Water heater improvement (Timer)
GE 15207 timer was $38 at Home Depot.
http://waterheatertimer.org/images/G...or-outdoor.jpg http://waterheatertimer.org/15087-15...Manual-eng.pdf Before installing this timer on my hot water heater (actually my oil burner), I tested it with my Kill-A-Watt and got no reading. Used the VOM AC Amps and saw 0.02 Amp that's about 2.5 watts, so it's a keeper. The meter reading was less than 0.01 Amp without the two relays energized. (When the water heater is off. Clock motor only). It's a simple mechanical timer that does 30 minute increments. Can run on 120, 240 or 277 vac. (This is the indoor version). Not as fancy as a battery-backed-up LCD unit, but it's a lot less money. It can handle 8,000 watt loads, so my little burner should work fine. I'll try to post some pics of the install. Cheers, Rich |
Nice, that should definitely help out. I know Ryland praises them up and down.
How are you planning on setting it up? Just turning it off at night? |
For summer, I was thinking of running it for 1/2 hour around 8AM.
Since the boiler will be cool after a night of being off, it should run 1/2 hour, unless it hits max temperature before the timer shuts down. I might try switching it on again around noon time. If the temp is down, the burner will light off again. It's going to take some experimenting to see how the timer, Aquastat Min-Max, and us hot-water users interact. |
It works!!
It works pretty well. Installed it early this morning (00:30) and it came on at 07:30 and heated up the storage water (76 gallons) to about 145 dF.
Wiring was pretty simple, only 3 wires. Hot and Neutral to the clock (2 left screws). A short Hot jumper back to Common (relay 2), with the NO2 back to turn on the boiler. http://i46.photobucket.com/albums/f1...r/Solar/t1.jpg I'm saving relay-1 contacts for a rainy day.. :D Face plate installed. http://i46.photobucket.com/albums/f1...r/Solar/t2.jpg Case closed. http://i46.photobucket.com/albums/f1...r/Solar/t3.jpg Dang! We just had a 15 minute grid failure! Now, I have to go reset the clock!! Edit 19:20 We took 3 showers and did two loads of wash today. We still have 115 dF hotwater left over. Leaving the timer as is, for now. |
Looks good. I wonder how this would work on a 220V water heater?
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As long as it can handle the amperage your heater is, I'd say its perfect.
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For a little energy saving, disable the bottom element. That will reduce the volume of water that is heated.
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use the bottom one. The lines to the temperature switch removed? For current like that, perhaps both NO contacts could run in parallel? Maybe you can tell that I'm not really an Electrician, just an old retired Electronics guy. I was just thinking about wear on relay contacts. If it's only a couple of cycles per day, those contacts might outlive me and my offspring. When the contacts close on my system, there is about a 20-second time delay, before the oil burner motor can start (if the water temp is low). The time delay is caused by the initializing of two electronic controllers. So, there isn't a sudden motor load surge, the instant of relay on. I have a second relay to fall back on, and in 20 years if both are pitted, I can switch to the NC contacts and reverse all the time segment pins. :) |
I was just thinking about the advantages of using a timer with an electric water heater.
If you know the KW used and your timer setting, you can calculate the absolute maximum cost to heat your water. It might be less, on days when the timer comes on and the water is already pretty warm. It allows you to plan-control your max cost a little better. Oil makes my case is a little different. But using the 1/2 gallon-per-hour oil burner set up, I can see that a 200 gallon fill up will last about 400 days, burning 1/2 hour a day. 1/2 hour a day is my current setting, and it seems to be working pretty well so far. If the Sanyo keeps working this winter, we might be able to stay with this 1/2 hour setting for 95% of the cold weather. :D If the Sanyo fails again, the timer program segments will have to be radically changed.. :eek: Hey, the sun coming in the window just reminded me of the PV array. It's contributing about 1400 BTU to my hot-water right now. And it's free! A happy side effect of my tinkering hobby! :cool: |
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My understanding of how the water heater works is that it runs on the lower element most of the time which heats the entire volume of the tank. But if you put a great demand on it by using a lot of water quickly, it kicks on the upper element to get "quick recovery" so that you're not getting excessively cold water in your shower/tub, etc. So if I change it so that only the upper element runs, will my wife run out of hot water for her baths? |
If I have a lot of insulation around my water heater, will a timer do me any good? With a very slow rate of heat loss in standby (where supposedly the greatest amount of energy is used), am I gaining anything by putting the heater on a timer?
