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  1. #14
    Join Date
    Aug 2007
    Location
    East central Indiana
    Posts
    75
    Quote Originally Posted by zombietech66 View Post
    hello new to doing residential, and i have a herd time figuring out if a coil is txv or md when it is on top of a furnace which has no access panal, and there is nothing marked on casing of coil. i have been guessing MD , should i guess txv if condenser list sc temp, the a/h i do remove cover to look but its the enclosed ones i cant see which i hate guessing at, any help is appriciated
    I run into the same problem around here.

    I'm retired but work during the busy season for my old boss doing PM's. When I come up against this I'm stuck between a rock and a hard place.

    On the one hand, I hate to take the extra time to cut and patch a hole large enough to clean the coil and check the MD. After all, the boss is making very little if anything on these calls.

    On the other hand, I feel like I'm shortchanging the customer by not seeing if the coil needs cleaning and by not knowing what the MD is so that I know how to properly charge the system.

    What to do, what to do?

  2. #15
    Join Date
    Apr 2007
    Posts
    623
    Quote Originally Posted by RyanHughes View Post
    If a company has to use an uncased coil, then I think they should field install the TXV on the outside to make it easier for the service tech.
    If a company is having to use an uncased coil to save money, I think they need to find another way to save money, and put a cased coil in, It cant be saving them that much, Plus what about the time and material it takes to fab up and cram that coil in the plenum.

  3. #16
    Join Date
    Mar 2001
    Location
    North Carolina
    Posts
    428
    Quote Originally Posted by mldncx1 View Post
    I run into the same problem around here.

    I'm retired but work during the busy season for my old boss doing PM's. When I come up against this I'm stuck between a rock and a hard place.

    On the one hand, I hate to take the extra time to cut and patch a hole large enough to clean the coil and check the MD. After all, the boss is making very little if anything on these calls.
    Which is why you find repairs needed and upgrades.

    On the other hand, I feel like I'm shortchanging the customer by not seeing if the coil needs cleaning and by not knowing what the MD is so that I know how to properly charge the system.
    You are.if you are doing a preventive maintenance and you overlook the obvious thats not very preventive now is it?

    What to do, what to do?
    Perform your maintenance as normal. note all work home owner needs done, like accessing coil, any upgrades that they could benefit from, quote them a price and let them decide if they want to short change themselves.
    Maintenance agreements are a good thing!

  4. #17
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,900
    you can pull the blower and look up at the coil to see if it is clean , as for knowing if it is a piston or txv might as well make a access hole

  5. #18
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,793
    Doesn't work on 90% furnaces.
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    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  6. #19
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,900
    Quote Originally Posted by beenthere View Post
    Doesn't work on 90% furnaces.
    in your part of the country im sure there are many 90%furnaces in South Texas they are few and far between. As the price of gas goes up im sure they will be come more popular . back to the topic it is bs to install a coil with no access so i will have to agree with obxtech charge them extra to access the coil or check it the best you can without knowing

  7. #20
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,793
    Quote Originally Posted by catmanacman View Post
    back to the topic it is bs to install a coil with no access so i will have to agree with obxtech charge them extra to access the coil or check it the best you can without knowing
    You have to charge some of teh customers.

    Of course if the company someone is working for. Installed the unit in the last year or 2. Charging that customer, could make for an angry customer.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #21
    Join Date
    Jul 2008
    Location
    Southeast michigan
    Posts
    93
    you know the company i used to work at used uncased coil. we used to make a sleeve and door that was very easy to access. if the installers used pittsburgs than pop the pittsburg and charge accordingly. imo this is why every tech needs to install for a few years before they can be maint or service techs if you cant install it right how can you fix it right sorry if i piss anyone off just my opinion. and if the company that installed it isnt using a cased coil cause of price chances are there not spending the money on a txv cause of price either.

  9. #22
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,034

    Revealing Metering Device without physically looking

    Finding out which metering device the system has without physically looking.

    If you do not absolutely know whether the metering device is a TXV, or a fixed orifice device, or cap tube.

    Hook up your manifold gauges, block off considerable condenser air intake. If the suction pressure starts rising, you have a piston, or a cap tube.
    If only the high side goes up, you have a TXV.

    Have things with you in your van or truck to block-off the condenser air for a short time. Check every time you are not certain what metering device it has. There will be a lot of guessing in the future.

    Do this procedure on known metering devices to observe the difference. Report back how well it works for you.

    It could save you from cutting plenum holes - udarrell

  10. #23
    Join Date
    Jul 2008
    Location
    Southeast michigan
    Posts
    93
    good idea thanks for the tip and my count grows lol

  11. #24
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,841
    udarrell wins the prize!! Our guys just take a little rest on top of the condenser and watch their gauges. Takes less than 5-minutes and zero work and just like udarrell said, if it's got a working TXV, the low side pressure stays the same. If it's a piston, the low side goes up as the high side goes up. This also saves having to go indoors to determine what the MD is and tells you right away whether you're supposed to be charging to superheat or subcooling. Naturally you need to go in to get the rest of the readings but knowing whether you've got a TXV or piston/cap tube is one major hurdle jumped. FYI, Bryant/Carrier have gone to TXV's in all equipment so there's no mystery there for any of their new stuff.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  12. #25
    Join Date
    Aug 2007
    Location
    East central Indiana
    Posts
    75

    Smile Great tip!

    Quote Originally Posted by udarrell View Post
    Finding out which metering device the system has without physically looking.

    If you do not absolutely know whether the metering device is a TXV, or a fixed orifice device, or cap tube.

    Hook up your manifold gauges, block off considerable condenser air intake. If the suction pressure starts rising, you have a piston, or a cap tube.
    If only the high side goes up, you have a TXV.

    Have things with you in your van or truck to block-off the condenser air for a short time. Check every time you are not certain what metering device it has. There will be a lot of guessing in the future.

    Do this procedure on known metering devices to observe the difference. Report back how well it works for you.

    It could save you from cutting plenum holes - udarrell
    Thanks, udarrell, for a helpful tip.

  13. #26
    Join Date
    Oct 2007
    Location
    south of boston
    Posts
    174
    great replies guys i thank you alot, been alot of help, as far as accessing for cleaning i will ask who installed it before explaing cost to access it, and

    udarrel thanks for great tip i will certainly start trying that out on monday
    and get back to you

    thanks evryone

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