OAK........Sort of. Opinions?

[Melissa220]

When my Harman was installed, an OAK not installed as I was told I did not need one. Last night I discovered where my stove is pulling air from: outside! Attached is a pic of where my stove is vented thru the wall. They had to trim the right side of the wall plate (the black square the vent passes thru) to fit up against the corner wall trim. I found last night that cold air was rushing through the gap between the plate and the trim! The last few days my stove has been set at room temp 70 And the stove had been maintaining this.

Last night I put a piece of cold weather tape over the gap. My fire was not as active - although I would not call it lazy - and my actual room temps were 66 and 67 this morning even tho the stove was still set for 70. (Granted, it was 20 degrees out Last night, but still...)

I took the tape off turned up the room temp and the stove is now merrily working with a tall wall of flame and working to heat up the house.

I had questioned Harman about the need for an OAK thru an email and was told "The only time outside air is needed, is if your home is extremely airtight which would create negative air pressure inside the home. in this case the stove would not operate properly. You would be seeing soot build up inside firebox and would have a very lazy flame, and in most cases the stove would shutdown. If any of the above mentioned issues are occurring, I would recommend having your dealer install an outside air kit."

None of these issues have happened. But not sure that the only reason is because of the cold air around the plate!

Now - do I need to demand installation of an OAK this summer?

 

[Harman Lover 007]

I've never been convinced on the whole OAK argument but having said that, I would tinker with your theory of that nice cold air sneaking around your wall thimble by removing and replacing the tape at key times as you go through the winter season. Furthermore, if that exhaust is on an outside wall and it would appear that it is, an OAK install would be a slam dunk. They even make a thimble with the OAK inlet built into it.

 

[Trickyrick]

Air will come in somewhere. If you didn't have that it would be coming in through your doors and windows and bathroom fan. If I were you I would go get the parts and install it now. Will take you about a hour to do it right and you get the benifits of having it done correctly.

 

[SmokeyTheBear]

A stove is going to draw air through it for combustion this air must be replaced, since no air is created inside the house it must come from outside. It will get the outside air from every small (or not so small) penetration of the houses shell.

You can choose exactly how the stove gets its air.

I made my choice before the stove was installed.

This is your choice to make, all that'll you'll get from the dealers is the result of only caring if the stove will be able to get enough air so you won't be calling them up wondering why the stove burns like crap or that they loose the sale over a few dollars of pipe costing more than the next stove shop quotes you.

A big hint is that your stove maker recommends one, there are even a number of stoves that require one, in fact there is one maker that requires one for all of its stoves.

 

[SmokeyTheBear]

Must watch out for their profit margin, England provides it with their stove), what can I say.

Now I have to tend the chickens.

 

[BradH70]

I installed an OAK for my M55 insert this past weekend. I am now a believer in the OAK.

Improvements that I have noticed:
1. Heath exchanger air temp on heat level 3 (HI/LOW mode with T-Stat control) seems to be much higher. Now reaching 600* burning MWP blend. I was hitting about 500* before the OAK. I'm going to keep an eye on it and see if it is just coincidental with cleaning the stove.

2. The temperature in the house is being maintained for a longer period of time = less call's for heat by the T-stat.

3. Much less of a draft coming into the living area were the stove is.

4. The upstairs is about 1-2* warmer then it was before the OAK. Next project is to make a box out of rigid foam insulation to cover my recessed attic stairs and try to get another couple of degrees increase in the bedrooms.

When I go outside and feel how much air is being drawn into the stove, I know that the OAK has greatly reduced the cold air being sucked into the house through other avenues.

My Castile does not have an OAK but I am going to see what it will take to properly seal it up so that an OAK will be efficient on that stove as well.

 

[Shaw520]

Think of it as a turbo for your stove...pellet stoves are designed around this theory, hence the combustion blower.... fresh cool outside air is denser therefore creating a more available AND more consistent supply oxygen...resulting in a hotter more efficient burn.

 

[mepellet]

1. Heath exchanger air temp on heat level 3 (HI/LOW mode with T-Stat control) seems to be much higher. Now reaching 600* burning MWP blend. I was hitting about 500* before the OAK. I'm going to keep an eye on it and see if it is just coincidental with cleaning the stove.

Are you really getting 600 deg air on the discharge of the heat exchanger? How are you measuring this? What type of thermometer?

 

[BradH70]

Are you really getting 600 deg air on the discharge of the heat exchanger? How are you measuring this? What type of thermometer?

It's a very precise measurement using a magnetic stove thermometer . I have it stuck to the top middle of the front decorative door. Believe it or not, as long as I keep it in the same spot all of the time, the temp readings from it are pretty consistent, so when I saw an increase after the OAK was installed, I had to believe it to a certain degree.

 

[subsailor]

Your also reading the temp of the steel as well as the air.

 

[BradH70]

Your also reading the temp of the steel as well as the air.

That is absolutely true, but if the cast iron door is getting hotter, then the air coming out of the heat exchanger tubes must also be getting hotter. Correct?

 

[mepellet]

It's a very precise measurement using a magnetic stove thermometer . I have it stuck to the top middle of the front decorative door. Believe it or not, as long as I keep it in the same spot all of the time, the temp readings from it are pretty consistent, so when I saw an increase after the OAK was installed, I had to believe it to a certain degree.

Ok. To echo what subsailor said, you are measuring the temp of surface that the magnetic thermometer is stuck to. The only way that I have heard of people properly measuring the discharge air temperature is by using a thermometer that is suspended a couple inches in front of the heat exchanger in the path of the air.

 

[SmokeyTheBear]

More heat is being dumped into the room. Likely the air temp out the tubes has also increased, but that is a different measurement. Nothing wrong with it at all folks.

