Engineers advise restoring four-pipe HVAC at county complex; jail chillers flagged as priority

Ryan, a mechanical engineer, told the County Property Committee on July 11 that the county complex was converted from a four-pipe to a two-pipe HVAC system years ago and that returning the site to a four-pipe configuration would allow simultaneous heating and cooling year-round.

Why it matters: The two-pipe arrangement forces the facility to choose heating or cooling for broad areas at any given time, creating comfort problems in shoulder seasons and making it harder to meet modern ventilation and reheat code requirements after recent air-handler upgrades.

Ryan said the original complex had a four-pipe system but “at some point … part of those pipes had failures, … and the decision was made … to replace half of them and basically take the system from a 4 pipe to a 2 pipe,” a change he described as uncommon today. He told the committee the two-pipe setup “means you can either heat or you can cool, which is fine most of the time except in the spring and in the fall.”

The consultant summarized options: abandon leaking buried piping at the front of the building, split the complex into two chilled/heat plants (east and west), add chiller capacity and modernize pumping and controls, and replace aging chillers and controls so the complex can again “simultaneously heat and cool anytime of the year.” Ryan recommended designing the work as a single project where possible to avoid higher costs from multiple phases and multiple contractors.

Equipment condition and timing: Ryan said many chillers are near the end of their useful life and the jail’s chillers and some roof units are “at 25 now” and in worse shape. He warned that changes in refrigerants have limited availability of replacement equipment and parts, producing lead times of months for new chillers. When asked about schedule, he said design work could be complete and the project ready to bid by January 2026 and estimated a single construction season (about 30 working days for comparable work) for some elements; he also said some work must be tied to non-cooling or non-heating seasons because chillers and boilers cannot be taken offline in their respective seasons.

Zones and controls: The committee asked whether the conversion would add thermostatic zones. Ryan said it would not add zones by itself. He explained that the earlier air-handling replacement preserved existing multi-room zones and that adding zones requires intrusive interior work: “We did not change that as part of the air handling job, and basically kept those zones as is.” He said the four-pipe conversion would allow reheat and better humidity control but would not by itself change the number of thermostat zones.

Costs and next steps: The study included project-budget level numbers (including contingencies and fees) to help staff plan but did not present final construction bids. Ryan said the consultant included the jail in the scope because its equipment age poses near-term risk. No formal action was taken; the report will be folded into next year’s budget list from county facilities staff for further discussion.

Ending: Committee members asked follow-up questions about phasing and priority; staff said Ryan’s numbers and the consultant report will appear in the facilities budget recommendations for future meetings.