In other words, is it possible that with additional insulation the temp drop could be minimized to the point that the themostat would kick on the elements at the same time that the timer would if it were installed? |
A timer might help a little. Even with good insulation, it might turn on at 1AM
to keep the tank hot all night. If you could keep it from coming on between 10 PM & 5 AM, you might save some money. With super good insulation, the temperature isn't going to drop very low over night, when no one is using hot water.. So, the 5AM turn on won't have to be a long cycle. If you both work, does the hot water need to be on while you are both at work? No one using it, temperature pretty stable.?. Turn it off between 8AM & 4PM..?. IMHO, working people need a 7-day timer with a weekend program.. Mine is made for old retired folks.. ;) |
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You can try turning down the bottom element temperature until it's completely off or until the water just starts getting too cool. |
Update:
The timer has been installed a few days now and my wife gave it the :thumbup:
With the oil burner running 20 to 30 minutes at 7:30 every morning, and the Solar PV adding some heat during the day, we seem to have more than enough hot water to meet *our needs. (*two retirees). I'm not sure, but it seems like we have enough HW to take at least 4 showers a day. Have not tried it on laundry day, I suspect the last shower would be luke-warm.. :o Over-all, this mod was good one, that has improved our quality of life. We won't save as much, as if we ran the boiler manually, but that method has it's problems, when you are old and forgetful. I was getting ready to go bowling this morning and decided take a quick shower on the spur of the moment. Not possible with manual control. I like the idea of the boiler firing up once a day. Just in case we need it to heat the house in the winter.. Hopefully, it will just stay a hot water heater.. :) |
I'd be very interested to see how much oil this saves. I don't suppose there is a good way of measuring this though?
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Using on-demand with the switch is just too inconvenient for us. And, washing your hands during the day with cold water isn't fun.. (65dF) But, the total usage is not going to be super expensive, and it can be calculated easily. Summer time use is going to be 15 gallons (or less*) a month. At $3 per gallon (a guess for this winter) is $45 a month. Not that cheap! * It will randomly be somewhat less, if the PV is working well and/or we don't use a lot of hot water the day before. The burner will run a short-cycle for 15 or 20 minutes and shut off before the 30 minute segment is over. We have observed two short-cycle burns this week.. (Approx 20 min). It might be cheaper to use an electric HW heater, but we need the oil burner for back-up heat in the winter. (Which is long in this area). So, we are going to suffer with $45 per month until the price of PV takes a drastic drop.. :rolleyes: |
Burning oil
We didn't burn much oil during summer 2010. We got our Fall fill-up last week, 78 gallons. ($2.59 per gallon)
Since April 29, (until Nov,3) we used both the manual control & the timer. 6 months, 6 days = 189 days total, for 0.412 gallons ($1.07) per day. ~~ If we don't get too much super-cold weather this winter, with temps staying under 10 degrees F, for too many hours, we should be able to use the Sanyo ASHP to stay warm, and keep using 0.5 gallons a day (using timer) until the April 2011 fill-up.. :) ~~ If it's a really bad winter, and the Sanyo averages ~10 kwh per day, that's going to cost about $2.00/day ($60 per month). Haha.. That really puts the cost of heating hot water with oil into perspective, eh? ~~ I should also say, that good solar days will reduce the load on the Sanyo, (due to southern windows), and may slightly help the daily oil burn, due to the 500w PV heater in the oil burner. |
Using the left-over heat in the left-over hot water
The burner has been bringing up the water to 170 in less than 1/2 hour.
