Category Archives: maintenace

A/C Troubleshooting chart

furnace cooling repairs, maintenace, Uncategorized 07/29/2013 1 Comment

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Air conditioning basics

furnace cooling repairs, maintenace, Uncategorized 05/06/2013 1 Comment

Connecting Air Conditioning manifold

The gauges will have a high pressure (red) and low pressure (blue). The easiest way to remember which hose goes to the correct line is to think about a fluid going through the system. A smaller pipe size would need more pressure to move the same amount of fluid than a larger pipe size. So that would mean the smaller pipe will have the high pressure (red) hose from your manifold gauge set. While the larger pipe will have the lower pressure (blue) hose from your manifold gauge set. Yellow hose is for adding charge to you system, big black hose on 4-line gauge set is for vacuuming system down to 500 microns.

 

Approach Temperature method

This method can verify refrigerant charge without connecting a refrigerant gauge set. Before you begin the evaporator (inside coil above furnace) and condenser (outside coil) must be clean. You will find the approach temperature chart either in the manufacturers installation instructions or on the panel for the condenser. This chart will be specific to the condenser you are working on and will differ from other units.

Measure temperature of the air entering the condenser in a few places to get the average temperature being careful that the sun does not affect the measurements. Then measure the liquid line temperature (small line) with an accurate clamp thermometer. Determine the temperature difference between the liquid line temperature and the outdoor air temperature. The temperature difference is the approach temperature.

Adding refrigerant will decrease the approach and removing refrigerant will increase approach. Allow 10-15 minutes of operation for the approach to stabilize after refrigerant is added or removed. Insure you use proper recovery containers when removing refrigerant since it is against the law to release into atmosphere and comes with a big fine if caught.

Liquid line temp – ambient temp = approach temp

 

Superheat

Measuring Superheat tells you how effective the evaporator is working; normally best 10 to 15 superheat for air conditioning.

Superheat is the amount of heat added after the gas changes from a liquid to a vapor. Proper Superheat set point is important to an air conditioning system for these reasons

Low Superheat can cause liquid to get back to the compressor breaking internal parts.

High superheat will reduce the effective cooling, which happens best when liquid refrigerant changes state from a liquid to a vapor, also if too much superheat the compressor can overheat.

To measure superheat use the low pressure (blue) line of the refrigerant gauge set and clamp on thermistor to measure temperature at the suction line as close to the evaporator as possible. Suction line as close to evaporator outlet – saturation temperature of the refrigerant= Superheat

 

Subcooling

Subcooling tells you how effective the condenser is working normally you want 10 degrees subcooling but should always follow manufactures recommendations. 
Subcooling is the amount of heat removed by the condenser past the point of change from vapor to a liquid (saturation point). Proper Subcooling set point is important to an air conditioning system for these reasons.

Subcooling insures a solid column of liquid to the metering device and if set too low you could get flash gas, which will affect the meter device.

High subcooling will cause the refrigerant to stack up in the condensing unit bringing up the head pressure in the compressor. With higher pressures the compressor will need to work harder using more electricity and wearing it out faster.

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Presures

High side is ambient plus 30. A 75 degree ambient, for example, add 30 and get 105 degrees. That, on a P/T chart converts to about 253 psi

Low pressure side should run about 10 degrees cooler than space set point.

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Recommended tools

Engineered RTU, furnace heating repairs, maintenace, Uncategorized 02/28/2013 Comments: 15

 

Fluke 116/322 HVAC combo kit basic multimeter and amp clamp that will do anything in residential diagnostics.

Fluke 87V Digital Multimeter if you are working on any Engineer MUA (Make Up Air) or RTU (Roof Top Unit) you need the percent duty cycle option to set up combustion motor speed sensor properly.

Cooper SH66A Multi-temperature thermometer instrument. Good for measuring temperature on pipe or airflow

Ritchie Yellow Jacket LCD Vacuum Gauge 69075 senses the full range from atmospheric pressure down to 1 micron. I have had mine for 6 years and have never had any problems with it. It will give you exact number read out not just lights to indicate vacuum pressure

D-TEK Select Refrigerant leak detector this leak detector is the best one I have used it is very sensitive and will find the smallest leak. Some people believe it is too sensitive, because sometimes when it is moved fast it will beep. If you use the meter properly by moving it slowly around the leaks it will prove to be the best meter on the market. I would rather have a few false readings then to miss a leak that would cause me to return to the same job site a few times on callbacks.

