The Mendota

Built in 1901, The Mendota is Washington DC’s oldest luxury apartment building. This historic building has been painstakingly restored over the years to preserve its unique architectural details. The Mendota’s original heating system consisted of a coal-fired boiler, which was later replaced with a steam boiler on a one-pipe steam system connected to column-style cast-iron radiators. After 40 years of operation, the boiler became inefficient and unreliable. Among other improvements, Foley Mechanical installed a Weil-McLain LGB-20 atmospheric draft steam boiler which improved resident comfort and offered major energy savings. This project was featured in Plumbing Perspective, click here to read the article.


Mechanical room

Mendota building exterior

Building exterior






Mendota Project


Mendota Project



Mendota Project


Mendota Project


Mendota Project


Mendota Project


Mendota Project


Seymour Krieger House enjoys second generation of radiant along with complete mechanical update

This house, located in Bethesda, MD, was designed in the 1950s by internationally renowned modernist architect Marcel Breuer.  It is known as the Seymour Krieger House and is listed on the National Register of Historic Places.

The Seymour Krieger House currently is owned by an architect, and he wanted to restore the mechanical system while keeping the architectural integrity of the structure intact.

The house was originally heated by a radiant floor heating system.  The original boiler was still in place and operational, but the wrought iron radiant piping has corroded and was leaking in multiple locations.

We discussed multiple alternatives but in the end, the owner decided to go back with radiant floor heat.

The bluestone floor tiles were painstakingly numbered and removed.  The concrete overpour, along with the original wrought iron radiant tubing, was removed.

Old radiant pipe, torn out to make way for the new tubing.

The flagstones were carefully labeled so they could be returned to their original positions.

We installed the new Rehau PEX radiant tubing system, and a new concrete slab was poured.  The flagstones were carefully placed back in exactly their original positions.

We updated the entire mechanical system by installing a new Triangle-Tube boiler, HTP DHW tank, Viessmann solar heat and DHW system, and new Carrier high-efficiency AC system.

radiant heating Washington D.C. area

New Rehau PEX tubing.

HVAC hydronic system upgrade, Washington D.C., Foley Mechanical

Tight mechanical room showing Triangle Tube Prestige boiler, Grundfos ALPHA pump, Caleffi hydro-separator and Rehau radiant tubing and manifold.

HVAC AC solar Foley Mechanical

Four Viessmann flat panel solar collectors were mounted on the flat roof along with a Carrier 17 SEER AC unit.

We re-piped and re-controlled the radiant system to allow for multiple zones.  The Viessmann solar system will contribute to space heat when the DHW load is satisfied.

The clients were a joy to work for and appreciated the hard work done by my crew on this difficult and challenging project.

— Dan Foley




Lake Anna home features Uponor radiant heat and chilled water cooling

This new home on the shores of Lake Anna, Virginia, features radiant heat and chilled water cooling.

We designed and installed the mechanical system in this new home on the shores of Lake Anna, Virginia.  The house was designed by architect David Peabody, whom we’ve worked with on multiple projects over the last five years.

The project features Uponor radiant floor heating, two Lochinvar Knight boilers, DHW through an HTP stainless steel tank, chilled water cooling through two Unico chillers, tekmar and Taco controls, Nortec steam humidifiers and ventialtion through two Renewaire ERV’s.

Since this project is about a 1-1/2 hour drive from our shop, I designed redudancy into the mechanical system to minimize the chance of no-heat or no-cooling.