Seem like 15 or 20 minutes on some mornings. I don't like those short cycles. And, since the nights are getting down in the teens now, and the den had some spots that got down to 38F this morning, I've decided to start using the left-over heat in the burner (87 gallons of warmish water). Why let it just dissipate up the chimney over night? (note: The Sanyo is keeping the main living areas at a 21C 24-7) So, each night before I sleep, I'll open the free-flow valve and let the warm water circulate around the perimeter of the house, keeping those unheated rooms from falling into the freezing range.. http://i46.photobucket.com/albums/f1...r/freeflow.jpg I'll have to get up early each morning and close the valve too.. If this measure isn't enough to keep the baseboard pipes from freezing in the unheated rooms, I'll reset the timer to run the burner for 1/2 hour at 2AM.. I guess we can afford two 1/2 hour burns a day, when it's really cold.. Cheers, Rich |
I'm acclimated!!!
It was chilly yesterday but got up to 25F about noon time.
Weather history here. Weather Station History : Weather Underground And it's stayed around 25F for the last 20 hours. However, it was movie night in the den. I wanted to be warm to watch the new version of "Clash of the Titans". So, we had the free-flow on early in the evening to take the chill out.. Once the storage water temp dropped down a bit, after the movie, I ran the oil a little more. We had 170deg F hotwater at 10PM and the burner was back in the timer.. It was in free flow at bed time. Big mistake. I woke up this morning at 04:30 and it was about 68 in the bedroom. A bit too warm. Need 65-66 now that I'm acclimated. I looked at the meter, in 4.5 hours we had only used about 2 kWh! It's after 8AM now, and it's reading 3.55 kwh (for 8 hours=444w per hour). So, using the house as a Dump-Load for the extra water heat saves some power during the night.. And can make it a bit too warm to sleep with a lot of covers.. :eek: The timer came on at 7:30 to 8:00 this morning and ran the temp up from 70F to 142F. Which should be fine. And we might even get some extra BTUs from the new 400w PV today.. It will at least help counteract the hourly losses. I never thought that I would ever want to sleep in 66F room at night.. And I never would have guessed, I would ever consider 25f mild weather..:o |
Could you perhaps not open the valve all the way so the heat release is slower?
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Yeah, you're right. That small piece of tape in the photo says "4.5 turns".
But, that's a really slow flow. Of course I was in a hurry and cranked it up about 8 turns.. I'll have to see if 4.75 turns gives us a happy medium.. :) |
You may find this interesting:
(I copied and pasted as I could not post a link.) Bottom Line: Yes, it saves energy, but not a huge amount. Suppose you go on vacation one Saturday morning and return on Sunday evening a week later, which means you are away for a total of 8.5 days. Should you turn the water heater off or not? In reasoning this through I will use an electric water heater, but the same results apply to a water heater that runs on natural gas or propane. By the way, "turning off" an electric water heater generally means throwing the circuit breaker. The easiest way to reason through this problem is to look at the cumulative heat lost in both cases. All the heat that was lost must be replaced by the electric resistance heater inside the tank. Leave the Water Heater On: If you leave the water heater on then the heating element cycles on and off occasionally to replace heat lost through the insulation. The below graphic shows the rate of heat loss in btu/hr over 8.5 days for our 80 gallon R-16 hot water tank assuming the tank is left on. Because the thermostat in the water heater is keeping the water temperature roughly at a constant, then the rate of heat loss is constant over the entire 8.5 days. In the Hot Water Tank Heat Loss web page I computed this loss to be about 141 btu/hr. Water Heater Loss When On The "area under the curve" of this graph gives the total heat lost in btus over the 8.5 days. The calculation for total btu loss is: BTU Loss on vacation = 141 btu/hr x 8.5 days x 24hr/day = 28,764 btu The only way to replace lost heat is by turning on the electric resistance heating element, so all of these btus are supplied by electricity. Divide the btus by 3,412 btu/kwh in order to convert the btu loss to kwh supplied by the electric company: kwh supplied = 28,764 btu / (3,412 btu/kwh) = 8.43 kwh Multiply by $0.10/kwh to find the cost of