2021 Webinar Series - 15 Lisa Meline - Codes & Standards
Navigating Codes, Standards & Practical Experience in GSHP Design
Even though early ground-source heat pump systems were introduced in the USA over 80 years ago, building standards and codes have not adequately addressed this technology, providing necessary guidance to designers, installers, and the permitting authorities…until recently. An overview of the current ‘state of the industry’ will be presented with commentary about where improvements are still needed.
- Are most of either the designs or installation that you see warranteed? Do you see any responsibility taken by local building code officials to inspect the items that you discussed today?
- Engineers are required to have Professional Liability Insurance.
- Contractors typically provide a 1-year warranty from substantial completion.
- Local building code officials have to inspect what is in the Code and depending on their experience (because they have to know a little bit about a lot of different things) may not inspect what I have noted. I have actually had AHJs require me as the design engineer to ‘certify’ that my projects has been installed to the construction drawings (mine). So that liability would then come back to me as the design engineer.
- In your example of how to get debris out of this Y-strainer, excellent real life example, but what is your experience with using dirt and air separators instead of strainers to reduce the pump energy and have better separation?
- I have provided debris removal both ways. It’s engineering judgement and it also depends on the size of the project. Sometimes I have specified both.
- Do you know about the pilot project in Massachusetts for entire residential streets to share the cost of installing GSHP technology, and whether NY or Calif are contemplating the same?
- I can only speak to Calif. I have been involved in a residential community GSHP project in Jamestown, CA, but that developer opted to provide individual loops for each lot.
- 2 1/2" pipe is available but no one makes fittings for 2 1/2"
- I did know that 2-1/2 “ pipe is made but not common. I did not know 2-½” fittings are not manufactured. Thank you for that info - I learned something new today!
- In your geothermal sites Lisa, how balanced were the cooling and heating loads? and what happens when they are not balanced in other projects - Maybe more lessons learned?
- Heating and cooling loads are almost never balanced. If they are, there is still imbalance on the ground loop because of the heat pump compressor. We use that energy in the winter and have to manage it in the summer. There are things that can be done during design to mitigate imbalance, such as pipe spacing and on larger projects the building owner may consider hybridization. When possible, I opt for more loop because hybridization can add complexing and usually more controls. KISS.
- What’s the most important hindrance you’d like to see removed from the Code or change you’d want to see made?
- I would like the Codes to accurately reflect what is considered ‘standard’ by the industry.
- Thanks for sharing your perspective and experience, very interesting! Do you have any thoughts/opinions on property setback requirements? The ANSI-CSA standard calls for 3m (10ft) for vertical boreholes. It seems that the radius of influence might depend on whether the system is small and consists of one or two boreholes vs. a large borefield and also the net annual ground load.
- Yes, I have some responsibility for that particular item. When we were developing the vertical loop section of the standard back in 2015, there was a strong push by one of the participating associations to include setbacks. This was because often there are no setbacks prescribed by the AHJ - so the thinking then was that there would be minimum values set by the standard. In hindsight, the responsibility of setbacks really should be left up to the AHJ. We are working to adjust this.
- Glad you mentioned putting cold water/chilled water and hot water storage tanks in one of your examples; How often do you use such storage tanks in design?
- I always use buffer tanks for radiant heating systems. For chilled water systems it depends on the size of the system. If there is sufficient chilled water volume in the piping to ensure there is no cycling of the heat pump, I might consider leaving the chilled water tank out. Most of the time if I am designing a hydronic heating and cooling system I will have two tanks. If it is a residential project and the project location has very defined seasons, I will use one tank and change it over from summer to winter and visa versa.