[teddy bear]

So i posted here a few weeks ago about wanting a whole home dehumidifier installed. Well yesterday i had it put in..

Work i had done yesterday:
1. Installed sante fe ultra 70 dehumidifier. Installed with dedicated return in central location and the dehumidifier supply is ran to the supply plenum.
2. Fresh air ventilation.
3. Sealed all AC registers at the attic and inside. Some had very large gaps.
4. Added 2 new AC supply ducts. One to a walk in closet and the other to our laundry room.
4. Fixed multiple duct leaks. 1 large return leak and some on the supply.
5. Replaced bathroom exhaust fans and sealed around the. Previous vans had large gaps.
6. Added 3 12x12 returns in the bedrooms.

After letting the house cool back down for several hours, to get back to baseline after the AC being off for a while in the Texas heat, i started to monitor the humidity.
I have NEVER had the humidity is the house as high as it was last night. At night without any external dehumidification, the humidity in my house would be upper 50s / lower 60s.
Last night it was high 60s and in my room it was almost 70 percent.
So i turned off the whole home dehumidifier and started my portables and it brought the humidity down to the lower 50s which is what i am use to.

As i mentioned above the dehumidifier has its own central return and the dehumidifier supply is attached to the AC unit supply. There is a "gravity damper" installed as well.

Fresh air/dehumidifier set up:
When the dehumidifier runs so does the AC fan. I brought this up as a concern that the AC fan will blow humidity from the coil back into the house. I was told that the sante fe ultra 70 doesn't produce enough CFM to operate without the AC blower.
The 6" Fresh air is set up to an automatic valve on the return of the dehumidifer. They have it programed to run 15 min per house. It is also set to so that during that 15 minutes it will turn on the AC blower if the AC unit is not running.. Which i see as another issue.


I will be reached back out to the company that instlled everything this morning. And i am looking for suggestions..
I am going to request that they check the static pressure again..
But i am wondering about the set up itself..

Should the AC blower be running when the sante fe ultra 70 is running, even if the AC unit is not?
Should the fresh air timer turn on the AC blower when the AC unit is not running?

I will mention that the home is about 1700 sqft in houston tx.

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

 

[teddy bear]

So i posted here a few weeks ago about wanting a whole home dehumidifier installed. Well yesterday i had it put in..

Work i had done yesterday:
1. Installed sante fe ultra 70 dehumidifier. Installed with dedicated return in central location and the dehumidifier supply is ran to the supply plenum.
2. Fresh air ventilation.
3. Sealed all AC registers at the attic and inside. Some had very large gaps.
4. Added 2 new AC supply ducts. One to a walk in closet and the other to our laundry room.
4. Fixed multiple duct leaks. 1 large return leak and some on the supply.
5. Replaced bathroom exhaust fans and sealed around the. Previous vans had large gaps.
6. Added 3 12x12 returns in the bedrooms.

After letting the house cool back down for several hours, to get back to baseline after the AC being off for a while in the Texas heat, i started to monitor the humidity.
I have NEVER had the humidity is the house as high as it was last night. At night without any external dehumidification, the humidity in my house would be upper 50s / lower 60s.
Last night it was high 60s and in my room it was almost 70 percent.
So i turned off the whole home dehumidifier and started my portables and it brought the humidity down to the lower 50s which is what i am use to.

As i mentioned above the dehumidifier has its own central return and the dehumidifier supply is attached to the AC unit supply. There is a "gravity damper" installed as well.

Fresh air/dehumidifier set up:
When the dehumidifier runs so does the AC fan. I brought this up as a concern that the AC fan will blow humidity from the coil back into the house. I was told that the sante fe ultra 70 doesn't produce enough CFM to operate without the AC blower.
The 6" Fresh air is set up to an automatic valve on the return of the dehumidifer. They have it programed to run 15 min per house. It is also set to so that during that 15 minutes it will turn on the AC blower if the AC unit is not running.. Which i see as another issue.


I will be reached back out to the company that instlled everything this morning. And i am looking for suggestions..
I am going to request that they check the static pressure again..
But i am wondering about the set up itself..

Should the AC blower be running when the sante fe ultra 70 is running, even if the AC unit is not?
Should the fresh air timer turn on the AC blower when the AC unit is not running?

I will mention that the home is about 1700 sqft in houston tx.

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

 

[Newbtube93]

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.

 

[Newbtube93]

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.

 

[Poodle Head Mikey]

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
------

That looks terrible! Air flow will be lousy.

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

 

[HVAC_Marc]

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

Ductopus

 

[Newbtube93]

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.

 

[Poodle Head Mikey]

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

Please let us hear what happens as you evaluate further.

PHM
-------

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.

 

[teddy bear]

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.

