-3- A volume boosting relay may also be used as a two input low selector. True False -4- A snap acting air switching valve may be piloted by a two position controller or a modulating controller. True False -5- A modulating receiver controller may pilot a gradual air switching valve. True False -6- A reversing relay can effectively change a direct acting signal into a reverse acting signal and offset the signal. True False -7- Multi high-low selector indicates the highest input signal on its H output port and the lowest input signal on its L output port. True False -8- A minimum positioning relay assures the fresh air dampers are closed at night. True False -9- A biasing relay (ratio relay) allows co-ordination of heating and cooling in a logical sequence. True False -10- If two thermostats, set for 70°F, are averaged with one room at 80°F and the other at 60°F the average will be 70°F. The comfort in the occupied space will be acceptable. True False -11- Pilot positioners (positive positioning relays) are used on valves and damper actuators to position the devices accurately, compensating for varying resistance, as well as allowing alteration of the stroking range and start point of the devices stroke. True False -12-Relays are available to add or subtract a determined amount of pressure from another variable pneumatic signal at a constant rate. True False -13- A PE switch passes control air when it is energised. True False SAFETY LOOPS -1- Low limits (sometimes called freeze stats) have an averaging element and shut down the fan if the air is too cold. True False -2- High limits (sometimes called fire stats) should be only installed in the supply and mixed air. True False 10-182
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