furnace problem

[billdozza]

i have two furnaces sharing the same return plenum, problem is when one unit is on it spins squirrel cage on second unit in the opposite direction, which gives it enough inertia that when second unit calls for heat the fan continues to rotate in the opposite direction. It happens with either unit. plez only pros reply

[Magoo]

weighted back draught dampers

[install monkey]

most helpful-thanks for the link
otherwise if you start each furnace on its own does the fan spin the correct way?
as magoo suggests- back draught shutters prevent this- otherwise maybe running both fans simultaniuosly would also prevent this too

To short out this type of problem you must visit fo9llowing url
LINK REMOVED BECAUSE HAS NOTHING WITH FURNACES

[billdozza]

thanks for your replies and also thought of these options but are there any motors out there with some type of braking system

[NiHaoMike]

Install air check valves or one way clutches.