Fluke Alert Voltage Detector A/C 90-1000 Volts-1AC-A1-II & A/C 20-90 Volts. I always carry one of these detectors around sometimes I can diagnose a problem with it or double-check the power for safety. Always test detector against known power and use meters to insure all power is turned off.

Testo 510 Manometer is the best manometer I have found that will measure differential pressures. The unit has many switchable units of measure. Very accurate as mine is 6 years old and has never required calibration. Only complaint is max pressure 1.5 PSI.

Powers Pneumatic Calibration kit 832-177 comes with Siemens adapters should buy Honeywell and Johnson adaptor kits as well in order to do all thermostats.

Procore Ratchet Wrench 17-9568 only 5 degrees of operation is needed to use this wrench. All wrenches have opened end and ratchet box end, which makes easy work in tight places.

If anyone has a better meter they use please send a comment to me and I will add it. I know fluke has a new one with flexible amp clamp, but I do not have the meter so I can’t comment on it

Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topics to write so feel free to leave a comment asking about anything related to HVAC-R (Heating, Ventilation, air conditioning, refrigeration).

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Cracked heat exchanger

furnace heating repairs, maintenace 12/16/2012 Comments: 2

Heat exchanger can crack for various reasons and should be checked every time furnace is repaired or maintained.

Visually check heat exchanger for cracks

  • You will find most cracks form near the back and where the heat exchanger metal bends, Since this is where it will be weakest due manufacturer weakening the metal by bending it.
    Watch the flames as the furnace fan starts if you see the flames are blowing around or out the front of the burners then you will need to take a closer look at the heat exchanger

Water test

  • This test worked best on the old Lennox G8 and would find cracks or pinholes on the heat exchanger that sometime could not be seen.
    If there is no air conditioning then it will be easy to access above the heat exchanger through the humidifier. Once the heat exchanger cools down spray water on the heat exchanger from the top insuring full coverage and being careful of the electronics and motors. Then watch inside the burners for water to seep through, A good heat exchanger will not let moisture into burner chamber

Using carbon monoxide detector

  • Test for carbon monoxide at return air as well at supply air and compare the two readings or test at supply air with burners on then off making sure furnace is not back drafting and compare.
    If you take reading once and only at supply air you will not be 100 percent sure the problem is with the heat exchanger. You are testing the accumulation of carbon monoxide over a long period of time from other sources like the furnace or hot water tank back drafting also it could be from outside sources like a vehicles near the intake air.

Reasons for cracks

  • If the furnace does not have enough combustion air it will cause the furnace to run hotter then designed. Then with more expansion and contraction in the heat exchanger it causes cracks. The gas pressure must be set as per furnace name plate derated for location altitude if too much gas heat exchanger will run too hot.Blower speeds must be checked by comparing furnace temperature difference to name plate rating if running too hot increase fan speed and recheck temperature supply air minus return air.

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Any crack in a heat exchanger is dangerous and the heat exchanger must be replaced when crack is found

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Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write so feel free to leave a comment asking about anything related to HVAC-R (Heating, Ventilation, air conditioning, refrigeration).

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Furnace filter

maintenace 11/19/2012 Comments: 5

There are a few different types of furnace filters; they all have different capacities to clean the air and last different durations. On the side I have a link that will connect you to a chart for MERV (Minimum Efficiency Reporting Value) ratings and what each will clean out of the air. Every house is different for durations filters last depend on house (rugs, animals, etc) and area (construction, dusty areas, etc)

  • First one is flat; the surface area is only that of the filter. These filters will last 1 month 1 – 4 MERV
  • The next type of filter is the one I have pictured here, how is works is the media bends back and forth so if you were to stretch it out you would have material 3 times as long. This means they will last 3 months instead of the typical once a month filter changes. The filter would fit in same filter rack as regular filters and clean house better 4 – 8 MERV. Check out this filter on my affiliate website Amazon.
  • Another type of filter is the box type they can be 4 – 5 inch thick and require professional installation. Best part about this filter is that it only needs to be changed once a year, and are MERV 10 – 16. This is my recommended filter and is the same one I use in my house, It makes everything easier because you only have to change filter every fall not 1 or 3 month
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Click here to see my Post on protecting your home “Alarm for Home”

Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write so feel free to leave a comment asking about anything related to HVAC-R (Heating, Ventilation, air conditioning, refrigeration).

