Question:
I only need to have the burner going on my water heater for, say, a couple of hours in the morning, four hours in the evening, and then during daytime week-ends. As the energy bills have become huge – I am in CA – it would be great to be able to turn off the burner with a programmable timer, similar to what is used on furnaces and sprinklers. I called my local mega home improvement store, and they said there was no such product available suitable for water heater use. Are they right – seems like such product must be very similar to a furnace timer? If so, why? There would be fairly significant savings by running such system. Thanks for any thoughts. Sig
Response:
>I only need to have the burner going on my water heater for, say, a >couple of hours in the morning, four hours in the evening, and then >during daytime week-ends. As the energy bills have become huge – I am >in CA – it would be great to be able to turn off the burner with a >programmable timer, similar to what is used on furnaces and sprinklers.
Are you referring to an electrical or a gas fired water heater? If electrical, you can pick up a 220v Intermatic mechanical clock timer for $35 – $50 at pretty much any good electrical/hardware store, including Home Depot. You’d have to wire it in but it’s straightforward. Now keep in mind you’re not going to save a huge amount of money. In fact, it’ll actually be very little. But if you can shift your power usage off of peak times you’ll be helping everyone else (and indirectly, yourself). — Knowledge may be power, but communications is the key [to foil spammers, my address has been double rot-13 encoded]
Response:
> I only need to have the burner going on my water heater for, say, a > couple of hours in the morning, four hours in the evening, and then > during daytime week-ends. As the energy bills have become huge – I am > in CA – it would be great to be able to turn off the burner with a > programmable timer, similar to what is used on furnaces and sprinklers. > I called my local mega home improvement store, and they said there was > no such product available suitable for water heater use. Are they > right – seems like such product must be very similar to a furnace timer? > If so, why? There would be fairly significant savings by running such > system.
… Are you sure you are looking at the right energy? If you have a natural gas water heater it’s likely that it doesn’t consume more than $5 to $10 of natural gas a month. Natural gas, even with a price increase, is still pretty darn cheap. I can hazard a guess as to why you won’t find timers for natural gas hot water heaters. They don’t use electricity, don’t have any plug into the grid and don’t have any external controls (apart from a mechanical knob going hot<->cold). Typically they use pilot lights so you can’t just have a valve that turns the gas on and off. Your only option on most of these things would be to take it apart and make changes to the mechanical parts which operate it. No doubt this would be both a delicate operation and possibly a dangerous one as well. Anthony
Response:
Thank you for your thoughts – I run a natural gas burner, so I guess I am stuck running it 24/7. As to the usage estimate that Anthony gave, my water heater uses 330 therms/year (typical calculated usage given on the attached sticker – if I bought a brand new, energy-efficiennt one, this one would use 250 therms/year). At $1.75-2.00 per therm, which is what I have been paying here in San Diego, CA, for the last six months or so, monthly cost to run the unit seems to be around $40, rathe than the $5-10 given by Anthony. So turning it off my generate good savings for me – if it was possible, practical and legal! I lived in England for 7 years, where heating is based on hot water, as well. The water heaters are ‘dual-function’, providing energy for both heating and hot water. Invariably, they are equipped with timers so that they run only when you want it. Sig
Response:
I’ve been interested in the same thing for years. I did hear about a water heater timer many years ago. I’m also in CA and would like to know if such a device is available. Maybe what I heard about years ago may have been for electric water heaters, it’s been too long ago to remember. Mike
– Hide quoted text — Show quoted text -> I only need to have the burner going on my water heater for, say, a > couple of hours in the morning, four hours in the evening, and then > during daytime week-ends. As the energy bills have become huge – I am > in CA – it would be great to be able to turn off the burner with a > programmable timer, similar to what is used on furnaces and sprinklers. > I called my local mega home improvement store, and they said there was > no such product available suitable for water heater use. Are they > right – seems like such product must be very similar to a furnace timer? > If so, why? There would be fairly significant savings by running such > system. > Thanks for any thoughts. > Sig
Response:
Electric water heater (thank you for not saying hot water heater) timers were a part of life in the 1960s here in Wisconsin. Every house in my area had a clock on the kitchen wall that controlled the water heater. They have now been replaced with radio control. The power generating company, not the local power provider, can dump loads as needed. Normally they dump water heaters first followed by electric heat. They also control some large generators at farms and TV/radio stations and can shed load by starting backup gensets at larger users. But I question the $$ savings of turning off any water heater for a day. I shut mine down when on the road and it is still warm 2 – 3 days later. It is an electric with a blanket. kwd/KE9CS http://users.wwt.net/~dicksk/ – Hide quoted text — Show quoted text – > I’ve been interested in the same thing for years. I did hear about a water > heater timer many years ago. I’m also in CA and would like to know if such a > device is available. Maybe what I heard about years ago may have been for > electric water heaters, it’s been too long ago to remember. > Mike
Response:
> But I question the $$ savings of turning off any water heater for a day. I shut > mine down when on the road and it is still warm 2 – 3 days later.
