Garage Furnace Filter

[65Stang]

I have a house furnace (converted to propane) for my heat in the garage and shop. The return is located in the garage, which doesn't get much, if any, dusty work done in it and it is completely finished. The shop, which is separate, has a supply as well, but no return. I do wood working in the shop, none in the garage, which is just for storing my two summer drivers. I noticed that the garage wasn't warming up as quickly and took a look at the filter in the return vent and it was not getting much air flow. Removed the filter and lots more air flow. Filter has been in there for two months. Use the furnace/heat about two or three times a week.

1. Do I really need the filter? I am not worried about air quality, but what can dust do to the furnace.

2. Is there a better way to filter than this one.

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3. Or do I just need to stock up on filters and replace once a month... $$$.

 

[nehog]

Or a washable filter?

With no filter, the blades of the fan (squirrel cage) will fill with dirt and that will impact the efficiency of the fan. Years ago, when I did HVAC work while in school, one thing we always did was clean the blades carefully, and always noted a good improvement in the amount of air moved. Those who ran without filters (a few) always had blades that were totally crudded up.

 

[mobetta]

buy the cheepo blue fiberglas units by the case when they are on sale. that is probably what your furnace is designed for anyways.

 

[djjsr]

Definitely keep a filter in place. Aside from being better for your furnace, it'll reduce the amount **** you breath. I built a box that uses 2 of the cheap blue filters and attached it to a store-bought air filtration system. I'm amazed at how much dust it catches when I'm making sawdust even though I have dust collection on my saws.

 

[Jackfre]

Todays air filters are MERV rated. MERV indicates first day efficiency. The higher the merv rating the better the filter. The blue furnace filters don't filter until they get dirty. They are cheap and that is all. I would suggest that you certainly want to keep a filter in there. Buy pleated filters only and use at lest a merv 8. If I had warm air I'd be using 11 and 12's. I would watch for filter sales, buy by the case and change them regularly. A dirty filter on the return air cost more in energy loss due to poor air flow than the regular replacement of air filters.

 

[Designing Woman]

Hello 65Stang! I agree – you really do need the filter. While you need the air flow, the life of the furnace needs to be addressed. There are some great filters – some for larger particulates – and other that last 3 months (can save some money over the long run). Will you get much pollen in the springtime – I assume peak season for prepping the summer drivers? This will also contribute to the use. Best wishes on your wood working projects.

 

[jocool1585]

Can we see a picture of where and how the furnace is installed? Maybe you could enclose it and filter the air coming into the space?

 

[HDNewf]

+1 Jackfre
Hey 65Stang, HDNewf here from the Home Depot out of Chicago.
I agree that you should continue to use a filter, and that pleated ones are the way to go.

As Merv numbers climb, they indicate the ability to filter smaller and smaller particles. Filters that cost >$15 each tend to be HEPA rated electrostatics, which even filter out smoke and viruses.

For a garage/shop system, I think that a basic filter that handles dust, mold, bacteria and pollen should be sufficient. Currently you can get these for about $4 each, or in 3-packs for $6.48. They should be changed at least every 3 months, but even monthly changes are not very expensive:

NaturalAire FPR4 Merv8 special 3-pack: http://v.gd/GJExsT
I hope this helps,

HDNewf

 

[csp]

It's a garage. Use the cheap spun fiberglass filters. Two good friends of mine are in the HVAC business. One owns an HVAC supply business and the other is an HVAC tech and has been in business since 1980. Both say that the pleated, micro particle filters decrease air flow and decrease the life of the blower motor because it has to work harder. They recommend spun fiberglass. For people that need cleaner air they recommend a different type of filtering system with much thicker filters which don't decrease the air flow.

 

[rickairmedic]

Stang I use pleated filters in my house system . The ones I use I get from Homie Desperate usually in a 3 pack for less than $8.00. I dont recomend the more expensive 3M pleated filters as they reduce airflow to much as CSP stated . I buy these at Homie Desperate as I can get them cheaper there than at any of my supply houses . I also change them monthly period. I blow more on Powerball tickets than I do on filters.

Rick

 

[65Stang]

Here is the completed garage, supply on the right, return on the left. The openings are actually the same size, the right side grill is just larger that the opening since I already had the vents and used what I had.

View media item 6790
Furnace is located above in the attic space between the two, wood shop is through the man door with a separate supply in there. With the return in the garage, I still probably **** dust through the mandoor into the garage.

