Filter changing

John R. Hall

Please e-mail me with your names, company name, and location. Thanks. johnhall@achrnews.com

John R. Hall

Need suggestions for story

We all know that many commercial and residential customers SAY they change their air filters on a regular basis but we know better. I’ve been with techs when they have pulled out completely clogged filters in a furnace or rooftop unit.



What I am looking for is a compelling new way to attack this old problem. How can HVAC contractors convince equipment owners that a regular filter change program not only keeps building occupants healthy but is part of a regular maintenance program that helps equipment last longer and does not void warranties?



I am open to any new ideas that you have tried and had success with. I know there are some very innovative and creative contractors who have some good ideas and programs that NEWS’ readers can benefit by learning about. I want YOUR ideas.



This article is part of an overall series of articles I am writing on healthy IAQ. I’d like to publish the story in June. I’d also like some high-resolution photos of some of the nastiest filters your techs have encountered. Or maybe you know of a bad filter that I can take a photo of (I travel a lot, you know). I’d like all feedback and photos by June 5th. I sure hope you can help me!

Mike T., Swampeast MO

Electronic thermostats with a "filter change reminder" seem to work well. I'm sure that some just cancel the message, but they are likely lost causes...

Brad White_9

Filter Changing

Like diaper changing, everyone agrees it has to be done but no one wants to do it, it seems.

Some random thoughts:

I personally rely on pressure drop, a Magnahelic or a sensor if DDC monitoring is available. This makes far better use of expensive filters than a time-based change-out schedule.

To see the effect of dirty filters:
When you plot a given system fan curve starting with clean filters then add in the additonal DP when dirty, see what the loss of airflow is.

This is especially dramatic on low-pressure constant volume air systems. If the TSP is 2.5 inches with clean filters, dirty filters can add another inch or 40 percent increase in pressure drop. Depending on your fan curve, the operating point could wind up in the surge area and/or you could lose a significant portion of your airflow. The cost of that lost airflow in terms of HP over time can be quantified; add to that the lost cooling or heating capacity, over-heating the air in winter and if DX, possible coil freezing in summer.


Other thoughts/experiences:

I designed an animal laboratory at Harvard Medical School some years back. 8,000 CFM, 100% outside air, low velocity constant volume. Three (3) banks of filters, 30%, 95% and 99.97% HEPA filters downstream of the fan. Clean filter pressure drop was fully 60 percent of the total pressure drop. Heating and cooling coils plus external low velocity ductwork was the rest.

The problem became apparent during commissioning. Where does one make a base assumption of operating point? I chose the median filter loading points with clean HEPAs for they do not load much with proper upstream filtration.

Started with clean filters and almost 10,000 CFM -too much by 25%. As filters loaded we lost 25%, to 6,000.

In the end we installed a VFD to maintain a constant DP hence CFM across the fan. Nowadays, I would do this routinely, given drive costs are lower than they were.

No photos unfortunately, but stories? Yeah, we got stories.

My $0.02

Brad

EDIT: One More Story:

In 1987-88 I completed a house and pool HVAC design for a local Boston Hi Tech icon. The heart of this system was a heat pipe supply/exhaust unit, fans moving air in each direction.

One minor glitch was that the space was too dry even in winter; with OA at minimum and the pool cover off, we could not maintain 18% RH in there and one would feel chilled by skin evaporation. Not good. This was tracked down to a leaky rolling skylight overhead. That was sealed and RH's settled in the 45% range, perfect. I left the machinery in good working order with O&M manuals, maintenence schedule and some sets of spare filters. (Not bad service considering I was the design engineer )

Ten years go by, late 1990's. Owner's ex-wife -she got the house by this time- calls the architect. Place is humid, mold and condensation issues, what did you do to me, etc. etc.

She calls in a highly recommended building specialist who suggested wrapping the entire structure of exposed natural fir beams in foil-faced insulation board...

I go in to meet with the Owner, the specialist, the architect and the grounds person. Place was muggy and there was condensation that November day.

"Let me check the unit", I said. I went into the mechanical room and the dolly I had left for access was there right where I had left it. The boxes of filters were there with the dates visible, unopened. Uh-oh. Magnahelic gauges pegged to the stops...

I shut down the unit just to open the doors, the pressure was that bad. Never had the filters been changed in ten years. I choked to pull them out. Vacuumed what I could see and put in a fresh set. Started the unit. A cloud of dust emerged then dissipated but the glass condensation evaporated like an invisible hand and squeegee were drawn across it.

Giving an O&M manual is useless without telling people to read it I guess.

Unknown

ur right, John

Ur right about people not changing air filter on timely basis. I had one custmer not getting enough heat out of the furance while the unit shuttin itself on high limit, I pulled the plugged filter out and told him that he havnt replace it since last christmas... Asked me how I know it been that long, told him that this year xmas tree didn't have tinsels while the filter was loaded with last year tree tinsels...

