HVAC filters
- Thread starter factorytuned2012
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- Jul 10, 2022
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This is what I was trying to say. On an old furnace, the speeds are set by jumpers. Physically. Maybe there are 3. Maybe there are 5. They are not normally touched.
On an ECM like our new one, a tech uses a laptop and the blower is variable. But AC is much higher than heat. Maybe double.
Only when the motor is failing does the “I’ll use a $0.79 filter and change it ever 2 weeks” come in to play. This is to keep going. Otherwise heat will short cycle as a normal filter is now restrictive. I don’t know much just what I’ve been told.
Although the blowers have settings that are quoted in CFM for convenience, it's actually a shaft speed. The correlation between shaft speed and CFM is only valid at a certain level of pressure rise across the unit. At a given shaft speed a higher pressure delta means less flow (pounds mass per minute).
Commonly if a heat pump is right on the edge (airflow, refrigerant level, etc.) the difference between an appropriate filter and a restrictive one can cause high pressure trips, despite "having the CFM jumper set is right"
Evaporator coils sweat water from cold coil and warmer air blowing across, also drain pan full of water. Residential units will produce many gallons of water a day, which run out condensate drain. A humidifier operates similar, water is added to air with fan blowing.
The only moisture that gets reintroduced into the room, by the fan running, is that water clinging to the coil that has not dropped off.
Very minimal amount. It is still operating at a net loss.
There is no "increase" in humidity.
The unit without the fan running all the time has the same issue.
Water hanging on the coil still evaporates...not at the same speed, some drops off, still happens.
The unit case and duct work will also start to warm... so that water vapor and that heat gain is added to the room when the unit does start again.
Still a minimal amount.
A fan running all the time does a far better job of controlling the temperature.
Keeps the air from stratifying and eliminates warm spots.
Unless a humidistat has been added, the unit is not set up to control humidity.
Is there enough difference to matter?
I opt for better control.
The drain pan should not be holding water.
I’ve been fortunate in the deep models and always had the fingers.
Many filters are way overpriced in my opinion, wow must be big markups
Good chance I will try these filters, right now I have 12 months supply for both intakes changed every two months
Are you an HVAC contractor? Do a service or replace evaporator coil and there will be water in pan. You will raise humidity in home by running fan continuously, at least in humid south.
A drain pan should be higher on the non-drain end to insure it drains properly.
I live in SE TX.
You will be hard pressed to find a hotter more humid environment.
I run my fan 24/7 in cooling mode.... No humidity issues here.
You still have not explained how running a fan will increase humidity.
You do say a unit will remove gallons a day....but insist that a running fan can increase humidity???
A properly sized and installed unit should run long enough to create a sizable net loss.
For the record, I graduated Tech school in 1977.
The School of Applied Aerospace Sciences.
(Those who know, know.)
I retired in 2022.
I did take a 7 yr. break to work as an electrician.
Spent my whole life working in Tx.
I am a licensed Journeyman Electrician.
I am also a Certified Air Conditioning & Refrigeration Technician.
It's possible that I learned a few things along the way.
One of the things I learned would be the purpose of a "Drain" pan.
It's in the name..... drain.
A lot of them are even manufactured with a slope to them.
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If not already mentioned, Costco has Filtrete 2500 (Merv 14 rated) 4 packs on sale right now for $24. That's a really good deal.
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Where does this extra moisture come from ? I live in Louisiana . Humidity is a way of life around here .
Increase in humidity from a constantly running fan discussed in my post above.
I tested it after seeing @KJSmith's confidence and saw and felt an increase in humidity. The circulating air picks up the evaporating residual water condensed on the coil and in the drain pan. I'm sticking to fan only on when cooling is called for. YMMV!
There are times and people it does not work for.
A friend of mine from Pittsburgh was telling me his daughter's room, 2 story, her room upstairs, was staying warm.
I suggested he turn the fan to "on".
Next time I saw him he told me it solved all the issues he was having....except his wife hated it.
Apparently, wife overrode daughter.
My house I keep set at 78f. day until 11:00pm, 75f night until 8:00am.
I added ~'2 of insulation several years ago. Cuts down on heat gain and noise.
Early in the year, when it's not hot enough or the temperature doesn't rise enough, my unit won't run.
It can get a touch humid.
I bump the temperature down to 77 and that solves it.
I covered multiple buildings at work. Ranging in size from 120sqft to 35,000sqft.
However, all the equipment was designed for 105 ambient...essentially oversized in normal conditions.
We ran A/C 24/7/365. The fans in commercial buildings run 24/7/365.
Even the units that were multistage and /or set up for humidity control could have issues maintaining comfort at 78f.
I kept the majority set at 74f... kept the humidity under control...kept fellow employee's from complaining.
There were several buildings that were set up with units able to control humidity.
