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Data Logging Thermostats

Home Inspector Training

Heat Pump Defrost

HVAC System On or Off when Unoccupied?

Learning HVAC Controls

Honeywell Chronotherm Plus 8624D Thermostat Problem

Twinned Split System with a Single Air Handler

Data Logging Thermostats

1) Question: Is there a thermostat for a nursing home with a print out for temperature verification? There are a few options for you. The answer......

Home Inspector Training and High Performance HVAC

2) Thank you!! I am training to become a home inspector and the info contained on this site is helpfull in identifing issues that require a HVAC professional to resolve. Read more........

Heat Pump Defrost

3) Hi. I noticed my that one of my outside condensing units was laboring throughout the night. This morning I found ice/frost buildup on the radiator fins. I live in Tucson, Az. It has been colder than normal (below freezing) with a bit more moisture in the air than usual as of late. Can you please tell me what causes this frost/ice buildup, and how I go about rectifying? Does this mean that the condensor pump is shot? I'm originally from the midwest, and have never experienced this before. What should I be doing? Thank you for your help. The answer...............

HVAC System On or Off when Unoccupied?

4) Please confirm this advice if you would; it is better to have your thermostat left at 70 to 72 degrees during the day while your home is empty and adjust accordingly when you get home as opposed to shutting off the heater/ac and turning on when you get home. I would think this would put less strain on the unit. Thanks in advance for your help. The answer.......

Learning HVAC Controls

5) I want to learn about BAS and DDC. The answer..........

Honeywell Chronotherm Plus 8624D Thermostat Problem

6) I have a Honeywell Chronotherm Plus 8624D running a Trane XL19i with a Trane XV90 - all installed new in new construction in 2003. Every winter, during the morning warmup from 66 to 70, the burners stays on for approx 1.5 hours at 70, then rises quickly to 73 before finally shutting off. The only way to interrupt the process is to turn the system to OFF at the theromostat. The system is on AUTO with the cooling set at 75 for the winter. I have swapped the thermostats (there are two sets in the house, this is the one in the attic for the second floor) with the same results. I have not swapped the thermostat circut boards, but I can not see a reason to. The main floor is on the same schedule, but has never done this three degree burst. I have had three different contractors out, with correponding charges, with no luck. Have you ever seen this? Any thoughts? Thanks! The answer.............

Twinned Split System with a Single Air Handler

7) Richard Very nice site! I have a question; my home was fitted out by the previous owner with a twinned system, and a thermostat (Totaline P374-1900) which was not designed to control discreet, paired units. I confirmed this with Totaline. The result is only one unit runs, and the second unit is never activated. It functions, but not automatically. Your website mentioned dual compressors in one system, and mine is similar, two independent compressor/condensers. Seeing the separate condenser units, I first thought the house was zoned, and later discovered both units feed into one Aspen BHA40 4-roll coil. Besides the issue of the wrong thermostat, I'm having problems finding an HVAC person who understands these hybrid systems and will service it. Is this configuration that uncommon? I live very near Houston Texas, so if you know of a local HVAC person with the skills to help me out - let me know. PS - I checked with Honeywell about the possibility of their thermostats working with my setup. They emailed me - they would only work with a HVAC professional. I thought this was strange since they sell them in the hardware stores. The answer.............

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Comments (50)

• |2009-08-25 13:05:37 Steve Hill  - Belts and motor shaft heating up
  Mr HVAC,
  
  We have a 50 h.p. motor on a Air Handler that supplies a whole building. We just replaced the motor old motor had bad bearing. We put new belts on unit with correct tension and proper alignment. When the fan ramps up over 75% you can smell a burnt rubber throughout the building. Shut down the unit and the belts and motor shaft is so hot you cannot touch it. Could I have a bad pulley on the motor side? Do you have any suggestions for trouble shooting this problem.
  
  Thanks,
  Steve
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• |2009-09-22 07:23:03 g.gandhi  - tribleshooting
  hi,
  1.check the motor belt alligment because if belt allignment not proper,motor puly heated. so
  check belt allignment
  
  2.motor bearing housing is very loose, heat occured in shaft and pully
  
  3.if motor insulation resistance is very low,
  
  motor heated
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• |2009-08-25 14:03:15 Richard  - 50 HP Motor - Hot Belt and Motor Shaft
  I would say yes it is a possibility the pulley is bad. Is this an adjustable sheave and if so has it been re-adjustable since test and balance adjusted the sheave? Additionally, an amp draw with an amp clamp on the motor will also tell you a lot such as the possibility of a bad motor bearing or belt slipping. If this is on a VFD is this set for a soft start or does it ramp to 100% right away?
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• |2009-08-25 18:45:00 Carl Vuono  - installing hvac
  I would like to install a split system in my home. I have plenty of room for ductwork in the attic and basement and access to electrical . My question is I am a mechanic by trade and have done residential electrical work. Do you think I can install this system
  myself?
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• |2009-08-27 11:51:06 Richard  - Installing a Split System Yourself.
  Carl,
  
