Heating Appliances Flashcards
How many amps can a thermostat handle?
Less then 1 amp
What’s the purpose of the furnace board?
To pudge
Open gas valve
Send a spark
Sense a flame is present.
What does a thermostat measure
The intensity of the heat
What is BTUS
British thermal units
- the heat energy required to raise or lower 1 pound of water 1 degree F
What does the heat anticipator do?
It controls how fast the furnace kicks back on
Where should the thermostat be located?
The thermostat should be located in the common he place. Should be on an interior wall for the 4 1/2 feet above the floor
How far should A gas burning appliance be from any gas filler spout?
Must be at least 36” away
Where in must the gas burning appliance exhaust be?
Must exhaust out the side wall of the unit and where a door cannot come within 2 inches
How far must a flew terminal (exhaust) be from any opening
At least 9
What is the difference between a normal relay in a time delay relay
Normal really uses magnetic field to move the Bi metal strip
A time delay relay uses heat to move the bi metal strip
What is the purpose of the circulating air blower wheel
Circulates cool interior air past the exterior of the heat exchanger
What is the purpose of the combustion air wheel
Draws outside air into the combustion chamber for proper fuel to air mixture
What is the sales which do
Senses when the airflow is at least 75 to 80%
What is the limit switch
It’s a high temperature safety device on the furnace which will open when it exceeds the highest safest temperature
How does the gas valve operate
How many ohms per valve
Once the magnet is powered by at least 10 1/2 V it opens allowing gas through
30-50 ohms per valve
How does the thermal coupler work
When heated up it produces electricity which holds the gas valve open
How does the flame sense work
It sends power through the hydrocarbons in the flame ground into the burner
What is a general rule for size in a furnace
1,000 btu’s per 1 foot of the RV length. 1,500 btu’s per foot for slide outs
How far must exhaust pipe overlap
How far most of the intake pipe overlap
Exhaust must overlap inch and a quarter in the intake must overlap half an inch
The DSI circuit board sents how many volts to the electrode?
80,000v
What is the charge rate of a liner converter
3-5 amps
What converts the AC voltage into DC voltage in a converter? How does it rectify the voltage from AC TO DC
A step-down transformer is used to convert 120 voltage to 12 volts
Doides are used to rectify the voltage from AC to DC
How much voltage does a thermocouple produce under load
20-30 mVDC
What is a thermocouple and how does it work?
It is a safety valve on a pilot model thermostat. Basically a flame sense.
When heated up it produces an electricity which holds the gas valve open
What should be the gap between the electrode and ground?
Between 1/8- 3/16th
What should be the amp readings On a working flames sense?
Between 5-10 micro amps (mA)
Once the board receives power through the safety Circuit how long will it purge for?
About 20 seconds
What does a 2 stage furnace need?
Needs two gas valves and a special thermostat
What size are the hydronic systems typically?
50,000 btu or 1500W
What exactly does the thermostat in the hydronic system control?
It’s controls the solenoid/valve that allows the amount of warm fluid enters the heat exchanger
How much can you adjust the bay thermostat on the hydronic systems?
Only between 40-50•F
How is the hydronic system Plumbed?
The zones are plumbed in parallel and the zones themselves are plumbed in series
How hot does the hydronic system keep the fluid?
Between 160-190•F
What senses the flame on diesel hydronic systems?
A photo sense
How often should the hydronic system be checked?
Once a month along with the power steps
What is boiler antifreeze?
It is propylene glycol
What do you use to check the antifreeze mixture?
A refractometer
