Intermatic WH40 Electric Water Heater Timer Review

For many years, I've run my electric water heater with a timer that allows the water heater to run only at certain times during the day. I installed one for my current electric water heater about 15 years ago and the timer started making noises that made me think its time was up. So I went to Lowes and bought the Intermatic WH40 Electric Water Heater Timer for about $40 and replaced it last week.

What it is

The Intermatic WH40 is a metal box about 10 inches tall, four inches wide and two inches thick. It has a timer in it that controls a switch, and it's heavy duty enough to handle just about any electric water heater used in homes. In fact, the WH40 is rated at 40 Amps at 240 Volts, which is good for 9,600 Watts of power. My water heater is rated at 4,800 Watts (20 Amps), so it is well within the capability of the Intermatic WH40.

The WH40 contains a double-pole, single-throw (DPST) switch so that it can switch both legs of a 240-Volt circuit. Look carefully in the store, since there is a single-pole, single-throw (SPST) version that is good only for 120-Volt appliances.

The front panel has a good-sized lever to override the timer, so that you can manually switch your water heater on and off as you wish. As soon as the timer gets to its next on or off point, it will automatically go back on the timer.

Installing it

Of course, the first part of any electrical project is to cut power to the circuit. The second part is to check carefully to make sure you've cut the power. A really cautious person will check a third time.

I already had a timer switch installed for my water heater, so I just needed to remove it and install the Intermatic WH40 in its place. If you don't already have a switch (and few homes do), you will basically need to cut the wire running to your water heater and install the Intermatic WH40 at the point you cut the wire. This almost certainly will mean that you must run a new wire from your water heater to the spot where you are installing the WH40 switchbox. Using three screws, I mounted the Intermatic WH40 on the wall near the water heater. In my installation, about three feet of wire runs from the water heater to the WH40 switchbox. If you plan your mounting location carefully, you will have to replace only a few feet of wire.

Electrical wires can run into the sides or the bottom of the Intermatic WH40, and I ran mine into the bottom. Strip off about 1/2-inch of insulation on the white and black wires, and these bare sections slip under the screw terminals. Tighten the screws and you're done. Installation was pretty quick for me, probably only about 20 minutes from start to finish.

The last part of the installation is to attach the timer studs to the clock wheel. The timer studs are suppled loose in two plastic bags and there are two varieties of studs: one switches the Intermatic WH40 on and the other switches the unit off. The company supplied three of each type of stud.

I attached "on" studs at 6AM and 6PM, then attached "off" studs at 10AM and 10PM. This lets the water heater run from 6-10AM and 6-10PM. Obviously, you need to set the timer for water usage in your household, but the above numbers work for my wife and me.

The timer is set by pulling the clock wheel forward and aligning the current time with the big metal pointer. It's very easy. You will need to reset the clock wheel after long power outages, although an outage of a minute or two will not make a big difference. Having a timer on a battery backup would be a nifty convenience.

Living with it

The Intermatic WH40 Water Heater Timer is completely transparent in operation and I have all the hot water I want whenever I want it. Water stays hot in the water heater even when the switch is off, so there is plenty of hot water for washing hands and even a shower between on cycles. However, if we think we will use a lot of water (two showers, for example), we flip the manual switch on.

The purpose of installing this switch was to save money on the operation of our electric water heater. Does it save money? It's hard to tell. It might save a few pennies per electric bill but it's hard to say in my case. After all, I've had a timer operating for the past 15 years, so there are no before-and-after bills that give me a good point of comparison. I can say for sure that the Intermatic WH40 works, and I can just set it and forget it.

Summary

The Intermatic WH40 Electric Water Heater Timer was well built, easy to install and seems to work fine. It could have used better installation instructions and a built-in cable clamp would be a nifty addition, but the Intermatic WH40 is a good product at a good price. I recommend the Intermatic WH40 Electric Water Heater Timer.