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Community and Q&A

Hot water heater options – 8500 feet elevation / zone 4b

GeorgeMic | Posted in Mechanicals on

I have an electric-only home built 1977 at 8500 feet / zone 4b, built into the north face of a mountain.  Currently have a 120 gallon electric water heater from 1994.  It keeps chugging but is quite corroded.  It is in a small closet on an exterior wall.  Moving the location would be difficult.

Most houses here use a gas hot water heater. I have been told not to get natural gas because (1) natural gas water heaters derate at this elevation, (2) it would cost several thousand dollars to run a gas line.  

Energy rebates mean the cost of a HPHW is about the same as straight electric.  I want wifi connectivity because we are often gone 2+ months at a time then may have 10 people in the house.  

My options:

1) Electric with a booster to get closer to the existing 120 gallon capacity.  We have 50 amps available, which would work with a 30 amp electric and 20 amp booster.  With the hybrid close to the standard electric after rebates, I’m not sure this makes sense. 

2) Install hybrid hot water heater with booster.  The only space I have available is a small closet in the laundry room/office.  We have no basement, and the garage is detached.  

3) Clean out the existing hot water heater and pray it doesn’t burst.

I’m thinking of #2 (heat pump) but am not sure about ventilation.  I’m inclined to ventilate the intake at the top and direct the outflow to the bottom so the two vents aren’t too close, but basically turn it off for most of winter and run the electric.  

Our local plumbers haven’t dealt with heat pumps much or at all – they say most people have gas.  Appreciate your opinions.  Thank you.

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  1. JoelNiemi | | #1

    Is propane an option, if getting a natural gas line isnt?

    1. GeorgeMic | | #2

      High risk wildfire zone, so a tank requires a 10' clearance on all sides, which isn't feasible for our property - would cost several thousand dollars to prepare the site. (We are on the side of a mountain.)

      I also would think that if natural gas derates at this elevation, so would propane.

      1. Expert Member
        BILL WICHERS | | #5

        >” I also would think that if natural gas derates at this elevation, so would propane.”

        That’s correct, propane fired heaters will need to be derated at high altitudes too. The reason is the lower air pressure, so reduced oxygen per unit volume of intake air. Any combustion appliance will be affected. When I size generators for sites at high elevations, I have to derate the generators too. The lower air density at high elevations results in lower horsepower output from engines, and reduced cooling efficiency too.

        Any time you go over 1,000 feet above sea level you usually start having to derate things that rely on combustion for their operation.


  2. Aaron_P2 | | #3

    120 gallon water heater seems large - is it used for space conditioning as well as potable water needs?

    Getting 27 years out of the original one seems quite good. If a HPWH doesn't have the capacity, but is useful to you from a energy savings standpoint - you could put a second standard water heater in series after the HPWH and then you would only use that one with traditional elements for standby losses. Something like a Rheem Marathon might be perfect for that use due to the increase insulation and lifespan.

    Another thing to consider - going with the HPWH in a small closet is possible, but may either require a louvered door (which may be a noise concern) or need the ducting accessories where you can intake and exhaust air to a larger volume of space.

  3. walta100 | | #4

    How do you heat the house? If you use resistance for heating the HPWH will not lower your operating costs in the heating season.

    Do you need that large a water heater?

    Do you really have 9 people taking showers in an hour or two? Or is that an after skiing thing?

    A 20 amp 240 volt 4.8 kw booster with two 2.5 gallon showers flowing will give you a 12° temp rise.


  4. paul_wiedefeld | | #6

    Depending on your home's layout, you might be able to install a Drain water heat recovery unit, which would preheat the incoming water lessening your demand and thereby increasing shower capacity.

  5. PLIERS | | #7

    Got an instant 240v electric water heater a few years back. It's about the size of a small laptop, can run 2.5 appliances at once, like 2 showers and a dishwasher. Heat isn't instant but takes a few seconds. How frequently do you have 10 people at a time? Do you have 10 bathrooms? They are limited by how many showers you have. Unless they are paying rent tell them 2 showers at a time or go kick rocks. You could always get a bigger instant water heater but that requires more power and why would you want more than 2.5 showers running at once?

    1. Expert Member
      BILL WICHERS | | #8

      If you want to go with an electric tankless (instant) hot water heater, make sure your electric service has enough available capacity to run it. Those electric tankless water heaters use a LOT of power to run.


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