Haram P61 burning hot

[SteveMcCarthy69]

I have 2 Harman P61 pellets stoves. One of the stoves is way hotter then the other when idling. I have the thermostat set as low as it can go on both stove so both stoves are essentially idling with a very minimal flame. If I measure the temperature on the side of one stove it is 160F. The temperature on the other stove in the same spot is 290F.

I have had this stove for 25 years and do all of the cleaning an maintenance on it myself. I can't figure this one out. It feel like there is too much airflow in the stove causing the pellets to burn really hot.

This is what I have tried so far.

I have cleaned the stove completely,
Cleaned the inside of the burn pot.
Cleared all the holes in the burn pot.
Replaced the ESP.
Replaced the door casket.
swapped room temperature probes between the 2 stoves.
swapped the doors between the 2 stoves.
I tried different feed rate settings, it is set at 3 now.

 

[Tonyray]

you have mentioned everything except brand/type of pellets which i assume are same for both stoves..

 

[Whitenuckler]

I have 2 Harman P61 pellets stoves. One of the stoves is way hotter then the other when idling. I have the thermostat set as low as it can go on both stove so both stoves are essentially idling with a very minimal flame. If I measure the temperature on the side of one stove it is 160F. The temperature on the other stove in the same spot is 290F.

I have had this stove for 25 years and do all of the cleaning an maintenance on it myself. I can't figure this one out. It feel like there is too much airflow in the stove causing the pellets to burn really hot.

This is what I have tried so far.

I have cleaned the stove completely,
Cleaned the inside of the burn pot.
Cleared all the holes in the burn pot.
Replaced the ESP.
Replaced the door casket.
swapped room temperature probes between the 2 stoves.
swapped the doors between the 2 stoves.
I tried different feed rate settings, it is set at 3 now.

Do the flames look the same? Do they have OAK? Are the combustion fans set for the same minimum vacuum?

 

[SteveMcCarthy69]

I use Wood Pellet Co. Premium Hardwood pellets in both stoves. I have been using the same brand for 25 years now.

 

[SteveMcCarthy69]

Do the flames look the same? Do they have OAK? Are the combustion fans set for the same minimum vacuum?

I will have to take a close look at the flames when I get home. Neither stove uses an outside air kit. I don't know about the combustion fans set for the same minimum vacuum. Is there any type of adjustment for that?

 

[Whitenuckler]

I will have to take a close look at the flames when I get home. Neither stove uses an outside air kit. I don't know about the combustion fans set for the same minimum vacuum. Is there any type of adjustment for that?

Yes there is an adjustment POT near the igniter light on the newer control card and the instructions are in one of the manuals.
Do you think it's partly due to the stove's location? Does one have colder air it's drawing in or located in a cooler room?

 

[bogieb]

I'm trying to figure out how you even discovered this. I would never know.

• By chance does the cooler stove have heat baffles on the sides (or one side, like my P43) to reduce clearance requirements to walls?
• Are there items closer to the warmer stove (like walls or furniture) to one stove or the other?
• Are these new stoves, or have you had them a while and they were the same temp before?
• Why is this of concern? The stove is well within the heat it can handle and will shut down if too much heat is built up

 

[SteveMcCarthy69]

I'm trying to figure out how you even discovered this. I would never know.

• By chance does the cooler stove have heat baffles on the sides (or one side, like my P43) to reduce clearance requirements to walls?
• Are there items closer to the warmer stove (like walls or furniture) to one stove or the other?
• Are these new stoves, or have you had them a while and they were the same temp before?
• Why is this of concern? The stove is well within the heat it can handle and will shut down if too much heat is built up

They don't have any heat baffles on them. I have had one of the stoves for 25 years, and the other 21 years.

My biggest concern is the stove is no longer able to maintain a comfortable temperature in the area that it is in. It gets way too hot in the room it is in and the adjacent rooms. I only light the stove now when it is below 32. I have the ESP near the stove so it should think that the room temperature is warm enough. It seems to feed pellets more frequently then it needs to. If I have the temperature setting at 60F and the ESP is right next to the stove where it is much warmer I don't understand why it feeds so often. The hotter stove goes through twice as many pellets as the cooler stove. This has been going on for the last few seasons.

Last night I cleaned the air intake by blowing the shop vac through it in both directions. There was some stuff in there, but not much came out and the stove is still burning hotter then the other one. I am seriously considering a new control board at this point.

 

[SteveMcCarthy69]

Do the flames look the same? Do they have OAK? Are the combustion fans set for the same minimum vacuum?

The flame on the hotter stove is about 2 inches high. The flame on the cooler stove is about an inch. I also noticed when I open the hopper cover on the cooler stove the flame jumps like it just got more air flow. On the hotter stove opening and closing the hopper cover only makes a slight difference in the flame. One thing I haven't replaced is the ash door rope. It does seem like it is sealing good, but I figure it is worth a try.

 

[johneh]

The flame on the cooler stove is about an inch. I also noticed when I open the hopper cover on the cooler stove the flame jumps like it just got more air flow.

