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Open Roads Forum  >  Tech Issues

 > Better AC filter for those who havnt seen it yet

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wopachop

Who run bartertown

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Posted: 06/27/21 11:36am Link  |  Quote  |  Print  |  Notify Moderator

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.

[image]

Gdetrailer

PA

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Posted: 06/27/21 12:24pm Link  |  Quote  |  Print  |  Notify Moderator

Pleated filters like that are considerably more restrictive to air flow than the original washable foam filter.

It is good that you checked air flow but even a slight restriction under the correct conditions may result in the A/C cools to freeze up into a solid block of ice much faster than they would otherwise.

I use those filters on my wood burner fan box to reduce wood ash from getting blown through the house. I modified the fan box to use two filters in fact side by side and even that causes a noticeable change in air flow.

I won't even consider them on my home furnace, causes the furnace to trip the overtemp limits once and a while..

hypoxia

Arizona

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Posted: 06/29/21 06:00am Link  |  Quote  |  Print  |  Notify Moderator

Gdetrailer wrote:

Pleated filters like that are considerably more restrictive to air flow than the original washable foam filter.

Agree! The original style were there for a good reason. You are not doing your A/C unit a favor. These units were not made for that filter.


Jim

2007 Monaco Signature Noble III ISX 600HP

Cummins12V98

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Posted: 06/29/21 09:23am Link  |  Quote  |  Print  |  Notify Moderator

You guys need to put FACTS out with your opinions on the OP's filter mod.


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ktmrfs

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Posted: 06/29/21 09:42am Link  |  Quote  |  Print  |  Notify Moderator

hypoxia wrote:

Gdetrailer wrote:

Pleated filters like that are considerably more restrictive to air flow than the original washable foam filter.

Agree! The original style were there for a good reason. You are not doing your A/C unit a favor. These units were not made for that filter.


I suspect the reason for the original filter was issue of cost, size, and a few other reasons, none of which I'd consider "good" reasons.

A decent quality pleated filter resistance is measured in fractions of an inch of water column pressure. Fractions of a psi difference across the filter.

The pleated may be significantly more restrictive, but still not anywhere near enough restriction to affect performance. Ducting in the system likely has higher resistance to airflow than the filter.


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fj12ryder

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Posted: 06/29/21 09:56am Link  |  Quote  |  Print  |  Notify Moderator

"Ducting in the system likely has higher resistance to airflow than the filter."

That is probably true, but adding the pleated filter doesn't help the ducting any, and if it is indeed more restrictive, now you have double trouble.


Howard and Peggy

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Posted: 06/29/21 10:17am Link  |  Quote  |  Print  |  Notify Moderator

Exactly what kind of cooties are you trying to trap with that giddyup?
But it is "black label", which from my extensive drinking experience, means QUALITY! And on the upside, the drinking part makes me not care bout painter's taping a filter to my camper ceiling!


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red31

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Posted: 06/29/21 11:15am Link  |  Quote  |  Print  |  Notify Moderator

if I had ducts, I'd have rvairflow that smooths air flow in the plenum and also smooths/increases the intake area
https://rvairflow.com/pages/the-details

Gdetrailer

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Posted: 06/29/21 11:18am Link  |  Quote  |  Print  |  Notify Moderator

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..

[image]

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.

NRALIFR

Truck Camping Out West

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Posted: 06/29/21 11:19am Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

You guys need to put FACTS out with your opinions on the OP's filter mod.


What???

“Nattering nabobs of negativism” don’t need no stinking facts!

I know, I just dated myself. [emoticon]

[emoticon][emoticon]


2001 Lance 1121 on a 2016 F450


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