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Trane 2 Ton Heat Pump - high indoor humidity

Posted by LeLuni (My Page) on
Wed, Jul 23, 14 at 19:42

Hi Everyone, we're from Upstate South Carolina.

I just had a Trane Service Tech over, but I'm not sure we've really solved the problem. This is for a 2 Ton packaged unit that services 1,100 sf. It is 4 years old and is model number 4WCY4024A

The issue is that interior of our house is at least 60% humidity when we set our HP at 72-74 degrees. This seems at least 5 percentage points too high from everything I've read. This has come up because we would like to lay hardwood flooring, but want to make sure our environment is as stable as possible. According to my wife, the humidity has always been very high. She's more sensitive to these things.

Here are the facts that I established today:
-The refrigerant is full
- There is a 15 degree difference in temp between the inflow and outflow. It was 59-degrees on the cool side and 74 on the warm side. The tech said the difference in temperatures should be greater (he might have said 18 to 25, but I don't recall). He didn't really know what to do about it.
- Static pressure is 0.5 higher than spec, but should be close enough to not matter
- Dip switches #5 and #7 are in the up position, the rest are down (out of a total of 8)

The Tech didn't know anything about modifying dip switches to optimize humidity reduction. He called around, but even the Trane dealer tech said that he never messes with the factory settings, and that 5 and 7 up is correct for the 2 Ton packaged unit.

At the bottom of pg 5 here:
http://www.butcherdistributors.com/Images/Interior/4wcy4024a-sub-1b.pdf
It gives some tables on the dip switches, but I'm unable to translate what they mean.

Does anyone here know anything about this? Is there a way we can reduce the humidity by optimizing the blower settings via dip switches?

I'd be very grateful for any advice you may have.

Thanks,
John


Follow-Up Postings:

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RE: Trane 2 Ton Heat Pump - high indoor humidity

Just a homeowner here, but do you have the house fan set to "Auto" or to "Run" on the thermostat?


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Your home may have too much air infiltration.

Return air could be drawing hot humid air from outside source.

It appears it's set for 750-CFM which if ducts are okay should do okay with humidity control.


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RE: Trane 2 Ton Heat Pump - high indoor humidity

When the system runs, how long does it run? Continuous for hours or just a few minutes? Can you see condensate running our of the unit to the outdoors (or wherever it goes)?


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RE: Trane 2 Ton Heat Pump - high indoor humidity

From the model number, it appears you have a packaged heat pump. This unit has a var speed blower.

The fact remains that the factory default settings for the dip switches are rarely correct. These should be checked. Make sure comfort R is set properly for optimum humidity removal. This should be reviewed by the installing dealer. I do not recommend a homeowner make any changes. Takes maybe 10 minutes for someone familiar with this and who can read. I would also move the CFM setting down to 350/ton.

What Mdl thermostat? Should be Trane 803 or HW Mdl 8321. Doubt it is. Fan should be set on auto.

If this doesn't help, you need to understand air infiltration.

IMO


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Thank you very much for your help, and sorry for the delayed reply due to my travels.

I have this Honeywell thermostat: https://customer.honeywell.com/en-US/pages/product.aspx?cat=HonECC Catalog&pid=th9421c1004/U

I'm confused by 'comfort R' because I don't see that reference anywhere on the thermostat. It seems that it would be controlled from the thermostat and not set at the unit, but I have no point of reference for 'comfort R.' If someone could explain how that is set, I'd appreciate it.

Also, how to I adjust CFM settings? Is that basically through the dip switch settings? I have called around today, but actually have not found anyone who is knowledgeable on adjusting Trane dip switches. Three companies I spoke to today say they always leave them at factory settings. These are visible, reputable companies in my area. I'm starting to lose hope.

If I'm reading the literature correctly, my dip switch settings for 1-4 in the off position have me at 400 cfm, and that by adjusting the #4 dip switch to 'on' will get me to 350 cfm. Is this correct? Maybe this setting would help with my humidity issues?

Thanks again,
John

This post was edited by LeLuni on Fri, Jul 25, 14 at 21:15


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Assuming you are sized correctly and everything I have read says you are, you have a very nice system. The thermostat is a premium HW VP IAQ and can be set up for dehumidify on demand. I doubt that it was.

I do not recommend a homeowner start making dip switch settings changes.

3 things should help.

Comfort R should be set up.
CFMs should be dropped to 350/ton
And thermostat should be set up for independent dehumidify on demand.

The first two are relatively easy and won't take any time as long as performed by a Trane dealer. The third is more involved and needs someone familiar with that thermostat and DOD feature.

IMO


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Thank you very much for your reply!

I'm terribly disappointed with this install - I can't believe that they just dropped it in and turned it on without fine tuning the system at all.

I placed dip switch #4 to the on position, which I believe drops me down to 350cfm. I also placed #6 in the on position, which I believe puts me into 'Enhanced Mode' i.e. Comfort R.

