GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Heat Pump Water Heater

user-6610113 | Posted in Energy Efficiency and Durability on

We recently installed an AO Grand heat pumps water heater in the insulated but and indirectly conditioned (constant exhaust occurs from the basement pulling air from above) basement in Southern California.  Temperature and humidity in the basement are 60 deg and 50%.  The heater is set at 125.  

Two issues.
1) Despite not being used at all the heat pump runs nearly all of the time.
2) Despite the first fixture being only a few feet away the temp at the fixture is 110 max.  

The company is suggesting:
1) It is normal for it to run constantly.
2) The temperature of the basement is such that it can’t make the set point 

Does this sound correct?  
Anything I may be missing? 

Thanks!

– Matt

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. DCContrarian | | #1

    I'm not familiar with that particular model but this doesn't sound normal.

  2. brian_wiley | | #2

    Matt, I guess I would be hard pressed to say what normal is, but I have a similar setup so can provide a point of comparison.

    I have an AO Smith installed in a conditioned basement/crawlspace. It’s an average of 58 degrees with 40% humidity down there. The WH is set to 130f, and while it was hard to get a precise measurement of the water at the tap (which is very near to the WH; perhaps 8-10 feet of pipe) it seems to be around 114-119 on a digital thermometer. For what it’s worth, I don’t have the supply line insulated at all.

    As far as run time, it does seem to run quite a bit. We use hot water pretty frequently though, so it’s hard to tell what is “too much” in terms of runtime for our demand.

    Hope that helps.

  3. Expert Member
    Michael Maines | | #3

    I'm guessing you mean AO Smith? They are less efficient the colder the space is, but I believe the AO Smith units are designed for spaces that are 50°F. 50% RH at 60° is around 35% at 70°, no problem there. It sounds to me like there is a problem.

  4. user-6610113 | | #4

    Thank you. Yes. AO Smith. Thanks for catching my typo.

  5. Expert Member
    Akos | | #5

    Are you running recirc on the heater? A long uninsulated recirc line can cause the unit to run continuously.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |