Ventilating fan with grill having high static pressure resistance

Abstract

A bathroom-ventilating fan with grille having a fan hosing, fan scroll, inlet ring, outlet collar, fan grille, sound insulation and electrical box. The external motorized assembly backwardly inclined type impeller is used. The bathroom-ventilating fan with grille has multiple speeds controlled by multiple capacitor and has the performance with 100 CFM airflow rate at or higher than 1 inches static pressure, 5 Sones or lower than 5 Sones of HVI (Home Ventilating Institute) certified sound ratings and 3.08 or higher than 3.08 CFM per watt power consumption at 0.1 inch static pressure as well as the fan has the performance with 50 CFM at 0.4 or higher than 0.4 inches static pressure, 1 Sone or lower than 1 Sone of HVI certified sound ratings and 1.36 or higher than 1.36 CFM per watt power consumption at 0.1 inch static pressure.

Description

RELATED APPLICATION

This application claims domestic priority from U.S. provisional patent application No. 60/861,734 filed Nov. 30, 2006.

TECHNICAL FIELD

The invention relates to a ventilating fan with a grill and a high static pressure resistance, for example a fan adapted for use as an bathroom-ventilating fan exhausting through an external wall of a high rise building.

BACKGROUND OF THE ART

Traditionally, the ventilating fan used to exhaust air from the bathroom of residential house, apartment, or condominium have low static pressure performance. The reason for this convention is that normally short length of duct was used between the fan and outside wall, and counteracting external wind loads were relatively low. However, modern urban apartments and condominiums can be some of the highest buildings in a city, and may be unsheltered from wind over lakes or valleys. Further, concern over mold in buildings has increased and condensation of moisture within inadequately ventilated ducts is not only a corrosion risk but a health risk as well when mold or mildew are present.

The relatively ratings for conventional ventilating fans are often in the range of 100 cubic feet per minute at 0.3 inches static pressure. The low cost blower wheels conventionally used for residential bathroom fans normally are single or double forward curved fan wheels driven electric motors.

Needs of modern development of the condominium luxury high rise buildings having 40-60 floors or more exceed the capacity of conventional ventilating fans. Ventilating fans with higher static pressure capacities such as 100 CFM or more at 1 inch or more static pressure, are required to exhaust air out off the building. The reasons high performance fans are needed includes the following. Exhausting air out off a building against stronger winds is required since wind speed and exposure to wind are greater at higher elevations. To exhaust the air out of a tall building, more wind pressure resistance must be overcome by the ventilating fan and any check/backflow valve.

Further exhausting air out of a building against the pressure difference between outside and inside of the building is more pronounced at higher elevations. Wind flow around a building creates a pressure difference between the outside and inside air. For example in extreme hurricane or tornado events, the pressure differential can cause explosion of windows, or failure of roof and wall structures. When the building is high, the pressure difference between the outside and inside of the building will be larger, due to a larger temperature difference between outside and inside air. The higher the building, the high the pressure difference, the higher capability the fans need to against the air flow resistance.

Modern apartment designs often include long lengths of exhaust ducts from laundry rooms, bathrooms or kitchens located away from an external wall. The longer duct lengths added to the flow losses. Centralized ducting through a building to a roof vent is not preferred due to the risk of contaminated air, fire and smoke spread between apartment units. Further in a condominium each owner is responsible for the maintenance of their own unit and there is a strong incentive to avoid common utilities or infrastructure, thus making individual ventilating fans essential for each residential unit.

Conventionally exhausting air out of building against higher flow resistance required supplementary equipment such as multiple exhaust fans or an in-line booster fan. To meet the requirements of modern environmental concerns and energy savings of new buildings, heat recovery heat exchangers along with the exhaust air ducts recover heat from the exhausted air. These supplementary equipment greatly increase the air flow resistance in the duct during exhausting of air.

However along with the requirement of high static pressure performance and high flow rates comes the requirement of low noise levels since air is exhausted from residences or offices where people may attempt to sleep and avoid being disturbed. Requirements such as 100 CFM air flow at 1.0 inch static pressure with noise level at or under 5 Sones of sound rating, are not achievable using ventilating fans with an inlet grill and exhausting through use of a forwardly curved centrifugal fan wheel now on the market.

Features that distinguish the present invention from the background art will be apparent from review of the disclosure, drawings and description of the invention presented below.

