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Is it too cold outside to run my AC?

HeatingHelpHeatingHelp Posts: 247
edited June 2018 in THE MAIN WALL
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Is it too cold outside to run my AC?

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Comments

  • TWrichTWrich Posts: 1Member
    edited June 2018
    This thread seems extremely professional, well done! Great back and forth. Thanks.
  • unclejohnunclejohn Posts: 1,363Member
    I installed a furnace and A/C in Dec a few years back and got a call in early June to check the A/c it would cool a while and then not so good. Check it and found that the metal plate at the top of the A coil had blown off and was laying inside the evap cab. All the air was blowing straight up through the top of the coil. That was a first for me.
  • GBartGBart Posts: 753Member
    1 mismatched units, 3 ton outdoor 4 ton indoor, ok if blower dialed in correctly, 2 - 2 stage condenser, indoor section has to be configured to match in board during installation, unit is rated for 70*F outdoor, below 82*F outdoor the unit should remain in 1st stage, low ambient control kit recommended
  • GBartGBart Posts: 753Member
    outdoor manual - http://www.utcccs-cdn.com/hvac/docs/1011/Public/04/42101600100_ICP_10443.pdf

    indoor manual - http://icpindexing.toddsit.com/documents/086477/49621510300.pdf

    again, speculation is nice but the factory manuals are the Bible for any given unit
  • LeonardLeonard Posts: 816Member
    edited June 2018
    I know my 20 k window AC evaporator ices up after a while when it's <70 outside. But it's likely a midge low on R-22, I picked it up used 28 years ago at a yard sale. Only cleaned it and replaced worn switch. Some Vornado?? unit.
  • stonebutsonstonebutson Posts: 1Member
    One thing nobody is mentioning is that cold crank case. While it’s sitting in the cold the refrigerant is puddling up in the crank case. When it’s turned on in fifty or sixty degree weather all the oil foams up and gets pumped out into the system. The compressor is now running with no lubricant and the evaporator is coated with oil and reducing an already low superheat because there probably isn’t a load on the system anyway. We just want to play with our new toys or schedule tune ups because there’s nothing better to do. If it isn’t set up for low ambient running ( case heater and fan control) - DON’T RUN IT
  • LeonardLeonard Posts: 816Member
    Seen large HVAC on commercial restaurant building, has a crank case heater (always on) to warm the pump.
  • RONCASTLERONCASTLE Posts: 2Member
    a/c manufactures will supply the minimum ambient operating temp. ( OUTDOOR ) in the spec sheet for the unit, at least Carrier does.
  • ChrisJChrisJ Posts: 9,635Member
    edited May 9
    Leonard said:

    Seen large HVAC on commercial restaurant building, has a crank case heater (always on) to warm the pump.

    You need more than crankcase heat.
    I run a crankcase heater and a condenser fan controller on mine to keep the head pressure up. It's just a cheesy SCR controller but it gets the job done. The system behaves the same whether it's 40 degrees out or 90 degrees out.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,462Member
    I have been recently adding VFD's to condenser fans. We run pressure transducers on the LL to a simple Johnson controller which makes a 2-10vdc output which I use to throttle the VFD. These are in multiple fan condensers used at 50F and up. We've had lots of problems with one fan running, pulling the other(s) backwards and burning up the SCR controllers.

    Getting rid of the single phase motors and running 3 phase motors has also greatly increased longevity I've found.

    These are mostly on medium temp Agricultural storage warehouses. Been working very well so far.
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
  • jacobsondjacobsond Posts: 31Member
    Looks like another old thread. Anyway what really stood out to me was the wait a week for a TXV. If your the installing company shouldn't you have had one on the truck. Lo ambulant and loads create a special condition for techs. There are ways around,but a check back when the weather is above 75 is always best.
    coming to you from warm and sunny ND
  • CanadaKeithCanadaKeith Posts: 9Member
    Old post yes but I'm glad it got brought forward. As a home inspector , we use the guideline of don't run the AC unless it has been 16C,60F or better for previous 24 hours. In general I try to not be the first person starting up a unit for the season. However, I could never find support for that temperature in any literature. Based on what the pros are saying it seems that rule has some merit.
  • Jack GetkinJack Getkin Posts: 10Member
    This project appears to be a perfect example of a "failure to communicate". The contractor/installer must thoroughly understand the customer's needs and expectations and then communicate how the system to be provided will meet the needs. It appears as though some type of low ambient temperature control may be required in order for the system to function as desired by the end user. This should have been determined when quoting the system. Addressing it at this type is very likely going to result in a dissatisfied customer. We all need to remember we are the experts and, as such, the burden of communicating what is recommended & required rests with us. The business owner likely needs to take ownership of this and devote a little time to their customer to help them better understand what was provided along with any gaps in communication between the business and the customer.
  • Handyman 242Handyman 242 Posts: 10Member
    Many great comments. First issue is that the charge should be weighted in; getting the correct charge does not depend on outdoor temperature and will always be correct. Second issue which has already been stated is that other accessories should have been sold with the job to clean the air in the house. I run my AC fan in the winter to clean the air in my house (I have radiant heat) using a good media filter and a whole house mold, virus and bacteria killer.
    The owner of the business gets an F for salesmanship and a D for knowing AC installation practices. I see many contractors installing systems between Oct and April and then having to go back and recheck the charge when it gets warm outside as they did not weigh it in originally. What is the lost revenue of going back on call backs and not getting additional accounts when the warm weather hits. These contractors will always be marginally successful, have higher overheard and profit starved.
  • ChrisJChrisJ Posts: 9,635Member

    Many great comments. First issue is that the charge should be weighted in; getting the correct charge does not depend on outdoor temperature and will always be correct. Second issue which has already been stated is that other accessories should have been sold with the job to clean the air in the house. I run my AC fan in the winter to clean the air in my house (I have radiant heat) using a good media filter and a whole house mold, virus and bacteria killer.

    The owner of the business gets an F for salesmanship and a D for knowing AC installation practices. I see many contractors installing systems between Oct and April and then having to go back and recheck the charge when it gets warm outside as they did not weigh it in originally. What is the lost revenue of going back on call backs and not getting additional accounts when the warm weather hits. These contractors will always be marginally successful, have higher overheard and profit starved.

    So you feel weighing in a charge on a semi-accurate scale and never checking superheat or subcooling is acceptable?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,462Member
    Weighing in a charge? Um?

    Superheat and subcooling are what determines a proper charge. It is then recorded on the unit for the next guy.

    A charge is always weighed so I know how much refrigerant to bill the customer for.

    Its things like this that sound very similar to when you take your car in for a malfunction, and tell the counter guy that all that needs to be done "is plug in the computer" and it'll tell you what's wrong with my car.....
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
  • ratioratio Posts: 1,939Member
    To be fair, with some units the only way to correctly charge them is by weight, although a consumer-grade split is unlikely to fall into that category.

    If you weigh in the lineset adder, you should be close enough that the unit'll work; from my experience with retrofits the ductwork'll be bad enough that you'd never notice the charge is off.

    My biggest concern with weighing in the charge is that I have no way of verifying the factory charge.

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