Therma-Stor Products Group XT150H owner manual 4C Ducting for Fresh Air

FOR HVAC INSTALLER ONLY

3.4C Ducting for Fresh Air

Fresh air can be brought into the structure by connecting an insulated duct from outside to the 6" Ultra-Aire XT150H inlet and by turning on the fan switch or activating the humidity control (on units with the humidity control panel). Activate the ventilation timer on units with the ventilating and humidity control panel to bring in fresh air. Refer to Section 4.5 for programming instructions for the ventilation timer. Advantages of this form of ventilation include:

1.Outside air is filtered before entering the building.

2.Outside air will be dehumidified before entering if the Ultra- Aire XT150H is running in dehumidification mode.

3.Drawing air from outside and blowing inside aids in slightly pressurizing the structure. This helps prevent dirty and humid air from entering elsewhere. It also reduces the potential for carcinogenic radon gas to enter and provides make-up air for open combustion and exhaust devices like the clothes drier, fireplace, and water heater.

4.Adequate exhaust fans are recommended in the bath rooms and kitchen.

In cold climates or areas where the outdoor dew point is low at times, ventilation can be used to dehumidify the structure. This is accomplished by bringing the dry, low dew point air into the structure during these times. This approach is often more economical than running the dehumidifier to remove excess moisture from the structure. In cold climates, it is critical to adequately ventilate to reduce the inside moisture content to avoid moisture accumulating in the wall cavities. For example; in a house that experiences condensation on the interior surface of the windows during the winter, increasing the amount of ventilation will often cure the problem.

An insulated 6" diameter duct is generally sufficient to provide up to 125 CFM of outside air. Large quantities of outside air will either positively or negatively impact the performance of the Ultra-Aire XT150H, depending upon inside and outside air conditions. Consult the factory by calling 1-800-533-7533 for recommendations regarding the use of higher flows with your specific application.

The outside air duct should be connected to the 6" round collar on the filter enclosure of the unit. The 6" round collar includes a manual damper. Adjust the manual damper to provide the desired amount of fresh air for ventilation. The amount of fresh air should be based on the size and occupancy of the residence. If you are unsure of your ventilation air requirements, consult the factory by calling 1-800-533-7533 for assistance.

3.4D Installation in a Basement or Crawlspace with an Existing Forced Air HVAC System

It is recommended that a new, separate return duct be installed for the Ultra-Aire XT150H from a central area of the house. If this is not possible, and if the existing system has multiple returns, select one to disconnect from the existing forced air system and use it for the dedicated Ultra-Aire XT150H return. Always select a return from a central location in the structure in an area that is always open to the rest of the structure. Do not use a return from a room that may have its door closed much of the time.

If the structure in which the Ultra-Aire XT150H is to be installed has an existing forced air HVAC system, utilize the HVAC system to make the Ultra-Aire XT150H installation easier.

Basement Installation: Install a separate 10" return for the Ultra- Aire XT150H in a central area of the structure. Duct the supply of the Ultra-Aire XT150H to an optional 10" x 10" x 10" tee/damper that is 20% open to the basement. This allows the ability to discharge a variable amount of dehumidified air into a basement that may not be well served by the existing duct system. Duct the other side of the tee to the air supply of the existing HVAC system. A backdraft damper is required in the duct between the 10" tee and the central supply duct to prevent air from being discharged into the basement during central fan operation. Connect a duct from outside to the

6" collar of the Ultra-Aire XT150H if you wish to provide fresh air ventilation.

Crawl Space Installation: Install a separate return for the Ultra- Aire XT150H in a central area of the structure. Duct the supply of the Ultra-Aire XT150H to a 10" x 10" x 10" tee/damper that is 20% open to the crawl space if desired. Duct the other side of the tee to the air supply of the existing HVAC system ventilation. Connect an insulated duct from outside to the 6" collar of the Ultra-Aire XT150H if you wish to provide optional fresh air.

6 Ultra-Aire XT150H Installer’s & Owner’s Manual