M55 exhaust leak

[ohbix]

Hi again. Ran the stove, M55 steel FS last week at levels 1 and 2. Noted a faint exhaust smell after a few hrs. at level 2. Noted soot on the fan housing at the junction of the rectangular section to the rectangular foot plate (picture). Caulked that, then ran the stove during the Really Cold event. No longer detected odor in the room, but still very faint leak as noted by odor from left most convection air tubes. I found threads discussing slight leaks where I found one, as well as at the exhaust tube mounting. I did my cotton q tip test this am, and suspect I might have a leak between the housing and top of the mounting area. There should be a gasket there, but I suspect it might be leaking. I haven't ruled out the adapter or venting, but the nature of the leak makes me suspect these other areas. New install, duravent pro; adapter, 45 elbow, 3 foot horizontal out the wall to end cap. If I replace the exhaust fan gasket, do I need to disconnect the venting? Thanks for any suggestions. For the poster inquiring about buildup in the burnpot, yup, seems normal.

Also w/ the original convection fan (dealer said enviro won't replace it until/if I get shutdowns), at what levels did the shutdowns occur? Anyone still running this stove w/ the original fan?

 

[Lake Girl]

Hope you have a carbon monoxide detector in your stove room and another near your bedrooms... Did the manufacturer/dealer advise of the potential leaks? How old is the stove?

Have you contacted Enviro directly? I'm surprised that a manufacturer with a known faulty fan will not make it right before it fails. They must have a manufacture date/dates for the faulty fans... How old is the stove? Are they just trying to outwait the warranty period? Consumer rights??

 

[whlago]

Hi,
I have the M55 cast that had the old blower but my dealer replaced with the turbo blower after I bugged him enough. If you burn good pellets you will get the shutdowns. My shutdowns were occurring on Heat Level 3, even 2 at times on some pellets. The new blower is great!

Regarding the exhaust blower. I have no gasket on my exhaust blower motor. Never did. There is a gasket I believe on the exhaust plenum exiting the stove. I would have to check that though...haven't needed to touch that.

Good luck with the leaks and the blower.....however if you aren't getting shutdowns due to overheating of the hopper limit switch, not sure there is a reason to change.

 

[Lake Girl]

If the new blower generates greater efficiency (better heat transfer) and there are known overheating situations with the old blower, Enviro should be switching them out. Why wait until it is freezing cold out when you need that higher heat level only to have the stove shut-down? I know I would be extremely ticked if there is a known problem, it's -whatever out and my stove shuts down and now I have to wait for a replacement. I still would call Enviro...

 

[whlago]

Lake Girl I agree with you...but the problem isn't that severe. Enviro offered a "solution" to the problem by issuing an adjustable auger cover that reduces the amount of pellets that drop down the auger shoot. My put is that is not a fix but merely a bandaid because you are reducing the potential heat that could be produced. Enviro's contention is that the unit produces much more than the rated BTU's, and by using the auger plate you solve overheating shut down issue while maintaining the rated BTU's.

I still didn't buy it and persisted and now I haven't tripped the limit switch since, even with some of the worst cold we've seen in decades. Nothing breaks due to this problem. The heat sensor trips and the unit shuts down and you need to re-set the switch before you start up again, more of a nuisance and a frustration that you can't leave the stove alone on 3 or higher without worrying it will shut down.

The new blower throws a lot of heat into the house while at the same time getting it away from the stove thus being a double bonus.

 

[Lake Girl]

I realize it would trip the high limit - but if you are expecting heat from an appliance and can only run on half power during cold temps, it's usefulness is drastically diminished.

 

[ohbix]

Thanks all for the info. Yes, multiple digital CO and smoke detectors, nothing recorded on them, no smoke detectable on startup w/ flashlight. I've become very sensitive to exhaust, thus why I noted something w/out odor or smoke. I didn't push the dealer too hard, but Enviro told him no convection fan replacement unless I have shut down problems. Dealer ran it hard, but it was in a metal pole building w/ little insulation. He said it tripped once. There is a gasket on the exhaust starter tube, and another between the combustion fan housing and exhaust channel. For fan cleaning, do you just remove the fan from the housing, or do you remove the entire housing?

A general question: lean burn (enviro calls it dirty) vs rich burn. I thought the rich burn created the black ash, not the lean burn. Which is it?

 

[Lake Girl]

What do you normally burn for pellets? I think I would buy some Doug Fir pellets for "testing"

 

[SmokeyTheBear]

On the exhaust leak, if the area has a gasket you need to make certain the retention mechanism is closed properly, if it is an exhaust joint you may need some sealant.

It isn't uncommon for there to be leaks when first installed due to not taking time to do a proper sealing job. Once the curing smell starts it is difficult to determine what is what.

It is also possible that you have an early unit which sometimes had missing sealant in the exhaust system.

In any event you should locate that leak and seal it. Much better for you and anyone else in the house. All of the exhaust system from the combustion blower housing to the vent's thimble needs to be checked.

The only odor a new stove should have is the burn in smell which is paint curing, it is even better if the stove was pre-burned before installation. Each time you go to a higher heat level (firing rate) the curing smell will occur.

You should also make certain that the stove's damper was set using a differential pressure gauge. A lot of possible future issues can be located that way.

 

[vinny11950]

Like Smokey says, check the seals on the exhaust track.

I had similar issues with my install:

https://www.hearth.com/talk/threads/finally-fixing-the-m55-installation-and-some-questions.75676/

I ended up putting plenty of RTV on that perpendicular seam you show on your picture of the exhaust outlet.

Also check the Exhaust starter tube, the one that has one bolt on top and slips into a folder metal tab at the bottom. On mine, the tab was not bent far enough so it was not creating a tight seal which allowed some exhaust to escape from the bottom of the gasket seal. I kept the litherm gasket but also placed lots of RTV on either side of it when I reinstalled it.

I was also getting a leak from Duravent pipes and it was coming out of the seams and the stove adapter collar, in between the two metal tubes. Fill that space with more high heat RTV. And seal the joints too with RTV or metal tape.

Lastly, the exhaust motor sits on a plate that is screwed into the exhaust housing. There is no gasket between the motor plate and the exhaust housing. There is a gasket between the exhaust housing and the stove. You can buy the gasket already cut or you can buy the gasket material and cut your own.

It is a very good stove, but the exhaust connection mechanism could use some improvement.

Good luck.