Weatherwise Heating and Air Conditioning
Home
Services
Our Guarantee
Coupons
Blog
Contact Us

Weatherwise
Blog

Weatherwise Heating and Air Conditioning

Furnace Repair: Spark ignition with no pilot

by Weatherwise on 02/04/12

Here is a list of common problems :


Gas Furnace - Spark Ignition / No pilot


Draft motor does not start

Draft Motor 

(Check to see if motor is seized or hot, check load voltage to motor)

Thermostat

(Check 24V at C & W)

No Spark to ignite main gas

Open safety in control circuit 

(pressure switch, high limit, roll-out)

Ignition Module / Control board 

(Some ignitors are in the control board, 24V signal to the ignition module through the safeties, but no spark)

Thermostat 

(No call for heat)

Ignition wire / Ignitor 

(Loose connection or shorted wire)

Draft motor 

(safety monitored by “pressure switch” in control circuit)


Ignitor sparks, but no ignition

Ignition Module / Control board 

(Some ignitors are in the control board / No 24 V. signal from the ignition module to the solenoid on the gas valve)

Gas valve 

(24V signal at the gas valve, but no or low gas through the solenoid on the gas valve)

Improper ignitor grounding 

(often ignitor sparks, but fails before gas is activated)


Burners ignite, but shut off after a few seconds

Flame sensor

(Remove and clean flame sensor with sand paper)

Pressure switch 

(Check pressure switch tubing for obstruction)


Ignition to burners, no blower motor (furnace will overheat and lock out /high limit)

Blower motor 

(Check to see if motor is seized, check load voltage to motor)

Control board 

(internal relay not sending high voltage to the blower motor)

Run Capacitor 


 Ignition to burners & blower motor runs, but furnace overheats and locks out high limit

Dirty air filter

Dirty evaporator coil

High gas pressure

(Check outgoing pressure from the gas valve, adjust if needed)

Restricted ducting

(Test furnace with air filter removed & check temperature rise across the heat exchanger)


Blower motor runs continuously with no burner ignition

Thermostat 

(Check 24V signal at C & G)

System lock - out

(Check diagnostic codes at the control board)


Flames roll out of heat exchanger

Dirty burners 

(Remove and clean)

Blocked venting 

(Inspect flue piping and remove restriction - make sure there is more vertical rise than horizontal and the horizontal rises ant 1/4” per foot)

cracked heat exchanger 

(Perform visual inspection, video inspection, carbon monoxide test, or trace gas test as needed)


Troubleshooting a gas furnace for repair is a step by step logical sequence.  It is always important to look for the obvious.  For example, it is important to know what is working to quickly eliminate it from troubleshooting.  In the Denver area heating is crucial, so a technician will encounter a wide variety of situations of types of heaters from a standard gas furnace, high efficiency gas furnace, or a hot water boiler. Routine furnace cleaning can eliminate a lot of intermittent failures. Weatherwise is a Denver metro based HVAC contractor, with the tools and experience to handle all of your heating and air conditioning service needs.  Feel free to call our company for any questions you may have.  

Heating Repair: Common failures for a gas furnace spark ignitor with a standing pilot

by Weatherwise on 01/30/12

Gas Furnace - Spark Ignition with pilot


Draft motor does not start

Draft Motor 

(Check to see if motor is seized or hot, check load voltage to motor)

Thermostat

(Check 24V at C & W)

No spark to ignite pilot

Open safety in control circuit 

(pressure switch, high limit, roll-out)

Ignition Module / Control board 

(Some ignitors are in the control board, 24V signal to the ignition module through the safeties, but no spark)

Thermostat 

(No call for heat)

Ignition wire / Ignitor 

(Loose connection or shorted wire)

Draft motor 

(safety monitored by “pressure switch” in control circuit)

Ignitor Sparks and no pilot lit

Ignition Module / Control board 

(Some ignitors are in the control board)

               (No 24 V. signal from the ignition module to the pilot valve on the gas valve)

Dirty pilot orifice 

(Sometimes gas can be leaking out the back side of the pilot assembly due to the restriction)

Gas valve 

(24V signal at pilot valve on the gas valve, but no gas through the pilot valve solenoid on the gas valve)

Improper ignitor grounding 

(often ignitor sparks, but fails before pilot gas activated)

Pilot lights but no gas to burners

Dirty ignitor / flame sensor 

(No or low flame signal sent to the ignition module, Can be cleaned with sand paper)

