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HPWHs on the march

Post in 'The Green Room' started by woodgeek, Sep 23, 2012.

  1. woodgeek

    woodgeek Minister of Fire

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  2. begreen

    begreen Mooderator Staff Member

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    This seems like a mistaken, one-size-fits-all reg, unless there are exceptions. They are going to have to improve noise reduction and reliability to make these mainstream. And in some cases, they are not the best solution. Myself, I would prefer a solar-electric boosted water heater rather than a HPWH. I'm wondering how much more energy goes into manufacturing a HPWH? It certainly will increase freon use.

    Heat-pump water heaters rob heat from the house
    Because heat-pump water heaters extract heat from the air where they’re located, with most installations they increase heating loads somewhat. If you have an expensive fuel, such as baseboard-electric and are in a cold climate with a significant heating season, a heat-pump water heater may not make sense.
  3. woodgeek

    woodgeek Minister of Fire

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    I agree with most of your points, esp noise....but IMO the heat stealing issue is overblown. Savings in northern climes are lower than farther south, but not by much. Most current users of conv elec tanks would have a good payback on these now....learning curve will make that even better.

    Of course, all these units have a resistance mode than can be used during the winter when it makes sense to do so.

    Perhaps it will be the 'lightbulb ban' all over again!

    I am digesting the details of the law....will summarize later.
  4. woodgeek

    woodgeek Minister of Fire

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    Ok. Looked at the law, found here.... http://www1.eere.energy.gov/buildings/appliance_standards/residential/heating_products_fr.html

    Looks like the regs require higher EF values for all DHW equipment. For each type of equipment, it appears that the more/most efficient models (highest EF) currently available have a lower cost of ownership (higher up front + lower operating costs, assuming a reasonable discount rate for the payback and equipment lifetime) AND a lower carbon footprint. The new standards are for all DHW equipment starting in 2015, requiring minimum EF values after that for each category that are currently on the high end of the commercially available range.

    If you believe their $$ analysis, then this will save everyone money. If you believe in reducing energy consumption, then this will save energy. If you believe global warming is a problem and due to human derived CO2, then this move is an obvious 'low-hanging' fruit (in that it is negative cost) that is a necessary step in the right direction.

    For elec tanks 55 gals and below, this law will require, in practice, thicker insulation and decent heat traps. Above 55 gals, they must be HP based to give an EF>~2.0. EF values for fossil DHW tanks are also required to be higher....2015 minimum will look like current high end EF equipment.

    In many ways it is no different that requiring higher fleet mpg in cars, or SEER for AC units, or what they did with light bulbs (CFLs ARE cheaper than IC bulbs)...not banning incandescents per se, but requiring lumens/watt closer to the state of the art (a semantic difference that bans non-halogen ICs).

    For HPWHs, there will clearly be places where a retrofit after 2015 will be hard....no air circulation, adjacent to bedroom so noise is a problem, etc. We'll see how exemptions are handled and how the technology evolves. Hopefully, many of the cases of a tank in a kitchen or in a bathroom will be smaller units, and most big tanks will be in basements and garages already....time will tell.

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