU/ft3 (it varies, but let's use this for simplicity). And there's 3415.18 BTU/hr in a kW. So if I assume a regular gas hot water heater with 67% efficiency, then I'd be using:
3.6 kWh * 3415.18 BTU/1 kW-hr * 1 ft3/1000 BTU * 1/0.67 = 18.35 ft3 of natural gas.
Since I pay in therms I need to convert it (100 ft3 = 1 therm): 18.35 ft3/100 ft3 = 0.1835 therms.
The current cost for natural gas is $0.95208/therm. So...this equals $0.175/day which is roughly half of what I'm paying now using electricity. If I get a high efficiency condensing gas hot water heater, then the efficiency jumps to 95-97%...let's say 92% to be conservative. The revised cost is:
3.6 kWh * 3415.18 BTU/1 kW-hr * 1 ft3/1000 BTU * 1/0.92 * 1 therm/100 ft3 * $0.95208/therm = $0.127/day
This is a 27% reduction in the daily cost. Fantastic, right?
Now...one thing to factor in is that I'd have to pay a crappy "monthly charge" of $10/mo. That's right folks...$10/mo to have the honor of being a customer. Yes...I do pay a similar charge to be an electricty customer...but I can't turn off my electricty now can I?
I'll leave that be...
So the $10/mo over 30 days = $0.333 per day. So my daily cost is now $0.46/day (using the high efficiency gas unit). Could I use natural gas somewhere else? I guess so...I could switch my cooktop over to gas. And then there's my grill...natural gas certainly is cheaper than propane. I'd have to buy one of those $50 conversion kits though.
If I look back at my former townhome (we had natural gas hot water, heating, and cooktop...we had an electric oven), during the summer months we used about 7.5 therms per month (June through October 2009). So no heating...this is just hot water and cooking. And we should asterisk the hot water since I know I don't take long hot showers in the summer.
Anyway...7.5 therms/month = $7.14/mo. or $0.238 per day. Add in the monthly charge and I'm at $0.571 per day.
If I recall, my electric cooktop uses about 3 kW. It varies depending on which burner is uses...yadda yadda. Cooking generally doesn't take more than 30 minutes. But let's say an hour/day assuming I finally get my butt cooking more. 3 kWh is $0.255...so adding that in, I'm now at $0.561/day.
Given that I highly doubt I'll ever be cooking on average 1 hr/day every day, I gotta call this for electricty...at current rates.
What does this all mean? Well...it means I really need to think about what to do about the hot water heater and maybe get some consulting from my buddies. While gas would be nice...its tough to justify.
Any thoughts out there? Did I miss something? Yes...there's non-quantitative benefits that I've excluded for now...
Thursday, January 19, 2012
Sunday, January 15, 2012
January Energy Bill - 58% REDUCTION
Well...I've been waiting for this bill for a while and it finally arrived. It was a little unusual this time because my wife changed to an ebill so my daily walk to the mailbox was not there...but that's another story. So let's just see the results:
January 2011 Energy Usage: 3,224 kWh over 34 days = 94.8 kWh/d
January 2011 Bill = $253
January 2012 Energy Usage: 1,318 kWh over 33 days = 39.9 kWh/d
January 2012 Bill = $121
Reduction in Energy Usage = 57.9%
Savings on Bill = $132
Comparing to former 2009 1300sf townhome:
January Energy Usage = 70.99 kWh/d or a 44% reduction in energy usage
Ohhh yeah! As I've said in the past, heating is where the Geothermal system really shines. And its proven with the 58% reduction! This is right in line where I thought we'd be (estimating between 50 and 67%). And then being 44% under the former townhome (of half the size) is just icing on the cake.
Next month should be another poster month: Feb 2011 = 102.11 KWh/day. That month we used our gas fireplace a lot for heating so our actual electricity bill had only 70.2 kWh/day. Feb 2010 in the Townhome had 75.8 kWh/d.
January 2011 Energy Usage: 3,224 kWh over 34 days = 94.8 kWh/d
January 2011 Bill = $253
January 2012 Energy Usage: 1,318 kWh over 33 days = 39.9 kWh/d
January 2012 Bill = $121
Reduction in Energy Usage = 57.9%
Savings on Bill = $132
Comparing to former 2009 1300sf townhome:
January Energy Usage = 70.99 kWh/d or a 44% reduction in energy usage
Ohhh yeah! As I've said in the past, heating is where the Geothermal system really shines. And its proven with the 58% reduction! This is right in line where I thought we'd be (estimating between 50 and 67%). And then being 44% under the former townhome (of half the size) is just icing on the cake.
