Simplicity Combi Boiler Case Study: A High-Efficiency Upgrade

Old System, New Simplicity: A High-Efficiency Boiler Upgrade

New Hampshire Contractor Upgrades Aging System with Simplicity™ Boiler

Residential boiler replacements often involve more than swapping out aging equipment. Existing venting, piping and installation conditions can create challenges that contractors must address when designing a new system. In some cases, these conditions also present an opportunity to rethink how a home is heated and make the replacement easier to install, commission and service.

That was the situation Kris Record of Jeneral Plumbing encountered during a residential boiler replacement in Nashua, New Hampshire. The home’s existing atmospheric cast iron boiler had been operating under challenging conditions, partly due to an improper venting configuration.

The boiler’s five-inch flue connection had been reduced to four inches along the horizontal vent run before transitioning again on the way through the roof. According to Record, this configuration contributed to poor draft conditions and flue-gas spillage. A failing gas valve was also causing the boiler to overfire, compounding the problem and contributing to chronic overheating and deterioration of the cast iron heat exchanger.

“The venting had damaged the boiler to the point where we really had no choice but to replace it,” said Record.

For the replacement, Jeneral Plumbing selected the Simplicity™ combi boiler from Weil-McLain. The retrofit gave Record and his team their first opportunity to install Simplicity and transition the home from a traditional atmospheric boiler to a high-efficiency, sealed-combustion system.

Solving the Venting Challenge

The change in boiler technology directly addressed one of the most significant problems with the existing installation.

Unlike the atmospheric unit, the Simplicity boiler uses a sealed-combustion, direct-vent design that doesn’t rely on the home’s existing chimney draft. Its 3-in-1 vent adapter accommodates multiple approved vent materials and configurations, including PVC, polypropylene and stainless steel. This gives contractors flexibility when working within the constraints of residential retrofit projects.

For Record, that meant the team could correct the conditions that contributed to the previous boiler’s failure rather than recreate them with new equipment.

The upgrade also delivered a significant increase in rated efficiency. Simplicity provides 95% AFUE and features an insulated stainless-steel firetube heat exchanger with a vertical, self-rinsing orientation. A removable polypropylene condensate collector base is designed to resist corrosion from acidic condensate.

These features were particularly relevant in a home where the previous heat exchanger had deteriorated.

“Everything about the new system addressed what we were dealing with on the old installation,” Record said. “We were able to get away from the chimney and put in a high-efficiency system that was designed for the way we wanted to install and service it.”

The compact cabinet and streamlined connection points also helped Jeneral Plumbing create a clean installation within the existing mechanical space. Record noted the system’s quieter operation, supported by features including an air-inlet silencer and variable-speed blower.

Five Minutes from Phone to Startup

Commissioning provided another surprise for Record.

After completing the piping and treating the system water, the Jeneral Plumbing team used the Weil-McLain ProTools® Tech App and the boiler’s Bluetooth® connectivity to complete setup. The app and touchscreen controls use plain-language prompts to simplify setup without requiring contractors to navigate unfamiliar codes.

“The installation process was super easy,” Record said. “We did it on a phone, and in maybe five minutes the whole thing was up and running. We really liked that we didn’t have to sit there going through a manual for 20 or 30 minutes.”

Before startup, the team also performed a chemical flush and added an inhibitor to help establish appropriate system-water conditions for the new boiler.

For Record, these steps are an important part of protecting a contractor’s work long after installation day. An efficient commissioning process, combined with proper system preparation, helps contractors complete installations with confidence and prepare the equipment for ongoing operation.

For Weil-McLain, that contractor confidence is precisely what the Simplicity boiler was designed to deliver.

“Contractors need equipment that solves the immediate challenge but also gives them confidence that they can support that system for years to come,” said Boyd. “This installation shows how a well-planned retrofit can modernize a home’s heating system while giving both the contractor and homeowner a more efficient, flexible solution for the future.”

The Nashua installation demonstrates how the right high-efficiency boiler can help contractors address existing system challenges while simplifying installation, commissioning and ongoing service. With its flexible venting options, familiar components and streamlined controls, the Simplicity boiler gave Jeneral Plumbing a solution the team is confident recommending for future residential projects.

Learn more about the Simplicity combi boiler or download the full Case Study here. Watch the video of the installation coverage with our New England manufacturer’s rep agency, SRGI.