Gene_3

here in CT

it is now law that public schools must have a maintenance schedule for their equipment after a few years of bad indoor air quality problems

my issue with that is the morons in Hartford did not extend that to all buildings

many commercial buildings are cutting corners but they will save by doing the maintenance as required by the manufacturer and the usage of the unit, some run 9-5 M-F, some run 24/7, residential units generally don't run as much as comm but if they do get heat & a/c from the same equipment they should change the filter at the start of each season.

commercial may require monthly inspections or more, generally once a systems operating characteristics are known a pattern can be established and a set schedule follows

at any rate, any system will run better, more efficiently and save money while providing cleaner air if filters are changed at regular intervals, some units, like oil fired warm air, may get cracked heat exchangers from overheating due to dirty filters, costing them a new unit or even soot damage to the home, a real incentive!!!!!!!!!!!

GaryDidier

Changing filters

Forget it, most people will not change filters. Thats why yearly maintainence is done. I too have been out on no heat and low heat calls due to plugged filters.

Gary from Granville

Paul Fredricks_3

When I worked for a LINC contractor (all commercial) the sales people used a presentation that put a dollar figure on potential savings. Very powerful when talking to the building owner who is always looking to cut costs.

John R. Hall

Please keep the ideas coming

I appreciate the input so far. I'd like some more thoughts as I will be compiling my article over the weekend. Please keep some picture ideas in mind if any of you are doing clean and checks in the next couple of days. A good digital pic may make it to the front page of The NEWS. Thanks!

Techman

Filter

HI John!Compressors,Expensive Compressors,Very Expensive Compressors!!! After hearing of the replacement prices for the most expensive part of the system my customers willingly allow me the honor of changing filters ,twice a year, once per season.Plus filters are only part of a full inspection,ALL customers must agree to inspections or prompt responce to service calls is not guranteed, ALL inspection customers get 1st responce ,then time allowing the non-inspection customers get service.Losing a non-inspection customer is no big deal,Gaining an inspection type customer is very important.

joel_19

simple

Sell them a maintenance contract which includes changing the filters. or sell them a service contract where you fix anything that breaks except for big ticket items emphasize that this extended warranty is VOID if you don't change the filters , just like changing the oil in your car. Some guys sell it as monthly monitoring fee as opposed to yearly.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Jeff Lawrence_24

Here's some.

The first two pictures are from a house that I did a furnace changeout about a year before. I made sure that it had a easily changed filter with a rack on the front.

The second set is of a blower that I pulled. Based on the condition of the bower, I did check the evap coil, but it was amazingly clean.

Please realize that these pictures are full sized. I have not re-sized them at all.

John R. Hall

Thanks Jeff (nm)

hr

Make them easier to FIND and replace

To often the homeowner does not know where the filter is located. Often they have cheesy, ill fitting "tools required" acess doors.

A niced hinged lid with a bright sticker would probably help encourage filter maintanance.

Good quality washable filters would be another suggestion for installers.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Tombig_2

Filters

I once tore down six apartment furnaces and thoroughly cleaned. One filter (and front panel access) was in the back of a clothes closet behind a panel with screws to remove. I reworked and added filter grilles. Left a case of filters each and notes to change the filters as often as they like, at leasdt four times a year. The landlord will bring more. A year later and only one tenant even changed it once. The rest had a full case of filters in their pantry and furnaces that needed cleaning again.

S Ebels

Jeff

Twice this past winter, I encountered blowers that were Soooooooo bad that I took them out of the house and down to a local car wash to hose them out. One furnace had a filter in it that obviously hadn't been changed in years if not decades, the other had no filter at all.

In talking with the owner at that place, he claimed that in all the time living in the house he had never changed a filter because he couldn't find one. Figured the system didn't need one and he had lived there for 12 years! It was completely covered over with dust, debris and cat hair. You literally couldn't see the vanes of the blower wheel.

When I re-installed it and the blower came on he asked what the noise was. It was air coming from his registers. He also mentioned that the high limit had been replaced by other furnace guys three times in the last 5 years. Duh!! I wonder why? I also wonder how anyone claiming to be an HVAC tech could have "overlooked" the cause of the blown high limits. The limit being blown was the reason for the service call I did. Guess that makes 4 in 6 years........Makes you wonder sometimes.

Jeff Lawrence_24

no cooling coils?

I installed a humidifier for a customer not long before Christmas. As I was doing the metal work, I noticed the burners kept coming up and going off. I mentioned it to the homeowner and they asked me to look further.

Here's the resulting find.

The burners kept running the entire ~20 minutes I had them on after the coil was cleaned, where before they would run 2 to 3 minutes and cut off.

