Less Heat for a Given Feed Rate, Same Coal

Fourth year with Pocono, absolutely excellent service last three years.

From startup this year, less flame height for same feed rate from last year, same Blaschak entirely dry coal . Replaced back grate gasket though a smoking wood match suggested blow thru on sides of grate bottom box and cast iron grate. Tried to really push down on the grate front to try to ensure a tight fit, this seemed to work for 2-3 weeks though now it seems the flame height is clearly less than last year for the same feed rate and coal as last year. Also really cleaned the combustion fan fins & underside of grate at beginning season. Combustion motor speed seems happy. A window outside is open a bit so not concerned about an vacumn issues in the house. Holes in grate are open, cleaned with a drill.

Interesting, stove side wall temps are down this year as well, 270F temp compared to something like 350 F last year for same feed rate.

In my opinion the combustion box and/or the grate has warped slightly with combustion air leaking. I'm thinking of using some refractory cement to seal the grate to the metal underlying housing. This will pose a removal issue to clan under though it may need to be done..

Comments ?

Thanks!!

Bruce

You got me. I don't own that stove,but dammit,something changed. If you're using last year's dry coal,we know the fuel hasn't changed. It has to be something to do with the draft(Bird or Squirrel's nest built in the off season?) or something in the combustion air travel path. Other than that,I dunno !

Yepper it sure sounds like you need to seal the grate sides, top and maybe the bottom so the air only goes through the holes.

Rev. Larry

Uglysquirrel wrote:Fourth year with Pocono, absolutely excellent service last three years.

From startup this year, less flame height for same feed rate from last year, same Blaschak entirely dry coal . Replaced back grate gasket though a smoking wood match suggested blow thru on sides of grate bottom box and cast iron grate. Tried to really push down on the grate front to try to ensure a tight fit, this seemed to work for 2-3 weeks though now it seems the flame height is clearly less than last year for the same feed rate and coal as last year. Also really cleaned the combustion fan fins & underside of grate at beginning season. Combustion motor speed seems happy. A window outside is open a bit so not concerned about an vacumn issues in the house. Holes in grate are open, cleaned with a drill.

Interesting, stove side wall temps are down this year as well, 270F temp compared to something like 350 F last year for same feed rate.

In my opinion the combustion box and/or the grate has warped slightly with combustion air leaking. I'm thinking of using some refractory cement to seal the grate to the metal underlying housing. This will pose a removal issue to clan under though it may need to be done..

Comments ?

Thanks!!

Bruce

Are you sure the grate is back all the way and down? Sometimes they need to be persuaded back. You should only feel 1 lip in the front.

Flyer5 wrote:
Are you sure the grate is back all the way and down? Sometimes they need to be persuaded back. You should only feel 1 lip in the front.

Flyer5, good idea....thanks !

when cleaning up the grate holes this year I found a couple 'goobers' on the edges of mine that kept them from seating properly. I also thought mine were warped because after setting the one in place the second grate would rock and not sit all the way flush with the other. these 'goobers' were just like the deposits that I cleaned out of the holes. I scraped them off and everything set nice and flush with no rocking.

Flyer5 wrote:

Uglysquirrel wrote:Fourth year with Pocono, absolutely excellent service last three years.

From startup this year, less flame height for same feed rate from last year, same Blaschak entirely dry coal . Replaced back grate gasket though a smoking wood match suggested blow thru on sides of grate bottom box and cast iron grate. Tried to really push down on the grate front to try to ensure a tight fit, this seemed to work for 2-3 weeks though now it seems the flame height is clearly less than last year for the same feed rate and coal as last year. Also really cleaned the combustion fan fins & underside of grate at beginning season. Combustion motor speed seems happy. A window outside is open a bit so not concerned about an vacumn issues in the house. Holes in grate are open, cleaned with a drill.

Interesting, stove side wall temps are down this year as well, 270F temp compared to something like 350 F last year for same feed rate.

In my opinion the combustion box and/or the grate has warped slightly with combustion air leaking. I'm thinking of using some refractory cement to seal the grate to the metal underlying housing. This will pose a removal issue to clan under though it may need to be done..

Comments ?

Thanks!!

Bruce

Are you sure the grate is back all the way and down? Sometimes they need to be persuaded back. You should only feel 1 lip in the front.

Backed off the feed rate, put on my leather gloves and used an adjustable c-clamp to lightly compress the upper front grate edge against the lower sheet metal box edge while still burning. The grate did move a scoshe down. Flame seems a scoshe higher .

Whats a "scoshe"?

It is what it is.

That's a New England word.

I'm adding a couple points to consider in this discussion:
Any time there is a change in stove behavior don't forget the other side of the equation, the chimney or power vent. For a given CFM combustion air/coal BTU value burning there also has to be a corresponding volume and pressure to effectively take the products of combustion and expel it outside. If the draft is low (still negative but say -.02"WC instead of -.04"WC) it can affect the burn rate and size of the flame. We have seen customers prove this by keeping their stove stove lit solely with the power vent after the combustion fan failed by cranking it up all the way and holding the baro shut (don't try this at home kids, guaranteed hopper fire!). Another possibility is some kind of restriction not allowing full flue gas flow (such as fly ash built up in an area not cleaned or a birds nest), this can affect the size of the flames and burn rate of the coal.