replacing the lost heat: Cost of kwh supplied = 8.43 kwh x $0.10/kwh = $0.84 So the cost of the electricity needed to keep the tank hot over this 8.5 day vacation is a little less than a dollar for our system. Turn Off the Water Heater: If you turn off the water heater then its temperature slowly coasts down according to Newton's Law of Cooling. No electricity is consumed while you are away, but once you return and throw the circuit breaker on again the heating element turns on and stays on until the tank is back up to temperature. The below graphic shows the rate of heat loss in btu/hr over 8.5 days for our 80 gallon R-16 hot water tank assuming the tank is shut off. As the temperature slowly declines during those 8.5 days the rate of heat loss also declines. Water Heater Loss When Off The equation for this theoretical heat loss curve can be constructed as follows. Start with the equation for the temperature over time: T(t) = 60 + 60e-0.00351 t (This equation is derived in the Sample Calculation at the bottom of the Newton's Law of Cooling web page.) Next consider the equation for heat loss through the insulation: H(t) = A(T(t)-TA)/R where H = Heat loss in btu/hr A = Area of tank walls = 37.5 ft2 for our tank T(t) = Temp of the hot water as a function of time TA = Air temperature surrounding tank = 60 F R = 16 ft2hrF/btu (This equation is described in more detail in the Hot Water Tank Heat Loss web page.) Substituting T(t) into the H(t) equation and simplifying: H(t) = 141e-0.00351 t This equation states mathematically what the above graph shows visually. The "area under the curve" of the graph gives the total heat lost in btus over the 8.5 days. All of this lost heat is replaced at the end of the vacation when the electric resistance heating element turns on after your throw the breaker on. To compute the area under this curve we take the integral of the H(t) equation from time = 0 to 204 hours (8.5 days). Cumulative heat loss = ∫0204141e-0.00351 tdt = 141*(e-0.00351*204-1)/(-.00351) = 20,540 btu Divide by 3,412 btu/kwh in order to convert the btu loss to kwh supplied by the electric company when we turn the breaker back on: kwh supplied = 20,540 btu / (3,412 btu/kwh) = 6.02 kwh Multiply by $0.10/kwh to find the cost of replacing the lost heat: Cost of kwh supplied = 6.02 kwh x $0.10/kwh = $0.60 Conclusion: So if we leave our hot water heater on it costs about $.84 of electricity to keep the water hot while we are away on an 8.5 day vacation, and if we switch the hot water heater off it costs about $.60 of electricity to heat the water back up to temperature when we return. The net energy savings is about 2.4 kwh, which translates into a cost savings of about $.24. How might these results vary for other households? If you have a poorly insulated water tank, or lots of heat loss from the pressure relief valve and the hot water pipe, then you might save two or three times as much from turning off the breaker. Does this result depend on the length of the vacation? The longer the vacation, the more you save. The only case in which turning off the water heater would not save energy and money would be a vacation so short (a few hours?) that the thermostat would not have turned on to top off the heat anyway. So is it worth shutting off the breaker, then shutting it on again for a savings of $0.24? My immediate reaction was "No way". But wait. I would certainly stoop down to pick up a quarter that I saw on the sidewalk. Just how much effort would I be willing to expend to retrieve a quarter? If I saw a quarter at the bottom of a floor heating vent I would be willing to spend 30 seconds to remove the vent, pick out the quarter, then replace the vent. Thirty seconds is about how much time it takes me to turn off the breaker, then turn it on again when I get back from vacation, so logically I should be willing to do this. What is the effective pay rate for shutting the breaker off and on again? To make the calculations easier, assume a savings of $.25 for 30 seconds of effort. That's $.50 per minute, or $30 per hour. But that is an after-tax rate of pay, which might translate to $40 per hour before tax, or a taxable salary of about $80,000/year. So for that brief 30 seconds I'm earning an implied salary of $80,000/year. Isn't math wonderful? Possible Downside of Turning Off the Water Heater During Vacation? Could the additional thermal cycling due to turning off your water heater tank during vacation cause it to fail sooner? If so, then the cost and energy savings of shutting off the tank may be entirely swamped by early tank failure. Early