BY ROBERT P. MADER
Of CONTRACTOR’s staff
ST. PAUL, MINN. — The latest American Lung Association Health House here didn’t start out as a showcase home – it evolved into one. Homeowner Chuck Knight, an architect, just wanted to build a family home with builder Kise Homes.
The house was a “design-as-you-go” project that just kept growing in scope, said Roger Conrad, new home project estimator for Apollo Heating & Ventilating in Oakdale, Minn.
Kise Homes’ standard is high-efficiency Len-nox equipment. The 5,300-sq.-ft. home originally was supposed to have a forced-air system. Conrad sold them, however, on putting radiant floor in the basement.
The change to a combination system meant the heating equipment would be a Lennox CompleteHeat. The builder liked the idea of sidewall venting the unit, Conrad said, because it eliminates “clutter” on the roofline.
The radiant portion, Conrad said, escalated to the entire main floor, then to all the hard surfaces on the second floor, which includes the master bathroom, a second bathroom and a laundry room.
The CompleteHeat is contained in a basement mechanical room. It’s piped to a fan coil unit for forced-air heating on the second floor and to manifolds for the radiant floor. Northern Radiant Floor in Lino Lakes, Minn., donated the manifolds and radiant tubing to the Health House.
The basement has two radiant zones with two manifolds. The homeowner has a home theater with a projection TV, so part of the basement is sunken 3 ft. to accommodate the large screen. The home theater is one zone, and a recreation room, bar area, finished bathroom and storage area comprise the second zone.
The foundation contains crushed rock for drainage and 2 in. of polystyrene insulation under the slab to contain the heat.
“We have a high water table around here,” Conrad noted.
The first floor contains three radiant zones: a sunken entryway and den are one, and the balance of the first floor containing the great room, kitchen with walk-in pantry and a powder room are two more zones. A single thermostat, however, controls the latter two zones at the request of the homeowner, Conrad said, because he wanted to minimize the number of thermostats on the wall.
Apollo Heating, nevertheless, installed the wiring for the second thermostat behind the wall so if the homeowner isn’t satisfied with his comfort and changes his mind, the thermostat can be easily installed.
The second floor has three separate zones of radiant heat to cover the children’s bathroom, the master bath and the laundry room.
The upstairs radiant floors are controlled with tekmar 150 slab-sensing setpoint thermostats embedded in the lightweight concrete. Conrad knew he had to control the slab temperature separately from the forced-air system.
“We found out the hard way that a radiant floor would never come on because the air ‘stat would be satisfied and the floor would be cool,” he noted.
The ductwork on the first floor is for cooling only and has its own thermostat. A Lennox 5-ton, single-speed 12-SEER air conditioner provides cooling. The ductwork for the carpeted areas on the second floor handles both heating and cooling and is zoned with Honeywell duct dampers.
Conrad calculated the cooling load at 62,000 Btuh so the unit is slightly undersized, but he figures the 5-ton unit can handle it because of the zoning. He calculated the heat loss at 95,000 Btuh. The CompleteHeat, which also produces domestic hot water, can put out 137,000 Btuh.
The CompleteHeat contains a 30-gal. domestic hot water tank internally. Conrad supplemented that with a 40-gal. storage tank next to it.
According to Minnesota code, all the ducts have to be sealed with tape or mastic and insulated to R-8 in unconditioned spaces.
Most of the equipment that makes the Knight home a Health House is in the basement mechanical room.
The ductwork contains two Honeywell ultraviolet lights to kill microbes, Honeywell electronic air cleaners, and a Honeywell 200-cfm energy recovery ventilator that exhausts air from the kitchen and bathrooms and puts fresh air into the conditioned air stream. A humidistat-controlled steam humidifier controls humidity levels regardless of whether the fan coil is operating.
A Honeywell bypass HEPA filter in the basement pulls air out of the return duct and likewise dumps it back into the return after filtering it. The attic space above the second-floor laundry room contains two more HEPA filters that draw from two locations in the central hallway and dump the filtered air into the bedrooms. Each HEPA filter moves 300 cfm when it’s running on high, Conrad said, and he figures the three of them can scrub the air in the house eight times per hour.
In addition to providing all the air-purification equipment, Honeywell donated its communicating thermostats with a telephone access module. The thermostat can call with a reminder to change the filters or alert a homeowner that the heating system is malfunctioning.
Conrad said he thinks the communicating thermostats are a great idea. He plans to sell them to “snowbirds” so the thermostat can call them in Florida if the heating system breaks down. It’s a less expensive alternative, Conrad noted, to a monitored security system.
“Maintenance on this house would drive a normal guy nuts, so he’s on a maintenance contract,” Conrad said. His service technicians will check out all the equipment and change the media in the HEPA filters once a year.
All in all, Conrad estimates that vendors donated mechanical equipment with a retail value of about $20,000.
The house hosts a variety of other features that make it a Health House, such as a method of radon control, stone flooring, and low-emission carpeting, furnishings and paint. The Knights, whose oldest daughter has asthma, will know that their house provides the healthiest environment possible.