Should we install a gas water heater timer?

[DainBramaged]

First, do they have them?
Second, should I install one?

Why?

 

[Capt Caveman]

Why would you want one?

 

[DainBramaged]

Why would you want one?

The assumption is that it'd save £££. But the potential that my assumption could be wrong is why I'm asking.

 

[jagec]

It would be far better to spend that money on a water heater blanket...or just shave 30 seconds off of your shower time and spend the money on a cup of coffee instead.

 

[nickbits]

You don't save any money because the unit has to spend more time recovering because the unit was off.

 

[Greenman]

No.
No.
Because they don't save any energy.

 

[DrPizza]

You don't save any money because the unit has to spend more time recovering because the unit was off.

Not true. Conservation of energy. When the heater is heating the water, it's using energy. 100% of the time, it's also losing energy to the surroundings. The rate at which it loses energy is proportional to the difference in temperature between it and the ambient temperature surrounding it. Any energy lost, obviously has to be replaced. By allowing it to drop to a somewhat lower temperature, it reduces the rate at which it loses energy, thus reduces the total amount of energy required for the next time the hot water is used.

The OP would probably save more money simply by simply installing a blanket for increased thermal insulation. I doubt the amount saved with a timer would make it worthwhile.

 

[SlitheryDee]

I thought stuff you can do to your water heater to increase it's efficiency would only save you at most a couple of dollars a month anyway. I think I would turn my attention to that only after I had shored up all the other money sinks in the house, if then.

 

[MixMasterTang]

Why not a tankless water heater?

 

[vi edit]

Probably save more money putting one of those insulating blankets around it.

 

[Red Squirrel]

I had thought of it, but figured it's not worth the effort. While you WILL save energy, it wont be all that significant.

I do wish water heaters would work like high efficiency furnaces though, where they dissipate a larger % of heat and it's a closed combustion system. That alone would save lot of energy. The fact that you can burn yourself on the exhaust pipe shows just how much energy is being wasted too, not to mention the fact that it's sucking indoor air outside, thus sucking cold, outdoor air inside. I'm sure you can buy some, but they're probably ridiculously expensive as it's not standard. It should be standard.

Tankless are only good in the south. Delta T is a bigger factor with them, while with a tank, it will maybe take longer but it will eventually reach the right temp and you have a reserve. Though, the colder the water is, the faster your reserve cools down as new, cold water comes in. I tend to jack the temp up in winter to make up for that.

What is surprising is how high quality the built in insulation in a water tank is. It's incredible that you can touch it and it's very cold despite the water no more than a few inches away from your hand is scalding hot. Not sure how much of a difference those blankets do given the insulation is already really good, but I'm sure it still makes a small difference that's worth it for the cost. It's also much better on electric ones as you can completely seal it up real good.

Also an electric would be super easy to rig a timer for, so I'd do it just because of how easy it is. Basically just need a high amperage contactor and a control circuit. (arduino, etc) For gas, you'd need some kind of actuator to turn the knob, or a gas valve replacement that can be controlled.

 

[DrPizza]

Why not a tankless water heater?

Tankless water heaters are more efficient and save fuel costs. However, in the long run, it would take longer than the lifespan of the tankless water heater before he broke even on the investment.

http://articles.chicagotribune.com/...es-20100210_1_tankless-water-heater-hot-water

 

[edro]

If you don't use it every day, it might be worthwhile.
You could probably turn it of while on vacation. (hmmm... I never thought of that)

 

[EagleKeeper]

It would be far better to spend that money on a water heater blanket...or just shave 30 seconds off of your shower time and spend the money on a cup of coffee instead.

Blanket and insulate your hot water pipes as much as possible.

Maybe learn to take a Navy shower or one from a garden hose.

 

[EagleKeeper]

If you don't use it every day, it might be worthwhile.
You could probably turn it of while on vacation. (hmmm... I never thought of that)

Just kill the fuel source manually

 

[edro]

Just kill the fuel source manually

That's what I meant. Turn the heater off while on vacation.
I have no idea how often they cycle when not using hot water.

In a typical basement of 65°F, 50 gallon, 4500W electric.
How many kWh are used over a 7 day period? (with no water usage)

Efficiency would play a part here, but I think it is a little more complicated that that.

 

[edro]

Bam! I love the internet.

http://www.leaningpinesoftware.com/hot_water_heater_vacation.shtml

 

[DainBramaged]

Thanks for all the responses. Sorry didn't get around sooner, got busy unpacking and then ADD took over.

 

[sixone]

Don't know about your water heater, but wanted to say HI.

