Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Ductwork to Make a Wethead Happy

To Mike T.

I can't answer that. My first hi-velocity system and my knowledge of and experience with the sealed portion of refrigeration systems is sorely lacking.

Modern mixed refrigerant gasses utterly threw me for a loop when I found that (like my mixed mica radiator paints) they keep their individual characteristics.

If I ever find time, plan to attend vo-tech as an adult.


  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    For a high-velocity (Unico) A/C system with heat pump for very early/late heating season.

    From Spiral Manufacturing Co., Minneapolis, MN.

    Offset and round-to-rectangular are custom. Rest stock. Ordered 5/19 and arrived today!

    VERY easy to order custom fittings using their catalog.

    I usually groan at the lack of quality in ductwork and especially fittings--not with this!
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Does Anyone Need

    Two 8" die formed elbows?

    Order was perfect except they sent me 8" els instead of 7". Called and she said, "Oh-Oh. I just had a call a few minutes ago from someone with the same problem. Will ship them today."

    They don't want them back, so you can have for shipping cost only. Price about $17 each and not too heavy so surely shipping will be less.

  • bigugh_4
    bigugh_4 Member Posts: 406
    All designed, cut out and fabbed by machine!

    Wetheads need to visit a real sheetmetal shop. That material was most handled by man in the picking and shipping of it to you. Like kitchen Cabinets and so many other things machine made is surpurb. exact fit neat and well constructed. I think the auto industry started the machine made! Oh and they cut out fittings by computer controlled plasma arch cutters, a whole warehouse full at a time!
  • bigugh_4
    bigugh_4 Member Posts: 406
    Sounds like the shoulders and arms of a robot is about

    exist at Swamp!
  • don_128
    don_128 Member Posts: 1

    job Mike..and may I say excellent choice on round over square.Ouch..that hurts me to say sometimes being I have a sms and make alot of square fitting.LOL.

    And just looking at the lack of reply to your post,I wonder
    are wetheads still shying away from long radius ells?

    If I recall the only long radius fitting I've seen at the
    wall is Hotrod and his tubingbender jobs.That is if we exclude pex.

    Does it not take a bigger circ to over come the pressure drop of a short radius ell verse a long radius ell?

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    They don't even make short-radius els! Their "gored" (multi-section) els have the same geometry. If my memory serves, rise is 1.5 times the diameter.

    Check out their "airflow" tees if you want to see some really neat ductwork. Would have used (despite the expense) but they added too much length.

    From my understanding of high-velocity air systems, you want to keep your friction loss in the mains as low as possible. This is a double-branch system unlike any of their examples. VERY highly engineered. Proposed design got me a job offer from the owner of a St. Louis company. Unico approved.

    9" main with two 7" branches. 30% of airflow AND load to each branch. Remaining 40% equally divided among before first branch, between branches and after second branch.

    I doubt that Hotrod has to consider his curvo jobs as having fittings...
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    Don't doubt at all that they're machine made.

    Certainly plasma cut.

    Would LOVE to see the machine that made the multiple small breaks on the rectangular-to-round fitting!

  • Empire_2
    Empire_2 Member Posts: 2,343
    Mike T

    During the A/C season have you noticed that the S/H on the unico systems run at 30 to 40* superheat?. I have contected the Manifct. and am waiting for a reply as to if this is normal. Seems very hi to me.
  • don_123
    don_123 Member Posts: 3

    depends Mike T..How high was the humidity and ambient?That high of a superheat would say to me thats you are using all your coil.Aka... she loaded.

    Or could be pulling additional heat from leaky return duct.
  • Boiler Guy
    Boiler Guy Member Posts: 585

    Hmmmm, what pipe dope is best for 7" fittings? 2 0r 5 wraps of yellow teflon or is 3 wraps of pink. Questions, questions, too many questions! :D
    So what size aluminum "pipe" wrench do I require to twist that stuff into place !? :D:D
  • Rudy
    Rudy Member Posts: 482

    the evaporator superheat seems to be hi. the compressor will operate at ahigher temp and the evaporator may be short of refrigerant.if this is an orfice tube metering device please see if the manufacturer supplies a charging chart.if the system is equipped with a thermostatic expansion valve take the suction line temperature at the outlet of the evaporator.
  • Empire_2
    Empire_2 Member Posts: 2,343

    I read your answer and I know the system is charged correctly. Used sub-cooling method.(TXV) I did receive a call from Manufacturer, which stated that they do run a higher superheat. I am just saying that I personally would like to see about 10-15*......We actually took alot of time with this unit even measuring the air flow at each outlet. Don to ans. your Q: Indoor ambiant 75* - R/H 54%, .Wet bulb was 64. Sub-cool method of charging to 20*
  • don_129
    don_129 Member Posts: 1

    Mike T.I'm going to have to agree with Gus.With those temperture and humidity..I too would have to say you are
    starving the evaporator.

    Subcool temp are alittle high as well..appears she needs some more juice.
  • don_130
    don_130 Member Posts: 1

    forgot to mention...or could be a possible restriction.

This discussion has been closed.