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Comfortmaker Heating System Short Cycling

SolrwindSolrwind Posts: 3Member
Hello!



I'm a new condo owner (new construction) and with the temperatures finally dropping, I'm noticing that my heating system is cycling on and off quite a bit.  When I say quite a bit, it goes through periods where the heater cycles on, the blower starts shortly thereafter, and after running for about 30 seconds or so, it shuts off.  Is this normal?  I also have reason to believe that of my three returns, only one is functioning properly.  When I called about another issue (somehow the system sucked the filter material off of the filter - TWICE), the tech tested the returns with a piece of toiled paper.  My return downstairs had a lot of suction, while the largest of the three barely had any suction.  The third return in my bedroom had none at all. 



I explained this to the on site person for the company and he suggested that I shut off some of the registers.  Could the returns not working be causing the short cycling? Is there anything that I can do myself?  I'm not about to climb in the attic, but would like to know at least what to tell them when I call them on Monday to try to get this resolved. 



To make matters worse, the rooms on the opposite end of my condo are

noticeably colder than my great room.  Again they say this is "normal"

for this model.



I'm sorry for the long post, but I'm about at my wits end with this!!



Bob

Comments

  • Wayne_16Wayne_16 Posts: 130Member
    /check temperature rise

    Some thoughts on your system,.  Check temperature rise across the furnace.  Any probe type thermometer will work.  For a home owner an inexpensive hardware store thermometer will work.  You may have to punch holes in the duct work to insert the thermometer.  Be careful of any refrigerant coils.  This is done by measuring the return air temperature and measuring the supply air temperature.  Subtract the return air temp from the supply temperature.  This is your temperature rise.  Your furnace data tag will state the required temperature rise.IE; 35 to 65 degrees or 50 to 70.  Your target is in the middle. 50 degrees or 60.  use your furnace specs.



    Here comes the interesting part.  Once you have measured the temperature rise across the heating section, and compared to the manufacturers specs.  If the temperature rise is above the range stated on the data tag, (which I suspect is the case0  then the question is, is the duct work causing the problem or is the fan speed set wrong. 

    You do not state the type of comfort maker you have so I am going to make some assumptions, 90+ percent with a 4 speed indoor blower fan.  If this is the case. then place the high speed motor lead (black) on the heating terminal and use a different fan speed for the air conditioning speed.  If you have a ecm motor then follow the instruction manual to set the fan speed in the heating mode.



    That was the easy fix and if it works fine.  I really suspect the supply duct work is undersized for the furnace or like you suspect the return duct is inadequate.  This requires checking cfm at diffusers and return grills.  Testing with toilet tissue is not adequate or a qualified result.  It will tell air movement, what we need to know is how much air at each grill.



    All furnaces need the required cubic feet of air flow in a minute (cfm) as designed.  Most sales people and installers under-size both the supply and return ducts to such an extent the furnaces fail prematurely.  A properly sized air delivery system is both effective in delivering the right amount of air to each room and operating quietly
  • SolrwindSolrwind Posts: 3Member
    model number found - still unsure of type

    not to sound completely stupid, but I'm not sure of the type.  I have what I believe is the model number ( they didn't leave the manual, only the installation instructions).  The model number is EDD4X42FAT2.  I got this number off of the unit itself.  I'm still trying to track down a PDF of the manual on the internet as we speak. 



    I'm going to ask them to check the registers to see how many CFM's are moving through the returns now that you mentioned that.  I'm sure that if the registers aren't working properly that they should be able to fix it.  The "this is normal for your model" isn't going to fly with me, but I want to let them know that I know what they need to be checking. 



    Thanks for your help and suggestions.  I'm also going to try the thermometer test as well. 
  • Wayne_16Wayne_16 Posts: 130Member
    CFM

    Let us know the what temperature rise you measure.  By the model number, it looks like you have a high efficency furnace with a ecm blower motor.  Properly sized duct is very important.  These motors will try to deliver the required air flow at a hugh energy expense if operated at less than design conditions.



    cfm delivered by the furnace can be calculated by knowing the temperature rise and the net btu delivered.  Take the net btus from the model number data tag.  Do not use the input.btus ie; 60,000 input 54,000 output.  the 54,000 output is the number to use. you may have to calculate the output if it is not listed specifically.  Output t time efficiency rating of the furnace



    CFM = net btu/1.08 x temp rise.  Once actual cfm is determined, then the problem solving begins.  Compare the actual delivered cfm against the design cfm at at a given fan speed will lead in the direction needed to solve the air delivery problem.



    keep us posted,

    Minnesota Wayne
  • Wayne_16Wayne_16 Posts: 130Member
    CFM

    Let us know the what temperature rise you measure.  By the model number, it looks like you have a high efficency furnace with a ecm blower motor.  Properly sized duct is very important.  These motors will try to deliver the required air flow at a hugh energy expense if operated at less than design conditions.



    cfm delivered by the furnace can be calculated by knowing the temperature rise and the net btu delivered.  Take the net btus from the model number data tag.  Do not use the input.btus ie; 60,000 input 54,000 output.  the 54,000 output is the number to use. you may have to calculate the output if it is not listed specifically.  Output t time efficiency rating of the furnace



    CFM = net btu/1.08 x temp rise.  Once actual cfm is determined, then the problem solving begins.  Compare the actual delivered cfm against the design cfm at at a given fan speed will lead in the direction needed to solve the air delivery problem.



    keep us posted,

    Minnesota Wayne
  • GerryEGerryE Posts: 3Member
    FURNACE MODEL

    THE MODEL # YOU GAVE IS FOR THE EVAPARATOR COIL....( IT'S A 3 1/2 TO R410A COIL. ) . THE MODEL # OF THE FURNACE WILL BE LOCATED IN THE BURNER COMPARTMENT ON THE LEFT OR RIGHT SIDE!
  • SolrwindSolrwind Posts: 3Member
    Update

    Before I begin, I would like to thank all of those who responded to my posting.  My system is a split system, and the model number is NA43.  It took a while to figure this part out.



    The tech came out today and my problem was with the electronic damper being stuck closed.  No air was going to the front part of my condo.  It's currently open until they get the new one in.  They also adjusted another damper on the heater and now everything seems to be working fine.  The returns are also functioning properly as well. 



    The new part should be here in about a week. 



    Thank you again!!



    Bob
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