Things to keep in mind. With the indoor temperature at 71^F, 50%RH, a 50^F dew point and with the outdoor dew point at 66^F, any outside air is 16^F dew point higher than inside air. The vapor pressure moving the moisture toward the inside is very high which causes moisture to condense on all of cool damp side of the drywall and migrating into the home. 100 cfm of infiltrating/ventilating fresh air 2-3 lbs. moisture per hour of dehumidification load.

Warming your home to 74-75^F, 48%RH, 54^F dew point will dramatically reduce the moisture load on the home from vapor pressure condensation and ventilation. Currently your home is like a can of cold beer with condensation forming on the cool insulation/drywall and migrating slowly into the home. Warmer inside temperatures decrease the dehumidification load 30-40% by avoiding overcooling. Warmer indoor temperatures and lower indoor %RH to be comfortable will make this easier. Many are targeting are 76-78^, 48%RH and indoor air movement like ceiling fans for comfort. The a/c and dehumidifier will run less.

Next we need to look at the indoor CO2 levels to match fresh air ventilation to times when the home is occupied and fresh air infiltration is low. Are you monitoring CO2 levels? Any duct leakage increases moisture loads and decreases the need for high ventilation rates. We can figure the air change rate of your home comparing the number of occupants and the CO2 levels. One adult occupant with indoor CO2 levels of 650 ppm is getting 55 cfm of 450 ppm CO2 fresh air. Your home needs a max of 100 cfm fresh air to purge indoor pollutants and renew oxygen.

This a great learning session for your contractor and . All of us have been through these lessons. And the lessons will continue for all of us participating is the process.

If you need help with the CO2 monitoring, let us know.

We really appreciate your efforts to learn the ins and outs of your home and systems. This is a sort of mating process.

Regards Teddy Bear

 

[jacob-k]

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

If the static pressure is good, and the airflow in the house is acceptable, who cares what the crawl space looks like.

Sent from my SM-G998U using Tapatalk

 

[Newbtube93]

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.

 

[Newbtube93]

If the static pressure is good, and the airflow in the house is acceptable, who cares what the crawl space looks like.

Sent from my SM-G998U using Tapatalk

I agree. If i can get it to function well with it looking like a mess. I am ok with it.

 

[Newbtube93]

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.

 

[teddy bear]

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

 

[teddy bear]

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?
Send me a private message with your 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

 

[Newbtube93]

I also forgot to mention that i reached out to santa fe directly about running the AC fan with the dehu.
And they literally sent me a like to my exact thread asking if it was me. Then proceeded to say "you got one of the best in the industry responding - teddy bear".
That made me feel like i was in the right place forsure! Once again thank you.



So right now i have the Tstat at 73F which seems to put the majority of my house around 75F. (Current outside conditions. 90F/47%/66F dewpoint)
As you mentioned the humidity might take a while to stabilize. Maybe a day or so to get to a good baseline?
Per sketch above the office is at 50%, master bedroom 55% and the living room is at 50%. The hallway is about 53%.
The common trend i have noticed is that the master bedroom is always higher than the rest of the house.
The dehumidifier is set at 50%. So it has not stopped running this whole time.

I just set the fresh air to 5min per hour as the outside humidity right now is <50%.


And the home is built on a concrete slab. There could be some level of slab sweating i imagine, especially with keeping the temps lower in the house?? The bedrooms and 1 small hallway are carpet and the rest of the house is tile.


As far as CO2 monitoring goes what do you recommend buying? I am interested in monitoring it. Especially if i can get to a point where i can use the fresh air.

How about hydrometers? i ordered some salt test calibrating thing to try for the ones i have. Not sure if its a scam or not, but it says it will calibrate to 75%. Any experience with this? If not how do i calibrate what i have?
I am also not against buying a hand held. Right now my smart hydrometers are calibrated to my thermopro meter, which is within 2% of a handheld that was used last week when i had a company do mold testing on the house.

 

[jacob-k]

I also forgot to mention that i reached out to santa fe directly about running the AC fan with the dehu.
And they literally sent me a like to my exact thread asking if it was me. Then proceeded to say "you got one of the best in the industry responding - teddy bear".
That made me feel like i was in the right place forsure! Once again thank you.



So right now i have the Tstat at 73F which seems to put the majority of my house around 75F. (Current outside conditions. 90F/47%/66F dewpoint)
As you mentioned the humidity might take a while to stabilize. Maybe a day or so to get to a good baseline?
Per sketch above the office is at 50%, master bedroom 55% and the living room is at 50%. The hallway is about 53%.
The common trend i have noticed is that the master bedroom is always higher than the rest of the house.
The dehumidifier is set at 50%. So it has not stopped running this whole time.

I just set the fresh air to 5min per hour as the outside humidity right now is <50%.


And the home is built on a concrete slab. There could be some level of slab sweating i imagine, especially with keeping the temps lower in the house?? The bedrooms and 1 small hallway are carpet and the rest of the house is tile.