The point I think you are making is a valid one – it is possible that modern water heaters (gas or electric) are sufficiently efficient, in terms of insulation, that they only kick in when drawn on anyway, so that turning them off (except for during long absences) would not generate significant savings. Sig
Response:
>…I question the $$ savings of turning off any water heater for a day. >I shut mine down when on the road and it is still warm 2 – 3 days later…
The $$ savings come from lower off-peak electric rates (about 5 vs 15 cents/kWh where I live.) The actual energy saving is negligible. Nick
Response:
>I only need to have the burner going on my water heater for, say, a >couple of hours in the morning, four hours in the evening, and then >during daytime week-ends. As the energy bills have become huge – I am >in CA – it would be great to be able to turn off the burner with a >programmable timer, similar to what is used on furnaces and sprinklers.
More tank insulation isn’t going to hurt anything. And exposed water lines.
Response:
I would just turn it’s thermostat down to the lowest setting. A timer could be wired to a solenoid valve to cut the gas line on command, the problem is re-lighting the pilot when it’s needed again. An auto coil and spark plug might do. Reheating the water from 60 back up to 120 or so might use more fuel than maintaining it at a lower temp. If you really want to make a change, hook up with alt.solar.thermal and screw together a solar water heater. If your cost estimates are accurate it’d be paid for in a few months. Same system makes a good space heater if you can run pipes under the floor. If your water spends $40 a month I hate to think what your furnace is going to cost. How much is your fridge costing you a month? Mark Van Nordstrand in North Hollywood, CA My web site: http://markvan.virtualave.net
Response:
Mark, > If you really want to make a change, hook up with alt.solar.thermal and screw > together a solar water heater. If your cost estimates are accurate it’d be paid > for in a few months.
I don’t know for certain that the estimates are right in my situation – I just took the estimated average annual consumption (330 therms/year) from the sticker on my gas water heater and multiplied by what I have been paying lately – $1.50-$2.00 per therm. You live in SoCal, too, you know what the rates have been like for the last year or so! > How much is your fridge costing you a month?
I don’t know, it is a brand new energy-efficient (Star-rated) model – I guess another $40 or so. I am not worried about heating, live less than half a mile from the Pacific ocean and I am only running the furnace burner for max. 25-50 hrs. per year. I like your idea of solar panels, though, and will investigate that further (and I also liked the crate setup in your window!) Sig
Response:
I have a lp gas stove and just turn off the gas when not in use.I use a 5 gallon tank and with the pilots running it lasts 2 weeks.Turning them off and lighting when needed I get 7 weeks.It costs $10.00 to fill the tank. Pilot lights burn more gas than one would think. I don’t know if you can do your water heater the same way.It may be to much trouble. The only thing is you would have to wait until it heats up for use.If you don’t know how to do it get some help before you try. (Safety is the important thing)
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Most hot water heaters have a pilot and no electricity needed. A few have electric ignitors and those have a flame sensor circuit, both of which require electricity. With this type you should be able to plug the heater into most any lamp timer and set the on-off cycle to suit you. ben
– Hide quoted text — Show quoted text -> I only need to have the burner going on my water heater for, say, a > couple of hours in the morning, four hours in the evening, and then > during daytime week-ends. As the energy bills have become huge – I am > in CA – it would be great to be able to turn off the burner with a > programmable timer, similar to what is used on furnaces and sprinklers. > I called my local mega home improvement store, and they said there was > no such product available suitable for water heater use. Are they > right – seems like such product must be very similar to a furnace timer? > If so, why? There would be fairly significant savings by running such > system. > Thanks for any thoughts. > Sig
Response:
If it is gas, just insulate it. Properly insulated, the water will stay hot all day without having to reheat it. A good UL rated insulation blanket might run you $30.00 or so. I just wrapped one in fiberglass one time, keeping it away from the burner. Saved about $3.00/month in summer and $5.00/mo. in winter. But, fuel was only about $15-$20/mo., anyway. If it is already insulated, you can still – Hide quoted text — Show quoted text – > I only need to have the burner going on my water heater for, say, a > couple of hours in the morning, four hours in the evening, and then > during daytime week-ends. As the energy bills have become huge – I am > in CA – it would be great to be able to turn off the burner with a > programmable timer, similar to what is used on furnaces and sprinklers. > I called my local mega home improvement store, and they said there was > no such product available suitable for water heater use. Are they > right – seems like such product must be very similar to a furnace timer? > If so, why? There would be fairly significant savings by running such > system. > Thanks for any thoughts. > Sig
Response:
> But I question the $$ savings of turning off any water heater for a day. I shut > mine down when on the road and it is still warm 2 – 3 days later. It is an > electric with a blanket.
