25-PDVC... couple of questions

[kharrisma]

Hi everyone,

Since I'm having some trouble with this thing, I'm giving myself a crash-course, picking up everything I can learn about it. Have a few questions that aren't on the Englander site (not that I can find, anyway,) and that searches of this forum came up empty.

First: that little sliding "shutter" just above the top auger, at the bottom of the hopper: what exactly is it's function, and how do I know when it's adjusted correctly?

Next: I really clean the dickens out of this thing before each heating season, but the heat exchanger bothers me... it's behind the impingement plate, and I can see that the air path runs down and left & right through the baffles... but I can reach only a little of it. It appears that there's more going down beyond the bottom of the "window" behind the plate, but without knowing what's in there and not being able to see it and with no way to get at it, short of a cutting torch, I've no way to know whether the passages are clear, or clogged. What's the best way to be sure that the full length of the heat exchanger passages is thoroughly cleaned?

Also, I was going to ask all these questions on one post, but after typing up a question about what a good vacuum reading would be (using a magnahelic or equivalent gauge), I posted it without adding these additional questions.... duuuuhhh.

Last... would there be any benefit in replacing the exhaust blower with one that moves more air (since it appears that the air-moving capability of this stove is marginal to begin with), and does such a beast even exist? Or is this opening up a whole 'nuther can of worms, with unknown/unpredictable results? Could be dangerous ground??

Been using it for about 8 years, without any trouble other than simple/obvious ones like auger motors, vacuum tubing, exhaust blower (it was really noisy) until recently, and I'm learning that I don't know what I don't know. And, since I'm literally playing with fire, a little knowledge can be a dangerous thing.

Thanks for educating a relative newbie!

 

[Ssyko]

The little plate is a sort of throttle for the amount of pellets allowed into the upper auger.

Many have bottle brushes and custom cleaning tools but the best results for cleaning most any stove is the “leaf blower trick” and a rubber mallet.

Yes you could go with a slightly stronger motor but you must stay below 1.4 amp draw on the motor. I would lean more towards experimenting with impellers. Harman uses a double blade impeller. Quad and whitfield use a taller 9 petal blade, there are also some tall 11 petal blades. Its your stove you can decide which way to go. The risks are yours

 

[kharrisma]

The little plate is a sort of throttle for the amount of pellets allowed into the upper auger.

Many have bottle brushes and custom cleaning tools but the best results for cleaning most any stove is the “leaf blower trick” and a rubber mallet.

Yes you could go with a slightly stronger motor but you must stay below 1.4 amp draw on the motor. I would lean more towards experimenting with impellers. Harman uses a double blade impeller. Quad and whitfield use a taller 9 petal blade, there are also some tall 11 petal blades. Its your stove you can decide which way to go. The risks are yours

Thanks Ssyko! Wow, the mallet/leaf-blower thing sounds like a royal mess. What do people do who have these things inside their living spaces?

I like the idea of a different impeller better than a whole new blower; probably be a real pain trying to match up mount-hole pattern/spacing, and yes, there's the current draw issue (those aren't big triacs driving it, wouldn't take much to overload 'em and smoke the board.) What's a good source for impellers? Grainger, or McMaster-Carr or somebody else?

 

[Ssyko]

Ive gotten alot of my um frankenstove parts from all over the net. Google is a great tool. The leaf blower trick is actually one of the best ways to clean the stove. Just leave the stove door open.

 

[kharrisma]

Ive gotten alot of my um frankenstove parts from all over the net. Google is a great tool. The leaf blower trick is actually one of the best ways to clean the stove. Just leave the stove door open.

Ohh.. I see. Really good way to clean it out, given that flue setup. Mine has a 90 right at the stove, and another 90 at about head height where it goes into the chimney (and I guess a third 90 of sorts, where the gasses turn again to head up the flue.) Chimney exits at about 25'. No external "T" do do a cleanout. Maybe I could rig up a cover plate for the heat exchanger opening and run compressed air through it? Probably have to pull the exhaust blower and cover that opening up as well; I know if you apply current to a motor, it turns, but if you physically spin the motor, it generates current (at least with a DC motor... dunno about AC motors, and don't want to run the chance of back-feeding current to the board,) plus the impeller would tend to interfere with the air flow.

 

[Ssyko]

Thats a lot of evl for a pdvc or pdv. That might be half your problem.

 

[Mt Bob]

(and I guess a third 90 of sorts, where the gasses turn again to head up the flue.) Your statement.With all the problems you are having,you should have had the flue pipe off several times by now,cleaned and inspected,and the chimney inspected.If you have a 90 inside the chimney pointing up,that is where ash will collect.Heck you might have a partially restricted chimney or cap.

 

[kharrisma]

(and I guess a third 90 of sorts, where the gasses turn again to head up the flue.) Your statement.With all the problems you are having,you should have had the flue pipe off several times by now,cleaned and inspected,and the chimney inspected.If you have a 90 inside the chimney pointing up,that is where ash will collect.Heck you might have a partially restricted chimney or cap.

@Ssyko: evl?

@bob bare: Despite scrubbing and blowing them out in September, I had the pipes off as soon as I noticed that I wasn't getting the flame pattern or heat I should have been getting, . No buildup or anything going on in there, as I expected.

