I prefer a CO2 control for operating the Outside Air damper.

15 minuets may be too much and there's your issue.

I'm still confused why there running the A/C fan at the same time? If the A/C calls fine if not let the dehumidifier do its thing.

 

I know very little about HVAC.. However what i do for a living is all about pressures/temperatures/flows.
And i too cannot understand why the dehumidifier is calling for the AC fan to run if the AC unit is not.
The comment about not having enough CFM to distribute the air in the house almost seems irrelevant, because you are still drying the air that the dehumidifier pulls in. You just might not feel the air coming from the ac vents.

 

All the dehumidifier wants is its rated CFM. Eventually the A/C kicks in and mix's the air.

Again operating the outside air damper on time may raise the RH rather than lower it.

 

Several things.

If you had your A/C off for most of the day you may have added a lot of moisture to the house. Moisture can be added a lot faster than it can be taken out in many circumstances.

You said you sealed up a lot of the duct leaks. Adding the fresh air damper may be bringing in more humidity than the duct leaks you had. You may not need to be bringing in as much fresh air as you are, but there is math to tell you that.

I would not think you would need to run the blower to circulate the air off the dehumidifier. No the Dehum. does not have a strong blower but it will still push out what it draws in and when the blower does start it will still circulate though out the house.

 

The AC was off for several hours, but while cooling the house back down the humidity got down into the low 40s.
I waited a few hours after to start monitoring because the house was back down to normal temperature. I also ran my portable dehumidifiers all day while the unit was down and when we finally turned it back on. I only shut the portable dehumidifers off because the temp and humidity in the house was normal at that time.
Once the house was back down to temp for a few hours is when i started to monitor. and am curranty monitoring now.

I text the installer this morning and he immediately called me. (He seems very passionate about what he does and i do trust him to make adjustments until we get it worked out. However i am needing some suggestions on what additional info to tell him).

1. I requested that he check the static pressure, to which he agreed.
2. I mentioned about not running the AC blower while the dehumidifier is running. (Unless the AC unit is on)(He said we will have to play with the system, but wanted to check the static pressure before we make any other changes)
3. I turned down the fresh air to 5 minutes per hour.

 

Here are two pics.
1 is of the fresh air controller.
The other is of the fresh air valve.
On the fresh air valve itself there is an indication for open/closed and there is a +/- adjustment.
I am assuming the +/- adjustment is to control how far open the fresh air valve will go??

 

Can you get some pictures further away

 

Here are the pictures of most of the set up.

 

That’s what I was afraid it looked like.

 

Can you elaborate?

 

It’s all flex and run poorly
Garbage in my book

 

Ductopus

 

well is there anything else i can have him look at tomorrow besides making sure the static pressure is low enough for the dehu and to stop the dehu from turning on the AC van?

 

That looks terrible! Air flow will be lousy.

Flex duct should be straight and stretched tight. Use metal elbows for turns.

 

That all may be true about the ductwork - but the duct system was working adequately well for AC in the house before the whole-house dehumidifier was installed and all the stated improvements made.

With that in mind I would want to look primarily toward the latest 'system' changes for finding the cause of the recent performance concerns.

PHM
------

 

Well at this point i guess i just wasted a ton of money.

 

Not necessarily. He likely just sold you what you asked for and did his usual crappy flex work.
The installer really should have recommended that the existing duct system should be redesigned and replaced.Doing so is likely to improve the performance of your system. Then the ducts for the dehum could be corrected.
I love my dehum, but as with all HVAC work, the installation means everything.

 

It happens. A lot of hvac people hear about a product to help people but never learned all it takes to make them work.

Fresh air is needed in a lot of situations but that does not mean the affects of the fresh air won’t have to be properly countered. In some locations it doesn’t take much and the air is just fresher. In places like Huston with high humidity it takes a lot to counter the fresh air.

If you ever notice it being really hard to open the door on a eating place but once the door gets opened part way you feel a draft and the door now opens the rest of the way easily, they have the fresh air damper shut so the don’t have to condition it as it is costly.

 

The sad part is, he seemed to be the most knowledgeable of the SIX companies i had come look at my system. I have never gotten so many opinions/quotes in my life for a home project.
The other sad part is that all of my duct work was replaced 2 or so years before this project.
So at this point i have a ton of money tied up into my HVAC system and i cant spend anymore.
I literally saved for 2 years to get come up with the money to get rid of my 2 noisey portable dehumidifers for a whole home.
I really just hope that he can get it working good enough to manange the humidity.
If not i will be asking for some sort of compensation.

 

Yeah i wasnt sold on the fresh air thing because of that.. Or at least running fresh air with this unit. Maybe the slightly large sante fe dehu. which i should have brough up going with the large one anyway.

 

Where is this home?

 

Houston texas

 

Not sure how I missed your initial post.

The good news is that it sounds like you a/c and ducts have been improved to the point that the a/c with significant sensible cooling loads will maintain <50%RH, right? Or are your portable dehus doing that?

Is the Santa Fe removing moisture? Measuring the condensate or temp/%RH supply will confirm how well the dehumidifier working.

I see no reason the a/c blower needs to run with the dehumidifier.

Short term, Block the fresh air until we know that dehumidifier is functioning normally. Inspect the dehu filter for a blockage.

With all the improvements to your a/c- and the addition of Santa Fe 70H, we will have success after we find the bug.

Keep us posted.

Regards Teddy Bear

 

Not sure how I missed your initial post.
Looks like more fresh and no dehumidification. What are your current outside temps/%RHs/dew points?

The good news is that it sounds like you a/c and ducts have been improved to the point that the a/c with significant sensible cooling loads will maintain <50%RH, right? Or are your portable dehus doing that?