Ignition module / Control board 

(Some ignitors are in the control board, No 24V signal sent to the main gas solenoid on the gas valve)

Gas valve 

(24V signal at the main gas solenoid on the gas valve, but no gas)

Ignition to burners, but no blower motor (furnace will overheat and lock out /high limit)

Blower motor 

(Check to see if motor is seized or hot, check load voltage to motor)

Control board 

(internal relay not sending high voltage to the blower motor)

Run Capacitor 

(Check microfarads)

Ignition to burners & blower motor runs, but furnace overheats and locks out high limit

Dirty air filter

Dirty evaporator coil

High gas pressure

(Check outgoing pressure from the gas valve, adjust if needed)

Restricted ducting

(Test furnace with air filter removed & check temperature rise across the heat exchanger)

Blower motor runs continuously with no burner ignition

Thermostat 

(Check 24V signal at C & G)

System lock - out

(Check diagnostic codes at the control board)

Flames roll out of heat exchanger

Dirty burners 

(Remove and clean)

Blocked venting 

(Inspect flue piping and remove restriction - make sure there is more vertical rise than horizontal and the horizontal rises ant 1/4” per foot)

Cracked heat exchanger 

(Perform visual inspection, video inspection, carbon monoxide test, or trace gas test as needed)


At Weatherwise heating and air conditioning we provide Denver with furnace, boiler, air conditioner, and evaporative cooler repair and service.  Weatherwise has the staff to support residential equipment and commercial equipment repairs for all of your HVAC service needs.  As a licensed heating and air conditioning contractor throughout the Denver metro area and along the Colorado front range, our company can respond to your installation and repair needs fast.  

Gas Furnace: Common Failures with a Standing Pilot

by Weatherwise on 01/20/12

Here is a list of common situations you may come across with a gas furnace with a standing pilot.


 Gas Furnace - Standing Pilot


No pilot light

Thermocouple 

(Check for corrosion and wear)

Gas valve 

(No pilot gas through valve, try to relit to test)

Dirty pilot orifice 

(Often gas will leak on the back side of the pilot assembly after it is lit indicating a blockage)


Pilot light, but no ignition to burners

Thermocouple 

(Check for corrosion and wear)

Auxillary limit control 

(This is wired across the thermocouple on the gas valve)

Gas valve / gas pressure 

(24V signal to gas valve, but no gas)

No 24V signal to gas valve

(Check control circuit)

Dirty burners 

(Remove and clean)

Dirty manifold orifices 

(Clean with compressed air or nitrogen)

Thermostat 

(No call for heat)

Power 

(Check line voltage and low voltage across the transformer)


Ignition to burners, but no blower motor - system overheats 

Blower motor 

(Check if motor is seized, check load voltage to motor)

Fan / Limit Control 

(Check to see if temperature dial rises on the fan control)

Run Capacitor 

(Check microfarads)

High gas pressure 

(Check outgoing pressure from the gas valve, adjust if needed)


Ignition to burners & blower motor runs - system overheats (short cycles)

  Dirty air filter

Dirty evaporator coil

High gas pressure 

(Check outgoing pressure from the gas valve, adjust if needed)

Restricted ducting

(Test furnace with air filter removed & check temperature rise across the heat exchanger)

Fan / Limit control 

(Limit setting in not accurate to the temperature rise)


Blower motor runs continuously with no burner ignition

Fan / Limit control 

(Fan circuit stuck closed through the fan control)

T-stat calling for fan 

(Check 24V at C & G)

Fan relay 

(Contacts in relay stuck closed with no 24V signal at the coil)


Flames roll out of heat exchanger

Dirty burners 

(Remove and clean)

Blocked venting 

(Inspect flue piping and remove restriction - make sure there is more vertical rise than horizontal and the horizontal rises ant 1/4” per foot)

Cracked heat exchanger 

(Perform visual inspection, video inspection, carbon monoxide test, or trace gas test as needed)

 


Weatherwise heating and air conditioning is available in Denver and the surrounding Denver metro area for all your Denver HVAC needs.  Weatherwise can provide service for your furnace, boiler, air conditioner, or swamp cooler.  Weatherwise if fully staffed for residential or commercial HVAC repair in Denver.  For the best heating repair Denver has to offer call Weatherwise today. Visit our coupons copage for valuable Denver HVAC service repairs.