  I would say it is not impossible for you to install yourself but I encourage you to hire someone who really knows what they are doing. There are so many different things you need to know to install a split system properly. There are code issues and technical things you need to know to successfully and safely install a split system yourself. There are also many specific tools you need to purchase to install it successfully and safely yourself. I think it would be prudent that you find a good contractor to install the new split system and then you can let them worry about warranty issues.
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• |2009-08-27 11:35:31 Steve  - Belts and motor shaft heating up
  Richard,
  It is not an adjustable sheave. The motor is on a VFD and the speed is based on static pressure of the building. I did do an amp check. The FLA of the motor is 57 and at 80% I was drawing about 42 amps. This unit has been in service for about 10 years and never had this problem. The sheave holds four belts again the shaft of the motor the pulley of the motor along with the belts are smoking hot, but the fan shaft and the fan pulley is cool. It did seem like the outer belt is running about 15 degrees hotter than the other three belts. So I removed the outer belt ran the fan with three belts and no difference in temp on motor shaft and motor sheave.
  
  Thanks,
  Steve
  
  
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• |2009-08-27 11:41:35 Richard  - Belts and motor shaft heating up
  Steve,
  
  Without being there to look at it myself I really couldn't tell you but it looks like you have done a great job of troubleshooting this problem. I would replace the sheave as it appears the motor and the belts are okay. I have changed a few sheaves out that were experiencing similar issues. Perhaps over time the sheaves wear out. Maybe just a millimeter or less of wear but that would definitely cause the belt to slip especially at higher speeds as in this case.
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• |2009-08-29 18:30:16 Scott  - thermostat for heat pump
  Mr HVAC,
  I am trying to install a honeywell digital thermostat that has RH, RC, W,Y,G wires. My existing thermostat has R,G, C O,Y, and W.
  From what I can tell the R goes with the RH, The O goes to RC, and all the others seem obvious except the C. What do I do with that? Do I need it?
  Thanks,
  Scott
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• |2009-09-22 07:35:18 g.gandhi
  HI
  RC = COMMON
  RH = LINE
  Y= OUTPUT (24 V )
  
  THAT Y IS CONNECTED COMPRESSOR OR THREEWAY VALVE
  RC=C= O VOLT
  RH =R=24 VOLT
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• |2009-08-31 05:44:48 Jack Morris  - Unique P control signal on Carrier Heat Pump?
  I have a Carrier 38SQ split heat pump system. The Carrier supplied thermostat PN HH93AZ186 subbase has a unique output connection labeled P. The thermostat schematic indicates that P is energized (24VAC) whenever the thermostat selector switch is in the cool or heat position. (P is open when the selector switch is in the off or supl. heat position). The Honeywell TH8320u1008 Digital Thermostat that I want to use to replace this thermostat does not have a corresponding terminal to support this P wire. I don't know if the TH8320u will work since it appears that the 38SQ heat pump control board needs this P control wire to determine if the thermostat is set to the cool or heat position. Without this signal, I doubt that the control board will know how to operate the heat pump.
  
  Any suggestions?
  
  Thanks,
  
  Jack
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• |2009-09-07 16:20:25 JR  - heat pump
  my heat pump condenser fan keeps blowing backwards its blwing down threw the coils in stead of blowing the heat up. i stop m y thermosat and restart it sometimes it will blow the right deriction
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• |2009-09-18 05:06:09 robert
  check for a shorted condenser fan motor capacitor. replace same, should take care of problem
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• |2009-09-12 09:04:42 Roberta Keeney
  i have a digatal thermostat for a rheem heat pump and it says no power and the outside unit won't come on. I can push the button down on the contactoer and the unit will come on. do u know what may be going on? Thanks
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• |2009-10-08 01:04:32 Anonymous
  Check control voltage 24v on t/stat, if no voltage check step dn trans. in id a/h
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• |2009-09-12 23:34:11 Kayla Williams  - schematics
  I need to know where I can find schematic pictures online for a single-phase various speed fan motor.
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• |2009-09-14 16:48:59 Roberta Keeney
  i don't want notified
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• |2009-09-14 16:51:10 Roberta Keeney  - re:
  Roberta Keeney wrote:

