Hooking up my backup element on my Hot Water Heater after 15 years

peakbagger Posted By peakbagger, May 17, 2017 at 9:44 AM

  1. peakbagger

    peakbagger
    Minister of Fire 2.
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    Jul 11, 2008
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    Loc:
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    Blame me for the upcoming hot stretch in New England. I figured if I hooked up my backup element to my solar hot water tank that the weather would warm up.

    In the winter I run a Amtrol zoned "hot water maker" manually by heating it up when my storage tank is up to temp and my boiler is at full temp. Unlike a typical hot water tank, I have it heavily insulated and run it up to 180 degrees. The tank is fed preheated water from my flat plate solar hot water system (which doesn't get warm enough in the winter) for makeup so I can run a couple of days with one charge of heat in the Amtrol.( Note I have Honeywell integrated mixing and anti scald valve downstream before it goes in the house). It also can run off my oil boiler but about the only time the oil boiler runs is when I am gone for a few days during very cold weather. By timing my major hot water use to line up with times when the storage tank is fully charged and the boiler is hot, my actual normal hot water usage is low. I am single so I put up with it, not sure how a spouse would deal with it.

    During a normal spring summer and fall, I valve out the Amtrol and run directly off my solar hot water system. The SHW has a Rheem electric hot water heater tank that was factory modified for solar by the addition of a multiwrap copper coil around the tank before it was insulated. It looks like a normal hot water heater except for a few extra ports and a missing bottom element. It does have a top element which I never hooked up until recently.

    Prior to running a minisplit for shoulder season heating, it worked out pretty well but one of the down sides of mini split is no capacity for heating water. This spring has had several colder than normal stretches and the net result is that the minisplit has been running hard. This takes care of the household heat but hot water has been lacking. Rather than fire up the wood boiler I have on occasion resorted to running the oil boiler. I still have oil in the tanks so its effectively "free" but out of general principle I resist it. One minor annoyance is without a source of heat in my basement, its decidedly cool to work down there.

    After a stretch of no hot water this past weekend, I finally ran the wires and installed the breaker I bought long ago. Having never owned a electric hot water heater I was surprised that they actually made noise. When I turned it on I could hear a faint sizzling from the coil. After 30 minutes or so, I think the tank hit setpoint and I had plenty of hot water. Unlike the Amtrol I am just going to set the element at 130 F and cycle it manually when I need it. I have net surplus power for my PV system so running the electric element is "free" until I run out of my surplus. I do have fairly non aggressive water and keep an eye on the anode in the SHW tank so expect the element was in good shape despite not being used for 15 years.

    Given the forecast for the next week I expect I will have more than enough SHW without the element but I finally have an alternative for shoulder season.
     
  2. Highbeam

    Highbeam
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    I have an electric resistance water heater. Only 30 or 40 gallons for family of 4. It's pretty awesome and recovers very quickly. They get a bad rap because they use 4500 watts when they're running but they only run for a short time, are cheap to buy, no moving parts, no flue, no CO, really pretty great. Also provide us with a source of drinking water in a big emergency. Our power costs are pretty low at 10 cents per kwh so I may have a different opinion if power cost 30 cents per kwh!

    Mine makes a little sizzle noise and even a slight electric hum. If your breaker is getting hot or making a similar buzz then swap breakers.
     
  3. Circus

    Circus
    Feeling the Heat 2.
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    Jan 11, 2013
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    Electric sure is easier to turn on when adding those last couple of needed degrees. Barely any standby loss either.
     
  4. woodgeek

    woodgeek
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    Welcome to the future of Solar Hot Water. :cool:

    When your HW panels finally need replacement (I wish them a long life) you will get a HPWH instead (which will likely be COP/EF = 4+ by then) and use the area on your roof for more PV (if it all pencils out).
     
  5. peakbagger

    peakbagger
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    I definitely recommend a HPHW htr and a few extra PV panels to anyone withnet metering who hasnt already bought SHW panels. I got the SHW panels so I will run them as long as they will go.
     
  6. Circus

    Circus
    Feeling the Heat 2.
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    Jan 11, 2013
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    Panels last forever.. Common weak link to all schemes is the tank. I can't imagine the complexity needed to replace my simple thermosyphon SDHW. Plus there's no fickle authority's blessings needed. In winter, what replaces the heat taken from the basement when using a HPWH?
     
