Top Ten Hydronic Issues & Fixes

Great video!

If you're collecting stories of less common hydronic problems, I have one: Improper conversion from steam to hydronic.

In 2008 I bought a 4-unit property that was originally a large single family home, built in 1909. In the 1980's the previous owner had the single boiler 2-pipe steam system converted to multiple hydronic systems, using the existing cast iron radiators.

After a few years of ownership, I saw that the tenants of the large first floor apartment were using electric heaters in some rooms. They said the radiators didn't get hot in those rooms. In retrospect, the collection of old circulator pumps being used as doorstops in the boiler room probably should have clued me in…

The system has multiple "zones" (loops) but they are all fed in parallel by a single circulator pump. When I tried to flush the loops, it became obvious that there were restrictions. I eventually discovered that the steam traps had restrictors that not been removed 30 years prior, when the mechanical contractor converted from steam. Once I removed them, the system worked much better!

There is another cause for increasing pressure and/or opening relief valve. If the boiler is equipped with a tankless coil, the coil may be perforated; this will cause domestic water pressure to pressurize the boiler beyond the 30 psi limit. Likewise if equipped with an indirect water heater, the water heater coil could become perforated, with the same result; domestic water pressure pressurizing the boiler. I've experienced both scenarios.