tank failure means that the purchase and installation cost of the tank is spread over fewer years, so you pay more per year for the tank. Building a water heater tank takes energy, so early tank failure means the energy embedded in making the tank is spread over fewer years, so the embedded energy use per year is higher. Of course, if the tank were poorly insulated, then early tank failure might be a net positive. The analysis of tank life will require some further research... This site is still under construction…to be continued… You can e-mail me at support(@ sign goes here)leaningpinesoftware.com. He basically says that shutting off an electric water heater will have negligible savings and does the math to prove it. I think you have the same setup I have, tank-less coil on the oil fired furnace. One of the least efficient ways to make DHW. I the summer with no heating requirement, I was using about 1 gal/day for DHW about $90/mo. I switched to an 80 gal electric which should only cost about $25/ mo to run. It is less because I have a solar and wood stove pre heater. |
Our boiler has a 76 gallon water jacket, and once it's heated up in the morning,
it can provide enough hot water for our daily needs. And it's even hotter if there is some solar assist. :) When things are going well, and the weather isn't too crazy, we use 1/2 gallon of oil a day typically. During sunny weather, the timed 1/2 hour burns are sometimes actually about 20 minutes. At our last fill up we paid $2.59 a gallon, so it's costing us about $39.39 per month. The oil burner is our main backup heat, so we need to keep it in good shape. We need to be confident that it will power up and heat the house when we need it. So, running it 1/2 hour a day is about the best way I know to insure it's good to go. I can't really justify buying an electric hot water heater, just for summer use. As you know, sometimes we don't get much of a summer.. Like in 2009.. :eek: Yeah? wasn't 2009 the year when global warming gave us an 800 hour summer? :mad: Although, I would really love one of those heat-pump hw heaters for summer use.. It would keep the basement air dry too. Since we use GSW (Geo-Slab-Warmth) downstairs, I think our basement is a little too cold in the winter time for much heat to be pulled out of it's air. I want to be able to go down to my shop, without wearing a parka.. :rolleyes: Cheers, Rich |
Home heating oil is around $4 a gallon right now, but since we are timed to be only burning
0.5 gal per day, $2 for hot water isn't that bad of a deal. :o But Solar HW is starting to look better and better! About 15 gallons a month for the 8 warmer months, comes to 240 gallons. Our typical fill-up in the early fall is normally around 200 gallons.. But, that might be way off base this year. The last bill I can find shows a fill-up on 02-02-11. I just looked at our 275 gallon tank, and it looks pretty full.. Just under 3/4 full. It goes up to 7/8 after a fill-up, so it only looks like we've used about 40 gallons during the last 7 months. Should have been more.. 214 days * 0.5 gallons is 107 gallons (of burn per the timer). I wonder if the new lower water temp setting (140F) has the Aquastat shutting off the burner after 10 or 15 minutes.?. I'm never up at 7AM when the timer starts it up.. :o Anyways, I'm looking forward to only needing about 60 or 70 gallons for our fall fill-up..:D Even with the 140F water, we've never had any problems taking showers in the evenings. I think the solar PV assist might be bigger help at low water temps.. I'm working on boosting the PV power to the heater. Got the parts, just need to do some soldering etc.. |
You really dug out some of my memories. I remember getting the same experience. Thanks for your post.
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.... ... ..... summer ....... winter 7-11AM .... mid-peak ..... on-peak 11-5PM .... on-peak ..... mid-peak 5-9PM.... .. mid-peak ..... on-peak 9-7AM ..... . off-peak ..... off-peak So, a timer has to be worked around this as well, which could be beneficial in that one could use power during the off-peak times. Edited for clarity |
"9-7AM off-peak off-peak".. That's a big window of low cost power!
Working people who shower before bedtime could have it come on at 9PM. Those who shower in the AM could have it come on early in the AM and go off by 7AM. (That would be my choice, being retired).. |
I'm curious what is the cost/kwh for off-peak, mid-peak, and on-peak. They are still debating going to smart meters here but when it happens I expect to see this type of scheme looked into.
