New Trane system, 2010, whats the best way to get my humidity under control?
I asked questions here back in 2010 prior to replacing my HVAC system. I have become increasingly unhappy with my system in that it doesn't keep my humidity below 60%. I see other humidity questions frequently asked in this forum but I don't see anything close to my situation so I appreciate any help with this. My system was replaced in late summer 2010 by a local authorized Trane dealer. Afterwards I was somewhat concerned about abilitiy to keep humidity low but did not question it until the spring of 2011 in which I had my local Trane dealer come and make adjustments, mainly lowering the fan speed.
This spring 2012 my allergies were especially bad, I know it was a bad season in most of the country. I became so concerned with the humidity that I purchased a humidity gauge and then realized how high it was. It was then that I realized that my system is likely oversized for my house and then now nearly two years later I don't feel I can ask my Trane dealer to correct this. I explained to my Trane dealer that before the system was replaced I was comfortable at 74-75 in the summer and now find I have to set the temperature at 69-71 to get the humidity lower. I wish I could roll the clock back to two weeks after it was instaleld and I would ask that it be fixed. My Trane dealer is now mostly ignoring me after an additional check this spring. He told me then it was not set for Comfort R mode. He did that but it hasn't helped. I have told him that I would not expect him to replace my system this late but I just want to make sure it is working as well as it can.
So here are a few details...hosue is a 1300 sq ft. ranch on a slab, house is very tight (i've had a blower door test), house had windows and doors replaced in 2009 with low e and argon glass. I have linved in the house since 2001 and my previous 2 ton system was very comfortable. I had a natural gas furnace. What I replaced it with with an XL15i 2.5 ton heat pump and natural gas XC80 furnace with a 3 ton coil and Trane Clean Effects. The let my Trane dealer recommend the size. I pressed my dealer to get me a more efficient system then he first recommended. I also find that when I walk into my house I find the air stale. I don't really know how to describe it. On a warm day 90+ at 5pm the system runs about 10 minutes on 10 minutes off. I don't believe this would be very efficent for dehumidifying the air. What can I do to better dehumidify the air in my house. Thanks for any replies.
No that you have painted yourself into a corner ... You need a smaller A/C unit OR a dehumidifier.
Originally Posted by supermaxhd
At > 90'F it ought to run about 54 minutes out of 60.
Last edited by dan sw fl; 08-21-2012 at 08:42 PM.
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What is your location?
What thermostat was installed with new system? Does existing thermostat have adjustment for CPH? If so any idea what yours is set at?
Any idea of your blower setting as far as CFMs per ton?
If your blower setting is at 350-400 CFMs/ton and comfort R is set correct but not giving you the result you need, perhaps a thermostat that has "dehumidify on demand" feature might be an alternative to a dehumidifier.
Your blower fan is in auto setting for AC cooling?
Originally Posted by tigerdunes
Trane TCONT800 Series thermostat
CPH adjustment, I don't think so, I have looked at all of the settings in the installer setup.
blower setting CFM, don't know it
Correction to first post, I said I had an XC80 but I have an XV80.
Thermostat with dehumidify on demand, how would that work?
1) Set the blower speed down (way-down) less than 300 cfm per ton.
Originally Posted by supermaxhd
2) Make sure your thermostat has the ability to read humidity AND if it sees that the humidity level in the house is higher than your setting, it will turn the A/C on to remove the humidity. If you can find a good tech, he can do it easily. My house runs at 240 CFM per ton.
3) If those 2 steps won't get your humidity level down, then get a humidifier.
Is your fan setting on your thermostat in "on" or "auto" ?
Should be in auto so that you don't reintroduce humidity that evap coil has removed.
Verify and post back.
Are you familiar at all with dip switch settings in the controls inside your furnace?
If not then forget about it. Installing dealer should come back and verify that Comfort R is set correctly and your CFMs/ton are set correctly.
This should be your starting point. If this does not help, then we can come back to dehumidify on demand which would involve a different thermostat like HW VP IAQ model. Dehumidify on demand allows the var speed blower to run on low with HP condenser when humidity level is above your setting.
Just curious. Did you have inside humidity issues with your old system?
Other then getting a new correctly sized unit. A whole house dehumidifier would work.
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You have got a lot of advice, some very good. This must be confusing to a homeowner and the local tech.
I see the priority this way.
1. You need a 45-50^F a/c cooling coil to get to <50%RH at 75^F . This is more than a 25^F temperture drop of the air flowing through the coil to remove the right amount of moisture quickly.
2. The a/c needs a cooling cycle long enough to load the cooling coil with moisture and drip to the drain. 10 mins. is too short. It takes +20 mins. to load a coil and start draining. Slowing the fan will get you the cold coil. Increasing the dead band of the t-stat to increase the time of the cooling cycle. During the hottest days, your a/c will maintain <50%RH. During days of low/no cooling loads, it is impossible for any a/c to maintain <50%RH when the outdoor dew points are +55^F. You need supplemental dehumidification to maintain <50%RH which is a must to avoid mold and dust mites. On cool wet days, you must dehumidify 3-4 gallons of moisture everyday to maintain <50%RH. This is the moisture from the occupants and the infiltrating/ventilating fresh air.
You have additional indoor air quality problems in addition to high indoor %RH. You need an fresh air change in 4-5 hours to purge indoor polutants and renew oxygen. This would be 50-70 cfm of fresh air when the home is occupied at a minimum.
I suggest you get you a/c setup properly and then get a small whole house ventilating dehumidifier like the Ultra-Aire 70H. This type unit will provide the right amount of friltered fresh air on a occupancy schedule and maintain <50%RH when the a/c does not have enough cooling load.
Fresh air ventilation and <50%RH will make your home healthy and and comfortable. It will take a month or two of fresh air and <50%RH to stop the dust mites and mold from affecting your allergies.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"
I think I like the idea of a whole home dehumidifier. I just watched a couple of youtube videos Without being specific what would something like an Ultra-Air 70 H cost? I have no idea, a few hundred, a thousand or a couple of thousand? I googled and can't find a price on amazon, ebay or the manufacturers web site.
Dehumidier machine is the last resource.
Originally Posted by supermaxhd
Why buy the rags to clean your oil spill, where you can stop the oil spill????
I am sure there is a GOOD tech out there can help you resolve your problem with what you have.
As for your FAN MODE, leaving it ON all the time is not help you at all. Instead it does worse. BUT you need it ON for the filter system to work.--- Can you set it to CIRC (circulating mode) ? My guess is that your thermostat does not have this CIRC feature either. It does not have the DEHUMIDIFYING feature too. If the answer is NO to both than you are not taking FULL advantage of the system yet.
Get a GOOD tech.
I do have CIRC but no dehumidify.
Originally Posted by just_opinion