This condominium complex in Johnson City, TN had a striking view of the Smoky Mountains, but not much else going for it.

Only 18 of the planned 42 three-story units were completed. One of the last houses built had more than a few problems. A water heater in the basement had a leak and was out of service. A third-floor water heater also sprung a leak and damaged the ceiling below it. The drip pans under the duct coils in the basement and attic started leaking.

Want more? In the basement, the gas-fired furnace and the water heater had open flames and drew the combustion air from the garage. There was no dedicated source of combustion air so it created a fire hazard and indoor air quality problems. The dripping condensate flowed over the furnace combustion chamber in the basement and caused rust.

The woes went on. So when plans were made to get things under control, it was decided not to try to do any repairs or even replace the defective equipment with like components. The decision was made to come up with a new design based on IMS, or integrated mechanical system.

A single gas-fired, sealed combustion, combination residential space and water heater — the Triangle Tube Model G30 — was chosen to replace two water heaters and two furnaces. The unit supplies two closed loop hydronic heating and cooling systems with two air handlers with 'A' coils and TXVs.

According to those on the project, the possibility of water freezing was minimized by a 30% polypropylene glycol antifreeze solution used in the primary circuit. The domestic hot water is generated in an inner stainless steel tank.

Newman Heating & AC of Jonesboro, TN, was selected as contractor. Owner Gary Jones and his crew rerouted the exhaust from the old inducted draft furnace in the basement to the sealed combustion G-30 heater. The Class B vent for the old water heater was used as the flue from the G-30. The 3/4-in. black iron gas line from the basement to the attic furnace was put in to use as a primary water supply to a new Triangle Tube Model S3-63A horizontal air handler-heating coil.

A second black iron pipe was routed up the elevator shaft for the return.

A Taco 007 circulator and pump relay was mounted in the attic to make use of the existing thermostat wiring. A built in aqauastat in the air handler was installed to ensure that on a call for heat, the blower doesn't start unit the coil is heated. The 3-in. Class B vent from the old furnace was fitted with a damper and routed to the attic return duct to provide fresh make up air.

The original air-conditioning condensing units were retained. The existing refrigerant lines to the attic were connected to the new 2.5-ton 'A' coil and thermostatic expansion valve in the attic air handler. The existing control circuit was retained. The existing refrigerant lines to the basement duct coil were retained and connected to the 'A' coil in the vertical air handler in the basement. For economic and environmental reasons, the combination water heater was maintained at 180 degrees F.

To provide domestic hot water at a safe temperature, a Sparco anti-scald valve was installed so as to keep tempered water at 120 degrees or below. A connection was made to the existing 3/4-in. copper riser serving the basement and first floor. A second riser was routed up the elevator shaft to tie into the existing hot water service that previously came from the third floor heater. The line was tapped at a second floor bathroom that backed up to the elevator shaft. A Laing ACT-303-BTW sealless, leakproof automatic instant delivery hot water circulator was installed under the spa on the second floor to minimize the wait for hot water.

After some fine-tuning, the extensive changes were deemed a success. So for at least one condo, the Smoky Mountains can be viewed in comfort.

John Howell is executive director of the Hydronic Foundation, Johnson City, TN. Phone 423-929-8548.

Publication date: 01/28/2002