WESTWOOD, MASS. — Last year, homeowner Lincoln Kaiser and a group of his neighbors in Westwood, Mass., persuaded NSTAR, the local gas utility, to put a natural gas supply line down his street.  Once the fuel was available, the Kaiser family moved forward with a heating system retrofit.  Out came the old oil burner, and in went a high-efficiency natural gas boiler.

“Our family has grown since we purchased the house,” said Kaiser. “We’d like to have a little more space, but don’t want to part with the home.  Since we didn’t want to use any yard space for an addition, we decided to go up, not out.”

The 1,850 square-foot, ranch-style house went through a second-story addition this past fall, adding four new rooms. Although much of the mechanical system retrofit took place before the addition, the future connected load was taken into account. To read Part1 of the all-American retrofit article go to http://bit.ly/Owgq1q

Plans Change

Before the retrofit and addition, the home was heated using two zones of fin-tube baseboard connected to a 125,000 BTU boiler. Taco’s FloPro Designer software was used to calculate the existing heat load at 58,200 BTU/H, and with the extra load of the second story addition, the new system was designed to provide a total of 85,400 BTUs plus DHW. By doing a proper heat load analysis, even with the new square-footage, the new boiler is smaller than its predecessor.

The mechanical room with the Alpine wall-hung boiler.

The Kaisers wanted to abandon the fin-tube, preferring to heat the home with in-floor radiant.  They quickly learned that this would require major changes to their near-boiler piping. While reluctant to have the whole system re-piped yet again, they held fast to their original desire to have an all-American boiler room.

When the oil-to-gas retrofit took place – months before work on the addition started – the new 105 MBH Burnham Alpine high-efficiency boiler was piped to accommodate a two-zone radiant system. Burnham boilers are built in Lancaster, Pa., and the company also has a foundry in Ohio.

But as walls went up, and their vision of the home became reality, the Kaisers realized that maybe two zones weren’t enough. They soon decided they wanted an ultimate comfort system.  That meant more zones, web-enabled thermostats, and new components in the boiler room.  They were also hoping the system could provide ultimate efficiency. 

Two-Temp Supply

The Kaisers hired Mike Casey, of KC Plumbing & Heating, to re-pipe the boiler room according to the new design criteria, and to install the radiant system. Casey runs a one-man shop in Sharon, Mass., and specializes in subcontracting for builders.  Homes under construction are his specialty.

Downstairs, the baseboard was removed and Watts Onix EPDM tubing was stapled into joist bays with access from the basement. “If it’s a staple-up job, I prefer EPDM tubing over PEX because of the flexibility,” said Casey. “It’s not like wrestling a python in tight quarters.” The staple-up portion is designed to use 140°F supply water. Watts’ wide product offering comes from numerous locations across the country, and the company recently opened a new foundry in New Hampshire to cast lead-free plumbing products.

A portion of the main floor is built over shallow crawlspace. Here, and across the entire upstairs addition, new Watts SmartTrac radiant panel system is installed over the OSB subfloor. 

Made almost entirely of recycled material, SmartTrac offers all the benefits of a poured gypcrete slab, with less weight and thickness and no drying time. The system works with all floor coverings.

“The panels installed quickly, making them perfect for a roof-off project,” said general contractor Jim Kane.  “After the material was down, Casey just had to walk 3/8-in. PEX or PERT into the grooves.” The SmartTrac portion of the system averages 125°F supply water. 

Casey used a simple but effective means of supplying two temperatures. Between the system’s buffer tank and the five supply manifolds, a pair of three-way Taco iSeries mixing valves provides correct supply temperature. With a full-featured outdoor reset control built into the actuator, the valves modulate based on the outdoor temperature and the required supply temperature. That means year-round comfort control, efficiency and temperature delivery for every zone by supplying optimal water temperature.