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pilot flame colour orange or soft blue

maintenace 11/11/2012 1 Comment

Best pilot flame will be one that makes little noise and has a sharp blue colour

  • Orange pilot flame is called a carbonizing flame, Means that it is running with low primary air
  • Low primary air is due to dirty pilot you will need shut gas off and remove pilot orifice and clean
  • Soft blue flame is caused by low gas pressure to the pilot, Which can be adjusted on the gas valve . If by adjusting pilot does not solve problem then gas valve is restricting gas too much and may need replacing.
  • Sharp blue flame that is too noisy will be opposite as soft blue flame the gas pressure is set too high, Pilot flame could lift off the pilot housing and go out .
  • Pilot flame should burn around the top 1/2 inch of the thermocouple in order to produce the proper dc voltage to hold the safety open for the gas valve to operate.check my links on side bar for thermocouple/thermopile charts where you will see a chart on how to test thermocouple/thermopiles

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Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write so feel free to leave a comment asking about anything related to HVAC-R(Heating, Ventilation ,air conditioning, refrigeration).

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Yellow burner flame

maintenace 11/10/2012 1 Comment

Yellow flame

The reason for burner flames to be burning yellow is because they are deprived of oxygen. With incomplete combustion there will be less CO2 Carbon Dioxide and more CO Carbon Monoxide.

  • High efficient furnace are two pipe system that have combustion air going into the furnace
    and exhaust air coming out. They both should be piped to an outside wall with the least amount of horizontal lines as possible . The reason for this is the furnace will produce water with vent temperature running warm and condensation will be produced. The water will be piped to a floor drain or pump.

  • The first thing you should check is outside intake pipe make sure it is not plugged with snow or frost blocking or restricting air flow. Exhaust air is warm and moist and the intake will suck this air in while mixing with cold air from outside and the moisture will frost up on the intake pipe. exhaust pipe should be extended 8 inches past the intake pipe to minimize this problem. As well be careful of fences or walls where the exhaust could bounce back to the intake pipe.
  • Next thing to check is the intake and exhaust pipe for places where water could collect due to wrong slope or sages in the pipe. If the pipe does not have enough hangers then it will sag and collect water in the valleys .
  • high efficient furnaces with only one exhaust pipe to the outside and combustion air inside building will bring air into the building similar to a mid efficient furnace . Both will bring in combustion air in through a combustion air pot usually 4 or 5 inch insulated pipe that comes from outside. It must be located as per code level to one foot above burners and within two feet horizontal. Outside will have a mesh screen that is designed to keep small animals and birds out, the screen could be plugged and needs to be cleaned, lots of times the backdraft safety switch will trip if there is not enough combustion air.
  • If cold air is noticed coming out of combustion air pot when furnace is not running this means the basement is in a neg pressure . The cold air can be stopped by a Hoyme combustion air damper that is connected to the furnace heat cycle and only opens on a call for heat.

    Click here to see my Post on protecting your home “Alarm for home”

    Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write so feel free to leave a comment asking about anything related to HVAC-R(Heating, Ventilation ,air conditioning, refrigeration).

    Thanks for reading my blog

    • Picture of fresh air intake under deck

    maintenace 11/10/2012 Comments: 10

    Dirty fresh or combustion air intake screen similar to the one in this picture will cause the furnace to not get the proper air it needs to run, Because of a negative pressure in the room. This negative pressure will cause air to be brought into the room through the only duct to the outside which is the furnace exhaust vent. The furnace will have a back draft safety switch to protect the home owner from carbon monoxide poisoning and when the safety switch trips it can be easily reset, But once reset the reason for it triping in the first place must be addressed .

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    Click here to see my Post on protecting your home “Alarm for home”

    Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write so feel free to leave a comment asking about anything related to HVAC-R(Heating, Ventilation ,air conditioning, refrigeration).

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