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Xringer 09-03-10 04:07 PM

Water heater improvement (Timer)
GE 15207 timer was $38 at Home Depot.

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.


Daox 09-03-10 04:21 PM

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?

Xringer 09-03-10 04:37 PM

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.

Xringer 09-04-10 10:10 AM

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.
I'm saving relay-1 contacts for a rainy day.. :D

Face plate installed.

Case closed.

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.

Patrick 09-05-10 09:14 AM

Looks good. I wonder how this would work on a 220V water heater?

Daox 09-05-10 09:36 AM

As long as it can handle the amperage your heater is, I'd say its perfect.

Patrick 09-05-10 09:50 AM


Originally Posted by Daox (Post 7956)
As long as it can handle the amperage your heater is, I'd say its perfect.

It currently has 2 4500W heating elements. I think it starts with the bottom one and if the temp gets too low it adds the top one.

NiHaoMike 09-05-10 10:08 AM

For a little energy saving, disable the bottom element. That will reduce the volume of water that is heated.

Xringer 09-05-10 10:30 AM


Originally Posted by Patrick (Post 7958)
It currently has 2 4500W heating elements. I think it starts with the bottom one and if the temp gets too low it adds the top one.

That's a lot of juice! Maybe you could disconnect the top heater and just
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. :)

Xringer 09-05-10 10:59 AM

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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