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Opinions on the Heatworks Model 3 no-elements water heater?

Jeff Cooper | Posted in Mechanicals on

Any insights into how well this Heatworks Model 3 water heater, “The world’s only water heater powered by Ohmic Array Technology instead of metal heating elements,” should work?  It’s basically a more efficient tankless without elements:

https://myheatworks.com/products/model-3-water-heater

My area has extremely hard water.  I just dug two gallons of limescale flakes out out of the bottom of my water heater tank after they destroyed the lower element.  I replaced both elements with the low-watt-density type that are supposed to produce less scale, but a water heater that produces no scale at all, is more efficient, and is smaller has a lot of appeal.  A heat-pump water heater shouldn’t produce scale either, but I would have to put it in a utility room (no basement or garage), where it would cool the house during heating season (and during cooling season, on the plus side), depending on how and when I might duct it to the outdoors.

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Replies

  1. Charlie Sullivan | | #1

    That's an interesting product. Two things that are clear are:

    1. It has the same efficiency as any other tankless water heater, and the same as a well-insulated electric tank unit. Don't be mislead that its novel setup somehow offers improved efficiency over normal electric heating.

    2. It has the same problem as other electric tank heaters: it needs huge current in order to provide a large temperature rise at a significant flow rate. That might mean your cost to install it is huge (need an electric service upgrade) or it might mean that it can't supply the flow rate and temperature rise you need, or both. There's a chart in the manual. And even if it can do what you need, it's not very friendly to the grid to draw power in big pulses when you are showering. If everyone in your neighborhood did that, they'd need to upgrade the distribution system to handle it.

    Questions would be:

    A. How do they achieve electric safety while running current directly through the water? They warn that it will trip a GFCI and so can't be used with one, and I see nothing about it being UL listed.

    B. Does it really solve the scale problem? Can it be cleaned if needed?

    C. It works over a limited range of water conductivity. Is your water in that range?

    Given the known disadvantages, I wouldn't actually bother trying to answer those questions but would go ahead and get a heat pump unit. It's true that the cooling effect is unwanted in the winter, but the overall efficiency is considerably better than the efficiency of this unit, and it's much better in the summer. Even if we give this system all the benefit of the doubt, and even if you have excess capacity on your panel, there's no upside to this compared to a heat pump.

  2. Jeff Cooper | | #2

    Great points well reasoned, Charlie; thank you!

  3. Jeff Cooper | | #3

    An update: My assumption that a heat-pump water heater won't produce scale may have been unfounded, as noted in my more recent question, https://www.greenbuildingadvisor.com/question/limescale-production-in-heat-pump-water-heaters, and as a result, I'm reconsidering the Heatworks, as they claim quite certainly that it does not produce scale, and my water's conductivity is in the required range. I can set it to run at 70 amps for my fairly small uses of hot water. The high cost of a heat-pump water heater wouldn't make sense if it will be ruined by scale in a few years. I'm far from a final decision and would greatly appreciate any further input.

  4. Charlie Sullivan | | #4

    Do you have sufficient electrical capacity available, and have you looked at what it would cost to add a 100 A circuit for that? That might make the $600 water conditioner look cheap.

    I'm still concerned about the electrical safety issue.

  5. Jeff Cooper | | #5

    Thank you for staying with this and for good questions, Charlie.

    I do have the electrical capacity, and the materials cost for the 100 amp breaker and #4 copper wire would be <$100, but Heatworks requires a licensed plumber and electrician to do the installation, which would raise the cost considerably. After finally finding some reviews that aren't on the Heatworks site, though, I've decided having it as my only water heater is too risky (even before taking into account electrical safety). The reviews on https://www.kickstarter.com/projects/550514292/model-3-tankless-electric-water-heater-and-mobile/comments are mostly terrible. The most recent is roughly a year old, and some of the unhappiness may be attributable to people suffering the company's growing pains, but of the 219 comments, very few are positive, and no one has come back more recently to reflect a more positive trend.

    It looks as if my best choice is a heat-pump water heater with a TAC conditioner to protect it from scale. I just hope replacing the TAC media isn't overly expensive and that I don't need other filters to protect it from premature expiration.

  6. fhelliott | | #6

    I have been working as a kickstarter supporter (buying 3) since they introduced the model 1. I went through 9 of the model 1's and none of them worked for more than a day. They finally canceled the Model 1 and replaced it with the model 3 and upgraded my 3 units to "ONE" model 3. I put it in my son's house and had it fail in less than a week. Multiple efforts to fix it failed. After six months we requested warranty on this unit and got a second Model 3 which have just installed in a cabin using hauled in cistern water. I can honestly say it has worked for at least the first 30 minutes. This is a casually used cabin with a 500 gallon storage tank (used as our cistern) that we fill with city water from my house 10 miles away. To make a long story short, the sales pitch is fantastic but the failures over the last 3 years and the failure to give me more than one model 3's for the 3 model 1's was a big disappointment. If this unit works as it should I will live with it. If it fails again, I will request a refund and conclude they don't yet know what they are doing. We have been dealing with calcium from the local water supply as well. We "kind" of solved it in our cabin environment by heating reverse osmosis water in a 25 cup coffee pot as our hot water dishwater supply and for cooking. We have been using N Eemax 220v tankless water heater for showers but it has been very sensitive to air in the system causing element failures. If you've got $750 or more to spend the Model 3 might be a solution. The water never goes over 130 deg, with 120 deg standard and can be set down much lower so the calcification problem should be addressed, if it survives normal usage. So far I have a 50-50 failure rate and only 30 minutes on the second unit.

  7. Jon R | | #7

    The standard way to address hard water is to add a water softener.

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