Replies

1. GBA Editor
   Martin Holladay | Jan 22, 2013 01:33pm | #1

   Michael,
   Lots of questions.

   First of all, if you build a utility room for your heat-pump water heater, the room has to meet the minimum volume requirements established by the water heater manufacturer. Too small is no good. Your 960 cubic foot room might just barely be big enough. More information here: Heat-Pump Water Heaters Come of Age.

   If your heat-pump water heater has fittings for ductwork, it likely has both an intake and an exhaust port. If you hook up your ventilation system exhaust to the intake of your heat-pump water heater, make sure that the air flows match. If you aren't supply adequate air flow to the water heater, it won't operate efficiently.

   I'm a little suspicious of any ducting arrangements that require readjustment every spring and fall. Experience shows that homeowners either get tired of the twice-a-year chore, or sell their house to an ignorant new owner who never operates the equipment properly.

2. 
   user-1140356 | Jan 22, 2013 03:45pm | #2

   Thanks for your response, Martin.

   Given your caveats (I will be careful to match the flow rates, I plan to keep the house myself -- at least to the life of the heat pump or my own and, though somewhat ignorant, I am anal retentive enough to switch the vent twice a year), I still would like your opinion: is this worth doing?

3. GBA Editor
   Martin Holladay | Jan 22, 2013 03:56pm | #3

   Michael,
   It isn't necessarily a good idea to run your ventilation system for 24 hours a day. You can save energy, for instance, by turning the ventilation system off when everybody has left the house.

   Your heat pump water heater won't be running for 24 hours a day, of course; it will turn itself on and off as needed. So your suggested arrangement has to come up with a way to address the mismatch -- the non-simultaneity -- between the flow of ventilation air and the flow of air needed by the heat-pump compressor.

4. 
   user-1140356 | Jan 22, 2013 04:04pm | #4

   Excellent point. Thanks very much. I suppose I will simply direct the HRV exhaust at the water heater in winter.

   How about pushing the cold dry air into my humid crawlspace in summer? Worth it? Or is there a problem I'm not recognizing.

   Thanks again, Martin. If you are ever in South Jersey, you are very welcome to come by and visit. I really appreciate the website you have created here.

5. 
   mackstann | May 28, 2014 04:01pm | #5

   There is a ducting add-on for the Geospring? I can't find anything about such a thing.

6. GBA Editor
   Martin Holladay | May 28, 2014 04:12pm | #6

   Nick,
   I think you are thinking of the AirGenerate Air Tap unit, not the Geospring unit.

   Information from an online web forum:
   "The only heat pump water heater manufacturer that allows for ducting that can pull air from the exterior of the home & exhaust cold air to the outside is AirGenerate out of Houston, TX. Using air from the outside and exhausting cold air to the outside of the home maximizes savings with heat pump water heaters. Here comes more information: http://www.nwwaterheaters.com."

   Here is the link again: Direct-vented Air Tap water heaters.

7. 
   mackstann | May 28, 2014 05:18pm | #7

   Martin, I was just going off of where Michael said, "The GE HWH unit I'm considering has an add-on kit for directed venting". Maybe GE was a typo.

8. 
   rpertusio | Jul 07, 2016 01:04pm | #8

   FYI, the GE GeoSpring ducting part # is: GVK8HS