DISCLOSURE OF THE INVENTION

The invention provides a high rise bathroom ventilating fan with grille which compose of a fan housing, fan scroll, inlet ring, outlet collar with optional back draft damper, fan grille, sound insulation, and electrical containment box. The fan can run at different speeds controlled by multiple capacitors. An external motorized assembly with backwardly inclined type impeller may be used.

DESCRIPTION OF THE DRAWINGS

In order that the invention may be readily understood, one embodiment of the invention is illustrated by way of example in the accompanying drawings.

FIG. 1 is a partially exposed perspective view of a fan housing with removable grill over the bottom inlet, with internal scroll, and motorized assembly with backwardly inclined impeller blades.

FIG. 2 is a graph of an example test of a fan assembly showing a substantially linear transition between static pressure range from 2.25 inches at 0 CFM, to 0 inches at 225 CFM, with a target performance of 1 inch static pressure at 100 CFM well within the performance envelope.

FIG. 3 is a graph of the same example test of FIG. 2 showing the noise level generated for a range of frequencies all below 60 decibels.

Further details of the invention and its advantages will be apparent from the detailed description included below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a ventilating fan 1 with removable grill 2 over the bottom inlet opening of a fan housing 3. Inside the fan housing 3, there is the insulation to decrease the sound level and a fan scroll 5 in which an external motorized assembly 4 with backwardly inclined impeller blades. An inlet ring is connected to inlet of the scroll 5. The fan scroll 5 with motorized assembly 4 can be removed from the fan housing 3 easily to facilitate maintenance, eliminate theft during construction and simplify assembly during manufacturing. A back draft damper 6 at the outlet collar 7 of the fan protects the upstream environment when the fan is not running.

The motor is controlled by at least two capacitors for two or more different speeds. In the example setup tested as shown in FIG. 2-3, high speed is controlled by a 6 λF capacitor where the fan has a rated performance of 100.9 CFM airflow rate at 1.227 inches static pressure, 5 Sones of HVI (Home Ventilation Institute) certified sound ratings at 0.1 inch static pressure and 3.08 CFM per watt power consumption at 0.1 inch static pressure. The low speed is controlled by 1.2 λF capacitor, where the fan has a performance of 49.5 CFM at 0.411 inches static pressure, 1 Sone of HVI certified sound ratings at 0.1 inch static pressure and 1.36 CFM per watt power consumption at 0.1 inch static pressure.

Although the above description relates to a specific preferred embodiment as presently contemplated by the inventors, it will be understood that the invention in its broad aspect includes mechanical and functional equivalents of the elements described herein.

Claims

1. A ventilating fan comprising a fan housing with a fan scroll having an impeller, an inlet ring and an outlet collar with a back draft damper, the fan housing including a fan inlet grill, sound insulation, and electric motor, wherein the impeller has backwardly inclined blades.

2. A ventilating fan according to claim 1, wherein said fan is used to exhaust air from a bathroom.

3. A ventilating fan according to claim 1, wherein the fan has a performance of 100 CFM airflow rate with at least 1 inch static pressure.

4. A ventilating fan according to claim 3, wherein the fan has a performance of 49.5 CFM airflow rate with at least 1 inches static pressure.

5. A ventilating fan according to claim 1, wherein the fan has no more than 5 Sones of HVI (Home Ventilating Institute) certified sound ratings at 0.1 inch static pressure.

6. A ventilating fan according to claim 5, wherein the fan has no more than 1 Sones of HVI (Home Ventilating Institute) certified sound ratings at 0.1 inch static pressure.

7. A ventilating fan according to claim 1, wherein the fan has a power consumption of 3.08 CFM or more per watt power consumption at 0.1 inch static pressure at a high speed setting.

8. A ventilating fan according to claim 7, wherein the fan has a power consumption of 1.36 CFM or more per watt power consumption at 0.1 inch static pressure.

9. A ventilating fan according to claim 1, wherein the electric motor has different speed settings controlled by at least 2 capacitors.

10. A ventilating fan according to claim 9, wherein the capacitors are 6 λF capacitors.

11. A ventilating fan according to claim 9, wherein the capacitors are 1.2 λF capacitors.

12. A ventilating fan according to claim 1, wherein the fan has sound insulation inside the housing.