 

High Pressure and Low Pressure Failures: Air conditioning repair Denver

by Weatherwise on 06/23/11

The refrigerant circuit for an air conditioning system is divided into two sides.  The high pressure side and the low pressure side.  The refrigerant pressures are typically measured at the service valves at the ac condenser.  The high side is located at the smaller refrigerant line known as the liquid line, and the low side service valve is located on the bigger refrigerant line called the suction line.  The suction line can also be identified by the pipe insulation (armaflex) around the line. The high side pressure in the HVAC industry is identified as the head pressure and the low side pressure is called the suction pressure.  To keep it simple, think of the high side as the pressure and temperature of the outdoor condenser and the low side as the pressure and temperature of the indoor evaporator coil. (Located adjacent to the furnace)

Examining Typical Pressure Failures:  Ac repair Denver

High Pressure Failure
1. Condenser fan defective
2. Run capacitor defective
3. Dirty condenser coil
4. Defective compressor valve
5. Excessive refrigerant
6. Restriction in refrigerant circuit ( thermal expansion valve, liquid line filter drier, piston, filter screen)
If an air conditioner is not equipped with a high pressure safety, catastrophic damage can occur if the ac system is not turned off.  Most modern compressors are equipped with an internal thermal overload if it overheats due to high head pressure.

Low Pressure Failure
1. Defective indoor blower motor
2. Defective run capacitor
3. Dirty evaporator coil
4. Dirty air filter
5. Low refrigerant charge
6. Restricted ducting - inadequate airflow

These are the most common types of high and low pressure refrigerant failures. Weatherwise strives to be the best HVAC repair company Denver has to offer. With our one year repair guarantee and diagnostic service guarantee, we can't be beat. Our experienced HVAC technicians and support staff have the know how and tools to get the job done right the first time. Feel free to call or email us anytime for any questions you may have.  All of our repairs are approved by the owner before any work is done. Check out our facebook for up to date specials and coupons.




Air Conditioning Denver : Troubleshooting a low voltage short

by Weatherwise on 06/19/11

Low voltage shorts in your air conditioning system are some of the most difficult failures to diagnose.  Some shorts are direct shorts, which commonly causes a fuse in the furnace to open.  If the control system in the furnace is not protected with a low voltage fuse, additional failures may occur to include damaging the transformer in the furnace.  

One of our Denver air conditioning technicians came across two different low voltage shorts this week.  Both shorts had similar readings caused by different reasons.  The first short in Denver gave the technician a reading of 24 volts at the condensing unit contactor, but the contactor would not engage.  The most logical first reaction is that the contactor coil is defective.  When a new contactor would not resolve the issue, further troubleshooting was needed.  When an experienced tech comes across this type of instance he or she learns not to trust what his meter is reading.  A backfeed or improper common through the control system can give false readings.  To resolve the backfeed problem, the ac tech isolated the control wiring at the furnace by disconnecting the thermostat wiring at the control board in the furnace.  Testing the resistance of the wires determined that none of the wires were shorted to ground or to each other.  
When all of the control wiring is removed from the diagnostic, then the ac system can be tested by jumping the controls directly at the control board.  The Denver air conditioning repair technician needs to make sure the thermostat is disconnected as well.  In this instance, the air conditioner tested ok with the thermostat removed.
The 24V reading from the thermostat to the contactor was a false reading.  When the thermostat was replaced and the control wiring was connected the entire system ran properly.
The second low voltage short failure that week was traced to improper wiring. The homeowner had their furnace replaced over the winter and the control wiring for the air conditioner in the furnace was improperly connected.  The technician began by reading 24V at the contactor in the condenser, but the contactor would not engage again.  When the common leg of the control wiring was bypassed by connecting the common side of the contactor to ground the contactor engaged. This lead the technician to trace the missing  common control wire.  The failure was in the furnace.  Whoever had installed the furnace had not wired in the common control wire.  Instead the low voltage wiring to the condenser contactor had been looped between the R lead and Y lead at the furnace terminal board. No common leg of low voltage wire was connected at all.  Rewiring the air conditioner control wiring in the furnace easily fixed the problem.
Low voltage shorts come in a variety of disguises.  It takes time and experience to properly troubleshoot shorts.  Weatherwise Heating and Air Conditioning strives for 100% diagnostic service.  Weatherwise guarantees to properly diagnose your heating and air conditioning equipment right the first time, or the service call  is free.  For the best air conditioning service Denver has to offer call Weatherwise today.

Denver Rocky Mountains
Weatherwise Phone