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Hi Tricia: My apologies for not replying sooner. Until I read your footnote #2, I didn’t think I had anything to contribute.
Our project consists of three tall buildings with two hot water boilers in each, which deliver hot water to perimeter heating through vented steel baseboards in units. The temperature is controlled by one or two thermostats in each unit which manage the water flow through zone valves. At each end of a ‘run’, there are shut-off valves so that a zone can be isolated for maintenance or repair in the event of a freeze and burst. Each unit or zone is fed by a riser delivering the hot water and a return pipe which takes the cooled water back to the boiler.
At first, we had a lot of problems. The buildings were erected in 1979 and ‘renovated’ around 2000. No renovation or maintenance was done on the heating system. The pipes needed intensive cleaning and flushing to get the water to flow correctly. Some additives were put into the water to let it easily slip through the old iron and copper pipes. Many zone valves did not respond to the thermostats because they were old and burned out. Many thermostats were wrongly wired (like yours), so they reacted perversely!
Some users opened windows to cool their units in winter, which caused perversely wired thermostats to shut down, resulting in standing water in the copper pipes. They then froze and burst, flooding many units below and beside the frozen one, with a consequent massive repair bill and insurance claim. The corporation decided to install bypasses around the zone valves, controlled by a manual valve operated by the building operator, to allow a minimal hot water flow even if the thermostat had closed the valve because of excess heat. This has saved several freeze-ups.
The corporation examines and ensures the zone valve bypasses are working correctly at the beginning and end of the heating season. Every unit receives a notice about the correct operation of the heating system at the beginning of each winter. Most units have fireplaces; proper operation in those circumstances means the fireplace thermostat must ALWAYS be set lower than the heating system thermostat.
All that sounds like a lot of work; however, preventive maintenance has saved a lot of problems resulting from improper operations.
Not all of these actions will apply to your situation; these posts are read by many in similar situations. I hope to offer helpful remarks to others. Feedback is always welcome.
