Aquastats (Hot Water Thermostat Control) and Hot Water Boiler Components

Question 1

What is an Aquastat?

Answer 1

A thermostat control for a hot water heater or hot water boiler.

Question 2

A Hi-Limit is a ___________ switch.

Answer 2

normally closed (N/C)

Question 3

A Hi-Limit breaks on _________.

Answer 3

temperature rise

Question 4

A Hi-Limit shuts off the _______ and leaves on the _______ if the thermostat is still calling for heat.

Answer 4

shuts off the main burners and leaves on the circulator if the thermostat is still calling for heat.

Question 5

A 2nd Hi-Limit is used on _______.

Answer 5

commercial boilers

Question 6

A Hi-Limit is set at ______.

Answer 6

190 degrees

Question 7

A Hi-Limit has a fixed differential of _________.

Answer 7

10 degrees

Question 8

A 2nd Hi-Limit is used when___________________, which includes __________.

Answer 8

there are 3 or more zones, which includes an indirect heater

Question 9

When would a 2nd Hi-Limit shut off the main burners?

Answer 9

In the event that the 1st high limit fails

Question 10

The 2nd Hi-Limit reset should be automatic or manual?

Answer 10

it should be a manual reset

Question 11

A 2nd Hi-Limit should be set higher than, lower than, or the same as the first limit?

Answer 11

higher than

Question 12

A 2nd Hi-Limit should be set higher than the 1st Hi-Limit by how many degrees?

Answer 12

10-15 degrees

Question 13

What is the Low-Limit used for?

Answer 13

to maintain boiler water temperature

Question 14

The Low-Limit is a __________ switch.

Answer 14

normally open

Question 15

The Low-Limit makes on _________.

Answer 15

temperature fall

Question 16

Aquastat Terminal Connections:
Volts: AC/DC: Input:

Thermostat gets wires to:
L1- ______ ______ ______
L2- ______ ______ ______
C1- ______ ______ ______
C2- ______ ______ ______

Answer 16

Aquastat Terminal Connections:
Volts: A.C./D.C. : Input:

Thermostat gets wires to: T-T
L1- 120volts A.C. hot power input
L2- 120volts A.C. neutral power input
C1- 120volts A.C. hot circulator
C2- 120volts A.C. neutral circulator

Question 17

If the Aquastat has a vent damper plug connection and vent damper has been connected and cycled once, what happens?

Answer 17

Then a fuse blows

Question 18

If a fuse blows in an Aquastat, what needs to happen?

Answer 18

The Aquastat must always be used with a vent damper

Question 19

Burner Connection Options for an Aquastat:
B1-B2:
B1-B2:
B1-B3:
B1-B2:

Answer 19

Burner Connection Options for an Aquastat:
B1-B2: 120 volts
B1-B2: 24 volts
B1-B3: 24 volts
B1-B2: powerpile

Question 20

When connecting an Aquastat to a Hot Water Boiler, the normally static water pressure of the boiler should be

Answer 20

12psi

Question 21

When connecting an Aquastat to
a Hot Water Boiler, the boiler working pressure should be

Answer 21

15 psi - 18 psi

Question 22

When connecting an Aquastat to a Hot Water Boiler the boiler requires

Answer 22

a 30 lb/psi relief valve

Question 23

When connecting an Aquastat to a Hot Water Boiler the boiler requires what to be installed

Answer 23

a back flow preventer on water supply

Question 24

When using an Aquastat the Diaphragm Expansion Tank should be

Answer 24

Precharged at 12 psi

Question 25

When using an Aquastat the Diaphragm Expansion Tank is used to

Answer 25

provides a place for heated water to go when it expands 5% from 60 degrees- 240 degrees

Question 26

When using an Aquastat the Diaphragm Expansion Tank should be installed

Answer 26

on circulator's suction side

Question 27

If diaphragm expansion tank is bad this may cause

Answer 27

the relief valve to discharge water

Question 28

When sizing a replacement hot water boiler measure only the (partial? or total?) ______________.

Answer 28

baseboard element

Question 29

When sizing a replacement hot water boiler how do you find the btu/hr if low-output?

Answer 29

total element x 600 btu/hr per foot Multiply total element by 600 btu/hr per foot if low output

Question 30

When sizing a replacement hot water boiler how do you find the btu/hr if high-output?

Answer 30

total element x 800 btu/hr per foot Multiply total element by 800 btu/hr per foot if high output

Question 31

A circulator does what?

Answer 31

moves water through a heating system or zone

Question 32

How is a circulator lubricated?

Answer 32

by water or oil

Question 33

All new water boilers require _________.

Answer 33

A low water cut off

Question 34

1 psi raises water how many feet high?

Answer 34

2.31 ft

Question 35

What is a hot water boiler's psi at cold start?

Answer 35

12 psi - 15 psi

Question 36

What is a hot water boiler's psi while operating?

Answer 36

18 psi

Question 37

An expansion tank should be set at ______ psi and it's _________ doesn't require power.

Answer 37

set at 15 psi and it's relief valve doesn't require power.

Question 38

True or False? The expansion tank and feed valve do not need to match.

Answer 38

False. The expansion tank and feed valve need to match.

Question 39

True or False A backflow preventer is required by code for all systems.

Answer 39

True.

Question 40

What does an automatic fill valve do?

Answer 40

adds water and keeps the system filled to 12 psi

Question 41

The water temperature of baseboard heating is ____________.

Answer 41

180 degrees (a 10 degree differential with 190 degrees from the supply and 170 degrees from the return)

Question 42

What do air control devices do?

Answer 42

remove air from a hot water system

Question 43

Coin vents

Answer 43

air control device used on the return side of baseboard heating (manually opened with a key)

Question 44

Automatic air vents are what kind of device? Where is it used?

Answer 44

air control device used on top return line at boiler

Question 45

Air scoop what kind of device? used where? pipe size

Answer 45

air control device supply line before all zone takeoffs 18" pipe

Question 46

Microbubbler what kind of device? used where?

Answer 46

air control device supply line before all zone takeoffs