Desuperheater with Air Source Heat Pump

[newhouse]

Does anyone have experience with using either Doucette or Therma-stor desuperheater coupled to residential air source heat pump. We are building a new home and will have 5 ton and 3 ton Trane XL1800's and I'm considering the desuperheater to either preheat (w/Doucette) or replace (w/Therma-stor) the hot water heater. Therma-stor looks interesting because it provides 120 gal combo desuperheater with conventional electrical backup to eliminate need for separate preheat tank. The only drawback is the heat exchange is inside the tank -- so it is not possible to clean if it fouls. The Doucette requires separate tank, and small circulation pump, but the tubes can be rodded / cleaned.

Doucette claims 2 year payout on 12 hour per day operation. My math says more like 10 years. The Therma-stor may have good payout if it doesnt scale up over 10-15 year life of the tank.

 

[Goorah]

No experience with this; other than having worked with Trane residential products for awhile. Call the Clarksville, Tennesee planr and ask to speak with a guy named Skip Winters.

Some comments:

Two year payback vs. 10 yrs is an order of magnitude difference! (almost)

What electric rates were assumed for the two?

Did you factor in energy rate inflation in the 10 year result?

12 hours per day of operation seems like a lot .... especially in those in-between seasons like spring and fall.

But yes: It seems like good sense to harness normally "wasted" energy.