ReplyIt depends on teh humidity of your area, and how often your A/C runs also.
2 tons sounds a little big for 800 sq ft.
your blower may need slowed a little.
Have your install install dampers and slow the blower.
Regular Guest
I recently posted an issue I was having with my AC in this forum and received A LOT of great help/advice so I have another question. During the warmer months when people use their A/C's, isn't the indoor humidity suppose to go down?
I'm noticed that my indoor humidity is about 45 - 60% when the temp is at about 73 - 75 degrees. The A/C servicing my second floor (where I'm noticing the issue) is a 2 ton Weather King. My second floor is about 700 - 800 square feet. Something worth mentioning is that I'm also having an issue with my system not being balanced so one of my bedrooms gets a lot cooler (in the summer) / warmer (in the winter) than my other bedrooms and I found out that the HVAC installer didn't install dampers.
So my question is would it be normal for an area that's being air conditioned by a central AC have such a high humidity level? If not, what should I be checking for?
Thanks!
God Speed, Jim. We'll miss you - 2-26-23
It depends on teh humidity of your area, and how often your A/C runs also.
2 tons sounds a little big for 800 sq ft.
your blower may need slowed a little.
Have your install install dampers and slow the blower.
Banned
50% is a good humidity level
even i think your system is oversized, and i dont say that too often
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as stated slow the blower down for lower humidity percentages!
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Professional Member
a ton for 400 square feet sounds like a home in the tropics with no insulation
you must be upstate NY, not all that humid up there, otherwise I think you would end up with higher RH
God Speed, Jim. We'll miss you - 2-26-23
You sir. Are an imposter, posting under airmechanicals name. He would never say that.Originally Posted by Airmechanical
even i think your system is oversized
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Banned
You sir. Are an imposter, posting under airmechanicals name. He would never say that.
your correct, i would never say that, someone must have hacked into my computer yesterday
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God Speed, Jim. We'll miss you - 2-26-23
LOLyour correct, i would never say that, someone must have hacked into my computer yesterday
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Professional Member*
Are you noticing these swings in humidity during the course of a day, or at random times you measure? Are the temperature swings concurrent with swings in humidity, or does the temperature hold fairly steady while humidity swings?
If the latter, be sure you are not running your indoor blower continuously. Let it cycle with the outdoor unit.
Oversizing is not the only contributer to inadequate dehumidification. If the house leaks in outdoor air like a sieve, the a/c can be overwhelmed and not be able to keep up with removing enough humidity to keep you comfortable. Being this is an upstairs area, you may have light fixtures and other ceiling penetrations that are leaking air into or out of the attic, which means you are not containing the air you are paying to cool as well as it should be.
Regular Guest
Thanks for the info. I'll have my new HVAC guy take a look at my ducts to see if any air is leaking and if he could slow down the blower. He can probably do this when he installs the dampers the originally HVAC installer FAILED to install. One thing that the new HVAC guy said overall is that a 14" x 8" return duct was really small for an entire second floor so he's talking to me about making it larger.
BTW - The house is located in Bergen Co, NJ. As for the humidity levels throughout the day, I would say that the level remains the same all day/night long. In terms of the A/C usage, the thermostat is set to run automatically so from one of the post I'm guessing I should try running the fan on constant.
God Speed, Jim. We'll miss you - 2-26-23
24/7 fan operation can increase humidity.
Regular Guest
Oh... okay! I must have misunderstood. I'll leave my thermostat to "auto".
Thanks,
Regular Guest
Some more questions regarding high humidity levels.
I was recently told by my new HVAC guy that the original installer never installed filters in either of my units (he actually left the construction filter in) so I went out and purchased some disposable 3M three month filters which I installed. In addition I set the small fan in my attic to automatically turn on when the temp reaches 75 instead of 90 like previously set.
After installing the filter and turning on the attic fan I noticed the humidity in my second level jumped to 62 percent during the night time hours but during the day the level dropped down to 49 - 52 percent. Could installing the filter or turning on the attic fan made my humidity problem worst?
Also, while at Home Depot picking up the filters I started talking to the sales guy and explained my situation. He said if my return register was too small (its only 25" X 18") that my system could be straining to suck in the humid air. Is this true? If so, how large should I make my return if I have a total of 14 supply registers, 9 which I constantly leave open.
Thanks.
Professional Member
Did you get pleated filters?
If your guy is already telling you your system is restrictive those things won't help just fyi.
If your attic fan leaves your attic in a negative pressure and not sealed off completely from the house (most likely not unless you know it is) it can cause higher outside air infiltration rates. Then it would depend on outdoor conditions to know which direction the humidity will go.
I like using dew points because % RH can be deceptive unless understood.
Regular Guest
I did get pleated 3M filters (model 1700). Questions, what does it mean to cause negative pressure and is there any easy way to tell if its causing it? As for its being isolated from the rest of the house... the only thing dividing the attic from my second floor is one of those pull down staircases and I know the seal around that is not air tight.
In terms of the smaller than desired return, does one 25" x 18" for 9 open registers sound little to you guys?
God Speed, Jim. We'll miss you - 2-26-23
Its small for your system size.
Remember, when you start closing off supplies. If your supply duct has leaks, you increase teh amount of air being blown outside of the conditioned space. And can cause more fresh air to be drawn into the house, raising humidity.
Neg pressure from the attic fan will draw the air from your house into the attic, and cause fresh high humidity air to be drawn into the home.
Reset your attic fan to 90, and see if it makes it better in your house.
Regular Guest
Great. Thanks for the explaination on the negative pressure thing. I thought I was helping out my system by cooling the area it was installed in but now I see I could have been doing myself a disservice. I'll set that fan back up to90 degrees to see what happens.
As for the return... I'm having my HVAC guy come back out on Thursday to install some dampers in my 6" flex pipe and to check if my upstairs unit has a leak because I lost a pound of frion within 14 - 20 days. While he's out I'll ask him to make the return a larger size.
BTW - You guys had suggested that I make the blower speed lower to help with the humidity problem but when I passed this info to the HVAC guy he said he wasn't aware that the speed of a blower can be modified unless it was a variable speed. Is the blower speed something that can be modified for all units?
Thanks!
God Speed, Jim. We'll miss you - 2-26-23
New air handlers have multispeed blowers, Either 3 or 4 speed. (low, med low, med high, high) He should be able to set it to a lower speed.
Regular Guest
Is everybody going to be OK with 3M filters on this thread? They have been discussed so many times before on this forum I expected an immediate reaction.
Speaking as a homeowner I would ask your AC pro about whether a generously large filter and return could be put on your system.
Regards -- Pstu
God Speed, Jim. We'll miss you - 2-26-23
Bigjon, already told him the pleated can restrict air flow. That jon guy is on top of things.
But yes, 3M makes just about the most restrictive.
Regular Guest
Can anyone recommend a good disposable filter?
As for the blower speed. I told my new installer about the multiple speeds and he told me that he doesn't want to lower the speed because cool air is heavier than hot so it will be harder for the system to push the air. You guys on this forum have done me right in the past so I'm starting to question my new guys comments.
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