As far as CO2 monitoring goes what do you recommend buying? I am interested in monitoring it. Especially if i can get to a point where i can use the fresh air.

How about hydrometers? i ordered some salt test calibrating thing to try for the ones i have. Not sure if its a scam or not, but it says it will calibrate to 75%. Any experience with this? If not how do i calibrate what i have?
I am also not against buying a hand held. Right now my smart hydrometers are calibrated to my thermopro meter, which is within 2% of a handheld that was used last week when i had a company do mold testing on the house.

I need to find hiw much people are charging Teddy Bear to say nice things about him!

Sent from my SM-G998U using Tapatalk

 

[teddy bear]

I also forgot to mention that i reached out to santa fe directly about running the AC fan with the dehu.
And they literally sent me a like to my exact thread asking if it was me. Then proceeded to say "you got one of the best in the industry responding - teddy bear".
That made me feel like i was in the right place forsure! Once again thank you.



So right now i have the Tstat at 73F which seems to put the majority of my house around 75F. (Current outside conditions. 90F/47%/66F dewpoint)
As you mentioned the humidity might take a while to stabilize. Maybe a day or so to get to a good baseline?
Per sketch above the office is at 50%, master bedroom 55% and the living room is at 50%. The hallway is about 53%.
The common trend i have noticed is that the master bedroom is always higher than the rest of the house.
The dehumidifier is set at 50%. So it has not stopped running this whole time.
Occupants release .25 lbs. per hour per adult by breathing and sweating. Higher %RH is expected.

I just set the fresh air to 5min per hour as the outside humidity right now is <50%.

Dew point is a better reference for moisture in air. Dew points are steady during 24 hours in a day.


And the home is built on a concrete slab. There could be some level of slab sweating i imagine, especially with keeping the temps lower in the house?? The bedrooms and 1 small hallway are carpet and the rest of the house is tile.


As far as CO2 monitoring goes what do you recommend buying? I am interested in monitoring it. Especially if i can get to a point where i can use the fresh air.
We need to verify that the ducts are reasonably air tight. You will probably need fresh air during calm winds and when the a/c blower is not running.

How about hydrometers? i ordered some salt test calibrating thing to try for the ones i have. Not sure if its a scam or not, but it says it will calibrate to 75%. Any experience with this? If not how do i calibrate what i have? Table salt saturated water in a sealed container generates 75%RH>
I am also not against buying a hand held. Right now my smart hydrometers are calibrated to my thermopro meter, which is within 2% of a handheld that was used last week when i had a company do mold testing on the house.

Looking like the Broan Overture CO2 monitor that will monitor CO2 on a phone app on your phone. The same sensor operates a switch that will activate your fresh fan.

https://www.broan-nutone.com/en-us/overture

Keep us posted.

Regards Teddy Bear

 

[Newbtube93]

Where is this home?

Houston texas

 

[Newbtube93]

Looking like the Broan Overture CO2 monitor that will monitor CO2 on a phone app on your phone. The same sensor operates a switch that will activate your fresh fan.

https://www.broan-nutone.com/en-us/overture

Keep us posted.

Regards Teddy Bear

OK I will look into it.

I think my expectations were just a little to high for the whole home dehumidifier because of my house and the outside environment in my area.

After monitoring for several days now I can tell that it works.
The humidity overnight still climbes to around 53-55 percent (partd of the house are lower than 55. 55 is just my bedroom)by the time i wake up. But when the outside humidity is 80-90% and the ac is not running much, it makes sense.
During the day there are good improvements. Before I couldn't set my tstat temp higher than 72 during the day because the humidity would be through the roof from the AC not haveing to work as hard (this was even with my 50ppd portable dehu running). Now I am running my Tstat at 72 while sleeping, 76 when I am at work and 74 while I'm home and the humidity is anywhere from 47-52% during the day. Now that is with the dehumidifier running almost the whole day.
The other thing I have noticed is that my portable dehumidifiers will bring then humidity down very quickly when there is a change, and the whole home dehumidifier is more of a slow continuous decrease. That also makes sense because it doesn't move much air and it is putting the small amount of air back into the ducts going to the entire house, not just the immediate area.

Overall I am satisfied so far but not happy if that makes sense.
It is working and has allowed me to not use my 50ppd portable for now.
We will be getting rain soon, so I am curious to see how the whole home preforms in all weather conditions.

For now the compromise is to keep my 20 or 30ppd (can't remember which) in our bedroom.
In the past we wouldn't run it all the time, only when needed.
But now the plan is to run it non stop while we take showers at night and for 1 hour after.
Then during the day we will set it at 55% just to make sure it doesn't go above that in the room.
Set at 55 percent during the day it shouldn't run but maybe a few short cycles a day. And that's only because it seems to read a little higher than the other two sensors in the room.