Air filter?

[Gareth96]

I'll be running my BK Princess for the first time this winter.. was planning on keeping my furnace/ac (heat pump) fan running to help circulate the heat. I have been using just the cheap fiberglass filters, should I go to one of the pleated MERV filters or shouldn't it be an issue? Main worry is buildup of any particulates on my condenser/heater coil..

 

[Lumber-Jack]

I always use two filters. I put a cheap filter in front of a more expensive filter and replace the cheap filter two or three times before replacing the better filter.
I would never rely on those cheap fiberglass filters alone to keep the condenser/heater coils clean.

 

[Jags]

Using the furnace to move heat has had very mixed results. Often it has been found to not work as planned. Much of this depends on the insulation on the duct work. Before you get all crazy with filter configurations you might want to find out how this process is gonna work for you.

 

[Lumber-Jack]

Jags is right, blowing all your money on two 2 filters is quite a crazy idea, especially if one of them cost more then $5. What was I thinking??? LOL
Sorry Jags, couldn't help myself.
I
Actually Jags has a point, not that spending a few bucks on extra quality filters is crazy or a waste of money, because those filters can only help protect your furnace as your were suggesting in your original post, and also a good quality filter can help clean the air in your home. But there is a possibility that running a furnace fan might not work to spread the heat around because apparently a lot of houses in the US run their ducting through un-insulated spaces in the house and can and will loose heat as the air gets pushed through those un-insulated areas.
In my case all my furnace ducting is contained within the insulated envelope of the house, so there is no heat loss, just a smooth uniform mixing of the air within the house when running a furnace fan. That is not to say the temperature is exactly the same in every room in the house, that is not possible. However, it keeps the stove room cooler and the cooler rooms warmer, while at the same time cleaning the air in the house, which is nice because wood stoves tend to create extra dust in the home.
The other alternative way of moving the air around in the house that is often suggested in this forum is placing fans around on the floor and blowing the cold air towards the stove, or stove room. If the furnace thing doesn't work for you for some reason, and you don't mind tripping over fans once in a while, and don't mind the extra dust they kick up, that might be the way to go for you. Of course they won't clean the air in your home, and they will likely cost more then quality furnace filters, and they tend to be noisier than running furnace fans on low, but they do seem to work for some people.

 

[Jags]

With my furnace there is no option to stack two filters unless I was to alter the ducting. That would lead to a bit pricey (re: hepa filter) filter. Not that there is a down side to that, but I think I would want to know if its gonna work first before I even bothered.

 

[Lumber-Jack]

Fair enough, not every furnace accommodates 2" of filter space, but many do.
Actually you don't need to stack the the quality filters, they come in 1" size. I just like to stack them with a cheap filter first because it extends the life of the more expensive filter. By putting a cheap filter in front the bulk of the coarse dust gets caught first and the fine filter only has to filter out the fine stuff that gets through the cheap filter. I'll go through 2 or 3 cheap filters before I need to replace the expensive filter.
Many HVAC guy recommend using the better quality filters to protect the insides of the furnace. They don't have to be HEPA filters, but those cheap $2 filters let a lot of crap through that can over time plug up the coils and condensers.
All I'm saying is whether Gareth uses his furnace to circulate the warm stove air in his house or not, a quality filter is not such a crazy idea.

 

[Jags]

a quality filter is not such a crazy idea.

Agreed.

 

[Sconnie Burner]

Yes get a good filter. Burning wood creates a lot of extra dust. I don't run my furnace fan 24/7 but have it on for a few hours a day to help clean up the air. I do have a humidifier on there as well that helps keep the house from turning into an electrical field of dryness! As mentioned, it will keep the temp most consistent between rooms, and from the reading I've been doing it may not be the most efficient as far as getting the most heat out of your stove/wood, as the air will cool flowing through the duct work, insulated or not. It sounds like the fans blowing towards the stove is going to be the best bet to get that heat moved out of the area to the rest of the house.

 

[Lumber-Jack]

as the air will cool flowing through the duct work, insulated or not..

Actually the laws of physics dictate otherwise. The heat must go somewhere, ducts are not black holes, they can not continue to suck heat out of the air and make it disappear into nothingness.
It's true that if you start blowing warm air through cold ducts the air will cool,,,, until the ducts warm up to the temperature of the air, after which the air will no longer cool as it passes through the ducts. Later if the air temperature being forced through the ducts becomes cooler than the ducts for some reason (eg; the stove goes out), the duct will give off some that stored heat and actually warm the cooler air as it passes through them.

 

[Gareth96]

Yep.. all my ducting is in interior walls (or between floor levels) so any heat loss into the ducts would still go toward heating the innards of the house. Furnace is in the basement, wood stove on the main floor.

I did some internet searching and it looks like filter type is a heated topic in the HVAC community. Wood stove aside, some say the fiberglass are best so you maximize flow across your coils, some say the pleated MERV filters are best.. So what's everyone's opinion on the lowest MERV you would go for just wood stove particulates?

Oh, and I currently can't stack two filters.. but, the original filter location was blocked by a drain pipe, so they made an alternate location when the furnace was installed (before I bought the house). I'm planning to replace the drain pipe after AC season because the angle they have sucks, it's angled wrong and leaves water backup in the tray around the coils causing sludge.. so if I can route it around a bit I can access the original filter location and then be able to use two filters. Once I do this I can run a cheapo fiberglass in the first filter position.. then put the lowest MERV rated filter of use in the second position so I get the best airflow without straining my blower.

 

[Lumber-Jack]

I did some internet searching and it looks like filter type is a heated topic in the HVAC community. Wood stove aside, some say the fiberglass are best so you maximize flow across your coils, some say the pleated MERV filters are best.. So what's everyone's opinion on the lowest MERV you would go for just wood stove particulates?.

That is the problem I found with the all the higher rate MERV filters is they plug up quicker and reduce airflow, but there doesn't seem to be any way around that except for changing the filters frequently, or as I do put a sacrificial fiberglass filter in front of the higher quality filter. The higher the MERV rating, the more stuff it will catch, the quicker it will plug up. As to whether to use just a standard fiberglass filter or a higher MERV rating, you have to decide just how much stuff you want to suck through your furnace coils and/or blow back into your house. Personally, after running two filters and seeing just how dirty the higher rated MERV filter still gets after going through the fiberglass filter, it is pretty convincing evidence that those fiberglass filters let a lot of stuff through.
Of course it's good to maximize the airflow across your coils, but I think the best way to do that is using quality filters and change your filters often when they start to plug up, not use a lower quality filter that allows more stuff to flow through. Otherwise if you were just going for best air flow situation you could just use no air filter at all. At least until your coils plug up anyway.

I paid big money to have my heat pump system and ducting installed, so I want to take care of it. Also I rarely ever get to use the actual heating cycle on it because I burn wood, so for me at least using the air blower yo circulate the wood heat helps to justify the expense.