Basic Hot Water Heating systems Flashcards Preview

Electrical Lab HVAC Period 2 SAIT-Alberta > Basic Hot Water Heating systems > Flashcards

Flashcards in Basic Hot Water Heating systems Deck (17)
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1
Q

What is another name for Hot water heating?

A

Hydronic heating.

2
Q

What is a terminal unit?

A
An "outlet" for heat.
Examples are: 
radiators,
baseboard units, 
plenum mounted heat exchangers,
radiant panels,
unit heaters.
3
Q

___________ Pumps are typically used in hydronic heating systems to push the water through the piping.

A

Circulating Pumps.

4
Q

Can an individual zone operate independently of the rest of the system?

A

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.

5
Q

Must the electrical supply for a boiler be on its own branch circuit?

A

Yes, sec 26-800-808 tells us this.

6
Q

How far can a zone control transformer be loaded?

A

80% of it’s rating.

7
Q

What is the benefit of digital controllers?

A

They increase energy efficiency and provide for diverse control strategies.

8
Q

What device is typically installed in an intermittent circulation system to ensure there is hot water circulating?

A

A reverse acting aquastat (normally open).

9
Q

There are two additional flame detectors used in boilers as opposed to forced air system, what are these?

A

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.

10
Q

What voltage are zone valves typically operated under?

A

24V.

11
Q

If a three wire valve lost power, would it return to it’s closed position?

A

No, three wire valves require power to operate in either direction. They require a special thermostat.

12
Q

What is a typical power rating for a circulation pump?

A

Up to one hP. 1750-3450 rpm.

13
Q

What is the purpose of a low water cut out?

A

To shut down the burners on a low water condition. Often interlocked with a make up water system.

14
Q

How is an anticipator adjusted in a hydronic heating system?

A

To match the current of the circuit that it controls.

15
Q

What is overshoot?

A

When a heating system stays on beyond the point at which residual heat would satisfy the thermostat. The anticipator is used to decrease overshooting,

16
Q

What will happen if the bulb on an aquastat ruptures?

A

The contacts open, as it is designed to be failsafe.

17
Q

What are the two main types of aquastats?

A

Immersion and Surface mount.