Hot Water Tank -Programmable Switch

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  #1  
Old 08-30-06, 09:33 PM
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Hot Water Tank -Programmable Switch

I am installing a new electric hot water tank in a mountain cabin that could potentially freeze-up during the week in the winter when it is not occupied. The power supply to the cabin is buried so outages are infrequent. I was thinking of installing a programmable switch (Intermatic) so the power would automatically shut off on Sunday night and come back on Friday evening. However, this leaves a full cold tank that could potentially freeze. My alternative is to put in a 30 amp 240V switch (so I don't wear out the breaker) and shut it off when I leave and drain the tank.

I am wondering if any of you are aware of a programmable switch that could somehow reduce voltage or override the thermostat so the tank is left on but does not drop below 60 degrees.

Any other ideas would be appreciated on how to reduce power consumption while avoiding the potential freeze and the need to drain the tank every week.

David J
 
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  #2  
Old 08-30-06, 10:12 PM
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It's only abandoned for a week? I'd set it to its lowest hot water setting and leave it on.

Also, breakers are listed for use as switches, they shouldn't wear out.
 
  #3  
Old 08-30-06, 10:13 PM
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I have electric baseboard heat in my cabin in the mountains where winter temps get very low and the snow very deep. I leave it at lowest setting in winter when I'm not there and temperature usually never gets below 45. My water heater is electric. I turn it off after each visit. I have never had a problem indoors.

If you leave your cabin unheated over winter, it is recommended that you drain the water heater. If it is electric, the electricity should be turned off when draining and when refilling. If the electric element is on before you start filling, there's a chance that you will burn out the element.

There are direct wire timers available for water heaters. The Intermatic has a battery backup to protect time keeping and program info. You can set to go on and off multiple times per day, for certain days, etc. It's programming is flexible.

If cabin is left unheated, then you will have to take other winterizing steps to shut off main water valve, open all faucets inside & out, drain pipes and toilets, and pour non-toxic anti-freeze into drains and toilets. Since I never know when I will take off to the mountains in winter, I prefer to pay to keep the heat on low and continue to turn off my water heater when I leave. I also leave the cabinet doors below vanities & kitchen sink open so what heat is available gets to the pipes.

The first thing I do when I enter the cabin is flip the breaker to turn on the water heater. Then, I turn on the music and build a fire. Water heater heats up in no time. Showering and dinner can come later. I brew a pot of tea while I am running around and checking on everything. I do not planning on using hot water as soon as I get there, as I am too busy enjoying being there, so hot water from the water heater is not an issue for me.
 

Last edited by twelvepole; 08-30-06 at 10:27 PM.
  #4  
Old 08-31-06, 05:17 AM
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You will not have a problem with the water heater if it is in an area of the cabin that stays heated, as long as you keep the cabin temperature high enough. You need to do this anyway, so the water in the drains and water pipes doesn't freeze.
 
  #5  
Old 08-31-06, 07:30 AM
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Thanks guys,
Since the primary heat source is a wood stove, we ususlly drain everything before leaving. The plumbing system is set up to do that except for the hassle of draining a hot water tank. The intermatic timer (EH40) seems like the right choice. I could have it programmed to come on for an hour a day when I am not there to reduce energy consumption and know that it wouldn't freeze if the temp really dropped.

David J
 
  #6  
Old 08-31-06, 08:49 AM
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So how much money is saved for heating a cold tank of water versus keeping it warm for only one week? And subtract from those savings (assuming they are significant) the cost of the timer and time involved in its installation. I'm just not yet seeing the value.
 
  #7  
Old 08-31-06, 08:57 AM
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Originally Posted by MAC702
So how much money is saved for heating a cold tank of water versus keeping it warm for only one week? And subtract from those savings (assuming they are significant) the cost of the timer and time involved in its installation. I'm just not yet seeing the value.
I think it would depend on if we go to the cabin every weekend, or just once a month.

It might pay to have an engineer do a cost analysis.

I was thinking along the same lines. A good water heater blanket and leaving the water heater on, might be a better way to go. If noone is using the hot water, it should be cheep to keep it warm, just turn down the t stat a bit.
 
  #8  
Old 08-31-06, 09:02 AM
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Originally Posted by DavidJ
I am installing a new electric hot water tank in a mountain cabin that could potentially freeze-up during the week in the winter when it is not occupied. ...

Any other ideas would be appreciated on how to reduce power consumption while avoiding the potential freeze and the need to drain the tank every week.
Okay, upon rereading the OP, I'm a little confused. At first, I saw "during the week in the winter when it is not occupied" and thought there was a week during the winter when it was not occupied.

But the last part makes me think that maybe you meant it's vacant during the weekdays and you are there on the weekends?

I guess either still might want to have a cost analysis done, to some degree.
 
  #9  
Old 08-31-06, 10:05 AM
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The cabin is usually vacant during the week and occupied on weekends.

The cost of the in-line programmable timer is $70 so it is not a huge expense. With good insullation and no demand, the tank temp may not drop enough to warrant the timer.

I am going to be wiring in the new tank this weekend without the timer. Since it and the fridge will be the only thing left on in the cabin during the week I can take some meter readings to determine power consumption when the cabin is vacant. Watt hours consumed and the size of the tank elements should let me calculate how long the tank is on per week. Then I should be able to determine if it is worth it to install a switch.

Any thoughts on a better approach to determining power consumption would be appreciated.

David J
 
  #10  
Old 08-31-06, 10:45 AM
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David, I dont know where you live, but I am guessing that it is not yet freezing at your cabin.

You also need to consider that the heat loss this time of year will be alot less than it would be in the middle of the winter.

I would do two trial runs. One week leave the hot water tank off all week, the next week leave the hot water tank on.

I would make a tracking chart. log the kw reading when you leave, when you return, and when you guess the hw tank comes back up to temp. The last will be mostly a guess, but you can then look at all your data.

Does you timer run on 120 volt or the line voltage for the hot water tank?

I am done rambiling. once you have the data, you will know what to do.
 
  #11  
Old 08-31-06, 11:49 AM
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JWhite,
Sounds like a good approach.

The Intermatic timer I found on the net use a battery to maintain the program but I assume that the switch must be powered off of the line voltage.

The more I think about this, it seems as if an extra layer of tank insullation is the best bet.

Thanks for your advice.

David J
 
  #12  
Old 08-31-06, 11:52 AM
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David, just out of curosity, how do you drain all the P traps.

My grandmoms hunting camp used to always freeze the toilets p trap ..... I put several new toilets in there for her.
 
  #13  
Old 08-31-06, 02:16 PM
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Well, I knew a person who threw a handful of rock salt in the toilet when they left the cabin in the winter. I don't know what that does to their septic system.
We have the plumbing set up so everything can drain when the main is shut off. The toilets are flushed after the main is shut off and that seems to leave only a bit of water in the 'P' trap. If it freezes it has room to expand so does not cause a problem (I hope).

DavidJ
 
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