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  1. #1
    Join Date
    Aug 2018
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    Zoned system: Bypass and DATS questions.

    Hello all. This message is pertaining to zoning and DATS. Here is a little lead up as to why Iím asking about these things.

    I have a 3 ton Goodman heat pump with 2 zones.(split system) Yesterday I noticed it was feeling muggy in the house. I looked and the thermostats were calling for cooling. I went outside and the compressor and condenser fan were not running.

    I pulled the cover to the outside unit and looked at the wiring diagram. I had 240VAC to the contactor. I then pulled the high voltage disconnect. The contactor was not pulled in. I checked for 24VAC to the contactor coil and had nothing. I started looking at the diagrams and checked at the thermostat and all was good there. I went up into the attic to check up there as I remembered the zoning control board was up there which is a Honeywell HZ322. It was reading that the DATS was 33degrees and on low limit. This is impossible. As from the time I started trouble shooting until this point was 2 hours as I had stopped and did some other things as well.

    I didnít know what DATS was so I looked it up. I went through some of the settings and when I got back out of the menu it asked if I wanted to purge and if so to hit next. I didnít realize it but I actually hit next. All the sudden the DAT read out went from 33 to 55 and the outdoor unit started. It ran for a while then stopped again.

    I went back up and itís bouncing around showing a dat read out of 33-37 and on low limit. I went in to advanced options and disabled it and the outdoor unit started again.

    This brings me to my questions. I have been looking all over about these things. I have a bypass duct which I read is typically BAD and that the DATS is there to protect the coil from freezing and thus ruining the pump(my unit does have a LPS on it). But I also read that DATS is bad as it can cycle the pump a lot.

    As of right now the unit is working with DATS disabled and I have been going into the attic and checking to make sure I donít have any frost on the suction line coming back out of the evaporator. Just sweat, no ice.

    I turned off the biggest zone to see how much air was going through the bypass and the bypass opens around 1/4.

    So if bypass and dats are both not good what do I do? Can I leave it like it is with dats disabled or do I need to buy another one, install and let it go with it possibly short cycling the pump?

    I donít want dats to shorten the life of my pump but donít want evap freezing either although it seems at that point my LPS would protect my pump.

    Seems zoned systems are for the birds but I gotta work work with what i got at this point.

    Any insight, direction, and advice is appreciated. Thank you in advance.

  2. #2
    Join Date
    May 2018
    Location
    Knoxville, TN
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    388
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    A zone system can be an effective way to maintain comfort in different areas of your house with a single system, while bypass systems with Dats are not the best option available currently, they are still better than some options. In my opinion a bypass system is still better than a bleedby system (dampers open a bit to allow air into the zone that isn't calling for heat or cooling) or a dump zone ( dumps extra air into a room or space you don't mind over cooling or heating.)

    The down side is your unit cycles more, with a bypass/dats system. This can't be helped. however the fan should continue to run and the dats should allow the AC to come back on within 5 minutes or so of the dats turning the condenser off. More humid air is a side effect of a bypass zone system(only slightly more humid if designed correctly), that can't be helped either. I would have a tech check your system and make sure it is operating correctly, if this hasn't been an issue in the past I would think something has changed to cause the issue.

    It should be noted that very few hvac contractors design zone systems correctly. If your house didn't have a zone system before and you had one installed and they didn't change a good deal of the ductwork odds are it will never work right until this is addressed.

    This is of course just in my experience without being there to look at it, I can't say the ductwork, or anything is wrong with the system, which is why you should call a tech who is used to working on zone systems.

    I would highly recommend turning the dats back on and leaving the system settings alone. You could damage your equipment playing with it. The dats is to protect your system, let it do its job.

  3. #3
    Join Date
    Aug 2018
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    3
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    Thread Starter
    Thank you so much for the reply. I should have said I only turned DATS off as it appears to be defective and reading a low temp. At that time it was only meant as a temporary deal. Then I got to reading about DATS and by passes and that led me to write this post.

    I didnít go into this detail but I will now. My wife and I had this house built. It was just finished this past March. We had a contractor issue and had to fire the original builder. We had another builder come in to fjninsh everything. This builders HVAC company had a list of things that were done wrong with the rough in(done by the other company) Some things were to small of duct lines and I remember something being said at that time about a bypass wasnít installed(at that time I was completely ignorant to all this zone stuff and quite frankly still am). They made a host of changes. This unit is still under warranty from that company. Iím the type I like to keep from having people out.

    The only issue here so far is that the DATS is defective from what I am seeing.(reading a much lower temp than it really is) I am inclined to spend the $40 on a new one, install it and be done with it. But maybe itís better to have them come out under warranty, replace the DATS and check everything over. I had no complaints until yesterday with anything until all the sudden the DATS fails and keeps the zone control from sending voltage to the contactor coil.

  4. #4
    Join Date
    Jan 2004
    Location
    PA
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    Could be the DATS is defective, or it could be the zone panel is defective. A good tech will know how to check to see if either is really defective.
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  5. #5
    Join Date
    Aug 2018
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    3
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    Thread Starter
    Quote Originally Posted by beenthere View Post
    Could be the DATS is defective, or it could be the zone panel is defective. A good tech will know how to check to see if either is really defective.
    True, could be in the panel. Basically I just know that it was saying the DATS was 33 degrees and that certainly wasnít the case. I will call the company tomorrow and have them out to take a look.

  6. Likes bhenry1013, beenthere liked this post

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