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strogg wrote: ↑Tue Jun 30, 2020 9:53 pm

03Lightningrocks wrote: ↑Tue Jun 30, 2020 7:52 pm

LTUME1978 wrote: ↑Tue Jun 30, 2020 7:13 pm An inexpensive and easy solution is to get a dehumidifier. Cost a couple of hundred bucks and should do the trick. I have used one for years. Helps to keep the humidity down without keeping the temperature too low in the house. Also helps in the humid times of the year when it is not that hot and the A/C does not have to run very much.

By coincidence, his make up air system has an option to install dehumidifiers with them. If I am understanding him correctly, his blower on his unit is running any time the make up air determines fresh air should be introduced to his home. Any time the blower in an attic is running, it is circulating air through ducts that are located in an attic that may be as hot as 125-140 degrees in the hottest part of the day. The longer the air is circulated through those ducts,the more the heat from the attic is absorbed. The ducts act as a heat exchanger and will move heat into the home which will increase humidity far beyond anything a dehumidifier will take out. The humidity in his home is not from humidity outside alone. It is being created by the luke warm air being circulated through his 76-78 degree house.

You're spot on, 03Lightningrocks. The fresh air controller opens the damper, then turns on the blower w/o manually energizing the coils to circulate air. If the AC or reverse pump heat happens to be running, then lucky me. Otherwise, not so much. Based on the ASHRAE math, the dampers open for 13.5 and 16.5 minutes per hour for each zone before I messed with the schedule.

I was just thinking of something in the shower. What if I disable the schedules and rig the units to open up the fresh air damper to 1/3rd every time the air handler blower turns on via the thermostat, then have the damper close back up when the blower turns off? That would ensure a very small mix of fresh air with recirc air every time the AC/heater turns on. Would that solve the problem? Or would getting rid of the fresh air units and going for a standalone ERV be a better solution?

This is how I would approach it. Heck, even if the dampers were full open when the system calls for cooling it would be better than the make up air units calling for the blower with no AC running.This time of year the AC is going to cycle enough to bring in plenty of make up air anyway. Allowing that control to bring on the blower with no ac on is killing your humidity removal.

Just an FYI that you may have already figured out. When temps outside are mid seventies and below like in fall and winter, the way the unit is working now works great. Truth is, you need the fresh air more in the winter/fall anyway. But that configuration for the summer is just awful in a climate like Texas..

Readinng this on the instruction sheet leads me to think this setting disables the make up air from calling for the blower. I would have to spend some time studying this option and how it would work with no remotes. I am thinking setting this switch to off is key to setting it up like you mentioned above. In the fall you can switch it back to on so you get some fresh air circulating when when the heat system does not cycle as much On 70 degree days and below you should not have an issue with humidity. Heaters don't run nearly as often as the AC in our area so allowing the make up air to run would help keep the air from being stagnant.

7 Switch On (optimal ventilation)
Override
Off (Remote Only)
On (optimal ventilation) – W8150 ventilates, based on control settings.
Override – W8150 runs ventilation continuously.
Off (Remote Only) – W8150 supplies ventilation only when there is a
remote call.

I was just looking at the diagram for using a remote. The two terminals labeled for the remote look like they are designed to go to a switch. You can check this by turning the switch to off and then check the voltage at those two terminals. If you are getting 24V it means that this connection is designed to call for the make up air when a switch of some sort completes the circuit. I point this out so you don't send 24v to those terminals from the ac blower. You can verify this by jumpering the terminals if you read 24v on them. It should turn the make up air blower on when jumpered. If this is the case, a relay can be installed that is energized off an accessory terminal providing 24v from the blower. Just be sure this accesory terminal only sends 24V when the system calls for cooling. If it sends 24V when calling for cooling or heating it will still work. Then you have the option of leaving it set to remote or on if you like it coming on more in the cooler seasons. Set it for remote in the cooling season and set it back to on for the heating season. When the contacts on the relay close, it should bring on the make up air unit.

LTUME1978 wrote: ↑Tue Jun 30, 2020 7:13 pm An inexpensive and easy solution is to get a dehumidifier. Cost a couple of hundred bucks and should do the trick. I have used one for years. Helps to keep the humidity down without keeping the temperature too low in the house. Also helps in the humid times of the year when it is not that hot and the A/C does not have to run very much.

By coincidence, his make up air system has an option to install dehumidifiers with them. If I am understanding him correctly, his blower on his unit is running any time the make up air determines fresh air should be introduced to his home. Any time the blower in an attic is running, it is circulating air through ducts that are located in an attic that may be as hot as 125-140 degrees in the hottest part of the day. The longer the air is circulated through those ducts,the more the heat from the attic is absorbed. The ducts act as a heat exchanger and will move heat into the home which will increase humidity far beyond anything a dehumidifier will take out. The humidity in his home is not from humidity outside alone. It is being created by the luke warm air being circulated through his 76-78 degree house.

strogg wrote: ↑Tue Jun 30, 2020 2:21 pm

Archery1 wrote: ↑Tue Jun 30, 2020 1:02 pm What system do you have? I know the Aprilaire controller will not allow operation if outside air temp is high. In a perfect world where all this stuff works as advertised, it should never allow the indoor humidity above the set amount no matter the controller settings.