  i have a digatal thermostat for a rheem heat pump and it says no power and the outside unit won't come on. I can push the button down on the contactoer and the unit will come on. do u know what may be going on? Thanks
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• |2009-10-19 02:59:19 Bill  - NEI
  Not enough information
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• |2009-09-18 05:16:12 robert
  you have no power from the step down transformer. (this is what reduces whatever voltage come to your furnace to 24 volts for control purposes) Check for a fuse in the control board ( it looks like a car's blade type fuse) it is normally a 3 or 4 amp fuse.
  If that does not help, and not power is present, INSURE that power to furnace is present.
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• |2009-09-26 15:09:54 Anonymous
  Why is it necessary to have air venting in a hot water system
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• |2009-10-13 00:09:09 Anonymous
  If heat is supplied by combustion, the combustion must always be vented.
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• |2009-09-28 02:24:07 raul  - ice on suction pipe and comp.
  i was checking a split ruud 3 ton sistem, wich
  was makeing ice, i checked the air flow, wich
  is all rigth, also checked all the inlet grill´s to be open, no dirt on filter or inner
  coil, freon charge o.k. (60/255 at 90° F),
  this unit ran all summer long whit very dirty condensing coil on temperatures up to 122° F,
  do you think it is possible that the ice makeing is do to damaged compressor valves (reciprocal) as the freon runs slower through the sistem?
  
  thanks.
  
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• |2009-10-19 02:57:31 Bill  - Ratios
  Yes it is possible. What is the compression ratio?
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• |2009-09-29 13:27:53 imran  - critical pass indoor-outdoor
  york split a/c ducted type copper pipe longest distance is 40-45mts from indoor to outdoor its possible or not
  not -according to mfg 25 mts
  so i need te solution
  clearence distance of outdoor unit
  model hb480/lb480
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• |2009-10-19 02:58:32 Bill  - Shorter distance or bigger compressor
  You either need a shorter distance or a larger capacity compressor
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• |2009-10-03 15:50:12 dustin  - heat turns on but wont trigger blower fan
  last week i fired up our heater for the first time. it worked perfect. 2 days ago i turned the thermostat to heat the unit fired but the blower fan didnt come on. its probably something simple but not sure where to go from here. thanks.
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• |2009-10-03 16:51:30 Kim Key  - Hvac Tech
  When replacing a condensor fan motor that has a brown wire and a brown/white wire for the run cap., can you only hook up the brown/white wire to a dual split cap. and not use the brown wire?
  
  Thanks!
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• |2009-10-19 02:54:05 Bill  - Label on the motor
  Follow the instructions as provided on the label of the fan motor.
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• |2009-10-07 20:29:00 Robert  - Repeating shut downs.
  Whenever my forced air heating unit completes it's heating cycle, the blower will shut off and then immediately restart briefly several times before remaining off. I suspected an anticipater circuit in the thermostat but I couldn't find one. What do you think?
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• |2009-10-19 02:53:07 Bill  - Gas Furnace Problem
  the problem lies elsewhere............you need an HVAC tech to look at it.
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• |2009-10-08 14:11:22 Jim Little  - Boiler Piping Temp
  How hot would you expect the actual distribution piping in my home boiler / radiator system to run? It shouldn't be over 180F, should it?
  
  Are there code restrictions on that temp...makes me nervous when it is distributed throughout the house.
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• |2009-10-16 00:12:04 Richard  - Loop Temperatures
  180 degrees F is normal for loop temperatures for a hot water boiler and higher temperatures for steam loops (of course). There are codes concerning flues which penetrate floors, walls, and roofs but with your typical hot water or even steam the pipes never get hot enough to cause combustion of the materials which your home is constructed of...............
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• |2009-10-17 16:30:46 Crystal Lewis
  How do I light the pilot for a Carrier model number 58pb075121c
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• |2009-10-19 02:51:20 Bill  - light the pilot for a Carrier model number 58pb075
  Look at this link for lighting your pilot light: http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/om58 -20.pdf
  
  or you can also find it here:
  