Next month should be another poster month: Feb 2011 = 102.11 KWh/day. That month we used our gas fireplace a lot for heating so our actual electricity bill had only 70.2 kWh/day. Feb 2010 in the Townhome had 75.8 kWh/d.
Friday, January 6, 2012
Energy Star Yardstick
So I was searching the 'net (really for homemade storm windows...that's a different story) and I came across the Energy Star "Assess Your Home" website (Click here to check it out). It's a fairly simple...you input where you live, how many folks in the household, the size of the house, and then your annual utility bills (electrical, gas, etc). The key here is annual...you can put in monthly bills, but there has to be 12 months worth.
So I put my information in. The only thing is that I haven't run the Geothermal for a year yet. Nor have I received last months bill. So for my January bill, I used the TED5000 values (which have always been high). And then for the next two months (my system was installed in February 2010), I just used a rough estimate compared to previous years.
To recap...I've used 7,182 kWh over 272 days (9 months) which is 26.4 kWh/day. For last months (arriving any day now) bill, I put in the TED value of 1281 kWh. Then for the next two months I assumed 1,000 kWh and 750 kWh. With those assumptions, that put me at 11,166 kWh/year or 30.6 kWh/day.
Putting in all this information gave me the following:
Yeah...I'm a little excited about getting a 9 out of 10. That's pretty cool....and this is a "normal" house (no superinsulation...no solar panels (yet)....etc) I'm totally going to be interested to see if/how my score changes once I have a full years worth of data in there. What's kind of neat is the "Set your Goal" info at the bottom. I put in an assumed 10% reducation goal (equal to ~1,117 kWh/yr or 3.06 kWh/day) and it said my Score would increase to a 9.4. Well...my next project will most likely be my hot water heater. Currently hot water is using about 3.6 kWh/day (~0.75 hours @ 4.8 kW). So reducing this in half would give me about 1.8 kWh/day of savings. I'm still trying to figure out how to get one of those heat pump models in there which accomplish two goals: (a) I'd have a preheat tank for the geothermal desuperheater to maximize its efficiency and (b) I'd have a high efficiency unit which would be 2.6x more efficienct.
After that...well...I don't know what else to do. I was planning on re-doing my house siding which includes housewrap. That's *supposed* to reduce energy consumption by 10-15%. Then there's solar panels...but those are pretty expensive. Who knows what else after that...any ideas?
So I put my information in. The only thing is that I haven't run the Geothermal for a year yet. Nor have I received last months bill. So for my January bill, I used the TED5000 values (which have always been high). And then for the next two months (my system was installed in February 2010), I just used a rough estimate compared to previous years.
To recap...I've used 7,182 kWh over 272 days (9 months) which is 26.4 kWh/day. For last months (arriving any day now) bill, I put in the TED value of 1281 kWh. Then for the next two months I assumed 1,000 kWh and 750 kWh. With those assumptions, that put me at 11,166 kWh/year or 30.6 kWh/day.
Putting in all this information gave me the following:
After that...well...I don't know what else to do. I was planning on re-doing my house siding which includes housewrap. That's *supposed* to reduce energy consumption by 10-15%. Then there's solar panels...but those are pretty expensive. Who knows what else after that...any ideas?
Thursday, January 5, 2012
UPDATE: Geothermal Aux Heat and Desuperheater
Per my post yesterday I got to work on my HVAC system. I completed the following:
So...what's the results of this? Well this AM was another Brrrr cold AM. It wasn't as cold as yesterday (low of 21F), but it was still fairly cold (31F). TED data shows that I used a lot less energy from 12AM to 10AM:
Jan 4: 26.7 kWh
Jan 5: 20.4 kWh
Savings: 6.3kWh
While I can't say for sure unless I get another identical day, I'd like to think I created some savings. I certainly didn't see the Aux Heat on this AM. But only time will tell....and I'll be watching it like a hawk...hopefully reporting results...
- Increased my minimum "away" temperature to 64F instead of 62F to minimize my temperature rise. It was previously 7F and now its 5F.
- Set both thermostats to 2 cycles per hour (heat and cooling)
- Set the backup heat lockout temperature to 30F (if outside temp is >30F, then the backup heat won't come on, even if called for)
- Set the backup heat droop temperature to 5F (if the system calls for heat and the temperature continues to drop 5F, then the backup heat will be called on)
- I set the upstage timer to 60 minutes. So if the running system cannot meet the temperature setting within 60min, then the next stage will be called on)
- I insulated the desuperheater piping (geothermal unit to the HWT).
