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Any Fujitsu guys out there?

ChrisJ
ChrisJ Member Posts: 16,316
in THE MAIN WALL
I'm trying to help my sister remotely with her Fujitsu mini split setup and I'm hoping someone can help.

The unit has two heads in bedrooms and then what looks like a ducted air handler for the rest of the house.

The house handled by the ducted part tends to run high humidity.  Like in the 60%+ area.

This is the thermostat she has.   Is there a way to make it run the fan on the lowest speed?  Is it already according to that water drop?  I know absolutely nothing about this thermostat so trying to do this remotely isn't working.



Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

Comments

  • pecmsg
    pecmsg Member Posts: 5,298
    The “A” next to the fan icon says Auto mode
    Solid_Fuel_Man
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    Doesn't pushing the fan button cycle through fan speeds? There's also a humidity mode.

    There was an error rendering this rich post.

  • ChrisJ
    ChrisJ Member Posts: 16,316
    pecmsg said:
    The “A” next to the fan icon says Auto mode
    STEVEusaPA said:
    Doesn't pushing the fan button cycle through fan speeds? There's also a humidity mode.
    From what she said hitting the fan button didn't do anything.  I had her try holding it with also didn't do anything.

    I assume auto means variable speed but I'm not so sure it doesn't just mean auto on/off like Normal stat?


    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Should to be able to manually set the fan and have it not in Auto. But, with the air handler and multiple heads it may lock you out of manual for drying. This is due to freezup potential, and the unit not "knowing" what the pressure loss is of the ductwork. If it were a wall unit (ductless) then it would allow you to set the fan speed, this is due to no pressure loss from ducting. 

    Multiple heads just complicate the problem. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Big Ed_4
    Big Ed_4 Member Posts: 3,020
    Works on cool but setting to humidity , it does not work well ? I would check the duct work , but where you are , I would tell her to set to cool ....

    There was an error rendering this rich post.

    Solid_Fuel_Man
  • HVACNUT
    HVACNUT Member Posts: 6,334
    Don't know how old that is, but the newer ones need to be programmed to sense at the thermostat, not the thermistor in the air handler. 
    Is there a model number for the air handler?
    Solid_Fuel_ManChrisJ
  • ChrisJ
    ChrisJ Member Posts: 16,316
    HVACNUT said:

    Don't know how old that is, but the newer ones need to be programmed to sense at the thermostat, not the thermistor in the air handler. 
    Is there a model number for the air handler?

    I'll try to find out.
    The house was built in 2018-2019.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Yes! There is an installer meun and you change it to sense at the stat not the return plenum. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 16,316
    HVACNUT said:

    Don't know how old that is, but the newer ones need to be programmed to sense at the thermostat, not the thermistor in the air handler. 
    Is there a model number for the air handler?

    Solid_Fuel_Man said:

    Yes! There is an installer meun and you change it to sense at the stat not the return plenum. 


    Air handler model : ARU24RLF

    How do I get into the installer menu to see how and if it was configured?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • HVACNUT
    HVACNUT Member Posts: 6,334
    edited September 2023
    whoops, it came out 2,1,3.
    ChrisJmattmia2
  • ChrisJ
    ChrisJ Member Posts: 16,316

    So this issue is still going on.

    I had then run the fan on the lowest setting and the system couldn't keep up and it was still very humid, high 60s.

    With the fan higher it keeps up but it's very humid. The only thing I can imagine is the coil simply isn't getting cold enough for whatever reason.

    The air handler is model ARU24RLF and the outdoor unit is a AOU45RLXFZ. I don't know what the two other heads are but I'm told those rooms are nice cool and dry. I'm told the original installer was asked to check things out and told them it was all working perfectly. I'm not sure how an indoor dew point of 63f is even remotely perfect. The system has been running plenty it's just not cold enough.

    Even the toilet tanks are sweating.

    Any ideas?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,492

    Just as a test maybe shut the other two heads off temporally and see if that changes the ahu performance.

    Have someone or the services tech back and check the ahu return temp and supply temp to see what is going on. Also check superheat at the ahu and at each remote head and at the condensing unit to see what is going on

    ChrisJ
  • pecmsg
    pecmsg Member Posts: 5,298

    time to call tech support.
    1 thing there going to ask is the weight of the charge so be prepared.
    my personal tri zone a few boards were replaced before I installed a ICM493.
    I’ve also changed the sensors for the EEV,s.

    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 16,316
    https://forum.heatinghelp.com/discussion/comment/1806198#Comment_1806198

    I'm probably going to have her call a contractor.