  http://www.high-performance-hvac.com/gas-furnaces/hvac-heating/gas-fur naces/how-to-light-a-pilot-light/menu-id-69.html
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• |2009-10-18 02:26:26 Brittany  - a/c installation
  Hello, we are installing a new air conditioner unit on my home and we are doing some of it ourselves. We were told that we have to use acetylene to weld the copper tubing from the condenser to the evaporator (I hope I'm saying all that right!), and were also told that solder will not hold the pressure that the line needs. I've heard different things, but we want to do it right without having to spend unnecessary money! Thank you!
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• |2009-10-18 12:27:51 Bill  - Yes but.............
  If you are asking a basic questions such as this then what other things are you missing that will lead to as poor installation. Absolutely it should be silver soldered by brazing the copper otherwise it will be a big problem for you with leaks. But do you know how to do this properly without oxidation in the system or adding a filter drier to the line. What about nitrogen purge and proper refrigeration evacuation? And what about mechanical code and electrical code issues that even the professionals get hit with. Sometimes it is best to leave certain things to the professionals. Spending unnecessary money can include improperly installing the air conditioner and having to call the professional to come and repair it over and over again for making simple installation mistakes. I live in Texas and I have seen these kinds of installs. Sometimes they work out good but most of the time it is a mess and the homeowner would have been more comfortable and saved money by having a pro do the in...
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• |2009-10-19 00:30:53 Ron Downs  - fan running all the time
  Why is my fan running all the time with the system turned off? I recycled the power, but theonly way I can get it to turn off is to turn the system on and adjust the temperture settings to satisfy the temperture inputs to allow the system to stop running. Then when I turn the system off the fan starts runnning again.
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• |2009-10-19 03:02:28 Bill  - Fan
  You have either a stuck contactor or relay or a bad circuit board. Call an HVAC tech to find the issue and resolve. Its high voltage and needs caution to change out after proper troubleshooting.
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• |2009-10-19 10:42:39 khalid
  I hear the sound of refrierant flow in my air conditioner( condinsing unit ) type split capacity 2 ton cooling and heating(reversing valve) . thank you and best regard
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• |2009-10-19 20:35:44 Anonymous
  In HVAC what does SFM and IPM mean?
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• |2009-10-20 15:21:12 Sean  - SEAN
  My thermostat says the heater is on ("heat" with flame by it) but its not. No air is blowing and the outside unit is not on (fan not turning. It will eventually turn on when it wants to. I have tried adjusting the temperature with no results. Any suggestions??
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• |2009-10-26 15:09:52 Kim Hickman  - Carrier Condensation
  I have a Carrior Gas unit. Model # 0D5axa030014aaaa.
  Just bought house few years ago.
  The condensation pump on the indoor unit in the basement is pooling up water. any ideas?
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• |2009-10-26 17:36:08 peter
  no chance of dammaged compressor as you are reading 60/250psig. what is the temperature in the house (return air) and what is the supply temperature? what is the discharge temperature on the liquid line and what is the suction line tempature? sounds like your short of refrigerant.
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• |2009-10-30 03:25:33 Shannon Williams
  I am looking for air filters for our HVAC system we have in our house. The size is 10X10X2 Pleated. Where may I order them and how much are they? Thank you.
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• |2009-10-31 09:22:35 Basheer  - Presurisation unit selection
  Please Provide Pressuristion unit selection Procedure in HVAC.
  
  Regards
  Basheer
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• |2009-10-31 09:24:00 Basheer
  Please Provide Pressuristion unit selection Procedure in HVAC.
  
  
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• |2009-11-03 17:54:04 Christopher Bryce  - Just Starting out
  Hello I am currently going to school for HVAC Service and was wondering what was the easiest way to find common run and start?
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• |2009-11-04 00:42:18 Dennis
  We installed a Westinghouse 95% efficient furnace and 14 SEER AC unit last summer and ever since these units were installed we have experienced high humidity levels in our house. Our house is 38 years old (so i wouldn't consider it tight construction) and has dbl. glazed replacement windows that are over 18 years old. We also added blown in insulation into our attic last fall (R=49+/-) We use exhaust fans in our bathrooms whenever we bathe and also use the range hood when we cook. We also are experiencing excessive dust migration so much in fact that we have installed apleated filter in the electronic air filter slot. What is causing our humidity problem and how do we fix it?
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• |2009-11-06 22:30:57 Gary Cooper  - hooking Hardy H-2 to Nordyne Mod. E2EB-020HB HVAC
  Dear Sir,
  
  I have purchased a Hardy Mfg. water stove Mod. H-2. I connected the waterstove as per manufacturers directions ( available on the net) used a Hunter mod.40035A thermostat with a 2-wire hook up. The Nordyne unit is controlled by a Janitrol Mod.HPT 18-60 thermostat.I can't get anything to work like it is supposed to, can you help???
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• |2009-11-07 10:09:40 dochvactech
  Your sheeves are shot probally all glazed.....
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