- I set the thermostats on the HWT. Upper one is set to 120F (no change), lower one is now set to 90F
So...what's the results of this? Well this AM was another Brrrr cold AM. It wasn't as cold as yesterday (low of 21F), but it was still fairly cold (31F). TED data shows that I used a lot less energy from 12AM to 10AM:
Jan 4: 26.7 kWh
Jan 5: 20.4 kWh
Savings: 6.3kWh
While I can't say for sure unless I get another identical day, I'd like to think I created some savings. I certainly didn't see the Aux Heat on this AM. But only time will tell....and I'll be watching it like a hawk...hopefully reporting results...
Wednesday, January 4, 2012
Geothermal, Aux Heat, and Desuperheater
So this AM after my normal morning shower, dressing routine, I almost always go and check the thermostat before going downstairs. I do this because the programmable T-stat lowers the temp automatically at 7am when we're typically done the getting ready routine. If I'm early, then I like to manually lower the temp to save some energy. I had also noticed recently that Stage 2 was running a lot...but I had chalked that up to the cold temperatures outside.
Well, today when I checked the t-stat, I saw the aux heat was on. REALLY?!? WTF?!? (Note: The Aux heat is 5 kW in each unit). Yes...it was cold this AM (20F), but there should be no reason the Geothermal can't handle it. It's not like the system is seeing the 20F. So I quickly lowered the temp to turn off the aux heat and ran downstairs...to find the same thing. The f*#$ aux heat was on! So that's 10 kW of extra electrical demand. Checking my TED 5000 confirmed the aux heat was on for roughly 40 minutes. That's an extra 6.7 kWh added to my bill. And yes...it appears it was on yesterday too.
Extremely pissed off, I went online to see if the thermostat was setup incorrect. I'll tell you what...the instructions on thermostats when it comes to these settings is damn near non-existent. I gave up and went to the T-stat settings (each one) and turned the Back-Heat to "Economy Mode", and turned the "Heat Control Mode" to "Less Aggressive". While there, I did the same for the "Cooling Control Mode". This was kind of arbitrary at the time.
I did some further searching later in the AM. I ended up in the GeoExchange forum finding that most thermostats aren't made for geothermal systems. So their default settings are NOT appropriate. Looking at my settings, the Stage 1 is set to run at 3 cycles per hour (CPH), Stage 2 is 3 CPH, and the Aux heat is 9 CPH. From reading the forums, most people have set the Stage 1/2 to either 1 or 2 CPH which apparently increases efficiency (i.e. allows each Stage to run longer). It's slightly confusing because the lower the number, the better apparently. The definition is:
"cycle rate is the ideal number of times a heating system will run, in an hour, to maintain temperature within one degree. For instance, gas or oil forced air systems have a recommended cycle rate of 6. With a cycle rate of 6, the heating system, at a 50% load, will cycle 6 times per hour. This breaks down to about 5 minutes on and 5 minutes off. Again, the actual on and off time of the heating system will vary as the load on the heating system varies."
So a setting of 3 is 10 minutes on/10 minutes off. And if this is correct, then a setting of 2 is 15 minutes on/off and finally a setting of 1 is 30 minutes on/off. Going with a longer run time allows for more air movement and a more "steady-state" operation.
I found a good explanation of CPH below:
"CPH, is the digital equivalent to the old heat anticipators that actually heated the thermostat.
In Honeywell thermostats its just an algorithm based on previous on and off times, to attempt to maintain an X amount of temp differential/deadband/droop, by increasing or decreasing the on and off times. And is only accurate when the homes heat loss or gain is at 50% of the equipments heating/cooling capacity. The size of the equipment will determine when the thermostat can maintain its set CPH. And as the outdoor temp varies, the actual CPH will also vary, and the duration of the on and the off time will change accordingly with one increasing and the other decreasing.
A thermostat set for 3 CPH, will have a continuous run time when the outdoor temps and indoor set temp are at design conditions, and the heating or cooling equipment is sized for those design conditions. If the outdoor temp rises 5 degrees above outdoor design in winter, even with the CPH set to 6, the system will be cycling at 1.5 or 2 cycles per hour. If it rises another 5 degrees, the stat may begin to have 1 or 2 minute off times, which becomes very annoying and hard on the equipment.
