M55C FPI + OAK

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BradH70

BradH70

Feeling the Heat
Feb 13, 2011
430
South West NH
Has anyone installed or know of an installation of the Enviro M55C fire place insert where the cold air intake was used? I installed an M55C FPI about a month ago and am considering adding a cold air intake line this summer. I'm going to check the vacuum level of the burn chamber this weekend, maybe it is not even necessary. My house is 7 years old and pretty well insulated, but I do have a walk out basement and the double doors leading to the outside are not considerably air tight. I removed the cleanout cover in the fire place and keep the cleanout door open in the basement. When I put my hand in the cleanout opening in the basement, I can feel a good amount of air being drawn up into the flue.

Looking at how the cold air line connects to the stove, and according to the technical manual, a 3" vent is connected directly to an opening in the back of the stove. Considering the stove is an insert and can be pulled from or pushed into the fire place via the rail system, it seems that connecting a 3" vent directly to the back of the stove would make the stove a more permanent install, and actually very difficult to connect considering that the stove would have to be fully pushed into the fire place to make a proper connection.

I'm going to call the dealer today and see if there is a OAK kit that can be purchased for this unit. I checked the web site and did not see anything nor is anything mentioned in any of the manuals.
 
I have a M55 insert and use an OAK. Mine is easy because I can pull the end of the 3" pipe thru my exterior wall when I slide the stove into place. I then pull the pipe thru the wall far enough to slide on the exterior vent adapter and screw the vent adapter to the wall. Mine is what I believe people call a pre-fab type of setup. It was not into an existing masonry fireplace. There is a "doghouse" built onto the exterior of my house which is where the stove slides into.
Flynfrfun
 
flynfrfun said:
I have a M55 insert and use an OAK. Mine is easy because I can pull the end of the 3" pipe thru my exterior wall when I slide the stove into place. I then pull the pipe thru the wall far enough to slide on the exterior vent adapter and screw the vent adapter to the wall. Mine is what I believe people call a pre-fab type of setup. It was not into an existing masonry fireplace. There is a "doghouse" built onto the exterior of my house which is where the stove slides into.
Flynfrfun
Click to expand...

Sounds like a good setup you have.

I called the dealer where I purchased the stove and he explained that unless the house is very small or very, very tight, then the OAK is not necessary. They are running the M55C insert at their shop as the primary heat source and they do not have the outside air connected. I will have to take his word for it, he sounded extremely knowledgeable about this stove and was able to explain in much detail as to how the stove operates and what would be affected by the many available adjustments to the user.

My initial concern for needing the OAK was that I have a lot of ash build up on the burn pot. I'm burning NEWP and he is seeing a decent amount of ash with the stove in his shop. His question to me was "do you get a lot of ash build up on the glass" and in fact I do. It only takes a couple of days for nice arc of ash to build up from the bottom right side that extends all the way to the top middle of the glass. He suggested that I use the damper adjustment lever on the side of the stove and pull it out by 1/4" and run the stove for a while and see if this helps. I may not have enough draft, which makes sense. My setup is a 4" vent off of the back of the stove frame into a 6" stainless rigid liner that goes all the way to the top of my chimney. The distance is about 24' in all.
 
Brad,
The OAK doesn't have anything to do with the amount of ash you are getting in the burnpot. Ash is a function of the pellet brand/type. It is normal for the glass to get ash on it just how you described. All of the M55 owners state the same pattern...from the lower right corner in a "swish" upwards to about the middle top of the glass. Mine starts hazing (light grey) about 6-8hrs from the time I clean it. After a few days it gets heavy enough to where it starts looking brown. I burn douglas fir which is supposedly one of the cleanest burning pellets.

The argument for the OAK is that the stove is sucking air from inside the house, using it to burn, then expelling it outside. This creates a negative pressure inside the house. It's always bad to have negative pressure in a home. That's why heating systems have fresh air intakes. In order to replenish the air the stove is burning, air has to come into the house from outside. So, any crack, loose fitting door, windows and etc. will be where the cold outside air will infiltrate the house to feed the stove. So, you are in effect letting cold air in to run the stove. Not really the most efficient method of heating a home.

Using the OAK allows the stove to bring cold air in from outside thru the OAK, burn the wood with it, then expel it outside. The stove then just recirculates the air within the home heating it over and over thru the heat exchanger.

