Air Conditioning - Magnehelic For Determing Filter Change

Wanted some opinions about using a Magnehelic Gauge for determining the proper time to replace fliters.

Here's the story, I am very allergic to Black Mold Spores and must use 4" Merv 11 filters. I am installing a new Frigidaire 2 ton 14 Seer A/C and matching variable speed air handler with TXV.

The question is: Will the magnehilic gauge give reliable results.

I will be using a 1" W.C. (full scale) gauge across the filter. The filters are expensive so I did not want to rely on time periods, as the filter may get dirty early or later than scheduled changes.

I also think a .4 increase in differential pressure is a good number to start with for changeing the filter.

Regards,
Sign-Man

I would go on the six mouth time instead of the magnehelic. If this is a space guard you can pig up the refills on the net cheap.

The air handler will be running 24/7.

Half speed when A/C or Heat are off.

Different tracts for different acts. I think that changing filters based on how many weeks/months of service or by visual inspection is silly. On the other hand, a Magnehelic will cost $50. and you could probably buy a half dozen (or more) filters for that price.

I don't have a filter gauge in my unit and I DO have a couple of Magnehelic gauges sitting on the shelf not five feet away from the filter rack so whatever I might state is only an opinion. :cool:

Black Mold - Stachybotrys chartarum - grows where you have severe water damage.
About Black Mold - MOLDetect.com (http://www.moldetect.com/black-mold.htm)
I would find the root source of this black mold.

Your family must be very sick all the time. In order to filter the black mold from the air it must be in the air in the first place. That means you are walking around your house in air contaminated with said black mold.

Makes me think of democrats throwing money at a problem. Fix the cause not the symptoms.

Mag gauge is commonly used in commercial apps to check filters.

You could install it, but it would be a trial and error thing. How long do you let the air handler suck mold from your walls before changing the filter....

I live in a Condo unit that is built back into the ground with only the front exposed. This building is at the lowest point of a hill.

The condo association has tried repeatedly to control the mold growth under the unit, to no avail.

At 12.00 a pop, filters can get expensive. They clog and turn black rather quickly.

I am upgrading the HVAC system in an effort to lower the humidity and inhibit some of the mold and mildew. Running the blower 24/7 helps very much.

As far as the Magnehelic goes it is purely a gadget to occupy some of my time (I'm 100% disabled). I'm an electrical engineer by background and rarely leave my humble abode anymore and am always looking for some technical toy to play with.

I don't want to create to much suction force on the blower motor by not minding the differential pressure. But then again I don't want to replace filters before their time.


:program:

Arbitrarily picking a pressure drop of .4" wc could be too much. Without knowing what the total static of your system is with a clean filter, you could be running a very high static. It could even be in excess of 1" wc (possible damage to guage).

With a variable speed air handler, the blower will ramp up to maintain airflow as the filter clogs. At a minimum, you electric usage will be higher; depending on static, could harm blower.

If you're using a 4 or 5" filter, you could probably get by with changing it twice a year (April and October is good), but should visually monitor it.

delta

Time out! You said your filter is getting black. Id bet you my pay check that it is not mold. Id bet that it is most likely from candles or suit from a fossil fuel appliance (stove, water heater. It could be from other sources but these are the most common. So how many candles do you burn?

Sorry Airman, I never burn candles and this is a total electric house.

You can see the mold growing behind the commode and the humidity in here (very high) combined with the lack of sunshine to all but the very front of the house leaves an optimal breeding ground for mold.

Second time out!!!
If you are seriously affected by mold and can see some I would spend the money for the gauge on cleaning up and preventing the growth the mold you can see.
You have a serious moisture problem and it has to be fixed before you go any further.

After you stop the water damage a static pressure gauge would be a big help in deciding when to change filters but I would not go by this alone.
As said, experimentation with pressure drop and filter appearance would be a good way to do it.
Besides, for some the more gadgets the better! :D

Time to move!!!

The condo association (or whomever) sold you a death trap. Take them to court and make them buy it back.

I agree.
I am not totally familiar with the operation of a condo association but is this entity responsible to individual unit owners in spite of being a owner run group?

The condo association has tried repeatedly to control the mold growth under the unit, to no avail.


This is serious and a lawyer could be very helpful in this.
Is your unit recently purchased?

Been here 34 years. I went up into the ceiling today and inspected the 10" space between the floor upstairs and the ceiling downstairs, every piece of wood and insulation has a fine coating of black mold.

There's no way to repair the damage, and there is no contractor to sue.

Just have to take steps to isolate the inside walls from the spaces outside and between the walls. In the mean time I filter the air 24/7.

One step at a time. :wall:

Id spend the money in a good dehumidifier before you work on your filter.

Is this on a crawl space. Has it been sealed.

Ouch, talk about a rock and a hard spot. First, have you talked to your insurance co. If you did not create the problem, maybe they are on the hook. Second, as posted, the mold is in the air and you can't be breathing it. You should be wearing the air filter. And airman is very correct, spend your money on dehumidifiers to eliminate the moisture, and then follow up with a total clean up (insurance). Once you have eliminated the conditions for the mold to grow, and have removed the current mold, your condo is clean and no filter is needed, unless you want to play. Right now, you are one of the air filters and if you have been there for 34 years, no wonder you are allergic to it.

Start at the source,
Bud

Everyone is correct about humidity control. My first objective is to get this antique air handler and non-matching condenser replaced.

I will be tuning the system for maximum moisture removal than max efficiency. This will cost about as much money in extra run time as using a dehumidifier.

Anyway, back to the original question of the max static pressure across the 4" filters between new and safe differential pressure of a dirty filter on a Frigidaire 14 seer system with the variable speed GE ECM blower.

Everyone is correct about humidity control. My first objective is to get this antique air handler and non-matching condenser replaced.

I will be tuning the system for maximum moisture removal than max efficiency. This will cost about as much money in extra run time as using a dehumidifier.

Anyway, back to the original question of the max static pressure across the 4" filters between new and safe differential pressure of a dirty filter on a Frigidaire 14 seer system with the variable speed GE ECM blower.

Two stage with VS blower will get you max RH removal. Longer run times at lower speeds. It should cost you less to cool. Take a look best on the market for RH Santa Fe Max Dry Dual XT (http://www.thermastor.com/Santa-Fe-Max-Dry/)