They are Honeywells of some sort. They use the W8150 controllers. They'll run regardless of what the climate is like outdoors. Seriously. My upstairs hygrometer reported 65% RH about an hour ago after the unit switched on without AC...

That is definitely what is causing your humidity problems. There are several methods for making that system draw in less air and run for less time. The best way to help you is to give you this link to the instruction sheet and trouble shooting chart for this controller/makeup air system. Personally, my goal would be to get it to run as little as possible. Regardless of what ASHRAE 62.2-2003 standards recommend. Reducing the run time on the blower assembly is far more important than amount of fresh air is added to system. What good is fresh air if it is creating 65% RH in the home? Here is the link. i hope it helps. https://forwardthinking.honeywellhome.c ... 8_0282.pdf

There is a way to reduce how much the damper is open in the device. The problem is bigger than just that. If this controller is calling for the blower while the AC is off, that air circulating through the ducts in your hot attic is just pumping heat into your home.

strogg wrote: ↑Mon Jun 29, 2020 10:39 pm

03Lightningrocks wrote: ↑Mon Jun 29, 2020 6:58 pm Oh... on the fresh air settings. If it were me, I would shut them down to near no fresh air in the summer months. The high heat outside is fighting your humidity removal. During the winter, crank them wide open.

What's your recommended intervals for fresh air ventilation throughout the year? I have a fresh air ventilation controller on each air handler, and I have a feeling the preset schedule is a bit too much.

I am not sure what options you have on your type controllers but I would set them up for minimal ventilation during the season it is 85 and above outside.

Archery1 wrote: ↑Mon Jun 29, 2020 6:11 pm

03Lightningrocks wrote: ↑Mon Jun 29, 2020 4:12 pm How long the system stays off once the stat is satisfied is a function of heat gain within the home. How long it takes to cool the home off once the system stat calls for cooling is a function of unit size. Thermostats are simply switches that automatically turn the system on and off depending on the temperature it senses.

You do bring up an interesting point to consider concerning heat gain and time elapsed. Yes, they do make thermostats with 3-degree variance, or adjustable to 3-degrees, but from what you point out, it isn't about that anyway. Plus, you then have to feel the temp swings more.

Heat gain being the function of the home design, it's going to gain the same amount no matter the change up on time a/c running. So it runs longer per period? Might be better on unit with longer cycling. But, for RH, seems total run time over 24 hours is a matter of heat gain v. heat removal (unit size and function) so total day's run time will be almost unchanged. Trying to learn a new zoned system myself with Aprilaire fresh air settings and RH settings. Still can't figure out why fan runs almost constantly some days and not so others no matter RH setting?

The air conditioning system has two jobs. Remove heat from inside the home and dehumidify the air. It will only dehumidify while it is running.Relative humidity settings are tied into the blower speed. The theory being that by slowing down how fast the air moves across the evaporator coil, it allows the coil to remove more humidity from the air. The catch to this theory is that the air also must move fast enough to keep the coil from freezing up. Variable speed and two speed outdoor units, when installed with variable speed indoor blowers, have been a big help in achieving this balance. If your humidistats are set up to actually call for the outdoor unit to run to bring humidity down, this would explain why the air is constantly blowing. If the air is blowing but the outdoor unit is not running, it will actually increase humidity in the home. I would recommend a setting for the humidity at no lower than 40%-45%. Any lower than that and it will likely run all the time. It is real hard in DFW and Houston to get the humidity in the home lower than that anyway.

Oh... on the fresh air settings. If it were me, I would shut them down to near no fresh air in the summer months. The high heat outside is fighting your humidity removal. During the winter, crank them wide open.

strogg wrote: ↑Mon Jun 29, 2020 4:56 pm

03Lightningrocks wrote: ↑Mon Jun 29, 2020 4:12 pm All of this said I am curious as to what the actual issue you are trying to solve is. Not what you think is causing it, what the actual issue is. I might be able to point you in a direction that does not involve unnecessary repairs that don't fix the problem.

Ultimately, I'd like to maintain a low humidity household. Unchecked, this place was consistently at a whopping 60-70% RH. That started leading me down this rabbit hole that makes my brain hurt. I definitely think it would help if someone came out to take a look at my current setup to give me best practices. Unfortunately, the only callbacks I've gotten so far were from the original installers. They haven't been all that helpful. The whole short cycling thing only came up when I learned that ACs running only 5-10 minutes at a time isn't exactly a good thing.

