Basic Hot Water Heating systems Flashcards
What is another name for Hot water heating?
Hydronic heating.
What is a terminal unit?
An "outlet" for heat. Examples are: radiators, baseboard units, plenum mounted heat exchangers, radiant panels, unit heaters.
___________ Pumps are typically used in hydronic heating systems to push the water through the piping.
Circulating Pumps.
Can an individual zone operate independently of the rest of the system?
A single zone may operate at one time, but it must be also interlocked with operation of the boiler and circulation pump, if they are not continuous.
Must the electrical supply for a boiler be on its own branch circuit?
Yes, sec 26-800-808 tells us this.
How far can a zone control transformer be loaded?
80% of it’s rating.
What is the benefit of digital controllers?
They increase energy efficiency and provide for diverse control strategies.
What device is typically installed in an intermittent circulation system to ensure there is hot water circulating?
A reverse acting aquastat (normally open).
There are two additional flame detectors used in boilers as opposed to forced air system, what are these?
Cad cells: High resistance material, resistance lowers in presence of light from flame and allows current.
Pyrostat (stack switch): A bimetal coil incorporated into a probe, sensing the heat of the flame to close contacts.
What voltage are zone valves typically operated under?
24V.
If a three wire valve lost power, would it return to it’s closed position?
No, three wire valves require power to operate in either direction. They require a special thermostat.
What is a typical power rating for a circulation pump?
Up to one hP. 1750-3450 rpm.
What is the purpose of a low water cut out?
To shut down the burners on a low water condition. Often interlocked with a make up water system.
How is an anticipator adjusted in a hydronic heating system?
To match the current of the circuit that it controls.
What is overshoot?
When a heating system stays on beyond the point at which residual heat would satisfy the thermostat. The anticipator is used to decrease overshooting,
