Replacing the old gas boiler and most of the radiators with a modern, energy efficient, condensing gas boiler and radiant floor heat was an integral part of updating the home to be more comfortable and supplement the passive solar heating system.
We chose the Challenger Boiler from Triangle Tube based on the company’s reputation for quality, the combination heat and hot water capability, its condensing energy efficiency, and the reasonable cost compared to other models.
Challenger Combination Boiler support documents
A gas boiler system relies on pumps to deliver the warmed water to the piping. I chose Taco pumps and decided on all stainless system to overcome challenges with the water quality.
Taco Circulator Pumps (pdf)
Taco curves 009-0014 (pdf)
After burning out two Taco 011 circulator pumps on the secondary system that feeds the zones I switched to a more efficient and smaller variable speed Grundfos pump.
In addition to the pumps, a control system tells the boiler when to run. The thermostat’s call for heat is directed through a zone controller that tells each zone valve to open and push water through the system as well as sending a signal to the boiler and the secondary pump to operate together.
This equipment makes up the control system.
Honeywell Zone Valves (pdf)
The boiler’s piping system needs some equipment to keep it clean and free from air locks. The water must stay at a certain pressure so a fill valve makes up for any lost water and the expansion tank allows the hot water within the system to expand without raising the pressure to a dangerous level.
SpirothermJrIOM-Air Vent (pdf)
Caleffi Fill Valve (pdf)
I learned that the domestic hot water side of the boiler required a pressure regulator to keep the water from entering the boiler too quickly when pumped through the hot water return piping.
The excess water that the condensing boiler drains from the system is highly acidic from the combustion process as well as dirty. I drain this small amount of water into our sump pit through a neutralizer which is filled with limestone.
The boiler combustion should be checked occasionally for efficiency by analyzing the flue gasses with an expensive tool that I purchased used through ebay and fixed by ordering a part for it.