That kind of humidity increase is usually due to one or both of your systems not running properly. Some things you can check for yourself are, filters, check for dirty coils on your outdoor units and wash the crud off if they are dirty. Turn the power off at the disconnects located by your units just to be safe before washing off the coils. If you have power attic ventilators on the roof, check to make sure they are working. High heat in the attic can cause humidity to increase in your home. Especially if the insulation has settled due to age. All blown in insulation settles with age and the Rvalue drops dramatically. Check the temperature drop of the system. Using the same thermometer, check the temperature of the air coming out of a few supply air grilles. (air blowing into house). Then check the temp of the air going into the return air grilles. The difference should be 18-20 degrees. A 16-17 degree drop will work but is not optimal.

Systems that are low on refrigerant will cause humidity issues. If you are not familiar with proper charging procedures, this is something a service technician will need to check.

I am not sure what area you live in and I usually don't look for work on the forum. I come here to get my mind off what I do for a living but. we service as far north as Frisco, as far west as Carrollton, south to North Dallas and east to Murphy/Saxy area. but don't get further out than that.If you are in our area we can check your systems out for you. The easiest way is to do a maintenance agreement which is 119 per system and includes one cooling maintenance and one heat maintenance per system. Most issues can be found on the maintenance checks. We also clean those outdoor coils.

strogg wrote: ↑Mon Jun 29, 2020 8:53 am I'm well aware of the long term issues. Unfortunately, I had no control over the initial installation of the AC units. They are undersized because there are far fewer people living here than the house was designed for. I'm very leery of replacing them with smaller units right now because they're still working perfectly fine, and it would cost thousands to replace with variable speed units. I'd rather spend the money later if I can. Now isn't all that great of a time.

Anyhow, I was able to get the cycle rate to go higher by closing off the vents to the rooms with the thermostats and by lowering the temperature by a couple degrees. The average cycle time is now about 10-15 minutes. Before it was 5-10. I'd rather not do that for the long run because it's getting chilly in here.

I guess I'll rephrase my question. Does anyone have any other suggestions? Otherwise, I'll probably end up getting new thermostats as a bandage until the AC units finally give in. I am hoping with the new thermostats can increase the cycle rates while increasing the time between cycles. It'll save power and allow the temperature to be warmer during the summer months. I don't really care if there's a larger temperature swing inside. That's the least of my worries.

How long the system stays off once the stat is satisfied is a function of heat gain within the home. How long it takes to cool the home off once the system stat calls for cooling is a function of unit size. Thermostats are simply switches that automatically turn the system on and off depending on the temperature it senses. There is no such thing as a stat with an adjustable cycle rate. Your stats have nothing to do with the problems you are having. They are simply turning the system on or off based on set point. A thermostat that takes the temperature lower than the off set point and does not come on until higher than the on set point is called "broken". If you are asking about stats that will call for cooling at say 78 and then run until the temperature is 76 before shutting off, there may be a stat that does this but I am not familiar with it. Most people prefer the temperature remain at the set point they are comfortable with. Even a two degree swing would feel warm by the time it came on and cold by the time it goes off.

Second. People load is not enough to create a sizing issue with your residential system. People are figured into a load calculation at about 400 btuh per person. Even 10 people is only 4000 BTUH for the entire home. That is only a quarter ton of cooling capacity.

A few things that can cause a system to not run long enough to remove humidity are installing too large of a system for the home. From what you said, you did not do this. If it was not doing this from day one, it is not doing it now unless. You increased the efficiency of your home through the addition of new insulation that has an R value far above the original R value. Replacing all the windows with more efficient windows than the original. Sometimes a new roof that holds more heat in the attic than the original can increase humidity. This is fixed with additional attic ventilation.

Closing off some of the vents near the thermostat can help because it makes it take longer for the area around the stat to cool off than the rest of the house. This can create larger temperature swings in the rest of the home below the set point on your stat. ie. stat reads 78 but the rest of the home is 76. The other issue to keep watch on with the grilles you have shut down is condensation around the closed off grille, leading to mold or even damaged sheet rock around the grille.

All of this said I am curious as to what the actual issue you are trying to solve is. Not what you think is causing it, what the actual issue is. I might be able to point you in a direction that does not involve unnecessary repairs that don't fix the problem.

strogg wrote: ↑Sun Jun 28, 2020 10:50 pm As the title suggests, I'm looking for a thermostat with an adjustable cycle rate. The HVAC I have right now is definitely way too large for my place and is short cycling like crazy. Does anyone have any suggestion on reliable thermostats that'll fit the bill? I would prefer thermostats that can work as designed without wifi. I'm not a fan of the whole IOT movement.

If your system is short cycling due to being over sized, changing the thermostat is not going to help. How did you end up with an over sized system? Most homes are designed with the correct HVAC system size to begin with.