 

[BradH70]

More heat is being dumped into the room. Likely the air temp out the tubes has also increased, but that is a different measurement. Nothing wrong with it at all folks.

Thanks Smokey. The surface area of the cast iron were the thermometer is being mounted is only slightly bigger then the magnet and a majority of the spring is being subject to the air coming out of the heat exchanger tubes. Considering I am measuring the temperature the same way all of the time, an increase in temp is just that, an increase in temp.

I have a K-type thermal probe that I will setup tonight and get a more accurate measurement.

But back to the OP's original question......

With your stove model and the way it is situated, an OAK would be an easy install. I would recommend installing one sooner then later in order to get the benefits. There is still a lot of heating season left.

 

[mepellet]

Thanks Smokey. The surface area of the cast iron were the thermometer is being mounted is only slightly bigger then the magnet and a majority of the spring is being subject to the air coming out of the heat exchanger tubes.

I still think that the thermometer is measuring surface temperature more than you think.

Considering I am measuring the temperature the same way all of the time, an increase in temp is just that, an increase in temp.

Correct on that.

I have a K-type thermal probe that I will setup tonight and get a more accurate measurement.

I am interested in what you find out. I was wrong once. A long time ago.

 

[SmokeyTheBear]

I have a t-shirt with a picture of Grumpy that says:

I may not always be right but, I'm never wrong.

 

[P38X2]

Melissa, by "demand", do you mean they should install one at no charge? Highly doubt that'll happen. However, I would install one. If it's not too late (thimble hole cutting wise) the Harman kit is very nice. Other manufacturers also offer thimbles with integrated OAK's that might "cover" your existing inside hole and outside trim/flashing, etc..if need be.

From an initial investment point of view I can MAYBE see where someone could make the argument AGAINST an OAK. Say the OAK costs $100-200 above and beyond the cost of the base installation fee. Well, $100-200 worth of pellet BTU's to compensate for the drafts caused by the lack of an OAK would last a long time. Hope that makes sense.

You gotta look at the big long term picture here. Saying "I'll just burn more pellets to offset the drafts" is wasteful and plain silly. I'm not saying this is YOUR reason. Just commenting on the people who believe this.

Ultimately, I can't understand why there is ANY argument against installing one. As MANY others have stated, it's a very basic common sense concept that I won't bother repeating. I wish someone would tell me a legitimate reason against using one.

 

[mrjohneel]

I think the most interesting part about this thread is that Melissa said she e-mailed Harman and they told her, "The only time outside air is needed, is if your home is extremely airtight which would create negative air pressure inside the home. In this case the stove would not operate properly." Because I always thought Harman -- the manufacturer, that is, in its manuals and in my e-mail with them when I had the same question -- always advocate for the OAK. It's the guys who sell and install them that almost always advocate AGAINST OAKs. I have one by the way, terminating in the same flue as my exhaust (but well below it).

 

[krooser]

Install an oak... you'll be glad you did. Most dealers AND manufacturers "customer no service" people are clueless... they probably heat with oil anyway.

 

[jlupi]

Ultimately, I can't understand why there is ANY argument against installing one. As MANY others have stated, it's a very basic common sense concept that I won't bother repeating. I wish someone would tell me a legitimate reason against using one.

My house is fairly tight. I have had wintertime humidity problems in the past resulting in excessive sweating on windows and mold on walls. last year installed a inline bath fan on a dehumidistat and often cracked a window on the other end of the house to lower humidity -worked well. only other option was to install a very exp HRV and ducting which wasnt happening at that time.

The pellet stove (W/O oak) exaust fan has eliminated the use of the bath fan (essentially serves same purpose). keeping us dry and warm.

May not be most peoples norm but it IS an argument against installing one in a certain circumstance.

 

[P38X2]

My house is fairly tight. I have had wintertime humidity problems in the past resulting in excessive sweating on windows and mold on walls. last year installed a inline bath fan on a dehumidistat and often cracked a window on the other end of the house to lower humidity -worked well. only other option was to install a very exp HRV and ducting which wasnt happening at that time.

The pellet stove (W/O oak) exaust fan has eliminated the use of the bath fan (essentially serves same purpose). keeping us dry and warm.

May not be most peoples norm but it IS an argument against installing one in a certain circumstance.

But yer still sucking cold air in someplace and losing efficiency, which is what an OAK remedies, in most cases. You're combustion air is still coming from outside

You have a pool in your house? Lol. I wish I had more natural humidity. I need to run a humidifier in the winter

 

[Northwoodneil]

OAK it and don't look back.

 

[Melissa220]

by "demand", do you mean they should install one at no charge?

No, not at all. I know they would not do it free of charge. By demand I mean I have asked twice about whether they were sure I did not need one ans was told I did not. That my stove would get air from a bathroom fan - which I do not have - or a kitchen fan - which I do not have - or a dryer vent - which is in the basement in another area of the house. I have had to put plastic on my windows due to cold air seeping through the windows so there is no air for the stove there.

 

[subsailor]

Are there any other dealers in the Bangor area you could check with?

 

[Melissa220]

I think the most interesting part about this thread is that Melissa said she e-mailed Harman and they told her, "The only time outside air is needed, is if your home is extremely airtight which would create negative air pressure inside the home. In this case the stove would not operate properly." Because I always thought Harman -- the manufacturer, that is, in its manuals and in my e-mail with them when I had the same question -- always advocate for the OAK. It's the guys who sell and install them that almost always advocate AGAINST OAKs. I have one by the way, terminating in the same flue as my exhaust (but well below it).

Thank you. I thought this was interesting as well. My manual recommends one, which is why I brought it up to the seller/installer TWICE. and twice was told "not needed".