Case Study Introduction

PROJECT OVERVIEW

Located on Rock Lake, halfway between Madison and Milwaukee in Jefferson County, Lake Mills, Wis., was founded in 1836 and is named for the lake and the first mill built by town founder Joseph Keyes. Today its population is 5,401.

On August 15, 1847, a group of nine residents organized a Congregational church. The first church building was finished and dedicated in 1852. Fifty years later, the church moved to its present building, which was dedicated in 1902. In 1961, the First Congregational Church of Lake Mills became part of the United Church of Christ and was renamed the First Congregational United Church of Christ, or simply, First Congregational UCC.

First Congregational UCC Meets Mitsubishi Electric HVAC

After 103 years without air conditioning, in January, 2007, the Church board decided it was time to air-condition the 3,000-square-footbasement. This included a fellowship hall, kitchen and four Sunday school classrooms. The basement area was serviced by a single large air handler and 7-ton boiler. The board turned to one of its members, Bruce Senti, for a solution. Senti is president of his own HVAC company, TemTek LLC, Lake Mills, Wis., and is the local manufacturer’s representative for Mitsubishi Electric HVAC Advanced Products Division.

Senti recently had been introduced to the new Mitsubishi Electric Hyperheating INVERTER (H2i™) systems, which are available in select Mr Slim® split-ductless and CITY MULTI® Variable Refrigerant Flow Zoning (VRFZ) models. Senti realized the system was ideal for the church because its revolutionary flash injection technology would actually condition the basement air in the hot summer months with a dry mode and offer remarkable heating capacity at extremely low temperatures during Wisconsin’s bitter winters. A Mr. Slim P-Series system was installed by a local HVAC contractor, Carew Heating and Air Conditioning, Watertown, Wis. Carew is a certified Mitsubishi Diamond Dealer™ and has been extensively trained on all Mitsubishi Electric HVAC systems.

“These new systems use a patent pending flash process to supply heating at extremely low temperatures,” Senti said. “This means the outdoor unit will operate at 100 percent of rated heating capacity at 5 degrees Fahrenheit. The H2i outdoor unit is the only heat pump of its kind that produces so much heat at such low temperatures. At minus 4 degrees Fahrenheit, the system operates at 87 percent of rated heating capacity; and at minus 13 degrees Fahrenheit, the system operates at 70 percent of rated heating capacity.”

According to Senti, traditional heat pumps do not operate at such low temperatures with full capacity compared to the new H2i outdoor unit. H2i systems employ technology that re-collects and uses heat energy that is normally wasted in the flash process at the outdoor coil. This process helps the H2i systems overcome issues commonly associated with conventional heat pumps such as decreases in lowside pressure, refrigerant mass flow rate and operational capacity. “The INVERTER-driven compressor in the H2i outdoor unit varies its speed to precisely match the zone load requirements for year-round comfort and effective use of energy,” says Senti.

Stable Heating Performance at 5 Degrees Fahrenheit Outdoors

With the help of Mitsubishi Electric HVAC and a generous donation by one of its members, the board proceeded with the installation. “When the unit was installed in February 2007, we were in the midst of a bitter winter,” Senti said. “The temperature outside was a bonechilling 10 degrees Fahrenheit (-12 degrees C); the indoor temperature was an uncomfortable 55 degrees Fahrenheit (13 degrees C). After the Mr. Slim H2i system was installed and running, the discharge temperature reached 128 degrees Fahrenheit and the indoor temperature quickly reached a comfortable 70 degrees Fahrenheit.

“The H2i system accomplishes this by gathering up heat that is normally wasted or lost and discharging it through the indoor units for maximum comfort and effective use of energy,” Senti said. “Unlike other heat pumps, the H2i systems will not rapidly lose heating capacity as the temperature outside falls.”

Church Trustees Impressed with Performance

“The trustees and I have been very impressed by the performance of Mitsubishi Electric HVAC products,” says First Congregational UCC Reverend Neil D. Partington. “During the coldest months of the year, the Mr. Slim system has consistently maintained the temperature selected.”

Partington further reported, “I have been very impressed by the amount of heat that the Mr. Slim system has been able to put out even when the outside temperature has been below zero degrees Fahrenheit. Also, the quiet factor is great; there is very little sound when cooling or heating. ”

“During the humid summer months, our Sunday school classrooms and fellowship hall were cool and comfortable and this has been the first summer they did not have the odor of a damp basement.”

H2i Saves Church $1,000 a Year

HVAC veteran Senti said the church has analyzed its utility bills over the last year and the electric service has increased an average of $2 per day while their gas has decreased by $5 per day. “That’s a net savings of $3 per day or over $1,000 for the year; not bad for a 3-ton heat pump unit that provides air conditioning where we never had it before!”

Mr Slim® Equipment Installed:

(1) PUZ-HA36NHA H2i P-Series Outdoor Unit
(1) PKA-A36BA Wall-mounted Indoor Unit
(1) PAR-21MAA Remote Controller