It seems you have answered your own Question
1 stove is getting more combustion air than the other
Check the combustion air intake

 

[Whitenuckler]

They don't have any heat baffles on them. I have had one of the stoves for 25 years, and the other 21 years.

My biggest concern is the stove is no longer able to maintain a comfortable temperature in the area that it is in. It gets way too hot in the room it is in and the adjacent rooms. I only light the stove now when it is below 32. I have the ESP near the stove so it should think that the room temperature is warm enough. It seems to feed pellets more frequently then it needs to. If I have the temperature setting at 60F and the ESP is right next to the stove where it is much warmer I don't understand why it feeds so often. The hotter stove goes through twice as many pellets as the cooler stove. This has been going on for the last few seasons.

Last night I cleaned the air intake by blowing the shop vac through it in both directions. There was some stuff in there, but not much came out and the stove is still burning hotter then the other one. I am seriously considering a new control board at this point.

The ESP probe is the one inserted into the exhaust pipe inside the stove. You are referring to the thermostat sensor. If not using a remote thermostat, or extending the probe (which is what I did) to a remote location in the room, the best place for the probe is 1 foot away from the room distribution fan. The manual says it should be in the return air flow.

On the stove that responds to opening the hopper door it could be having a hard time drawing air. Check the flapper.

 

[SteveMcCarthy69]

The ESP probe is the one inserted into the exhaust pipe inside the stove. You are referring to the thermostat sensor. If not using a remote thermostat, or extending the probe (which is what I did) to a remote location in the room, the best place for the probe is 1 foot away from the room distribution fan. The manual says it should be in the return air flow.

On the stove that responds to opening the hopper door it could be having a hard time drawing air. Check the flapper.

Yes sorry I meant to thermostat sensor. I checked the flapper is open and I feel the air flow going through it. I blew the air intake tube out last night with a shop vac in both directions to make sure the tube was clear. Not much came out when I did that. I am going to measure the airflow with a meter tonight.

If the air flow is reduced for some reason would that make the stove burn hotter? It seems to me the stove would burn cooler or poorly, Kind of counterintuitive. The flame appears to be burning well.

 

[Whitenuckler]

Yes sorry I meant to thermostat sensor. I checked the flapper is open and I feel the air flow going through it. I blew the air intake tube out last night with a shop vac in both directions to make sure the tube was clear. Not much came out when I did that. I am going to measure the airflow with a meter tonight.

If the air flow is reduced for some reason would that make the stove burn hotter? It seems to me the stove would burn cooler or poorly, Kind of counterintuitive. The flame appears to be burning well.

I'm starting to think it's the cooler stove that should be burning hotter:
"The flame on the hotter stove is about 2 inches high. The flame on the cooler stove is about an inch. I also noticed when I open the hopper cover on the cooler stove the flame jumps like it just got more air flow. On the hotter stove opening and closing the hopper cover only makes a slight difference in the flame. One thing I haven't replaced is the ash door rope. It does seem like it is sealing good, but I figure it is worth a try."
That could mean the ESP is dirty, or bad, or the control card dip switches wrong, or bad card.
Try running both in Stove mode, same feed rate ie 3, both set to minimum temperature and compare flame and stove temp.

Are you going to check OAK airflow, or vacuum?

 

[SteveMcCarthy69]

I'm starting to think it's the cooler stove that should be burning hotter:
"The flame on the hotter stove is about 2 inches high. The flame on the cooler stove is about an inch. I also noticed when I open the hopper cover on the cooler stove the flame jumps like it just got more air flow. On the hotter stove opening and closing the hopper cover only makes a slight difference in the flame. One thing I haven't replaced is the ash door rope. It does seem like it is sealing good, but I figure it is worth a try."
That could mean the ESP is dirty, or bad, or the control card dip switches wrong, or bad card.
Try running both in Stove mode, same feed rate ie 3, both set to minimum temperature and compare flame and stove temp.

Are you going to check OAK airflow, or vacuum?

I have an air flow meter to measure the airflow on the intake pipe of both stoves. I was actually wondering about the DIP switches on the control board, maybe they are set wrong. I have to check that too. I will try cleaning the ESP. I replaced it last season but it didn't make any difference.

The real problem I am trying to solve here is why the stove doesn't regulate the room temperature properly. The area of the house the stove is in gets way to hot, it didn't used to do that. I am assuming since the hotter stove is 130F hotter then the cooler one that is causing the room to heat up too much. Even though the room is very warm the stove feeds more pellets, more frequently then I think it should when the room is already warm enough. It seems to me it shouldn't feed any pellets other then just enough to keep the fire burning.

 

[Whitenuckler]

I have an air flow meter to measure the airflow on the intake pipe of both stoves. I was actually wondering about the DIP switches on the control board, maybe they are set wrong. I have to check that too. I will try cleaning the ESP. I replaced it last season but it didn't make any difference.

The real problem I am trying to solve here is why the stove doesn't regulate the room temperature properly. The area of the house the stove is in gets way to hot, it didn't used to do that. I am assuming since the hotter stove is 130F hotter then the cooler one that is causing the room to heat up too much. Even though the room is very warm the stove feeds more pellets, more frequently then I think it should when the room is already warm enough. It seems to me it shouldn't feed any pellets other then just enough to keep the fire burning.