Go outside and feel how much air is coming out of the exhaust while your stove is running. Without an OAK, imagine that is how much air is having to come into your home. It's A LOT.

I've given you the theory of the OAK, but the real test is "seat of the pants" results. If you don't feel cold drafts in various spots when the stove is running, then maybe an OAK wouldn't make much difference. BTW, the technical manual for the M55 strongly recommends using an OAK. The dealer might be trying to "take the easy way out" with his recommendation.
Flynfrfun
 
Hi Flynfrfun,

Thanks for the great reply. Your response is pretty much what I had already gathered from other posts on the same subject. Our heating area is about 2,100 sq/ft. with a walk out basement. I have the ash pan lid in the fire place removed and the clean out door in the basement is open. I can feel a good amount of air being drawn up into the flu to the stove so I think that his is providing a good portion of the air that the stove needs.

I was able to adjust the vacuum in the burn chamber this morning and I got it to the point were it was bouncing between 0.16 and 0.17 inches of water. I actually had to close the damper a quit a bit to get this. The vacuum was at 0.24 inches of water at first measurement.

I'm also trying a few bags of Okanaga pellets this weekend and I'm already liking them a lot better then the NEWP. There is considerably less ash building up in the burn pot so far.
 
flynfrfun said:
I have a M55 insert and use an OAK. Mine is easy because I can pull the end of the 3" pipe thru my exterior wall when I slide the stove into place. I then pull the pipe thru the wall far enough to slide on the exterior vent adapter and screw the vent adapter to the wall. Mine is what I believe people call a pre-fab type of setup. It was not into an existing masonry fireplace. There is a "doghouse" built onto the exterior of my house which is where the stove slides into.
Flynfrfun
Click to expand...

Got any pics? Thanks
 
roadrunnermoore said:
flynfrfun said:
I have a M55 insert and use an OAK. Mine is easy because I can pull the end of the 3" pipe thru my exterior wall when I slide the stove into place. I then pull the pipe thru the wall far enough to slide on the exterior vent adapter and screw the vent adapter to the wall. Mine is what I believe people call a pre-fab type of setup. It was not into an existing masonry fireplace. There is a "doghouse" built onto the exterior of my house which is where the stove slides into.
Flynfrfun
Click to expand...

Got any pics? Thanks
Click to expand...

Let me know what you want pics of. Attached below is a pic of when I was doing the install. I hadn't cut the hole for the OAK at this point in construction. The Durock board at the back is the exterior of the "doghouse" which is 2x4 stud framing. You can see how I can attach the OAK to my stove permanently, then slide the stove in. Then I reach thru the hole from outside the house and pull the flexible OAK pipe thru the wall, slide on the exterior vent termination and then push it back in and screw the termination to the wall.
Flynfrfun
 

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I had a OAK installed on my M55 last week. I could always feel cold drafts before I had this installed. It seems to have made a nice difference to the comfort level. You don't really feel the cold draft along the floor. Our house is only 7 years old.

On a side note.....we had an Enviro EF3 before this M55. Living in Canada we have many power outages. If the pellet stove was running when the power went out it would fill the house with smoke. Last night we had our first power outage with the M55 with an OAK and guess what.....no smoke!! I was so impressed. You had a slight smell of smoke but nothing like the old days where the smoke would fill the room etc. The wife became a believer of the OAK last night. I was paniced at the first waiting for the smoke.

Just thought I would throw that point in as well for the OAK.

Happy Heating!!!
 
JimmyJ,
So, what are your thoughts on the M55 compared to the EF3?
Flynfrfun
 
Flynfrfun

I was having some issues with the EF3. It was about two years old and would shut down over night filling the house with smoke. Dealer changed sensors, vent etc and it would still shut down. Having a newborn and a 3 year old in the house filled with smoke was not what I spent all that money on a pellet stove for. Dealer agreed and we did a switch to the M55 with some extra $$ from me of course.

To answer your question though....I ran the EF3 at about 85% all the time to heat our 2000+ sq.ft. of living space. It seemed like it was working too hard to heat our house. The M55 I have not run over 3 yet and our living room is constantly around 23 degrees and very cozy. It seems harder on pellets but that is to be expected with this stove.

In terms of the M55....I wouldn't say the hopper holds 80 lbs of pellets...more like 65 lbs I would think. Mine is the freestanding one.

Love the stove though. I have to get a wireless stat for it but never found one that was reasonable $$ yet.
 
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