Temp over rides CPH setting. The thermostat continually monitors temp, And recalculates when it should bring on the heat or A/C. And how long it should run it. And then when it brings on the equipment, in monitors the progress and recalculates how long it should keep on running the equipment. Along with how long it should keep it off once it shuts the equipment off. It is constantly recalculating the on and off time by monitoring the temp. Temp over rides CPH setting.
A higher CPH means more on and off times an hour, so the equipment will short cycle. But maintain a very tight temp control of the hose. Very comfortable, but hard on the equipment.
A lower setting will allow a wider temp swing in the house, and be much easier on the equipment. The temp swing increase will only be a few tenths of a degree."
I've seen stuff back and forth on setting the Aux Heat to the same as the heating/cooling...so maybe I'll do that as well. I also found out that with my outdoor temperature sensor, I need to turn on the "Outdoor Temperature Aux Heat Lock Out" which locks out the use of the Aux heat if the temperature is above a specified temperatures setpoint. I've seen numbers flying around but I would think it would make sense for this to be 30F just in case the Geosystem goes down and its below freezing to prevent any water pipes from freezing/breaking. Finally, there's a recommendation to change the delta between Stages 1 and 2 to be 3F so the first stage will run more often. However, my thermostat doesn't have this feature oddly enough....the closest I have is "deadband". There is an upstage timer which I think I could use...but I'd need to check. Increasing the timer means that Stage 1 will run for XXX minutes and then if the timer expires and the temperature has not yet been reached, then Stage 2 will come on, etc. I'll have to play with this that's for sure.
Oh yeah...almost forgot about the desuperheater. In the same forum I came across some folks talking about the desuperheater. Apparently I need to check out my installation. I've talked about it previously, but the most efficienct system uses a pre-heat tank and then the hot water heater (HWH). I don't have this (yet) so I only have my HWH. Well...apparently I need to make sure my upper and lower elements are at different temperatures. So the lower one needs to be set at 100F while the upper is at the normal HW temp...say 120-130F. This is because the desuperheater measures the water temperatures. If its above a setpoint (130F apparently), then it doesn't turn on (it says the HWH is already at temperature...don't bother). Well...I think my lower one is set to 120F and I've never checked my upper one. I know the installers didn't change anything because my HWH has a insulation blanket around it...and to get at the element thermostats you'd need to either remove the blanket or cut a hole. Neither was done beacuse I cut a hole in the blanket to get at the lower element this fall. So I definately need to change these settings! And I was wondering why I didn't feel like I was getting any "free" hot water from the desuperheater...that's because the HWH was maintaining the 120-130F setting and the geothermal system would sense it and say not to use the desuperheater or it would run minimally. Dang it!!!!!! Well...that'll be fixed today. Also, I need to insulate the piping from the HWH to the desuperheater. Looking at pics it doesn't have any insulation on it and I need this to (a) get a good temperature reading and (b) to make sure the heat that it put in is actually making it to the HWH.
Well, today when I checked the t-stat, I saw the aux heat was on. REALLY?!? WTF?!? (Note: The Aux heat is 5 kW in each unit). Yes...it was cold this AM (20F), but there should be no reason the Geothermal can't handle it. It's not like the system is seeing the 20F. So I quickly lowered the temp to turn off the aux heat and ran downstairs...to find the same thing. The f*#$ aux heat was on! So that's 10 kW of extra electrical demand. Checking my TED 5000 confirmed the aux heat was on for roughly 40 minutes. That's an extra 6.7 kWh added to my bill. And yes...it appears it was on yesterday too.
Extremely pissed off, I went online to see if the thermostat was setup incorrect. I'll tell you what...the instructions on thermostats when it comes to these settings is damn near non-existent. I gave up and went to the T-stat settings (each one) and turned the Back-Heat to "Economy Mode", and turned the "Heat Control Mode" to "Less Aggressive". While there, I did the same for the "Cooling Control Mode". This was kind of arbitrary at the time.
I did some further searching later in the AM. I ended up in the GeoExchange forum finding that most thermostats aren't made for geothermal systems. So their default settings are NOT appropriate. Looking at my settings, the Stage 1 is set to run at 3 cycles per hour (CPH), Stage 2 is 3 CPH, and the Aux heat is 9 CPH. From reading the forums, most people have set the Stage 1/2 to either 1 or 2 CPH which apparently increases efficiency (i.e. allows each Stage to run longer). It's slightly confusing because the lower the number, the better apparently. The definition is:
"cycle rate is the ideal number of times a heating system will run, in an hour, to maintain temperature within one degree. For instance, gas or oil forced air systems have a recommended cycle rate of 6. With a cycle rate of 6, the heating system, at a 50% load, will cycle 6 times per hour. This breaks down to about 5 minutes on and 5 minutes off. Again, the actual on and off time of the heating system will vary as the load on the heating system varies."