I just visited the IAQ setup instructions and see that it is possible to do dehumidify on demand via the setup screens. The Trane 'certified' tech that came by last week said that I needed a separate dehumidifier for that function to work - doh!

If I have Comfort R set to 'on,' does that override dehumidify functionality at the thermostat? Or do they both work together?


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Do you have the house fan set to "Auto" or to "Run" on the thermostat?


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RE: Trane 2 Ton Heat Pump - high indoor humidity

I have it set to 'Auto' on the thermostat.


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RE: Trane 2 Ton Heat Pump - high indoor humidity

I will not comment on dip switch settings. As I said, I think it is a mistake for the average homeowner to do this.

IMO


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Still no answer as to run times. Still no answer as to whether there is any condensate being produced.


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RE: Trane 2 Ton Heat Pump - high indoor humidity

There is no blockage on the condensate exit point, and yes, water flows out the pipe. I also opened it up and checked the pan, and there is no standing water.

As far as run times, I have not timed it, but I know it does not cycle on and off rapidly. My impression is that it runs for 20 or 30 minutes or so each cycle, but that is just a guess. It does not run for hours on end.

I already paid a 'certified' Trane guy $100 just to come out, poke around, and take some measurements. I've also called a few companies to gauge their knowledge on heat pump set-up, but they hadn't a clue. I would be very happy to pay someone who knew what they were doing to come out and optimize my system, but I haven't found that person yet. I'll continue to look.

Hopefully I haven't screwed anything up by moving the dip switches myself. So far, having run the new dip switch setup for a day, I'm now at 52%-55% humidity, which is 5-10% better than where I was. I think/hope it might be working.

Thanks again,
John


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Changing my fan speed last year (it was set on the highest) combined with a much friendlier weather pattern this year. My humidity is in the 48-52 range. Last year I had it in the high 60's! Last year the winter/spring were incredibly wet. Even my basement has lower humidity this year, so I think the weather had a lot to do with it.

I have conventional ac, but it was ME who figured out that the wire that was hooked up was for the highest fan speed when ac was in high (I have multi speed, not variable speed). I told the tech that I thought the wires should be switched because my fan was set too high, my blower is sized for my heater-which is bigger than my ac. FIgured it out by reading this board and learning that too fast cfm means less time for moisture to be removed, then I READ THE MANUAL. Much like the OP has done. I showed the tech (the experts they sent out when the first guy had no clue).

This year my doors aren't sticking. I think this is the least they've ever stuck (in the summer). Sometimes I think it's TOO dry (according to my throat/nose in the morning) but it might be allergies.

Yes, Homeowners shouldn't mess with things, but if we do we need to be sure to document what the original settings were so we can fix our fix if it doesn't work. (take a photo, or draw a diagram) Some of the charts and diagrams are pretty easy to understand. I wouldn't touch anything if I weren't certain.

My humididty might be even lower if we kept our garage doors closed all day and if we shut the front door. We let the dog look out the storm door, but it's a pretty good seal.


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RE: Trane 2 Ton Heat Pump - high indoor humidity

If it has a TXV on the indoor coil\; it is a heat pump with a suction line accumulator to catch any liquid refrigerant so you could set the blower for 325-CFM per/ton, or 650-CFM; with longer runtimes & a colder coil that should help get the humidity lower.


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RE: Trane 2 Ton Heat Pump - high indoor humidity

For udarell

I mentioned that in my suggested list yesterday. Again though, I don't recommend that homeowners start messing around with these dip switches.

3 things should help.

Comfort R should be set up.
CFMs should be dropped to 350/ton
And thermostat should be set up for independent dehumidify on demand.

The first two are relatively easy and won't take any time as long as performed by a Trane dealer. The third is more involved and needs someone familiar with that thermostat and DOD feature.

IMO


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RE: Trane 2 Ton Heat Pump - high indoor humidity

Having just the #4 dip switch on, will give you 350cfm which should lower the humidity. When using heat you would want more cfm.
I'm a homeowner who has little faith in AC "Pros" Install it and run. Nah, we never change the switches.

BS. Do it your self. Just understanding what it is doing.
You say the static pressure is .5 higher than spec. If the spec. is the max static, I would look into why it is .5 high.
I've heard that high static, will cause the blower to draw more juice and cost more to run, and ware out sooner.
But I'm not a "pro" so what could I know.

I had a system installed by a "Pro" and I kicked him out. Hired another company to recharge and check system. I asked him to check static pressure, and he said he didn't have the equipment to do it!
At least he repaired a piss poor line brazing and got it charged and running fine. Right now it's 77 degrees and 51% humidity. Humidity will go lower if we lower temp, and get longer run times, but we are comfortable at 77deg/51%
I did slow the blower down to 350 cfm (2 ton sys.) and it seems right.
Good luck


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