 

[JimKiler]

Bam! I love the internet.

http://www.leaningpinesoftware.com/hot_water_heater_vacation.shtml

Thanks for all the responses. Sorry didn't get around sooner, got busy unpacking and then ADD took over.

based on edro's link I would go with this:

Could the additional thermal cycling due to turning off your water heater tank during vacation cause it to fail sooner?

 

[DainBramaged]

Don't know about your water heater, but wanted to say HI.

Hey, sixxy! This being ATOT and all, I'm surprised that, despite your lack of knowledge of water heaters, you didn't give me a very opinionated post about them.

How've you been?

 

[T9D]

I had one in one place and disconnected the damn thing. It seemed like it was always cold at some point when I needed it. Just got to irritating.

 

[Jeff7]

Not true. Conservation of energy. When the heater is heating the water, it's using energy. 100% of the time, it's also losing energy to the surroundings. The rate at which it loses energy is proportional to the difference in temperature between it and the ambient temperature surrounding it. Any energy lost, obviously has to be replaced. By allowing it to drop to a somewhat lower temperature, it reduces the rate at which it loses energy, thus reduces the total amount of energy required for the next time the hot water is used.

The OP would probably save more money simply by simply installing a blanket for increased thermal insulation. I doubt the amount saved with a timer would make it worthwhile.

This.

Ohm's Law - it also works for heat transfer.

V = I R
electrical potential difference = current * resistance
current = electrical potential difference / resistance
If there's a voltage differential present, the charge will try to push through any resistance in an effort to reach an equilibrium. The rate at which that charge flows is the current. Assuming the resistance is constant, the current is directly proportional to the voltage.


Temperature:
Difference in temperature = heat transfer * thermal resistance
heat transfer = difference in temperature / thermal resistance
Here too, a difference in temperature represents how much the warm material "wants" to push its energy out into its surroundings, through a thermal resistance, in order to reach equilibrium.

Every degree of thermal differential you can eliminate, the less energy loss will occur. The idea of it taking more energy to "catch up" and get back up to temperature is just psychological trickery. So if you want to reduce the amount of energy lost from your heater to the room in the house, your only options are to fiddle with the two variables that equal the heat transfer: Either reduce the difference in temperature (lower the temperature of the water in the heater, or let the room get hot), or increase the thermal resistance, by improving the insulation around the tank.
The tank's already got pretty good insulation though, and heating up your house to reduce your water heating bill is only a good solution in the winter. So, your only option left is to reduce the water temperature.

But as we've seen here, the cost savings will be minimal.

I've got gas heat, a gas-fueled water heater, and a gas kitchen stove. In the summer, my gas bill is somewhere around $15/month.
Getting into the apartment's "basement" involves lifting a heavy slab of floor, and then carefully twisting and crawling down some rickety railing-free stairs into an old, dank, dirty, spider-laden basement, and then doing it again when the vacation's over.





The two occasions I did turn off the water heater helped me to decide not to do it again - besides the fun-filled visit down to Syringer's Dungeon, I also would end up forgetting to turn the heater back up to the normal temperature, and upon going to get a shower, was greeted with cold water from both sides of the faucet. (That gas burner does do a good job of boosting the temperature fairly quickly though.)

 

[jagec]

That's what I meant. Turn the heater off while on vacation.
I have no idea how often they cycle when not using hot water.

In a typical basement of 65°F, 50 gallon, 4500W electric.
How many kWh are used over a 7 day period? (with no water usage)

Efficiency would play a part here, but I think it is a little more complicated that that.

Electric heaters are 100% efficient (techically you might lose a little bit of heat in the wires and a little bit at the base of the element, but it amounts to almost nothing). So the answer depends entirely on (A)The temperature of the water, and (B)How good the tank's insulation is.

based on edro's link I would go with this:

Could the additional thermal cycling due to turning off your water heater tank during vacation cause it to fail sooner?

Thermal cycling, as in the tank itself expanding and contracting? Assuming that they user actually checks/changes the anode occasionally and flushes the tank once a year, this will not be a problem. Thermal cycling at the heater element? This will actually be lower if it's off for the vacation. On-off control systems are worse for the equipment when they're active than when they're on standby.

 

[timerpro]

There are two patented gas water heater timers on the market. Testing shows that energy savings are significant. Bradford White has one and American Pacific has the other. They both work on the same principal like a set back controller on a furnace or air conditioner. Just Google gas water heater timer and the info from Bradford White is on a PDF in the "Savings" page. Good reading and does away with the negative theories.