So a setting of 3 is 10 minutes on/10 minutes off. And if this is correct, then a setting of 2 is 15 minutes on/off and finally a setting of 1 is 30 minutes on/off. Going with a longer run time allows for more air movement and a more "steady-state" operation.
I found a good explanation of CPH below:
"CPH, is the digital equivalent to the old heat anticipators that actually heated the thermostat.
In Honeywell thermostats its just an algorithm based on previous on and off times, to attempt to maintain an X amount of temp differential/deadband/droop, by increasing or decreasing the on and off times. And is only accurate when the homes heat loss or gain is at 50% of the equipments heating/cooling capacity. The size of the equipment will determine when the thermostat can maintain its set CPH. And as the outdoor temp varies, the actual CPH will also vary, and the duration of the on and the off time will change accordingly with one increasing and the other decreasing.
A thermostat set for 3 CPH, will have a continuous run time when the outdoor temps and indoor set temp are at design conditions, and the heating or cooling equipment is sized for those design conditions. If the outdoor temp rises 5 degrees above outdoor design in winter, even with the CPH set to 6, the system will be cycling at 1.5 or 2 cycles per hour. If it rises another 5 degrees, the stat may begin to have 1 or 2 minute off times, which becomes very annoying and hard on the equipment.
Temp over rides CPH setting. The thermostat continually monitors temp, And recalculates when it should bring on the heat or A/C. And how long it should run it. And then when it brings on the equipment, in monitors the progress and recalculates how long it should keep on running the equipment. Along with how long it should keep it off once it shuts the equipment off. It is constantly recalculating the on and off time by monitoring the temp. Temp over rides CPH setting.
A higher CPH means more on and off times an hour, so the equipment will short cycle. But maintain a very tight temp control of the hose. Very comfortable, but hard on the equipment.
A lower setting will allow a wider temp swing in the house, and be much easier on the equipment. The temp swing increase will only be a few tenths of a degree."
I've seen stuff back and forth on setting the Aux Heat to the same as the heating/cooling...so maybe I'll do that as well. I also found out that with my outdoor temperature sensor, I need to turn on the "Outdoor Temperature Aux Heat Lock Out" which locks out the use of the Aux heat if the temperature is above a specified temperatures setpoint. I've seen numbers flying around but I would think it would make sense for this to be 30F just in case the Geosystem goes down and its below freezing to prevent any water pipes from freezing/breaking. Finally, there's a recommendation to change the delta between Stages 1 and 2 to be 3F so the first stage will run more often. However, my thermostat doesn't have this feature oddly enough....the closest I have is "deadband". There is an upstage timer which I think I could use...but I'd need to check. Increasing the timer means that Stage 1 will run for XXX minutes and then if the timer expires and the temperature has not yet been reached, then Stage 2 will come on, etc. I'll have to play with this that's for sure.
Oh yeah...almost forgot about the desuperheater. In the same forum I came across some folks talking about the desuperheater. Apparently I need to check out my installation. I've talked about it previously, but the most efficienct system uses a pre-heat tank and then the hot water heater (HWH). I don't have this (yet) so I only have my HWH. Well...apparently I need to make sure my upper and lower elements are at different temperatures. So the lower one needs to be set at 100F while the upper is at the normal HW temp...say 120-130F. This is because the desuperheater measures the water temperatures. If its above a setpoint (130F apparently), then it doesn't turn on (it says the HWH is already at temperature...don't bother). Well...I think my lower one is set to 120F and I've never checked my upper one. I know the installers didn't change anything because my HWH has a insulation blanket around it...and to get at the element thermostats you'd need to either remove the blanket or cut a hole. Neither was done beacuse I cut a hole in the blanket to get at the lower element this fall. So I definately need to change these settings! And I was wondering why I didn't feel like I was getting any "free" hot water from the desuperheater...that's because the HWH was maintaining the 120-130F setting and the geothermal system would sense it and say not to use the desuperheater or it would run minimally. Dang it!!!!!! Well...that'll be fixed today. Also, I need to insulate the piping from the HWH to the desuperheater. Looking at pics it doesn't have any insulation on it and I need this to (a) get a good temperature reading and (b) to make sure the heat that it put in is actually making it to the HWH.
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