Harman Stack Temp Question????

[SmokeEater]

Just had a "first fire" this past Monday in my new PB 105 and have burned 5 bags of Currans. I have a question for PB owners and other Harman owners on stack temps. Have a bimetallic (I know they're not super accurate) thermometer called a Chimgard on a single wall section of my vent pipe and at full burn I can only see a high temp of about 175 degrees. This seems wicked low to me, but I don't really have any other experience to base my observations on. Anyone out there who can help me out on this?

 

[smoke show]

Contribute that to the hi efficiency of the low efficiency solid fuel burning contraptions?

 

[smwilliamson]

Just had a "first fire" this past Monday in my new PB 105 and have burned 5 bags of Currans. I have a question for PB owners and other Harman owners on stack temps. Have a bimetallic (I know they're not super accurate) thermometer called a Chimgard on a single wall section of my vent pipe and at full burn I can only see a high temp of about 175 degrees. This seems wicked low to me, but I don't really have any other experience to base my observations on. Anyone out there who can help me out on this?

The PB105 uses a positive pressure vent. You should NOT be using single wall stove pipe anywhere, use only "PL" or "L" rated double wall pipe.

From the manual:
Vent Pipe
4†pellet vent pipe (also known as “PL†vent) is
constructed of two layers with air space between the
layers. This air space acts as an insulator and reduces the
outside surface temperature to allow a minimum clearance
to combustibles as low as 1 inch. In Canada the minimum
clearance to combustibles is 3 inches.
The sections of pipe lock together to form an air tight
seal in most cases; however, in some cases a perfect seal
is not achieved. For this reason and the fact that the boiler
operates with a positive vent pressure, we specify that
all joints within the structure should also be sealed
with silicone.
NOTE:Use only 4†diameter approved PELLET
venting system. Be sure to inspect and clean exhaust
venting system frequently.

But to answer your question, average temp in the stack is between 240 and 350 degrees depending upon whether the boiler is ramping up, or ramping down and the temp of the water coming in from your system.

 

[SmokeEater]

The PB105 uses a positive pressure vent. You should NOT be using single wall stove pipe anywhere, use only "PL" or "L" rated double wall pipe.

From the manual:
Vent Pipe. . . . frequently.

But to answer your question, average temp in the stack is between 240 and 350 degrees depending upon whether the boiler is ramping up, or ramping down and the temp of the water coming in from your system.

You would have to see this venting and the problem I had with it. I'm in the Adirondack foothills were the wind never stops, and is usually above 10 mph. So much so that there is a 600 MW wind farm around us. My 105 vents into a 6" stainless liner 30 feet long that created a negative pressure often over - 1.0 WC without the combustion blower on. The vent is a 4" Duravent vertical for about 4' to a cleanout T and then 3' to the thimble. Just before the thimble I had to put a 6" butterfly damper to be able to control the draft. The damper in a double wall Duravent adapter and to connect to the tiled thimble I used a 4" female female single walled connector silicone sealed to the adapter. That's where the thermometer is located. This is similar to having a threw-the-wall vent with a restricter plate. The restricter plate is suggested to be used in the install manual if the draft is too high (above -0.85"WC). Using a Magnehelic with a range of 0 to 1" WC, I adjusted the damper to give me the -0.85" when the combustion blower was run for the first minute with the feed adjust dial on TEST. The 105 seems to operate normally with this setting. Again, I have not seen the stack over 200 degrees.

 

[Delta-T]

175-200 deg is totally normal. 240-350 deg?? you shouldn't be able to boil water with your pellet stove exhaust.