    I just talked to her and the supply temp is 72f. The return temp is only 78f so it's definitely broken.

    Do EEVs fail much or is this likely suggestive that other things are actually wrong.

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • mattmia2
    mattmia2 Member Posts: 10,953

    Somewhere in here did we look at the size and how the lineset is run to the fancoil? Is it the same size as for the cassettes and to small for the "rest of the house" or is it forming a trap or kinked or something?

  • mattmia2
    mattmia2 Member Posts: 10,953

    Look in the fancoil and see how much of the coil is cooling, is it starved or icing?

  • pecmsg
    pecmsg Member Posts: 5,298
    https://forum.heatinghelp.com/discussion/comment/1806207#Comment_1806207

    tech Support.
    model serial and total charge recovered!

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,492

    EEVs can fail. That could be the issue especially if the two indoor heads are working and the AHU is not.

    A tech with the right equipment could find the issue.

    ChrisJ
  • HVACNUT
    HVACNUT Member Posts: 6,334

    @ChrisJ , if I remember right, you've got a Fluke 179. TS will want EEV measurements in mega ohms and most tech's meters can't do that. Around me anyway. So, road trip?

    ChrisJ
  • pecmsg
    pecmsg Member Posts: 5,298
    https://forum.heatinghelp.com/discussion/comment/1806207#Comment_1806207

    With these you cant troubleshoot over a computer!

  • ChrisJ
    ChrisJ Member Posts: 16,316

    So I'm going to assume that if anything static pressure is a bigger deal with these units vs a normal split? And if so, this looks like a serious problem, no?

    I didn't post many pictures but all of the duct work is similar. 20-30 foot runs of 7".

    I've asked them to get a contractor out there to go over everything but I've got a feeling it's not going to be good.

    I can't imagine this is how a Fujitsu ducted system is intended to be installed?

    Thoughts?

    Screenshot_20240801-183221~2.png
    Screenshot_20240801-183230~2.png
    Screenshot_20240801-183233~2.png
    Screenshot_20240801-183236~2.png

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • pecmsg
    pecmsg Member Posts: 5,298

    that system is a low velocity unit.
    that duct work will not work with it!


    The static pressure needs to be below .3. I’ll guess that’s 1.+ !

    ChrisJGGross
  • ChrisJ
    ChrisJ Member Posts: 16,316
    https://forum.heatinghelp.com/discussion/comment/1807285#Comment_1807285

    So, in other words, it's crap.

    I'm not sure what they're going to do in the end.
    They hired a GC to build the house, who hired the contractor to do the heating and AC. They have complained to the hvac contractor several times about the AC not working properly and when the guy came out he told them it was working good, the pressures are good etc. But, it's been 5 years now so I have no idea what that means.

    If the ductwork is botched, I wonder how well they did the refrigerant side of things.

    I'm assuming they're on their own and get to pay someone else to fix the mess. 😡

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • GGross
    GGross Member Posts: 1,295

    I am in awe that a contractor installed this like that on a new construction, that looks like a remodel install, a friend of a cousin install, there is even a light blocked off by the unit. The contractor should know just by looking at it that its not done right, 20-30 foot runs of flex on that low static unit is absurd. I would bring it up to the GC, they might not want to fix it but really they should. It is not installed according to manufacturers requirements and therefore should have never passed inspection, i guess the building department there is pretty hands off

    ChrisJpecmsg
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,492

    I was always told with flex you take a 25' roll of flex and cut it into 3 pieces and that is MAX length unless you seriously oversize it and can't use hard pipe do to obstacles.

    ChrisJ
  • HVACNUT
    HVACNUT Member Posts: 6,334
    edited August 2

    What controller is being used? Function 26 in the "Maintenance" section of the controller is used to set static pressure in pascal measurements. I believe the factory setting is 25 pa, and you can go up to 90 pa.

    Even if it's using an interface and standard 24 volt thermostat, it still needs to be set up with the Fujitsu controller.

    There's also another function so temperature is sensed from the controller , not in the unit.

    ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 16,316
    https://forum.heatinghelp.com/discussion/comment/1807338#Comment_1807338

    It's definitely using a Fujitsu control.

    90pa… is that only 0.36" of water!?

    Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.

  • GGross
    GGross Member Posts: 1,295

    I would check your units spec sheet Chris. they should list a max static pressure. Some low static models max out at 0.2, high static minis can be up to .7 but it depends on model and manufacturer. Duct sizing is very critical on them. Rigid duct is almost always required. Off hand I don't think any setting on the stat will make up for that ductwork

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