Measure Overview
For newly constructed process steam systems that have a pressurized deaerator and boiler design condition pressures of 100 pounds per square inch of gauge pressure (psig) or greater, this measure would require at least 50% of flash steam to be recovered or reduced using one or more methods such as the following:
- Makeup water preheating
- Deaerator heating with flash steam recovered from boiler blowdown
- Loads served with flash steam from high-pressure condensate
- Loads served with flash steam that is boosted in pressure by thermal vapor recompression (TVR) or mechanical vapor recompression (MVR)
- Pressurized condensate return
- Steam-to-hot-water heat exchanger preheating
This requirement would also apply to new, non-replacement process steam loads at existing facilities that are connected to system with a pressurized deaerator, are served by a header that has a design condition pressure of 100 psig or greater, and meet the conditions in Table 1.
Table 1: Steam Load Addition Code Trigger Criteria for Existing Facilities
| Steam Flow (lb/h)1 | Linear Length2 (ft) less than |
| >5,000, <7,500 | 150 |
| >7,500, <10,000 | 350 |
| >10,000, <15,000 | 500 |
| >15,000 | Any |
Notes:
- Steam loads under 5,000 lb/h are exempt for additions at existing facilities.
- Linear horizontal and vertical distance from the load to the nearest boiler plant deaerator or feedwater tank. (Calculation of linear length will be described in a Reference Appendix.)
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View the Energy Commission's proceedings and available proposed code language by visiting their CEC 2028 Proceedings Website page.
Scope of Proposed Code Change
| Building Type(s) | Construction Type(s) | Type of Change | Updates to Compliance Software | Third Party Verification |
| Nonresidential | New construction, additions, alterations | Mandatory | No updates | No changes to third party verification |
Justification for Proposed Change
When steam condensate is dropped to a pressure lower than its saturation (boiling-point) pressure, a fraction of it vaporizes, or flashes, into what is known as “flash steam.” Most sites vent flash steam to the atmosphere, resulting in significant fuel, water, and chemical losses. Many steam system design options are available to recover and repurpose flash steam for useful heating to serve low-pressure loads instead of using high-pressure live boiler steam for the same purpose. Flash vessels capture flash steam and allow it to be piped to various applications, and TVR and MVR can boost the flash steam pressure if needed. Alternatively, a pressurized condensate return system can minimize flashing of condensate as it is returned to the deaerator.
Flash steam recovery has been listed in Department of Energy (DOE) literature as a best practice since at least the early 2000s, and the DOE has five steam tip-sheets for different flash steam recovery methods. This proposed code change originated from discussions with California-based consulting engineers from strategic energy management programs and the DOE Industrial Assessment Center program.
To the Statewide CASE Team’s knowledge, flash steam recovery requirements have not been proposed in previous code cycles. In 2013, Title 24 first adopted requirements for process boilers. In 2022, Title 24 adopted requirements for strainers and fault detection and diagnostics in steam trap assemblies.
Requiring flash steam recovery would save fuel, water, and chemicals. When applied throughout typical steam systems, this measure is expected to save approximately 1% to 5% of baseline boiler system fuel use. In addition, the requirement would reduce water and sewer use and the associated chemicals used for water treatment, as the flash steam is no longer vented to the atmosphere and its condensate can be returned to the boiler plant. Ancillary benefits include improved plant safety and improved public perception through reduction of steam plumes.
Relevant Documents
Round One Utility-Sponsored Stakeholder Meeting Materials
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The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.