Done this the last couple summers with a household filter. Its the black label from Lowes. The different sizes are the same price, so get the 20x30 (or largest you see) if you decide to try it.
I remove the foam filter and the plastic screen. Last year i used a wind meter to measure air speed coming out of the vents. That was with a smaller filter last year and it didnt seem to restrict flow.
Also last year we had lots of fires. People were putting these filters on the back of a box fan to filter the air. Not the worse idea.
I remove the foam filter and the plastic screen. Last year i used a wind meter to measure air speed coming out of the vents. That was with a smaller filter last year and it didnt seem to restrict flow.
Also last year we had lots of fires. People were putting these filters on the back of a box fan to filter the air. Not the worse idea.
I see a return plenum of about 2" in depth with a filter surface area of at least 3X the original filter. The additional pleated filter surface area should more than make up for the restrictive nature of the filter. Increasing the plenum depth would help. Only an anemometer would know for sure.
I personally would not do this but I do not see a big concern with it.
Cummins12V98 wrote:
You guys need to put FACTS out with your opinions on the OP's filter mod.
HERE
"At the end of the day, the short answer is: yes, pleated air filters do restrict the air flow to your furnace. "
HERE
"Q. Do high-MERV filters reduce airflow?
A. Though there are considerable differences in how different filters affect airflow, Figure 2 shows that there is a definite trend toward lower airflow with higher-MERV filters for systems using PSC motors. Over the range of filters tested, there was no such correlation between airflow and filter MERV rating for the ECM, which can maintain constant airflow over a large range of external static pressure."
"Q. Do the reduced airflow rates of high-MERV filters in PSC systems affect compressor energy use?
A. Air conditioner and heat pump rated performance is a function of airflow over the indoor coil. Lower airflow can decrease capacity and consequently the EER or HSPF of the system. We looked at representative manufacturers’ performance curves and found that, over the less than 200-cfm reduction in airflow observed between MERV 2 and MERV 13 filters (see Figure 2), the impact on compressor power is almost insignificant.
However, filter pressure drop can more than triple when the filters are fully loaded with dust particles, so loaded filters probably affect system performance. The deeper-pleated filters allow dirt to be spread over a larger surface area, reducing pressure drop and/or allowing less-frequent filter changes before system performance is significantly affected."
"Pressure drop and system performance are definitely worthy of consideration when applying high-MERV filters, and duct design and filter sizing should be considered in the design process. However, if no accommodations are made for the greater pressure drop of high-MERV filters, airflow and energy penalties are not likely to be severe, at least until the filter is loaded with dirt. More study is needed in this area."
HERE
"MERV Filter Ratings and Efficiency
When selecting the right filter for your application, higher is not always better. Using an air filter with a MERV rating higher than what your furnace or air conditioner manufacturer recommends can actually impair its performance.
The smaller pores in more highly rated air filters create resistance to air flow, and if the filter is used in an HVAC system that is not designed to handle this resistance, it can lower the system's efficiency, decrease indoor air quality, and put strain on the system's fan."
HERE
"Some homeowners want cleaner air, so they buy an HVAC filter with a high "MERV rating." This rating, which ranges from 1-20, represents how well filter can catch smaller airborne particles ("1" meaning it can only catch large airborne particles, "20" meaning it can catch very small airborne particles.)
Here's the problem: Some filters with a high MERV rating can drop air pressure in your duct system, which can increase energy bills and damage your HVAC system.
For example, let's say you have a pleated filter that's 1-inch thick and has a 13 MERV rating. Because the filter is thin and the MERV is high, it reduces airflow into the duct system. And like we said before: low airflow = wasting energy. To make matters worse, this type of filter will reduce airflow even further once it gets dirty, which it will do very quickly. "
I could go on, and on and on..
Here is "proof" from the Filtrete pleated filters I have for my wood burner fan..
PD or pressure drop of that MERV 11 filter is .10-.52 depending on the CFMs being pulled through.
That IS considerably far more restrictive than the OEM foam filter that the RV A/C was designed for.
When my wood burner fan is running, the pleated filter is restrictive enough to hold the filter in place until the fan is shut down without any mechanical means.
It doesn't take a rocket scientist to figure this one out.
