The existing high-efficiency boiler failed earlier than expected. We replaced it with a right-sized Weil-McLain CGa-4 and rebuilt the piping around it.
This Bedford homeowner called after the existing gas boiler stopped working earlier than expected. We did not start by picking another boiler. We started with the basement.
We looked at what the boiler was serving, how water moved through the two heating zones and how the near-boiler piping had been arranged.
The existing system lacked effective air separation, dedicated purge points and isolation valves at the circulators.
The replacement was a Weil-McLain CGa-4 natural gas boiler sized to the home’s heating load. We also rebuilt the near-boiler piping, installed ECM circulators, added a Spirovent air separator and gave each heating zone its own purge station.
The Challenge
A Failing Boiler and Inadequate Near-Boiler Piping
The boiler itself was not the only issue we found.
Pespisa installs both standard and high-efficiency condensing boilers. The right choice depends on the heating system the boiler needs to serve.
In this Bedford home, several issues around the existing boiler needed to be addressed before installing replacement equipment.
- The baseboard heating system operated at relatively high water temperatures.
- The existing near-boiler piping had been carried over from the previous installation.
- The system lacked effective air separation.
- Neither heating zone had its own dedicated purge station.
- The circulators did not have isolation valves for easier servicing.
A straight boiler swap would have left those conditions in place.
Instead, we approached the project as a heating-system replacement rather than just an equipment replacement.
Our Boiler Replacement Solution
Weil-McLain Boiler Installation and Piping Rebuild
We installed a Weil-McLain CGa-4 natural gas boiler and rebuilt the surrounding mechanical system.
The Heating Plant
The project included:
- Weil-McLain CGa-4 natural gas boiler
- 105,000 BTU/h input as specified for this project
- 84% AFUE
- New vent connection into the existing masonry chimney
- New gas piping to the appliance
- Electrical work completed by a licensed subcontractor and included in the quoted scope
Two-Zone Distribution and Controls
The home has two heating zones.
We installed and commissioned:
- Two hydronic heating zones
- High-efficiency ECM circulators
- Isolation valves at each circulator
- Six-zone Taco switching relay
The six-zone control was intentional even though the home currently has two zones.
If the homeowner adds another heating zone in the future, the control infrastructure is already in place.
Water Management and System Protection
The near-boiler piping rebuild also included:
- Spirovent air separator
- New expansion tank sized to the system
- Caleffi fill valve with integral backflow preventer
- Dedicated purge station for each heating zone
The separate purge stations allow one zone to be flushed or purged without having to disturb the other.
Isolation valves at the circulators also make future pump service easier without requiring the entire heating system to be drained.
Chimney Venting
We evaluated the existing masonry chimney and reused it for the new boiler.
This allowed the installation to use the existing venting route without adding new vent penetrations through the finished exterior wall.
Why a Standard Boiler Fit This Bedford Home
The simple answer would have been to install another condensing boiler. We looked at the full heating system first.
The Existing Baseboard Required Higher Water Temperatures
Condensing boilers achieve their greatest efficiency when return-water temperatures remain low enough for condensing operation.
This home’s baseboard system was designed around higher water temperatures, particularly during colder weather. That reduced the expected efficiency advantage of installing another condensing boiler.
The Existing Chimney Could Remain in Use
The existing masonry chimney provided a venting path for the new boiler, allowing us to keep the project contained within the existing mechanical setup.
The Boiler Was Sized to the Home
We selected the replacement boiler based on the home’s heating load rather than simply copying the capacity of the boiler being removed.
Proper sizing helps reduce unnecessary cycling and supports more consistent heating-system operation.
This Was Not a Blanket Decision Against High-Efficiency Equipment
We install high-efficiency condensing boilers when the house and heating system support them.
Lower-temperature heating systems, radiant floors and appropriately designed hydronic systems can all be good applications for condensing equipment.
For this project, the existing baseboard distribution system, heating requirements and chimney led us in a different direction.
The system should determine the boiler.
The Result of the Bedford Boiler Replacement
The Bedford home now has a right-sized gas boiler serving two heating zones.
The near-boiler piping was rebuilt so air can be removed more effectively, each zone can be purged separately and either circulator can be serviced without draining the full heating system.
The existing masonry chimney was retained, and the required electrical work was included within the project scope.
Project Highlights
- Weil-McLain CGa-4 natural gas boiler
- Two hydronic heating zones
- Complete near-boiler piping rebuild
- High-efficiency ECM circulators
- Isolation valves at both circulators
- Spirovent air separator
- New expansion tank
- Caleffi fill valve with integral backflow preventer
- Individual purge station for each heating zone
- Six-zone Taco switching relay for possible future expansion
- New gas piping to the appliance
- New connection to the existing masonry chimney
- Electrical work included
- Completed July 2026
Bedford Boiler Replacement Project Details
| Project Detail | Specification |
|---|---|
| Location | Bedford, MA, Middlesex County |
| Project Type | Gas boiler replacement, hydronic heat |
| Boiler | Weil-McLain CGa-4 natural gas boiler |
| Input / Efficiency | 105,000 BTU/h input / 84% AFUE |
| Heating Zones | 2 |
| Controls | 6-zone Taco switching relay |
| Circulators | ECM circulators with isolation valves |
| Air Separation | Spirovent air separator |
| Fill / Backflow | Caleffi fill valve with integral backflow preventer |
| Expansion | New expansion tank sized to system |
| Purging | One purge station per heating zone |
| Venting | New connection to existing masonry chimney |
| Gas | New gas piping to appliance |
| Electrical | Licensed subcontractor, included in project scope |
| Completed | July 2026 |
Need a Boiler Replacement in Bedford, MA?
A boiler replacement is about more than choosing a new piece of equipment.
If a boiler fails earlier than expected, we look at the surrounding heating system before recommending a replacement. That includes system sizing, water circulation, near-boiler piping, controls, air removal and serviceability.
If a condensing boiler is the right choice for the home, that is what we’ll recommend. If another design fits the system better, we’ll explain why.
Pespisa Company provides boiler replacement and heating services for homeowners in Bedford and throughout Middlesex County.
Frequently Asked Questions
Why did Pespisa rebuild the near-boiler piping?
The existing system lacked effective air separation, individual purge points and isolation valves at the circulators. Rebuilding the near-boiler piping made the two-zone heating system easier to purge and service.
Why was a standard boiler selected instead of another condensing boiler?
The decision was based on the home’s baseboard distribution system, operating temperatures, existing masonry chimney and heating load. Pespisa installs both standard and condensing boilers depending on the home and heating system.
How was the replacement boiler sized?
The replacement boiler was selected based on the home’s heating load rather than simply matching the capacity of the boiler that was removed.