Ladia,
Mine is a self-contained unit (Waterfurnace)
It has a circulator pump built-in for the super-deheater, which can be switched off it you don't use it. (Why would anyone not use it?)
Interesting conversation and observations.
Jersey,
Any conventional AC or Heat Pump unit can have a desuperheter installed for heating water. It's not restricted to geothermal. However, with geothermal units it's typically much more convienient as many have the desup built in or as an easily installed option.
In cooling mode the desuperheater acts as additional condensing capacity utillising some of the heat wich would be rejected (to the air or pond loop for example) to heat water. There is no reduction in system capacity.
With a heat pump in heating mode the opposite is true. There is a reduction in system capacity (10-15%) if the desuperheater is used.
So this is definatly one area where seasonal adjustments or an extended control set might make sense. For example, one wouldn't want to be paying to run the heat stips on high demand nights because 10% of their system capacity is diverted to heating water while they sleep.
Hot water demand tends to be transient and there is typically very little relation to demand and outside temperature. It's certainly important that the controls for HW heat be setup properly. Ladia and I had a discussion offline about this. Thier system was initially installed with no temperature control for the desuperheater. The desuperheater ran all the time the system was on regardless of the HW temperature. Other than being inefficient, there is a danger of scalding in a situation like that.
This is certainly one area I would quiz the installers about if I had one of these systems. It's important to know the temperature settings on the hot water heater and desuperheater settings and make sure they are set properly. It's information that you need to know anyway so when the HW heater is replaced it can be setup properly. The desup settings should be less than or equal to the HW settings. Some systems have additional controls for the desup circuit and can turn it off based on staging for example. I'd ask if this is being utilised and how its setup. It may be an option you have paid for and the installer never bothered to turn it on.