The issue with them was if you tried to set the humidistat below 65%, and the TStat at 75f or higher it would run the unit based on the humidity.
In that mode, the compressor ran in normal cooling and reheat would come on to warm the air back to setpoint.
Wasteful at best. I felt was better just to set them at 74f and 65% and just let the normal cooling handle the humidity.
I took over 8 small buildings at one point. 120 sq ft.
Units (2 primary and redundant backup) were grossly oversized.
4.5 and 5-ton units depending on the site.
Actually, had mold forming in the buildings.
The unit would come on and shut off in under 5 minutes.
Not enough run time to remove moisture..... but its still not adding moisture.
These were the only buildings I ever ran in "auto/cool".
We ran the fan on the redundant units for air movement.
A few years later they replaced 1 unit per building with one of the more correct size.
A friend of mine from Pittsburgh was telling me his daughter's room, 2 story, her room upstairs, was staying warm.
I suggested he turn the fan to "on".
Next time I saw him he told me it solved all the issues he was having....except his wife hated it.
Apparently, wife overrode daughter.
My house I keep set at 78f. day until 11:00pm, 75f night until 8:00am.
I added ~'2 of insulation several years ago. Cuts down on heat gain and noise.
Early in the year, when it's not hot enough or the temperature doesn't rise enough, my unit won't run.
It can get a touch humid.
I bump the temperature down to 77 and that solves it.
I covered multiple buildings at work. Ranging in size from 120sqft to 35,000sqft.
However, all the equipment was designed for 105 ambient...essentially oversized in normal conditions.
We ran A/C 24/7/365. The fans in commercial buildings run 24/7/365.
Even the units that were multistage and /or set up for humidity control could have issues maintaining comfort at 78f.
I kept the majority set at 74f... kept the humidity under control...kept fellow employee's from complaining.
There were several buildings that were set up with units able to control humidity.
The issue with them was if you tried to set the humidistat below 65%, and the TStat at 75f or higher it would run the unit based on the humidity.
In that mode, the compressor ran in normal cooling and reheat would come on to warm the air back to setpoint.
Wasteful at best. I felt was better just to set them at 74f and 65% and just let the normal cooling handle the humidity.
I took over 8 small buildings at one point. 120 sq ft.
Units (2 primary and redundant backup) were grossly oversized.
4.5 and 5-ton units depending on the site.
Actually, had mold forming in the buildings.
The unit would come on and shut off in under 5 minutes.
Not enough run time to remove moisture..... but its still not adding moisture.
These were the only buildings I ever ran in "auto/cool".
We ran the fan on the redundant units for air movement.
A few years later they replaced 1 unit per building with one of the more correct size.
If you're running 1" filters, go this route 100% if your intake is deep enough. These will last 6-8 months.
I would investigate duct work in your attic. You are likely pulling air from the attic on the return side and that is what keeps your humidity high and the temperature rising during hot days.
As @alarmguy mentioned, an undersized unit will keep the humidity low even when it cannot keep up with the demand.
@factorytuned2012
Not sure your position if you are going to do anything about your 2 ton unit. As you all helped me figure out we have the same 2 ton for around the same sq.ft 1800
Clearly it is pushing the envelope but we are ok with ours, factory tuned seems to be a victim of whoever input the calculation for his system.
Previously posted this was explained by our AC company on our new build. I can see his point our house is always nice and dry. Taking into account is windows, insulation etc etc.
Someone failed factory as something is amiss with the high humidity and lack of cooling. I do believe for his situation the companies who looked at it said they felt it was undersized and should be a 2.5 ton. I agree and I even think we could have gotten away with a 2.5 ton and not had a moisture problem. But for us it is what it is and we are ok with it, not having the issue factory is but we had one instance that the extra cooling would have helped one hot day this summer.
Ok, back to the 2.5 ton. My son with the same sq footage but in the upstate of SC has a 2.5. It was 20 years old and recently replaced with a new 2.5. Granted in the 20 year old house compared to the new, we have better insulation, better low e glass, and better tightness of the home all around. I do wonder if @factorytuned2012 has an outside intake under his main filter because maybe disabling that would lower the humidity and also help the cooling by not drawing in the outside air.
Another point of my post, in fact the main point was I see someone was selling a 2 year old 2.5 ton unit with the air handler for less than 2k if he was interested and if still available. It was on Facebook Marketplace in Myrtle beach, the reason this person gave was it was undersize for his home and had it replaced..
Not sure your position if you are going to do anything about your 2 ton unit. As you all helped me figure out we have the same 2 ton for around the same sq.ft 1800
Clearly it is pushing the envelope but we are ok with ours, factory tuned seems to be a victim of whoever input the calculation for his system.