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EDIT: I also found their three tier prices: * On Peak - $.10658 * Mid Peak - $.05143 * Off Peak - $.04389 |
I'll bet a lot of Entergy customers do the wash at night.. :)
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Today we had the (late) Fall Fill-up.. 80.7 gallons @ $3.59 = $281.64 (after QPD). Since the last fill up on 02-02-11, It's been 288 days or 9 months, 15 days. That equals 0.28 gallons a day.?. $1 a day (at today's prices)!! :p This little timer has paid for itself and then some.. Seems that solar assist is helping out too. Dang, I've got to optimize that thing ASAP.. |
50.7 gallon oil fill..
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It's been 73 days, and we just had a visit from the Oil truck! He Pumped in 50.7 gallons. @ $3.49 quick-pay-discount, is $176.94 50.7 / 73 = 0.6945 gallons a day, which is only a tad high. That's more than our goal (0.5 gal per day), but we did have a couple of nights when we used some back-up oil-heat, and a few evenings, when we needed extra hot shower water.. :o Over all, we've been very happy with the operation of the Timer.. :thumbup: Edit: This morning, we decided to change the timer to 8:30 AM.. For reason, see http://ecorenovator.org/forum/solar-...html#post19447 |
It's been 95 days and today the oil truck was here again!
45.3 gallons ($3.69/gal) is 0.477 gallons per day. Pretty close to our goal of 1/2 gallon. In the fall, when I did the burner maintenance, I was really pleased to see how clean the filter and flame retention unit was. Running 1/2 hour a day has it's good points too. If I can get the heat pump project running, we might end up using much less (if any) oil. |
I hacked my water heater today before I read this thread. Its electric 4500watt elements. The top one comes on first, when it meets its setpoint it lets the lower have power to make its set point. I set the top to ~110 qnd the lower to 125. My timer is an intertec, ifound, it nneded a clock motor( $18 ). I put the timer in to interupt the lower elements normal cycle. It now only comes on when my solar pv panels should be producing. It is better to use than to sell. I have thoughts of putting lower powered elemnt in lower position. solar panels can barely hand an element.
I am retired so in the day time I try to do things that can use the solar power, and avoid night uses. I welcome suggestions and thoughts on my hack job. |
Hi Ferg,
I installed a new GE hotwater heater this summer. I think it also has 4500w elements. But, I got it for my A7 Airtap ASHP project and didn't plan to use the 4.5kW power hog mode at all. I did test the tank using the 120vac.. Works nice! http://ecorenovator.org/forum/geothe...html#post23896 Only uses 1.130 kW. Making 3856 BTUh of warmed up water.. :) Maybe your PV can handle the load at 120vac? At least during the daylight hours..?. The negative side is very long recovery time. But, it might be okay, depending on your hotwater needs. ~~~ Anyways, we're now using a timer that keeps the A7 off, between 10:30PM & 6AM. Since we aren't going to be using any hot water during those hours, I don't think we are going to run short of hot water at any point. (During our normal waking hours). There might be some small power savings.. I really don't care, since the power use by the A7 AirTap is already pretty insignificant at 15 cents a day. This PC uses a LOT more than that per day!! :o |
"Only uses 1.130 kW. Making 3856 BTUh of warmed up water.."
Umm 3.412 * 1.13 = 3.855.6 You've got the same efficiency as power hog mode, except with a long recovery time? ..or you've made a mistake somewhere along the line with the output or the input number. |
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I don't use the 4.5kW elements, I just tested them, using 120vac. I only use the A7 ASHP to heat my hotwater. Which is super efficient. <1kWh per day . I do use some resistive electrical heating in the old oil burner.. But it's all from PV.. (DC @ 800W max). http://i46.photobucket.com/albums/f1...W/Untitled.png |
120 volts huh, I,ll try that since the outlet was wired with neutral.
Any more suggestion to insure I make hay while the sun shines ( use solar automatically). |
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