When we moved into our current home, we had a propane stove and an electric water-heater. Replaced the stove with a new Hotpoint electric model. At the same time we installed a Home Depot electric water-heater timer. Results? No more propane bill. And, even with the electric stove being used regularly, our electric bill did not go up. So, apparently, the water-heater timer saved enough electricity to run the stove. And no more $125/year for propane. S. PS. Timer is ON from 5P -11P in evening. And ON again from 6-7A
Response:
>> …I question the $$ savings of turning off any water heater for a day.
You might save a penny a day… > When we moved into our current home, we had a propane stove and >an electric water-heater. Replaced the stove with a new Hotpoint >electric model. At the same time we installed a Home Depot electric >water-heater timer.
Deja vu? Was the timer an off-peak meter? >…even with the electric stove being used regularly, our electric bill >did not go up. So, apparently, the water-heater timer saved enough >electricity to run the stove… Timer is ON from 5P -11P in evening. >And ON again from 6-7A
Perhaps your water heater is very old and small and poorly insulated. How many gallons? What’s the water temp at the tap just before 7 AM, vs just before 5 PM? Is your "regular stove use" making a single cup of tea every day? 
Did you change your habits in the direction of saving more energy as you became more interested in energy conservation? More CF lights? Do you take shorter showers, knowing you might run out of water? Did the electric rate decrease? Say your stove uses 1 kWh/day, eg 1 burner for an hour a day on average. What’s the max R-value the water heater jacket could have while saving 1 kWh/day with that twice-a-day timer? Nick
Response:
>What’s the max R-value the water heater jacket could have while saving >1 kWh/day with that twice-a-day timer?
Turns out that’s a very low R-value, a lot less than a bare metal tank surrounded by air. We’d have to wrap the tank with lots of concrete or heat sink fins to get an R-value that low… How long would we have to leave a 40 gallon water heater turned off in order to save 1 kWh? Switching once or twice a day is almost useless, but how about turning it off over a weekend or a week’s vacation? Say it has a 25 ft^2 R10 jacket, so keeping the water 120 F in a 70 F room continuously takes (120-70)25/10 = 125 Btu/h. If the tank water cooled to 70 F instantly when the heater was off, we could save 1 kWh (3512 Btu, or 10 cents) by leaving it off for 3512/125 = 28.1 hours. But the water cools very slowly. RC = 40×8/2.5 = 128 hours. After t off hours, it cools to T(t) = 70+(120-70)exp(-t/128) F. The tank heat loss Q is the integral of (T(t)-70)25/10 over that time, ie Q(t) = 16K(1-exp(-t/128)). After a very long time, exp(-oo) = 0, and the tank water loses 40gx8Btu/F-g(120F-70F) = 16K Btu, right? To save 1 kWh, we have to wait until 3512 = 125t – Q(t), or t = 156.1-128exp(-t/128), ie about 95 hours (after a few iterations.) Almost 4 days… After that time, T = 70+(120-70)exp(-95/128) = 94 F. Leaving it off for 2 weeks in a row saves 125(336h)-16K(1-exp(-336/128)) = 27K Btu or 8 kWh, 80 cents at 10 cents/kWh, as it cools to 74 F. Nick
Response:
- Hide quoted text — Show quoted text ->What’s the max R-value the water heater jacket could have while saving >1 kWh/day with that twice-a-day timer? > Turns out that’s a very low R-value, a lot less than a bare metal tank > surrounded by air. We’d have to wrap the tank with lots of concrete or > heat sink fins to get an R-value that low… > How long would we have to leave a 40 gallon water heater turned off in > order to save 1 kWh? Switching once or twice a day is almost useless, > but how about turning it off over a weekend or a week’s vacation? > Say it has a 25 ft^2 R10 jacket, so keeping the water 120 F in a 70 F > room continuously takes (120-70)25/10 = 125 Btu/h. If the tank water > cooled to 70 F instantly when the heater was off, we could save 1 kWh > (3512 Btu, or 10 cents) by leaving it off for 3512/125 = 28.1 hours. > But the water cools very slowly. RC = 40×8/2.5 = 128 hours. After > t off hours, it cools to T(t) = 70+(120-70)exp(-t/128) F. The tank > heat loss Q is the integral of (T(t)-70)25/10 over that time, ie > Q(t) = 16K(1-exp(-t/128)). After a very long time, exp(-oo) = 0, > and the tank water loses 40gx8Btu/F-g(120F-70F) = 16K Btu, right? > To save 1 kWh, we have to wait until 3512 = 125t – Q(t), or t > = 156.1-128exp(-t/128), ie about 95 hours (after a few iterations.) > Almost 4 days… > After that time, T = 70+(120-70)exp(-95/128) = 94 F. Leaving it off > for 2 weeks in a row saves 125(336h)-16K(1-exp(-336/128)) = 27K Btu > or 8 kWh, 80 cents at 10 cents/kWh, as it cools to 74 F.
Two other losses from a hot water tank are conduction and convection through the hot output pipe, and leaky faucets. Even in the best case (pipe insulation and internal plastic thermal break) the hot riser is probably leaking around 10 watts. A 0.1 cc drip every second would waste about 10 gallons a day. Each would consume around 250 watt-hours or 3 cents a day at $0.12 a kWh.
Response:
> After that time, T = 70+(120-70)exp(-95/128) = 94 F. Leaving it off > for 2 weeks in a row saves 125(336h)-16K(1-exp(-336/128)) = 27K Btu > or 8 kWh, 80 cents at 10 cents/kWh, as it cools to 74 F.
I did an experiment a few weeks ago. I turned off my water heater. It stayed warm enough for hot showers every day and other incidental (small) uses for four days. The next morning I turned it on for a few hours up to and while I showered, laundry, etc. Turned it off again and had hot showers three more days. Then the wife and family got home. :) Oh, my water heater is in the basement. High temp in that area was 67F during that week. Low was 65F. sdb — More guns means less crime. ISBN:0-226-49363-6 *** IWant: Song of the South — any digital format *** Watch out for munged e-mail address. User should be sdbUse1 and host is at bigfoot.com Do NOT send me unsolicited commercial e-mail (UCE)!
Response:
Thanks for the idea. I think I’ll test this one out at my house. Y. – Hide quoted text — Show quoted text -> I did an experiment a few weeks ago. I turned off my water heater. It > stayed warm enough for hot showers every day and other incidental
Response:
To my knowledge there is no such product for gas water heaters. There certainly is such a product for electric hot water heaters and you can also automate the operation of electrica hot water heaters using powerline carrier control products. – Hide quoted text — Show quoted text – > I only need to have the burner going on my water heater for, say, a > couple of hours in the morning, four hours in the evening, and then > during daytime week-ends. As the energy bills have become huge – I am > in CA – it would be great to be able to turn off the burner with a > programmable timer, similar to what is used on furnaces and sprinklers. > I called my local mega home improvement store, and they said there was > no such product available suitable for water heater use. Are they > right – seems like such product must be very similar to a furnace timer? > If so, why? There would be fairly significant savings by running such > system. > Thanks for any thoughts. > Sig
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Response:
Years ago I did see such a device advertised somewhere. It was a little motorized thing that attatched to the knob of the thermostat and would turn the thermostat up and down. I can’t remember where I sw it–might have been Popular Science or similar magazine–but it was a long time ago. Obviously it was not a real big seller. However, you could install a solenoid valve in the line between the gas valve and burner that would operate off a timer. All gas water heaters I have ever seen have 2 lines coming out of the gas valve- a 1/4 inch for the pilot and usually a 1/2 inch for the burner, so the pilot would not be affected. Also’ the pilot energy is not really wasted. A lot of it’s heat goes to the tank to help keep the water warm.
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