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# Support for Tankless Water Heaters Edit Subject

I have tandem tankless water heaters in my home. How do I enter these on the home profile. Essentially the capacity of the water heaters is infinite, but there is no overhead of keeping a tank of water heated nor does insulating the tank make any sense in this circumstance.
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• EMPLOYEE
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Travis (Program Manager) July 06, 2009 23:01
Hi Mitch,
Thanks for your question. Support for tankless water heaters has not been implemented as of yet. These type of water heaters are planned for subsequent releases, meanwhile it may over-estimate your water heating costs.

Regards,
Travis
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What is the ETA to support Tankless?
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• I’m pretty OK with this workaround.
One way to emulate having a tankless water heater is to set your water heater capacity to zero ("0"), or something near zero.

Yes, the real capacity is "infinite", but the way the energy required to run your water heater is calculated is based upon keeping 30-50 gallons of water at 140F for 23 hours a day for no reason, and 1 hour of heavy use (showers).

If you want to be really technical about it, you can look at your Energy Guide sticker on your tankless heater and look at the "average" reference energy usage number vs. the tankless heater. Make it a fraction and multiply it by a real water heater's capacity in gallons to get a fictitious capacity.

Example I made up:
If a typical water heater costs \$160/year to operate, and your tankless is rated at \$55/year, 55/160 = 0.34ish.

Multiply that by 40 gallons (or whatever size is appropriate),
40 * 0.34 = 13.75ish, so it's like a 14 gallon sized water heater

That's just an example. Basically you just make a ratio that will fudge the correct yearly cost for your tankless water heater to get Hohm to be more accurate.

You can learn more about normalizing the costs per energy here and probably get an even better guesstimate based on your actual numbers from the manufacturer:

http://www.energysavers.gov/your_home...
• Karen (Official Rep) July 23, 2009 16:54
Fantastic - thanks for sharing this with the community! We are actively looking at tankless water heater support since there is an overwhelming set of feedback to support this. I can't commit to an exact timeline just yet, but as soon as I can, I will share it with everyone. Thanks!
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Here tankless water heaters you can find all the support you need. I hope it will help you
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Is there any progress on tankless water heater support?

Our home uses tankless on demand hot water via the same boiler that heats the home. As a result the propane usage data I enter (by converting LPG gallons into equivalent LNG therms) covers both heat AND hot water. It seems like, however, that Hohm is assuming there is an additional fuel usage to heat hot water creating inaccurate energy usage calculations. It would be nice to know for sure that Hohm is not trying to assume additional energy inputs and accepts that all the energy (electricity & propane) that I record is all the energy our home uses.
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