Harman Pellet Stove DIP Switch Settings Explained

If you own a Harman pellet stove, you may have heard about DIP switches. These tiny switches are located on your control board and act like the “settings menu” for your stove. They tell your stove how to ignite, how much fuel to feed, and even which temperature sensor (ESP probe) it should...

www.northeastpelletstoves.com

Here is a link I found for the switches. I have the pdf but this link might be better.

I would run in stove mode first and see how they work, then move on to thermostat/room mode.

The cooler one seems too cool to me. I believe the minimum exhaust temp is something like 300F. That
is documented somewhere on here. The user borrowed a scan tool.

 

[Washed-Up]

Sounds like one combustion blower is stronger than the other

 

[Washed-Up]

Have you ever replaced either combustion blower or are they both the older style 2 blade models?

 

[SteveMcCarthy69]

I measured the RPMs on the combustion motor for both stoves using a strobe.

Hot stove is 3300 RPM with the old style motor with the blades on it. That was replaced maybe 10 years ago.
Cooler stove is 3150 RPM with a new style motor with no blades on it.

Checked the DIP switches on the control board. They are set correctly for a P61 with the black ESP.

I am going to replace the ash door casket this weekend and clean the ESP.

 

[Whitenuckler]

I measured the RPMs on the combustion motor for both stoves using a strobe.

Hot stove is 3300 RPM with the old style motor with the blades on it. That was replaced maybe 10 years ago.
Cooler stove is 3150 RPM with a new style motor with no blades on it.

Checked the DIP switches on the control board. They are set correctly for a P61 with the black ESP.

I am going to replace the ash door casket this weekend and clean the ESP.

Are you going to try stove mode on both at the same time?

 

[SteveMcCarthy69]

Are you going to try stove mode on both at the same time?

Yes I will try the stove mode test. If the temperatures aren't similar I am going to assume the ESP isn't working properly. I am assuming Stove Mode control is based solely on the ESP reading.

 

[Whitenuckler]

Yes I will try the stove mode test. If the temperatures aren't similar I am going to assume the ESP isn't working properly. I am assuming Stove Mode control is based solely on the ESP reading.

Yes, exactly. I believe the stove will control the combustion fan speed also, but that is where the lowest setting on that POT comes into play. Yours might be at the factory default. If you get a tiny flat screw driver you can find out where each are set and then return them to where they were.

 

[Whitenuckler]

Yes I will try the stove mode test. If the temperatures aren't similar I am going to assume the ESP isn't working properly. I am assuming Stove Mode control is based solely on the ESP reading.

I found that thread:

Thread 'Harman "Stove Temp" results'

Feb 10, 2022

I hooked up my DDM to log what each number 1-7 represented in target ESP temperature. Here are my results:
1-251F
2-308F
3-343F
4-378F
5-411F
6-444F
7-470F

• rickwai
• Replies: 48
• Forum: The Pellet Mill - Pellet and Multifuel Stoves

• 

"If I measure the temperature on the side of one stove it is 160F. The temperature on the other stove in the same spot is 290F."

The 290F seems correct to me

"The best way to control creosote is to prevent its buildup by maintaining a briskly burning fire with dry wood. Maintain a flue temperature exceeding 250 degrees Fahrenheit to prevent creosote condensation."

I'd check your nozzle on the one burning at low temp to see if it's building up creosote.

 

[Washed-Up]

Overthinking Harman stoves is common, the simplest solutions and diagnostics are usually the answers people are looking for

 

[SteveMcCarthy69]

I found that thread:

Thread 'Harman "Stove Temp" results'

Feb 10, 2022

I hooked up my DDM to log what each number 1-7 represented in target ESP temperature. Here are my results:
1-251F
2-308F
3-343F
4-378F
5-411F
6-444F
7-470F

• rickwai
• Replies: 48
• Forum: The Pellet Mill - Pellet and Multifuel Stoves

• 

"If I measure the temperature on the side of one stove it is 160F. The temperature on the other stove in the same spot is 290F."

The 290F seems correct to me

"The best way to control creosote is to prevent its buildup by maintaining a briskly burning fire with dry wood. Maintain a flue temperature exceeding 250 degrees Fahrenheit to prevent creosote condensation."

I'd check your nozzle on the one burning at low temp to see if it's building up creosote.

Good call on the creosote. I checked the pipe and it was shinny and black. I had a bottle of creosote cleaner so I cranked up the stove and sprayed the cleaner in there 6 different times. I let the stove cook off for over an hour. I had to open a couple of windows. The inside of the pipe looks like ash now. I have to clean it out in the morning. I also have to clean the air intake pipe. It must be blocked or partially blocked. I should have realized this when I opened the hopper and the fire jumped. I was so focused on the other stove I didn't notice this one was burning poorly.

 

[Washed-Up]

I run mine at 4 and 4 stove temp at least once a week just to make sure there’s no buildup…running any Pelletstove on low will build up the bad stuffs