Previously posted this was explained by our AC company on our new build. I can see his point our house is always nice and dry. Taking into account is windows, insulation etc etc.
Someone failed factory as something is amiss with the high humidity and lack of cooling. I do believe for his situation the companies who looked at it said they felt it was undersized and should be a 2.5 ton. I agree and I even think we could have gotten away with a 2.5 ton and not had a moisture problem. But for us it is what it is and we are ok with it, not having the issue factory is but we had one instance that the extra cooling would have helped one hot day this summer.
Ok, back to the 2.5 ton. My son with the same sq footage but in the upstate of SC has a 2.5. It was 20 years old and recently replaced with a new 2.5. Granted in the 20 year old house compared to the new, we have better insulation, better low e glass, and better tightness of the home all around. I do wonder if @factorytuned2012 has an outside intake under his main filter because maybe disabling that would lower the humidity and also help the cooling by not drawing in the outside air.
Another point of my post, in fact the main point was I see someone was selling a 2 year old 2.5 ton unit with the air handler for less than 2k if he was interested and if still available. It was on Facebook Marketplace in Myrtle beach, the reason this person gave was it was undersize for his home and had it replaced..
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@factorytuned2012
These are photos of our main airbox intake.
I am wondering if you have a fresh air intake like we have in our house???? If so I was wondering if you disable it if it would help with your system as you no longer will be taking in hot air for the outside, granted its there for a reason and that is air exchange for the stale air in the house IF, IF your house is tightly sealed.
I leave mine active but I am wondering if this might help in your situation.
See photos.
This is the main airbox with a 14x25 filter behind the grill, second photo is grill removed and 14-x25 filter removed
Below you see a small 6x6 filter in the air box. This filters outside air coming in. A flap opens up and draws in outside air when the system turns on.
6x6 filter removed. It's actually surprising how dirty that filter gets from the outside air coming in.
That is the solenoid controlled flap that opens and closes when system turns on and off.
SIde note, even though it may not be cost effective it might make sense to install an attic fan to cool the attic. Im not a big fan of them (no pun intended) but might make sense for you if a powerful enough one was installed or possibly get the roof joists spray foamed.
These are photos of our main airbox intake.
I am wondering if you have a fresh air intake like we have in our house???? If so I was wondering if you disable it if it would help with your system as you no longer will be taking in hot air for the outside, granted its there for a reason and that is air exchange for the stale air in the house IF, IF your house is tightly sealed.
I leave mine active but I am wondering if this might help in your situation.
See photos.
This is the main airbox with a 14x25 filter behind the grill, second photo is grill removed and 14-x25 filter removed
Below you see a small 6x6 filter in the air box. This filters outside air coming in. A flap opens up and draws in outside air when the system turns on.
6x6 filter removed. It's actually surprising how dirty that filter gets from the outside air coming in.
That is the solenoid controlled flap that opens and closes when system turns on and off.
SIde note, even though it may not be cost effective it might make sense to install an attic fan to cool the attic. Im not a big fan of them (no pun intended) but might make sense for you if a powerful enough one was installed or possibly get the roof joists spray foamed.
- Joined
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my hallway and master just have one filter in each return grate. Pic posted are their sizes. That’s interesting the smaller duct inside the main return. I’m not an AC guy but never seen that set up in my time.
i use two. standard green bs filters, that are a dime a dozen, and a yearly change hepa filter near the unit.......looks kind of like an accordian
Yeah, I never saw it either. Not easy finding 6 x 6 filters but I was successful, a company that makes them, sells them a dozen at a time, so I have a dozen *LOL* I guess its something new now. Is out house really that airtight or a new building code I dont know but the hundreds of homes they are building here get them now. I dont see builders or their contractors putting them in at the extra cost if it wasnt required *LOL*
Yeah, our other filter is in the master, standard 14 x 14 no outside intake on that. Just seems weird to be taking in hot air from a vent in the roof no less. But whatever.
Wow, because someone just replied to your post I realized I missed this. I like that site that you posted.
Typically I just hunt around for best price in a Merv 8, sometimes all things equal I will get a Merv 11 on the master br one.
I like the verbiage and documentation on the website trufilter. Bookmarking for sure. Need to check my "inventory" to see if I am getting ahead of myself by ordering right now. Price is right too.
Right now I am using HomeDepots HDX brand, first time ever and they are pretty good considering the price.
Edit. I am impressed by trufilter website. It shows air resistance for its filters and has me convinced that using Merv 8s are solid thinking.
Anyway, great site. I was about to order both sizes (even though I have 9 months worth of other filters)
THe 14x14 is on sale, 6 pack merv 8 for $29... thing is, when you click the link it takes you to another size on Amazon and one that is not on sale. Looking further on Amazon, I assume the 14 x 14 Merv 8 is out of stock as no longer showing up on Amazon
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