  7. woodgeek

    woodgeek
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    free or cheap space heat in some percentage (typically less than 25% on a seasonal basis, due to recovery of otherwise lost heat in semi-conditioned spaces and delivery back to conditioned space). Better if space already needs to be dehumidified in some seasons.

    The point is that many solar HW systems seasonally deliver 50% BTUs from the panels, and 50% from electric backup (esp in the NorthEast). That's an EF = 2. Most HPWHs on the market today will use less electricity (EF=3+) to deliver the same HW BTUs, and cost less to install and maintain.

    Unimaginable complexity? About the same as a refrigerator compressor, literally.
     
  8. Circus

    Circus
    Feeling the Heat 2.
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    Jan 11, 2013
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    I was including PV, inverters and net metering, like you suggested as a replacement.
    Both HP and SHW comes up short in the winter but not 50% annually.
    I agree, most SDHW's are too expensive, complex and high maintenance. Not mine.
     
  9. woodgeek

    woodgeek
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    Jan 27, 2008
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    Studies of modern, commercially installed SHW in colder climates come up at an average 63% solar fraction on an annual basis:

    http://aceee.org/files/proceedings/2006/data/papers/SS06_Panel1_Paper11.pdf

    EF = 1/(1-0.63) = 2.70 or less.

    Figure in parasitic losses from the pumps in most systems (not in yours) and it is not hard to imagine a 50% seasonal, EF = 2 figure.

    The same paper says that SHW saved the study houses $60-100/yr or less on their energy bills.

    My HPWH is saving me at least ~$250/yr relative to a conventional electric tank, or $500/yr versus the oil-fired system I used to have.
     
  10. woodgeek

    woodgeek
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    PV is not so complex...panels, inverter and some wiring...no moving parts or fluids that degrade over time

    An inverter fails...get it replaced (maybe free under warranty)....its not going to leak glycol all over the place.

    Monitor performance over the internet, creating output charts and monitoring savings...unlike a SHW system where how much you are saving is typically not measured or reported...just 'free hot water'...that may cost more than the HW in the neighbors house, 'all in'.
     
  11. Circus

    Circus
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    Jan 11, 2013
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    My main future concern is a leaky tank. One can't just be bought at the local big box.
    Monitoring is fun but little value. I spliced a clock on my gas furnace to monitor the savings from my solar air heater. That took a little planning ahead but $4.00 a gal propane in 2007 was a great motivator.
     
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  12. peakbagger

    peakbagger
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    The rheem solar aid tanks are readily available. I keep an eye on my anode and check it every 3 years or so. Generally unless the water is super aggressive, as long as the anode is replaced when needed, the tank will last a long time. Let the anode go and the tanks doomed.
     
  13. Circus

    Circus
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    Jan 11, 2013
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    Nothing off the shelf works on a one of a kind design. I should build another tank proactively. The first one is a modified gas water heater, does anyone build gas water heaters with a stainless steel tank? I'll change the anodes meanwhile.
     
  14. woodgeek

    woodgeek
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    Yes. http://www.htproducts.com/phoenixld-solarwaterheater.html

    Couldn't find a price.
     
  15. peakbagger

    peakbagger
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    Jul 11, 2008
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    No need to change the anode if its still there. If it is corroded away completely it may be too late but if its just corroded you have caught it in time. I I don't have enough headroom on mine to pull the rod out in one shot so I had to pull it out part way, cut it off and then pull the rest. I replaced it with the flexible style that sort of looks like a string of hot dogs on a SS cable.
     
  16. Circus

    Circus
    Feeling the Heat 2.
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    Jan 11, 2013
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    Loc:
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    Impressive, sure ain't my fathers Oldsmobile. So different it won't work.
    Am I the only one leery of electronic controls? I have a 33 year old 80% eff furnace that runs fine. I also have three brothers replacing $3000 high eff furnaces every ten years. Just quits working. They're not saving a dime. All the other appliances, same story.

    I'll look for a stainless steel water heater at the junk yard. Maybe one with a bad electronic control.:)
     
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  17. woodgeek

    woodgeek
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    Jan 27, 2008
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    My HPWH has electronic controls and 'bricked' after about 3 years of use. I called tech support, spent 5 mins putting multimeters on the control board (myself), they FedExed a new control board that I installed. I was back up in two days with <1 hour of my time and no money involved.

    I am a big believer in whole house surge suppressors to protect appliances...that are all hardwired.
     

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