Plumdog_2

Pressure Differential

I see no good reason why a simple pressure differential device with an adjustable or variable set point switch couldn't be incorporated into the design of a residential furnace. The device would trip when the return/supply pressure differential reached a point (set by the installing technician) that indicates a degree of restriction likely to cause an increase in gas or electrical consumption. The T-stat could have an LED light that provides a gentle reminder at first and a warning above a certain restriction. Magnahelic gauges look impressive on commercial equipment; but the guys that are supposed to change filters don't know what they are. I have seen residential furnaces in crawlspaces that have never seen a light bulb in 20 years. Plenty dead mice inside.

Ron Schroeder

Plumbdog

And when it shuts down they will just set the limit higher until the same thing happens

S Ebels

And people wonder

Why their equipment dies and why they are always feeling ill or are outright sick. If they only would pay attention to a good heating tech and care enough to learn a little about their equipment..........

A stitch in time, saves nine............Grandma always used to say that when she came over and mended our socks when we were kids. I guess it applies to heating systems too.

Christian Egli_2

At least a clogged filter is a 99.999% dirt stopping filter

Just like the super tight HEPA ones you can pay good money for... without the hassle of changing them constantly. Ooooh.

Did the pictures of the caked on coils and fans actually have an air filter on line? or was the coil the only thing to stop the flying dust bunnies and other furry animals?

The worse unit I have seen is a Magic Chef downflow furnace. To get to the filter, simply remove a cover panel. So far, so good. This panel opens onto the flue passage, you then simply need to remove a portion of the smoke pipe. Then you're back at working on two tough cookies half panels that open on the blower compartment. It should have been all downhill from here on, but noooo, it's one of those shroud type filter that you wrap around the fan like a scarf. Impossible to get the bottom corners tucked in.

Reverse procedure for...

Perhaps I missed the part in the instructions that said you need to bulldoze half your home first. The part I didn't miss, is the one where the plant in Columbus (the one that built these beauties for a short while) has been bulldozed itself.

On a further note, what sort of 99.999% filter, anyone here would recommend for stopping raccoons?

Oh the irony of this, an Industrial Hygiene Lab in one of our buildings has a need for lots of clean (-ish) make up air. So, they installed an air handling unit that feeds on (fresh) air coming down a tube from the roof two stories up, a bit like the funnels on the Titanic.

Who knew, the sun deck was occupied by a family of raccoons and they transformed the air funnel into their penthouse. And then they partied.

I got involved when we started noticing bad smells, like those of a problem sewer. That's what we investigated for a long time. For various reasons, the air handler was never suspected until, one morning, after what must have been a disco night party at the raccoons, we found our make up air pipe busted into three chunks with the trashy belongings of those raccoons spread all around the floor.

The raccoons had made it all the way down to the air handler, that's what was amazing. We now believe they lived there for two seasons. So, here is the lesson:

Don't forget to install a raccoon filter and don't think it's a good idea to send furry animals down your pipes thinking they'll scrub the dust away cheaper than the air duct cleaning guy can.

But how else will you keep your pipes hygienically clean?

Jeff Lawrence_25

pictures

All 3 sets of the pictures were taken at differnt customers houses, amazingly enough.

The filters were from a rental. The blower and coil were still fairly clean.

The blower was in a condo. There was a filter in the system and I am still amazed that the coil was nearly perfectly clear.

The evaporator coil was a different story, I think. The house was a resale and the current owners had lived there for maybe 3 to 4 years in a house that was built 7 to 8 years before they moved in. Since you could nearly eat off the floor of the house, I'm guessing that the husband/father pulled the blower and cleaned it rather thoroughly, not thinking about the coil be downstream in the airflow. They did call a week or so later and mention the house was warming up better. I'm thinking the cooling was better also and possibly will be a little less expensive to run.

It's amazing what you find when you look, listen, and dig deeper. Checking evap coils can be a real pain in the you-know-what.

Matt Clina

Get a Cub Scout

I have been guilty of neglecting my furnace filter for 6 months at a time, but I have made a big effort recently to keep up with it. My main concern being energy savings, but we also have a house full of allergy sufferers.

I bought a supply of "better" filters, which come with reminder stickers. I change the filter, and stick the sticker at the top of the basement stairs with a date three months in the future.

But what REALLY helped, is when I was working on a Cub Scout achievement with my son, and we went through all of the household maintenance items that I normally do. Now he asks me every month whether it is time to change the furnace filter yet.

ljacobs1987

filter

I need someone to help me with this question. I know how to replace my



furnace filter and all but I don't know where to get them. I looked at



some hardware stores near my house and didn't see anything! I figured



that is where they would typically be. Guess not. I'm going to try to do



some online shopping for them, but I'm really hesitant to buy anything



online. Can someone let me know if this website that sells furnace filters would be an OK place to look? Let me know. Sorry, I know I'm a little behind on the technology.