View media item 1020

 

[Mike007]

It's a garage. Use the cheap spun fiberglass filters. Two good friends of mine are in the HVAC business. One owns an HVAC supply business and the other is an HVAC tech and has been in business since 1980. Both say that the pleated, micro particle filters decrease air flow and decrease the life of the blower motor because it has to work harder. They recommend spun fiberglass. For people that need cleaner air they recommend a different type of filtering system with much thicker filters which don't decrease the air flow.

Hate to disagree with your friends, but as the filter gets dirty and decreases airflow, the load on the blower motor decreases since it's doing less work. This can easily be demonstrated by covering the intake on a vacuum cleaner with your hand. The motor rpm increases because it's doing less work. I don't recommend the pleated type filters because I've found most heating and cooling systems do not have the ability to move enough air with a pleated filter. Especially if it's been in service for more then a month. Pleated filters generate a lot of repair work and generally waste a lot of energy.

 

[Mike007]

Hate to disagree with your friends, but as the filter gets dirty and decreases airflow, the load on the blower motor decreases since it's doing less work. This can easily be demonstrated by covering the intake on a vacuum cleaner with your hand. The motor rpm increases because it's doing less work.

I should add, this may not be true of a variable speed motor. As airflow is decreased by the dirty filter, the motor ramps up to keep the air flow constant in which case it would be working harder.

 

[csp]

The reference was in regards to a clean spun fiberglass vs. a cleated 'ultra-micron filtering' pleated filter.

I didn't say anything about dirty filters.

RPMs don't go up on a plugged vac motor either when you plug it. You're hearing the additional load when you plug it, not more RPMs.

I'll take the word of the pros who replace and provide the equipment any day over everyday joe's on the internet, thanks. These guys hear the what to do's and what not to do's directly from the manufacturers.

Go drink out of a straw. Now pinch the straw but not all the way shut. You'll have to **** harder to get the same volume of fluid through the straw in a given amount of time. It's simple physics.

 

[Mike007]

The reference was in regards to a clean spun fiberglass vs. a cleated 'ultra-micron filtering' pleated filter.

I didn't say anything about dirty filters.

RPMs don't go up on a plugged vac motor either when you plug it. You're hearing the additional load when you plug it, not more RPMs.

I'll take the word of the pros who replace and provide the equipment any day over everyday joe's on the internet, thanks. These guys hear the what to do's and what not to do's directly from the manufacturers.

Go drink out of a straw. Now pinch the straw but not all the way shut. You'll have to **** harder to get the same volume of fluid through the straw in a given amount of time. It's simple physics.

Believe what you want CSP. No offense intended. If you don't believe me, look at the amp draw on a motor running with a dirty filter, I have. I can tell you the amp draw drops because the motor is doing less work.

 

[6768rogues]

You said your shop has a supply and no return. Either the pressure in the shop will increase until the static pressure of the fan is met and then no airflow or the air is finding its way out or back to the garage. You can only shove so much air into a box.

 

[Jackfre]

This is way to animated for a friendly forum. That is a great garage with some great cars and gear. As to filters, everyone gets to choose what they like. I'll stand by my original post. I don't know everything about air filters. That was made abundantly clear to me by the many fine people I worked with in the 17 yrs I represented Purolator in the HVAC, P/H, Refrigeration industry.

 

[larry4406]

Sounds like the dust is being generated in the wood shop which is provided with a supply, but no return. There is a man door between the garage and the wood shop. The garage has the actual return. When the man door is closed, the wood shop is dead ended on air flow so hard to push air in.

Add a transfer grille between the wood shop and the garage and equip this with a washable filter (you could put this literally in the door); this should improve the temperature and air flow into the wood shop. This "pre-filter" will then lessen the load on the unit's main filter which is in the garage proper.

 

[klhitman]

Sounds like the dust is being generated in the wood shop which is provided with a supply, but no return. There is a man door between the garage and the wood shop. The garage has the actual return. When the man door is closed, the wood shop is dead ended on air flow so hard to push air in.

Add a transfer grille between the wood shop and the garage and equip this with a washable filter (you could put this literally in the door); this should improve the temperature and air flow into the wood shop. This "pre-filter" will then lessen the load on the unit's main filter which is in the garage proper.

or you could put a return vent in the shop with a return vent filter.

 

[henrysgarage]

No matter what filter you use change it!!! I went out to the garage and found it cool, 51* when it was set to 60*(-25C). The furnace would start then stop so I cleared away stuff(non combustible) from in front of the front panel to get access to the filter that is inside the furnace, bottom inlet type. It was so full of dust etc. Installed a new filter and it is working great, a pleated type, no reason for buying this type. I want to fab a filter holder to sit under the furnace to hold two filters or maybe 3 on each side attached to the steel legs.