Is the Santa Fe removing moisture? Measuring the condensate or temp/%RH supply will confirm how well the dehumidifier working.

I see no reason the a/c blower needs to run with the dehumidifier.

Short term, Block the fresh air until we know that dehumidifier is functioning normally. Inspect the dehu filter for a blockage.

With all the improvements to your a/c- and the addition of Santa Fe 70H, we will have success after we find the bug.

Keep us posted.

Regards Teddy Bear

 

I turned of the fresh air and was using my portable dehu last night. I also set the humidity controller high enough so that the santa fe would not run through the night.

The ac tech came out this morning...
Checked static pressure it was .36.
He lowered the fan speed two positions.
Checked static pressure again and it was .28.
He pulled the filter on the dehumidifier and confirmed the filter wasn't blocked.
Fixed a small air leak on the dehumidifier supply.
He insisted that he didnt want to run the dehumidifer without the AC fan running, but showed me how to change that on the thermostat.

As soon as he walked out the door i changed the setting on the thermostat so that the dehumidifier would not turn on the AC fan, and turned the fresh air off for the time being.

After the adjustments on the fan speed my unit is getting more run time, which should help with the humidity during the hot days.

Right now it appears my house on average is sitting at 50% humidity with the exception of my master bedroom, but i just showered so i will wait and see what it does.
This is with both the AC unit , set at 70, and the sante fe running. I have also been in and out of the house quite a bit all day too.

Weather.com is showing 89F/46% humidity/66 dew point.

 

Also,

Prior to all of the work being done and lowering the fan speed.
My house would be upwards of 60% humidity in some spots with no external dehumidification.
I would run 1 50PPD dehumidifier and that would bring me down to 55% at the highest, during the day. At night it would be slightly higher in the bedrooms. Thats why i wanted returns in the rooms, because they didnt have the best air flow.

 

After making the changes this morning everything seems to be quite a bit better.
Prior to the changes without running my portable dehu the humidity would be upper 50/ lower 60 during hot days.
Right now my whole house is sitting between 49 and 52% with the thermostat set at 71. But even here at 7:45PM the AC unit is running quite often.
Especially the way the Honeywell t10 works. That thermostat is literally keeping it at 71. It has not changed in hours, but yet cycles on and off. I have an additional temp senor right buy it and its confirming the thermostat temp.
My ecobee lite 3 i had before would wait a degree or 2 then kick on, then would run a degree or 2 past the set point.

I guess tonight as the outdoor temp drops and the AC unit not running much will be a decent test for the dehumidifier.
I have 5 temp/humidity sensors set up throughout the house that i can trend the data from in the morning.

 

Good man! Thanks for getting back with the results so far.

Please let us hear what happens as you evaluate further.

PHM
-------

 

Teddy bear i am learning a whole lot through this entire process and really dont want to throw in the towel until it is as good as i can get it with the currant duct set up.
Like most people i dont have the ability to keep throwing money at it. I am hoping with minor changes we can see further improvement.
The AC guy i used is at least receptive and seems willing to work through the process.

Part of the reason for doing all of this work is that my newborn has asthma and my wife has allergies. My thought was that if i could get AC returns in the bed rooms it would help turn over the air more in the rooms when doors were shut, and the dehu would keep the humidity at 50% or slightly lower. As of right now, at night, the dehu doesnt seem to be able to do that. However is it close to the target and hopefully we can drive it down a few more %.

Update from last night.
Tstat set at 71 throughout the night. Dehu set to 50% and fresh air off.

Front bedroom RH% @10PM 48% / @8AM 51%
Master bedroom RH% @10PM 52% / @8AM 54%
Living room RH% @10PM 50% / @ 8AM 52%

Through out the night the outdoor humidity was lower 80s with a high 60s dewpoint.
With these outdoor dewpoints being so high. The recommendation is to raise the thermostat temperature and use fans? By doing this it should lower the humidity further?

Also yes i am definatly interested in C02 monitoring and fresh air. I really want to get to a point that i can use the fresh air vent.

I am still wondering about the size of the dehu installed. I know that it is rated for the square footage of my home. But the house was built in 1976, so it is older. I have replaced 2 of the 3 exterior door and all of the windows, but there could still be a good bit of leakage that i dont know about. So what i am asking is would i have been better off going with the ultra 98? If so is there anything that the company who installed the equipment can do to get the physical dehu replaced without me having to pay for 100 percent of the larger dehu?
Because outside of the dehu the only thing that would have to be replaced, as far as i can tell, is the duct size to and from the unit. The fresh air duct size appears to be the same on the ultra70/98.

 

I have attached a rough sketch of the house for reference.. Might be overkill but i was bored last night lol.

A rectangle is a supply duct.
A square with an "x" is a return duct.
The square with a "o" is the dehumidifier return duct.

 

It does get that way sometimes when you have a newborn.

I have attached a rough sketch of the house for reference. Might be overkill but i was bored last night . . .

 

It takes some time to dry out inside of the house. Keep raising the inside of the home temperature and lowering the indoor %RH. If interested, I have a CO2 meter that you can use short term to check the CO2 levels to determent the fresh air infiltration that you are getting. The SF 70H is large enough for this home. Measuring the dehu in/out temp/%RH to confirm function would be assuring.

Keep in mind that the outdoor conditions, temp and dew point will continue to rise, the a/c will also remove more moisture. +75^F, <50%RH is the target with +-CO2 1,000 ppm.

Crawlspace, plastic covered earth and vents closed with a dehumidifier maintaining 50%RH?
Email me you address for the CO2 meter.

Keep us posted on the progress of raising the temp and lowering the %RH while being comfortable.

Regards Teddy Bear