# Hot water - Electric vs Oil



## lecomte38 (Oct 3, 2009)

Last year, due to the high oil prices I ran my electric hot water heater for the summer.  This year I ran oil for the whole summer.  For the months of May thru Sept I burned 91 gallons of oil  ($206) vs the previous year electric bill increase of $188 as compared to this years bills.  There are 2 of us in the house and there were no usage changes. Electric was only $18 cheaper but could radically change with the price of oil.


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## colebrookman (Oct 3, 2009)

We use electric instead of propane.  It's more convenient for tank placement,  we keep temps down so that we can shower without adding cold water and our front loading washing machine does well in cold water.  All the hot pipes are also insulated and I try to empty the tank once a year because we are on well water.  Have solar plans which will work well with electric back up. Be safe.
Ed
Check out the Marathon tread below


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## DBoon (Oct 3, 2009)

That's an awful lot of oil for the much hot water. 

Some calcs:

91 gallons of oil * 140,000 BTUs/gallon = 12.74 million BTUs
12.74 million BTUs/3414 BTU/kWh = 3732 kWh energy equivalence.

BUT, your hot water bill was $188 for the same time period, and $188/0.2 dollars per kWh = 940 kWh used, or 188 kWh/month.  That's about what my wife and I use, and we are very conservation-oriented, so good job there. 

So, what this tells me is that your oil burner is not very efficient at making hot water.  How old is your oil burner?  I'm guessing it is an older unit, and/or has a big cast iron boiler vessel that holds a lot of water that it needs to heat up every time you need a little bit of hot water.  Maybe there is something your plumber can do so it only kicks on to heat HW when your tank temperature is very low.


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## lecomte38 (Oct 3, 2009)

It is a 2 year old Buderus  boiler with a Superstore tank.  The hot water is on a thermostat control for morning and evening only except all day on weekends.  I think the loss is having to heat up the 13 gallons in the boiler twice a day and not utilizing it.  Also the electric tank is much closer to the high use area in the house therefor less water used.  It was interesting to see actual numbers rather then conjecture.


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## Hakusan (Oct 4, 2009)

It also depends on how you heat your water with electricity-coil heater tank, on demand, or heat pump. The heat pump is by far the most economical. You can get an add-on unit for a water tank--Air Tap. Or you can get a complete unit with the tank.


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## WES999 (Oct 4, 2009)

I just switched form oil to electric for DHW, you can read all about it here: https://www.hearth.com/econtent/index.php/forums/viewthread/39434/

I am pretty happy with the results, should work out to be a good cost savings.  The water temp is much more consistant, no more scalding.


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## Hurricane (Oct 7, 2009)

I had electric and switched to gas because the recovery rate was terrible. I mean over an hour to reheat the tank once the daughter ran it out.


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## stejus (Oct 8, 2009)

I heat my DHW with a tankless water heater in my Oil Burner Boiler.   I just turned down my aquastat to LO:140 HI:160 and DIFF:10.   The HI will never be used as I heat the house with the wood stove.  So for the most part, the boiler will be used to heat my water between 140 and 130 degrees, and with a lot less oil.  My oil tech had this on LO:190 HI:210 and DIFF:10.  That meant my hot water coil was sitting in some pretty hot water 24 hours a day.  I expect some savings running the boiler this way.


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## EJW1 (Oct 8, 2009)

[quote author="colebrookman" date="1254605137"]We use electric instead of propane.  It's more convenient for tank placement,  we keep temps down so that we can shower without adding cold water and our front loading washing machine does well in cold water.  All the hot pipes are also insulated and I try to empty the tank once a year because we are on well water.  Have solar plans which will work well with electric back up. Be safe.
Ed



Turning down the temp of your water heater below 120 degrees is not a good thing. You could be breeding bacteria.


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## EJW1 (Oct 8, 2009)

lecomte38 said:
			
		

> It is a 2 year old Buderus  boiler with a Superstore tank.  The hot water is on a thermostat control for morning and evening only except all day on weekends.  I think the loss is having to heat up the 13 gallons in the boiler twice a day and not utilizing it.  Also the electric tank is much closer to the high use area in the house therefor less water used.  It was interesting to see actual numbers rather then conjecture.





Why couldn't the Super Store been installed next to the electric tank at the high use area?


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## lecomte38 (Oct 8, 2009)

I installed it next to the boiler.  Other wise the finished basement would have to have exposed plumbing to the tank at the other side of the house.


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## Jerry_NJ (Oct 19, 2009)

Speaking of conserving hot water, we're resistive tank electric with a heat pump loop.  The loop in on a geothermal, so when we are doing cooling or heating we get some lower cost hot water.  We run the tank at about 125 degrees F, and with a dual heater have never run the 40 gallon tank out, then too our children are grown and gone... out on their own.

The good news here, and a factor to think about when you consider updating you dishwasher is: I knew the newer dishwashers, our old KitchenAid had was about 15 years old, are more efficient because they use a lot less hot water, and what I didn't count on, mine monitors the water temperature and turns on the built-in heater if the water isn't hot enough to do a good job.  So, we can keep the tank at 125 degrees, even less if we wanted to.


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## btuser (Nov 4, 2009)

lecomte38 said:
			
		

> It is a 2 year old Buderus  boiler with a Superstore tank.  The hot water is on a thermostat control for morning and evening only except all day on weekends..



How many gallons are you using daily?  I've got a boiler/indirect combo as well (albeit not as nice as yours) and I'm in the middle of coming to the same conclusion.  I put a hour meter on my burner so I could more closely monitor the usage, and so far it looks like I'm burning a heck of a lot of oil just to heat hot water!  

I live in a house with 5 adults and 1 kid.  
Near as I can figure by counting showers, dishes, laundry ect I'm using close to 200 gallons of 120 degree water daily.
200g x 8.4lbs x 80 degree rise =  134400 btu.    At 85% eff plus 10% standby loss I should be burning about 1.2 gallons a day for hot water, but I know its more than that, probably closer to 1.5


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