Friday, December 18, 2015

Potable Water for Heating with Titus Fan Coils


When it comes to heating and cooling facilities such as condominiums, apartments or small dwellings, the choices for providing comfort during heating can be interesting. The most typical systems for heating are the dedicated gas furnaces, heat-pump or the conventional electric heat elements. The dedicated gas furnace and heat pumps can provide a very cost-effective, energy-efficient system. However, the initial investment is high and gas furnaces cost more to install than electric systems.

Electrical heating elements’ initial investment and installation may be low, however, the operating cost will be high. This is especially true in regions where the heating season is longer or prolonged over 1 month.

An efficient and cost-effective alternative is to use the combination of a fan coil with a certified NSF/ANSI 61 hot-water coil and the domestic hot-water heater. An adequately sized L.P. or natural gas hot-water heater can easily provide hot water for domestic use and provide efficient heating comfort during the heating season. With today’s high-efficiency natural-gas water heater, the energy consumption can be minimized while maintaining a lower initial investment and installation cost.

DESCRIPTION OF OPERATION

The water pump and fan coil become energized when the room thermostat – either a conventional or programmable – senses the need of heating. Hot water will start circulating from the water heater to the heating coil and the fan motor will start blowing warm air throughout the ducts. With proper water-heater sizing, there will be enough capacity to handle the domestic hot-water needs. Sufficient heating comfort will be provided throughout the entire house, no matter the temperature outside. During the summer operation, when cooling is required, the thermostat will energize the condensing unit providing the required cooling capacities with the matching Titus refrigerant coil and expansion device.

EQUIPMENT SIZING

High Output -- High-Performance Fan-Coil Selection:

1st Step: Based on the cooling load of the condominium, select the fan-coil size based on 400 CFM per ton of cooling (1 ton = 12,000 Btuh). For example, if a cooling load of 48,000 Btuh is required, a 4-ton cooling system should be appropriate. Therefore, a 1600 CFM is suggested. 400CFM x 4 tons = 1,600 CFM. For lower energy consumption and LEED credit opportunity, an ECM motor is suggested as part of the specification. Also, an ECM will make it more independent from the static pressure requirements.

2nd Step: Based on the space heating load and the pre-selected fan-coil unit size, open the Titus Coil-Pro rating program to determine if one or two rows of heating coils will be needed to satisfy the heating loss of the apartment. This is based on a 120 °F entering hot-water temperature.

Water-Heater Selection: Because of variations in each family’s domestic hot-water needs, Titus recommends to contact a qualified professional engineer to obtain additional assistance in water-heater sizing.

For proper water-heater sizing, consider both the gallon capacity and the BTU input of the water heater.

1st Step: Determine heater GALLON CAPACTIY:


  • 600-800 CFM fan coils: No less than a 40-gallon water heater
  • 1,200 CFM fan coil: No less than a 60-gallon water heater
  • 1,400-1,600 CFM fan coil: No less than a 75-gallon water heater
  • 2,000 CFM fan coil: Recommendation based on water heater BTU’s (105,000 Btuh output).

2nd Step: For verification, determine water heater BTU INPUT: The heat loss of a dwelling needs to be known. Calculate heat loss of a dwelling, based on the ACCA or ASHRAE load calculation method. Water-heater recovery efficiency should be no less than 76%.


  • Mild climates: BTU INPUT = dwelling’s heat loss x 1.5
  •  Colder climates: BTU INPUT = dwelling’s heat loss x 1.6

MATCHING CONDENSING AND COOLING COIL TO COOLING LOAD

Manual J method or other approved heat loss/heat gain calculation procedure should be used to calculate the cooling load of a dwelling. The condensing-unit cooling capacities and efficiency information are available from the condensing-unit manufacturer.

Titus’ cooling coils are compatible with major brands’ condensing units. Depending on the condensing unit chosen and the Titus fan coil being selected, efficiencies up to 15 SEER can be provided.


Contact a Titus representative for help selecting the proper matching refrigerant and expansion device.