# Trevor Thompson Senior Project II Vermont Technical College Spring 2011.

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Trevor Thompson Senior Project II Vermont Technical College Spring 2011

Inefficient heat distribution from the living room woodstove to other rooms in the house resulting in ~7deg delta in temperature between the living room and the nursery (room 1). Living Room ~70 deg ~63 deg Room 1 Room 2 Room 3 Room 4 House Layout Room 5

Design a heat distribution system that takes heat provided from the living room wood stove and distributes it to other rooms when called for. If the temperatures are not being met the controller will trigger the furnace to turn on and compensate. Room 1 Room 4 Room 2Room 3 Living Room Controller V(T) Actuator room 5 Damper V(T) Actuator Damper ActuatorDamper ActuatorDamper Furnace Room 5 Outside Temp Intake Temp

Formula: BTU/hr Required = Volume of Room (ft 3 ) X Insulation Rating + (# of Windows X 1000) Length (ft) X Width (ft) X Height (ft) * All Formula’s Obtained at www.engineeringtoolbox.com

23000 Btu/hr 1 kW (kJ/s) = 859.9 kcal/h = 3,413 Btu/h (23,000 Btu/hr) X (1kW/3413Btu/hr) = 6.76kW Formula ~700 cfm Required Air Flow (cfm) = [(6.76kW)(3.42)] / [(1.08)(30deg F)] = 713 cfm

Main Branch Duct Calculation v = 900ft/min q = 700cfm *This will be used in the next step Duct X-Sectional Area = 144 X (700cfm / 900ft/min) = 112in 2 Area = pi X r 2 so; r = sqareroot (Area / pi) r = square root(112in 2 / pi) = 5.97 inches Duct Diameter = 12inches Air velocities in ducts should not exceed certain limits to avoid high pressure losses and unacceptable noise generation. Branch Duct Calculation v = 400ft/min q = 78cfm Duct X-Sectional Area = 144 X (78cfm / 400ft/min) = 28in 2 Area = pi X r 2 so; r = sqareroot (Area / pi) r = square root(28in 2 / pi) = 3 inches Duct Diameter = 6 inches Formula Step 1: Determine Desired Air Velocity Step 2: Calculate Duct Diameter

700 cfm Friction Loss = [0.109136 X (700cfm) 1.9 ] / (12in) 5.02 Friction Loss = 0.1 inch H 2 O Formula

Confirmation that the existing duct can carry the same air volume as the new 12” round.

What Do We Know? Each room has a fixed volume. As hot air is forced into the room existing cool air needs to be pulled out. Want air flow in each room to envelope the room with hot air to reduce cold air from penetrating the exterior walls. Since hot air rises I choose a low location for the return vent so the air that was force out was the cold air that resided in the room.

Initial Hot Air Vent Location Final Hot Air Vent Location

12 inch Main Trunk 6 in Branches Dampers Actuator Centrifugal Fan Duct Intake Main Existing Trunk Transition Box 45deg Elbow 90deg Elbow

Damper Duct Actuator Controllable Damper Assembly Damper Assembly

New Duct AssemblyExisting Duct Assembly Combined Duct Assembly

Centrifugal Fan Room 1 Actuator Room 1 Damper Room 2 Damper Room 3 Damper Room 4 Damper Room 1 Temperature Plate Room 5 Relay Room 5 Damper Room 2 Actuator Room 3 Actuator Room 4 Actuator Furnace Computer 0-10V Signal Ethernet Port 10K Type 3 24VAC Outside Temp Intake Temp Room 2 Temperature Plate Room 3 Temperature Plate Room 4 Temperature Plate Room 5 Temperature Plate

Four wire to each actuator. Two wire to; 1.Temperature Plates 2.Fan Control 3.Outside Temperature 4.Intake Temperature 5.Furnace Power to Fan. Power to Transformer. Tie into Controller FurnaceOA TempIntake Temp

8 Universal Inputs Temperature Plates (4) Outside Air Temp Probe (1) Intake Temp Probe (1) 4 Analog Outputs Actuators (4) 4 Digital Relay Outputs Furnace Centrifugal Fan 15 VDC Out Ethernet Ports Battery Backup Pack

1.Cut in zone control dampers and attach actuators 2.Install clearance extension 3.Install 90deg elbow 4.Install fan 5.Install 45deg tie-in elbow 6.Install back draft damper 7.Install 12” round duct pipe 8.Install Temperature Plates 9. Install Outside & Intake Temp Probes

 Cross sectional area of intake must equal or exceed that of the 12’ round duct.  Clearance behind woodstove limits width to 4 inches.  Intake must travel from duct in basement through floor to rear of woodstove.  Design must include a removable filter to remove dust/ash/smoke before going through system. Area of 12” Round Duct = (pi)r 2 = pi x 6 2 = 113.1 in 2 Area Intake = Length X Width Length = 113.1 in 2 / 4in = 28.3 in ~29 inches

1.Find location of woodstove in the basement 2.Review basement layout for any obstructions 3.Determine where to tie into existing duct

Run Trunk Line / Install Mounting Board Mount Controller Connect Wires to Terminals

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