Home AC filters

[Brett Miller]

Originally Posted By: benjamming
Originally Posted By: Brett Miller
My system has a 5" thick media filter. I usually get about 10 months before the system indicates changing. I have heard of a lot of problems due to the 3M filters since they are very restrictive. Iced coils, burned out blower motors, and cracked heat exchangers.


How does the system indicate changing - minihelic gauge?
How does it crack heat exchangers?


I have a Carrier Infinity system which measures the pressure drop across the filter. When the restriction reaches a certain point, it will indicate to change the filter. A cracked heat exchanger results from the poor airflow created by the 3M filter which causes the heat exchanger to get hotter than normal.

 

[benjamming]

Does it indicate it with a red/green visual indicator or is it that you read the value & when it reaches 0.75" wg change the filter? Thanks.
Do you have standard 1" thick return air filters in addition to the 5" thick filter?

 

[ZZman]

I like 3M filters but will use another kind that says it filters in a similar fashion. Those 3M's can be expensive!

You can have icing problems as my neighbor had that happen. Must be careful to change those filters out.

 

[oilyriser]

I've seen a fibreglass filter that had 1/4" of felt built up on it, and half the air was passing around the bend sides. But the air that did make it through was filtered really well.

 

[Brett Miller]

Originally Posted By: benjamming
Originally Posted By: Brett Miller
My system has a 5" thick media filter. I usually get about 10 months before the system indicates changing. I have heard of a lot of problems due to the 3M filters since they are very restrictive. Iced coils, burned out blower motors, and cracked heat exchangers.


How does the system indicate changing - minihelic gauge?
How does it crack heat exchangers?

No, the Infinity thermostat will indicate when to change the filter. Everything is electronic.

I have a Carrier Infinity system which measures the pressure drop across the filter. When the restriction reaches a certain point, it will indicate to change the filter. A cracked heat exchanger results from the poor airflow created by the 3M filter which causes the heat exchanger to get hotter than normal.

 

[Virtuoso]

I use the $3 MERV 7 pleated filters from Menards. True Blue Basic's or something like that. Change at one and a half months instead of three. So far so good.

 

[brianl703]

Originally Posted By: Brett Miller
cracked heat exchanger results from the poor airflow created by the 3M filter which causes the heat exchanger to get hotter than normal.


You can measure the temperature difference between the input and output air (the temperature rise) to be sure it's within acceptable limits. If not, you may be able to increase the blower motor speed--as I recall, it is usually set lower for heat than it is for cool.

 

[benjamming]

What is typical temperature differential?

 

[brianl703]

For my York 48K BTU 80% efficient upflow furnace, between 25 and 55F with a maximum outlet temp of 180F. That's per the manual.