The "3rd 90" was an "of sorts." There's no physical metal ell inside the chimney. Gasses are moving horizontal coming out of the stove, hit the first ell and turn vertical, run up the pipe to the second ell, turn horizontal again, then run into the chimney flue... where it once again has to turn vertical to go up the flue and out the cap. So that third turn isn't another metal ell within the chimney. I was all over the chimney during the pre-season cleaning... pulled the cap off, shined bright light down flue, mucked out the ash pit cleanout... everything is good. This is a sudden development, as in pretty much overnight, not a gradual deterioration of performance.

@general populace: Would there be any benefit in re-routing the piping to run straight out the back of the stove and into the cleanout door at the base of the chimney? This would completely eliminate any ells (other than the necessary turn from horizontal out of the stove to vertical up the chimney.) Too close to the bottom? Bad idea in general?

 

[Mt Bob]

Well,if it worked before,then internal passages of stove may be partially blocked,combustion motor may be weak,or getting wrong voltage from control board.Be nice if you could take stove outside,hammer on it and blow through all passages.If not,you could wire combustion blower to run all the time(plugged to wall outlet),hammer and blow in passages,so you do not have a big mess in house.

 

[kharrisma]

Well,if it worked before,then internal passages of stove may be partially blocked,combustion motor may be weak,or getting wrong voltage from control board.Be nice if you could take stove outside,hammer on it and blow through all passages.If not,you could wire combustion blower to run all the time(plugged to wall outlet),hammer and blow in passages,so you do not have a big mess in house.

Hi Bob,

Yep, that's my concern re: the heat exchange baffle passages. Can't get directly at 'em all (who designed this thing, anyway?!). At this point, taking it outside is becoming a more attractive idea.... though I do like your idea to run the exhaust blower on external power and then bang & blow on the stove... then see what turned up in the flue piping. I'll probably hear it clattering through the impeller. Probably ought to pull the exhaust blower after that, too, and muck that out. Thanks for the idea!

 

[Mt Bob]

Yes,if you do it inside,you should clean out blower and flue pipe.Good luck.

 

[kharrisma]

Yes,if you do it inside,you should clean out blower and flue pipe.Good luck.

I'll keep ya posted!

 

[chasf80]

Check out this thread https://www.hearth.com/talk/threads/heat-exchanger-25-pdvc.101554/
Its got the spots where the most ash collects in the exhaust path.

To clean mine I bought one of these https://www.homedepot.com/p/Everbil...10-ft-PVC-Clear-Vinyl-Tubing-702361/207144408
Or something similar and a couple of fittings so it would fit on the end of my vancuum. I jamb the end of the tube down each side and clean out the best I could during the season..

 

[kharrisma]

Check out this thread https://www.hearth.com/talk/threads/heat-exchanger-25-pdvc.101554/
Its got the spots where the most ash collects in the exhaust path.

To clean mine I bought one of these https://www.homedepot.com/p/Everbil...10-ft-PVC-Clear-Vinyl-Tubing-702361/207144408
Or something similar and a couple of fittings so it would fit on the end of my vancuum. I jamb the end of the tube down each side and clean out the best I could during the season..

Oh, that's excellent! I was convinced that there was a back-and-forth "zig-zag" of baffles and no good way to clean them. This looks easy, now that I know what's going on 'back there.' MUCH appreciated!

 

[Ssyko]

EVL = equivalent vent length
Cut n past from nevels stoves which is a 404 link (gone)
A rule of thumb equation we are using has been adopted by most pellet manufactures. The equation is called the sum of Equivalent Vent Length (EVL). All of the above mentioned venting restrictions have been assigned EVL values as follows:

Each 45 degree elbow = 3 EVL
Each 90 degree elbow and Tees with cleanout = 5 EVL
Each foot of horizontal run = 1 EVL
Each foot of Vertical run = 0.5 EVL
Elevations above 3000 ft with an EVL of 7 must adapt to 4 inch vent pipe.

If your installation is below 3000ft, we would need to do some math. The rule of thumb equations is that if the sum of the EVL is 15 or greater, then the pellet vent pipe would be increased to 4 inch diameter pellet vent pipe.

 

[kharrisma]

EVL = equivalent vent length
Cut n past from nevels stoves which is a 404 link (gone)
A rule of thumb equation we are using has been adopted by most pellet manufactures. The equation is called the sum of Equivalent Vent Length (EVL). All of the above mentioned venting restrictions have been assigned EVL values as follows:

Each 45 degree elbow = 3 EVL
Each 90 degree elbow and Tees with cleanout = 5 EVL
Each foot of horizontal run = 1 EVL
Each foot of Vertical run = 0.5 EVL
Elevations above 3000 ft with an EVL of 7 must adapt to 4 inch vent pipe.

If your installation is below 3000ft, we would need to do some math. The rule of thumb equations is that if the sum of the EVL is 15 or greater, then the pellet vent pipe would be increased to 4 inch diameter pellet vent pipe.

Thanks for that succinct description of EVL... I had guessed "exhaust vent length." Apparently whomever installed this stove knew about this formula; if added up, mine comes to about 17.5 EVL, but the installer used 4" pipes. Does that final 90-degree turn from the thimble adapter through the chimney (horizontal travel) to vertical travel up the chimney flue count as an 90 degree ell, or are we just talking hard piping here?

 

[Ssyko]

It counts as a 90 but if your at 4”” with pipe it should be good. The only thing is the 25pdvc has a weak exhaust system to start with it may still cause issues with the 3 90’s