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  1. #1

    Wrong size suction line Lennox HS26-060

    Our HVAC tech was out and just noticed that the original installer used the wrong size suction line. The Lennox specs called for 1-1/8 inches and they used 3/4. This is for the HS26-060.

    Our tech said this would cause premature compressor failure (10 years instead of 15-20) and 30% higher energy usage on our AC bill.

    The original install was done 7 years ago so I believe any install warranty is long gone.

    The run is 30 feet and I am wondering if I should get the suction line replaced or if the damage has already been done - our tech said the compressor already sounds like it's been overworked.

    Please help!

    Thanks,

    Steve

  2. #2
    Join Date
    Apr 2009
    Location
    Owsego, IL (Chicago)
    Posts
    58
    7 Years old?

    Probably a good chunk to replace the line considering thew cost of line set and labor.

    Maybe consider replacement and upgrade to a new higher eff 410a unit and get a nice $ back from our president who's been to all 57 states!

    other option - Contact the installing contractor and ask him what he will do for you, probably nothing but what does it hurt to ask. Thats why its always so important to shop for a contractor rather than a brand or a price!

  3. #3
    Join Date
    Apr 2009
    Location
    Owsego, IL (Chicago)
    Posts
    58
    Many times linesets are not changed for various reasons and if you were not the original purchaser of the equipment it will be well advised for you to find out why yours wasn't.

    An undersized suction line can inhibit the flow of oil back to the compressor and help in the premature failure but may not be the only cause of that.

    However, if the installer wasnt competent enough to realize the need for change or just didnt care, then your sure to have other problems that were not addressed at the time of installation. Was the coil changed and/or sized properly, was a metering device installed to match the outdoor unit. Ive seen plenty of installing techs buckets full of unopened orifice bags.

    Thats why I said to consider the replacement, why spend the dough to just make thru a few summers, cause after 2010 youll have to change the lineset again anyway when you go to a 410A system.

  4. #4
    Join Date
    Dec 2003
    Posts
    2,425
    An undersized suction line will guarantee you will get the oil back to the compressor.

  5. #5
    Join Date
    Jan 2004
    Location
    Burleson, Texas
    Posts
    1,741
    Interesting comments?.....any contractor should be able to go to the manufacturer of that brand and give you the effiency losses to your specific installation and/or warranty coverage issues ..different variables apply- TEL of line set and sizes of line set are the major ones...your losses could be minimal or degrading, only an onsite evaluation can determine this...

  6. #6
    Join Date
    Aug 2007
    Location
    Okmulgee, OK
    Posts
    184
    A 7 year old HS26 is a nice piece of equipment. You could go ahead and replace the line set now because whenever you replace the unit in X amount of years, the next 5 ton unit will also need an 1 1/8 suction line. If you go to a 410a system in the future, just have the lines cleaned as required. I would be curious to see how much that is affecting the suction pressure and such. I would guess quite a bit. I've seen plenty of 7/8 suction lines but never a 3/4!
    It's just rocket science. It's not like it's heat and air work or something.

  7. #7
    Join Date
    Jun 2007
    Location
    Round Rock
    Posts
    3,618
    I wouldn't sweat it at this point. The damage if there is any is done. Run it til it dies then replace it and put a new lineset in. I was at a Trane seminar yesterday and they are actually recommending a 3/4" suction line on their 5 ton heat pumps. I believe it was the 21 Seer monster. Something about keeping the velocity up during 1st stage. It wasn't much of a training session, just them extolling the virtues of the new communicating system.
    I like DIY'ers. They pay better to fix.

  8. #8
    Join Date
    Feb 2004
    Location
    New Mexico
    Posts
    5,646
    The 1 1/8" line is usually based on 50' run that includes some fittings. I wonder if the 3/4" was id.
    If the line size is 7/8' od, unless there are a lot of ells, it's probably ok. A set of gauges on the system will tell a tech right away as if the line is causing a restriction. Suction pressure will show it. So if pressures are ok and the compressor's superheat is ok, your probably ok. As long as the compression ratio is reasonable the life of the unit should be reasonable.
    The 30% increase in energy is questionable. Not sure how those numbers were determined as if the line were restricting the unit would pump less refrigerant and power use would be less.


    And like Bigtime said the velocity will increase in a smaller line and oil will return.
    Tracers work both ways.

  9. #9
    Join Date
    Aug 2007
    Location
    Winter Haven, FL
    Posts
    4,380
    If this were my house and the unit was cooling fine, I dont even think I would worry about it.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,572
    Is your cooling bill real high?

    Don't know about it using 30% more electric.

    You loss some capacity, and do use more electric then you need to, but doubtful its 30% more.


    After seven years of running like this. I'd run it until it dies, and then change out the system.
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  11. #11
    Join Date
    Aug 2011
    Posts
    7
    I have a new(days old) unit 5 ton lennox with 3/4 inch line and after checking power consumption it is using exactly 25 % more power than my OLD 10seer unit, this unit is 15+seer.. so something is about to hit the fan

  12. #12
    Join Date
    Dec 2002
    Location
    Arizona
    Posts
    4,421
    Quote Originally Posted by fbhero View Post
    I have a new(days old) unit 5 ton lennox with 3/4 inch line and after checking power consumption it is using exactly 25 % more power than my OLD 10seer unit, this unit is 15+seer.. so something is about to hit the fan
    Before you bite your contractors head off and look the fool you may want to make SURE thats not whats called for! Trane's top of the line 5 ton XL20i Heat pump calls for a 3/4" suction line, I don't know about Lennox but I sure would check.
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  13. #13
    Join Date
    Jul 2009
    Location
    South Carolina
    Posts
    3,340
    I don't see the 3/4" line causing any problem with the compressor.
    The smaller suction line can reduce over all system capacity but with only 30 feet I would think its not much at all. If it were my house I wouldn't do anything with the line until it was time to replace the system.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

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