Thankfully, the HVAC technician was able to get to the Library quickly. He determined that gasket on pipe in the boiler system was leaking and would have to be replaced. The pipe was isolated and heat restored, pending replacement of the gasket tomorrow since that's apparently a two-man job.
The elevator is working fine after its earlier bid for attention.
Early next week, I hope to announce our new Head of Maintenance. He can't start soon enough, in my opinion.