25 PDVC smoke in the room

[skibumm100]

To start, I'm not a first-timer.🙂 I have a 25 PDVC in my walk-out finished basement. It gets pretty cold in the winter. I usually run it 24/7 when it's cold out. I shut it down yesterday to do a deep cleaning. I had never pulled the combustion fan to clean it. The stove has a 3 foot horizontal exhaust with a 45. I put an OAK in last year. The fan blades had slight build up on them and there was quite a bit of ash built up behind the fan blade. I cleaned all the ash off the blades and behind the fan. I made a new gasket out of Lytherm sheet and put it back together. I had a tough time getting into the horizontal 3" flue. Everything is stuck together. The outer pipe actually came off the inner SS pipe and I pulled the whole outer pipe an 45 off. I was able to vac it out from outdoors. It was probably half full of ash. Shame on me. Once all cleaned out and reassembled, I started a fire in it. After 10 minutes I noticed a lot of smoke smell in the basement. It never cleared up. Not enough smoke to set of the smoke detector, but very noticeable. I shut it down and let it cool. Today I removed the outer flue pipe and elbow, plugged the 3" vent, plugged the OAK and lit 4 incense sticks (I use them to look for drafts) and closed the door. Let them fill the stove with dense smoke, pulled the plug out of the OAK and put a hair dryer in the OAK connection. Smoke was coming out of the combustion fan shaft are are pretty good. That makes sense because I wasn't getting noticeable smoke until after I cleaned it. I think the ash build-up was mostly plugging the area up. What type of seal are these combustion fans supposes to have? I ordered a new fan and full gasket set today. I'd like to see if I can fix the old one and use as a spare.

 

[ARC]

Don't usually get smoke from the exhaust fan as when fan is running it pulls air through stove (Negative Pressure Stove)and around the exhaust fan itself. I would suspect you are getting it from vent adapter on exhaust fan or the vent pipe itself. Outer pipe should not come off vent pipe is it did then the seal between inter and outer is broken. Are you saying you only have 3 ft of venting total or 3 ft horizontal then vertical? How much of the venting is inside of house? With only 3 ft of venting that you just cleaned I would say it would not create enough back pressure to leak from the exhaust fan

 

[ARC]

Let them fill the stove with dense smoke, pulled the plug out of the OAK and put a hair dryer in the OAK connection. Smoke was coming out of the combustion fan shaft are are pretty good.

You were creating a positive pressure stove which your stove is not. That is why it was leaking around exhaust fan. You would be better off filling stove with incense smoke and then starting the exhaust fan. Then watch adapter and vent pipe for smoke.

 

[skibumm100]

Yeah, I just got a new fan and there is no seal on the shaft. In fact, there a hole about 1/4" where the shaft goes through the plate. The motor fan acts as a repeller pushing air toward the combustion fan impeller. I noticed on my old fan there was a gap of about 1/4" between the back of the fan and the plate. I think that's too big. I'll throw the new fan in with that gap closed down and recheck for leaks using the combustion fan. In theory, the shaft area should be a low pressure area if there's no restriction in the vent pipe.

 

[skibumm100]

Don't usually get smoke from the exhaust fan as when fan is running it pulls air through stove (Negative Pressure Stove)and around the exhaust fan itself. I would suspect you are getting it from vent adapter on exhaust fan or the vent pipe itself. Outer pipe should not come off vent pipe is it did then the seal between inter and outer is broken. Are you saying you only have 3 ft of venting total or 3 ft horizontal then vertical? How much of the venting is inside of house? With only 3 ft of venting that you just cleaned I would say it would not create enough back pressure to leak from the exhaust fan

Sorry, missed your first reply on my phone. Yes, 3 feet total vent length. I'm not sure what brand this vent pipe is, but it's junk. The outer pipe pulled off the inner pipe. Pretty sure Duravent is completely crimped together. I did a few things to the stove yesterday. I got a new fan in the mail, as well as a full gasket set. It looks like the gasket between the fan housing and the stove may have been leaking. It's hard to tell. I changed the gasket with a new one from the kit. I will say that US Stoves did a really crappy job attaching the fan housing to the stove. Galvanized self-tapping sheet metal screws? Really? Maybe they were out of drill bits. Anyhow, 3 of 5 snapped off when trying to remove them. I was able to get 2 of the 3 broken ones out with vice grips. The third one at the bottom is unreachable, so I ended up redrilling next to it. I replaced the self-tapper's with SS 1/4" bolts and locknuts. I also replaced the fan with a new one. Behind the fan blade I made a 1/8" thick flinger out of Gore-Tex sheet gasket material. It's good to 500 deg F. That will restrict that 1/4" hole where the shaft goes through the mounting plate. I also moved the fan blade back towards the plate to reduce the space. In addition, I used furnace tape to seal between the outer vent pipe and the inner pipe. I started it up and no smoke in the house. I'll watch this closely and take a peek at the fan in a few weeks. I suppose it's possible the hole by the fan shaft is supposed to aid in cooling for the fan motor by keeping air moving over the shaft. We'll see. I think I might see if I can find a 3 or 4 foot long Duravent pipe to replace the "two-piece" junk on the stove now. Right now it's OK.