Air Conditioning - I have an overheating question (again).

I special ordered some MERV 11 filters for my system. I later read that it might not be a good idea. What should I be looking out for? I don't want to burn up anything. (We've already noticed a significant improvement in air quality, so we'd like to stay with these if we can. We live in the country and have lots of allergens, pollens, dust and all the rest.)

CANCEL THE ORDER :alarm: You are begging for trouble. If interested in IAQ (indoor air quality), you should be looking into a media filter. They do a better job without the air restriction you will get with a 1" Merv 11 filter.

The filters came in and I installed one. My wife loves it already, so I'm sol! We've been using MERV 6 filters that are 70 square inches smaller. Her argument is 20% more space should make up for 1/2 the MERV value change. She said if I clean all the system out (ducts, cage, fan, etc.) that we'd be able to use these filters.

I will admit that I agree with her on the IAQ being significantly better. It is tremendously (sp?) better in just a few hours! I would like to continue using this method, if someone can point out the "issues" I should look out for.

What they tend to do is restrict the airflow across the coil. You may be ok but these filters get dirty "clogged" much quicker and will require changing sooner. You may not notice the problem right away but with the lack of airflow across the coil you're taking a chance of sending liquid refrigerant back to the compressor and causing a slow death outside. Not saying it will happen but that is a chance you are taking.

If this filter is on a furnace, there is a very good chance you will overheat the furnace causing it to trip the high limit switch when heating. This can lead to heat exchanger failure.

Merv 11 great scott. What tonnage unit do you have and what filter face area do you have now?

If this filter is on a furnace, there is a very good chance you will overheat the furnace causing it to trip the high limit switch when heating. This can lead to heat exchanger failure.No. This is an attic mounted forced air A/C unit. Please provide more feedback. We're using 1 of them now and really do enjoy the cleaner air.

Merv 11 great scott. What tonnage unit do you have and what filter face area do you have now?I think the unit is 3 ton. The filter being used by prior owners was a dirty 14x25. I went with a clean 14x25 (merv 6), which improved airflow slightly.

They (previous owners) had a 5" spacer plugged in to fill the air intake. I decided to use the "proper" sized filter (which increased the intake area by 20%), but wanted to try "great" cleaning filters. We love the merv 11 filter, but what exactly should we look out for? I can see where the better filter will be needed to be replace more often, but we only use the unit a month of each year. That's one filter per year (in my opinion)..

We're learning this as we go, so please show a little patience. We're just trying to improve our lives a little bit at a time.

Thanks for all the help and advice!

Please pardon my skepticism, but I don't believe there would be any significant improvement in air quality in a few days, let alone a few hours. Many of these filters are treated with a substance to make the air smell "cleaner". In truth, clean has no smell. Odors, pleasant or otherwise, are caused by contaminants. If you doubt what I say, go into a clean room such as in an electronics, chemical, or medical reaserch facility sometime.

I hope you're right. I have already noticed that the filter is close to needing replacing. The cheap filters last several months. If there is no significant difference, I'd rather spend the $3-4 vs. the $10 twice as often. We do seem to require less dusting, though. Could just be our extreme dry season. We're haing our hotest and dryest season in 15 years.