By, Doug Carruthers 
In our most recent update to LoopLink we made a minor tweak to how we organized the options for hot water generation. This post is a quick breakdown of all of the different ways you can model hot water generation in LoopLink as well as a brief explanation of when each is available given your other project choices.
Adding A Hot Water Generation System
To add a hot water generation system into your project. Simply click the button found in the tool tray at the top of the right side bar. Or you can use the navigation bar on the top and mouse over 'Hot Water' and then click on 'New Hot Water' when it drops down.
There are a couple of reasons why you may not be able to add a hot water system to your project. If you have not filled out the Client Information and the Project Details pages, LoopLink will not give the option to add hot water (or do anything else for that matter). The only other reason you won't be able to add hot water is that you have already added hot water to your project. Each project can have only one hot water system which once added is accessible from the drop down at the top of the page or in the right sidebar.
System Options
When you create a new Hot Water system you are presented with a mostly blank page that has a drop down menu labeled 'Method of Operation'. From the list you have the possibility of seeing the following options:
- None
- Domestic HWG is optional for any GSHP system and does not need to be utilized. If domestic hot water will not be generated with the GSHP equipment, select this option. When None is selected, HWG calculations will be turned off.
- Desuperheater
- Select this option if domestic HWG is to be provided with a desuperheater in a supplemental capacity. When supplemental HWG with a desuperheater is used, the GSHP system will generate some (less than 100%), but not all of the required hot water. The actual percentage of domestic hot water made with the GSHP system will depend on the hot water usage profile as it relates to the building load profile and the storage system that is utilized. Additionally, when this option is selected, a conventional HWG system will need to be utilized to meet the portion of the hot water requirements that the GSHP HWG system will not satisfy by itself.
- On Demand
- Select this option if domestic HWG is to be provided with dedicated GSHP equipment with the domestic HWG set as the primary function and space heating/cooling set as the secondary function on the equipment control board. When domestic HWG is set as the primary function of a given GSHP unit, the GSHP system will generate all (100%) of the required hot water.
- On Demand (independent unit)
- Check this box if an independent unit will be used for domestic HWG. A unit is considered to be independent if its only function will be to generate hot water. If a GSHP unit will be used for HWG but also for space heating and cooling in the zone(s), the unit is not independent (leave this box unchecked).
- Water-Water w/ Space Priority
- Select this option if domestic HWG is to be provided with dedicated GSHP equipment with space heating and cooling set as the primary function and domestic HWG set as the secondary function on the equipment control board. When spacing heating and cooling is set as the primary function for a given GSHP unit, the GSHP system will generate some (less than 100%), but not all of the required hot water. The actual percentage of domestic hot water made with the GSHP system will depend on the hot water usage profile as it relates to the building load profile and the storage system that is utilized. Additionally, when this option is selected, a conventional HWG system will need to be utilized to meet the portion of the hot water requirements that the GSHP HWG system will not satisfy by itself.
Those are all of the options available and what they do. If you are interested in learning more about domestic hot water generation and geothermal heat pumps check out Section 9.1 (Chapter 9, pages 1-16) in IGSHPA's Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide.