How is a Drolet heat commander supposed to work?

[Citationls]

10-12 hours out of one load should be easy if your house stays that warm from the sun. You're saying your gas furnace still kicks on with the HC running at mild temps?

I reloaded my HC last night on top of a bed of coals. Loaded it about 75% full and here it is 10 hours later. Thermostat was calling for heat probably 25-50% of the time. When I woke up the thermostat was not calling for heat so I raked all the coals to the middle and bumped up the thermostat so it would call for heat. 10 minutes after doing that I took this picture. P damper was wide open, G damper was open about an inch.

My P damper is usually wide open once the fire is past the hottest stages. G damper is usually fully closed when the fire is hot. Once the fire dies down a bit the G damper will crack open. Having either of the dampers acting up can definitely cut your burn times/heat output.

 

[fields_mj]

You're saying your gas furnace still kicks on with the HC running at mild temps?

I reloaded my HC last night on top of a bed of coals. Loaded it about 75% full and here it is 10 hours later. Thermostat was calling for heat probably 25-50% of the time. When I woke up the thermostat was not calling for heat so I raked all the coals to the middle and bumped up the thermostat so it would call for heat. 10 minutes after doing that I took this picture. P damper was wide open, G damper was open about an inch.

My P damper is usually wide open once the fire is past the hottest stages. G damper is usually fully closed when the fire is hot. Once the fire dies down a bit the G damper will crack open. Having either of the dampers acting up can definitely cut your burn times/heat output.

Not really. If my gas furnace kicks on its because I'm down to a bed of coals, and its cold enough outside that I need more heat.

My G damper still isn't working correctly. I need to contact SBI bout it now that I've had a chance to put the unit through its paces for several days. They were going to send me a replacement, but wanted me to get a few of the other bugs worked out first to make sure that it was still needed.

Oh, and what picture

 

[Citationls]

Not sure why, but it wont let me edit my other post to add the picture. Just saw your other response.

Im with you on forgetting that you cracked the ash pan door! Made that mistake once due to having the attention span of a gold fish. Now I dont walk away from the HC if the door is cracked.

Those splits dont too big. I do find that the bigger splits take longer to get past the smokey phase after reloading. They also make it take longer for the unit to heat up. All my splits used to be about as big as yours when I first got my HC due to my old wood furnace being bigger, just like youre saying. Since then ive started using splits about half the size. Its made starting a clean fire much easier and the glass stays cleaner. Cutting the all the 24 inch splits in half really sucked. On the upside the 12 inch splits were really convenient for small fires.

 

[Citationls]

Haha glad you liked the first picture 😄. I seem to keep posting at the same time as you so sorry for the redundant posts!

Hopefully SBI can get the G damper sorted out quickly. You'll be walking around in a t shirt and shorts once the HC is running right!

 

[JRHAWK9]

Not sure why, but it wont let me edit my other post to add the picture. Just saw your other response.

Im with you on forgetting that you cracked the ash pan door! Made that mistake once due to having the attention span of a gold fish. Now I dont walk away from the HC if the door is cracked.

Those splits dont too big. I do find that the bigger splits take longer to get past the smokey phase after reloading. They also make it take longer for the unit to heat up. All my splits used to be about as big as yours when I first got my HC due to my old wood furnace being bigger, just like youre saying. Since then ive started using splits about half the size. Its made starting a clean fire much easier and the glass stays cleaner. Cutting the all the 24 inch splits in half really sucked. On the upside the 12 inch splits were really convenient for small fires.

Holy crap that's a mound of coals/ashes! So what do you typically do with them when you need to load?

 

[trx250r87]

Are you sure the G and P wires are not plugged into the the opposite ports on the board? I have hi I everything should be labeled or easy enough to figure out where each go.

Eric

 

[fields_mj]

Are you sure the G and P wires are not plugged into the the opposite ports on the board? I have hi I everything should be labeled or easy enough to figure out where each go.

Eric

Its wired correctly. I checked the signal back at the board. P is working fine now, but the servo motor for the G damper runs non-stop when the blower isn't running.

 

[fields_mj]

Not sure why, but it wont let me edit my other post to add the picture. Just saw your other response.

Im with you on forgetting that you cracked the ash pan door! Made that mistake once due to having the attention span of a gold fish. Now I dont walk away from the HC if the door is cracked.

Those splits dont too big. I do find that the bigger splits take longer to get past the smokey phase after reloading. They also make it take longer for the unit to heat up. All my splits used to be about as big as yours when I first got my HC due to my old wood furnace being bigger, just like youre saying. Since then ive started using splits about half the size. Its made starting a clean fire much easier and the glass stays cleaner. Cutting the all the 24 inch splits in half really sucked. On the upside the 12 inch splits were really convenient for small fires.

Since my G damper isn't really working right, I don't normally get that much heat out of a good bed of coals. Once that's fixed, I think everything will work great.

Long term, I will probably try to do a better mix on split sizes. I'm content with my 4"-6" splits, but I can see where it would be really good to have some even smaller stuff mixed in to get the temps up faster. Having smaller splits to mix in would also allow me to fit more wood in it Once the G damper is working right, I'll play around with split sizes and see how it effects my heat output and burn times.

 

[brenndatomu]

the servo motor for the G damper runs non-stop when the blower isn't running.

That sounds like a control board issue to me
Once the G is working right you'll be able to get some decent heat from the coals

 

[brenndatomu]

Are you sure the G and P wires are not plugged into the the opposite ports on the board? I have hi I everything should be labeled or easy enough to figure out where each go.

Eric

Yup, mine was wire backwards (correct spot, just wrong polarity) when it was fired up first time.
Sounds like SBI has a dyslexic person on the assembly line!

 

[Citationls]

Holy crap that's a mound of coals/ashes! So what do you typically do with them when you need to load?

I also have added an extra layer of firebricks on the bottom of my unit so might make it looked bigger than it is. Still a lot of coals though. That was from an overnight burn with close to full firebox. I wait for the coals to burn down then reload when there's a few handful of coals left if my next load will be medium size. Rake them over the grate and reload to start the process over.

 

[Citationls]

Long term, I will probably try to do a better mix on split sizes. I'm content with my 4"-6" splits, but I can see where it would be really good to have some even smaller stuff mixed in to get the temps up faster. Having smaller splits to mix in would also allow me to fit more wood in it Once the G damper is working right, I'll play around with split sizes and see how it effects my heat output and burn times.

Having different size splits definitely helps with the tetris portion of reloading! Also has kept my glass significantly cleaner.

 

[fields_mj]

Yup, mine was wire backwards (correct spot, just wrong polarity) when it was fired up first time.
Sounds like SBI has a dyslexic person on the assembly line!

Polarity should not mater. They are just a mechanical limit switch that closes the circuit when the spring arm is triggered. My issue is absolutely a control board issue. When the damper closes and the limit switch is made, I can see 0 ohms between the terminals on the board. Now, I HAVEN'T measured to see if I'm actually seeing any control voltage on either of those connections. The P damper, motor, and limit switch are all working correctly now so if I'm not getting control voltage on the G circuit, it would still be a board issue and not a blow fuse. Blown fuse would cause the same problem on the P side.

 

[brenndatomu]

Polarity should not mater. They are just a mechanical limit switch that closes the circuit when the spring arm is triggered. My issue is absolutely a control board issue. When the damper closes and the limit switch is made, I can see 0 ohms between the terminals on the board. Now, I HAVEN'T measured to see if I'm actually seeing any control voltage on either of those connections. The P damper, motor, and limit switch are all working correctly now so if I'm not getting control voltage on the G circuit, it would still be a board issue and not a blow fuse. Blown fuse would cause the same problem on the P side.

Sorry, I didn't finish my thought/explain too well...the thermocouples had the polarity reversed...made it act REALLY weird! I think there were a few of them that went out that way a couple years back.

 

[sleewok]

I installed a new heat commander this fall. I'm trying to work through an issue with one of the servo motors on the grate draft with their tech support (great folks). Along the way though, I've learned more about the unit and now I'm wondering exactly how I'm supposed to use the unit. I have it feeding into the duct work in my central air system. According to the manual, I'm supposed to build a fire in it and then let it burn down to almost nothing before reloading. When the house thermostat calls for heat, and the unit has heat available, the blower is supposed to kick on at its lowest speed and supply heat to the house. The manual also says that when the little green light is flashing slow or on solid, the unit thinks it has heat that it can supply. What I learned today is that the green light is tied to a thermocouple in the stove, but the blower won't actually kick on until the RTD temp probe reads at least 130 deg F in the plenum. Even with a big fire, the unit seems to have a really hard time reaching, let alone maintaining this temperature in the plenum. With a BIG bed of red hot coals, the surface temp on the plenum is only about 110 deg F. The unit itself gets plenty hot. It has no problem self cleaning any creosote build up off the glass on the door (+450 deg according to tech support). I have a barometric damper, and I measured the draft to be about 0.05" WC. Another thing that I learned from tech support is that the furnace will take at least an hour to get up to temp and allow the blower to kick on, and could take a lot longer (up to 4 hours), and its expected to have to reload the furnace with wood before reaching temp when starting a new fire.

If the fire box is hotter than 450 deg, and the plenum isn't reaching the minimum 130 deg, how is the unit ever supposed to pump hot air through out the house? I'm half tempted to run a 6" duct with a damper over to my cold air return in order to actually get some heat moving through out the house. I know its not a Kumma, but the furnace does seem to have a good following so I must be missing something somewhere, or doing something wrong.

Update: read the thread more carefully and see this is touched on. Good point that you are struggling to just get it to come on and this wouldn't be the problem.

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What is the static pressure of your plenum? If I recall correctly, if it is below 0.2 then the temp probe in the plenum will not read properly. That is from a Drolet technician. My guess is that is your issue. Connecting directly to your existing ductwork is not a standard install and you need to make sure you get your static pressure in the ductwork correct.

 

[brenndatomu]

I have owned/operated 3 different Drolet wood furnaces now, and I couldn't get anywhere near .2" SP on any them (2 different houses/systems too) without restricting the crap outta the ducts, and then it didn't seem to heat the house well, so I totally ignore that SP crap now. Many(most?) solid fuel furnace manufacturers don't even mention it.
My 2 ¢, just make sure you have large enough ducts (certainly not over .2 SP!)
Then balance them to get the heat where you need it, call it good.
But this does sound like a bit different kind of install, duct wise.

 

[fields_mj]

The install is right out of the owners manual actually. The thing that's not taken into account in the manual is that I run the blower on my central air system all the time. This means that the back draft on my HC plenum output is closed unless the HC blower is running. When I spoke to the techs at SBI about the air pressure in the plenum, he stated that the 0.2" WC spec is for when the blower is on and pumping heat, not for when I'm doing a cold start. Not sure exactly how there could be any significant positive air pressure in the plenum without a fan blowing. I also don't see how the RTD probe could be working as intended with NO air flow in the plenum. At that point, it would just be measuring radiant heat. This is why I installed a 6" duct that feeds into the cold air return for the central air system. The manual actually states that this is not allowed, and I can understand why. If the incoming air for the gas furnace is too hot, and its thermostat calls for heat, the entire unit will fault and shut down. At that point, both of your heating systems are down. Toggling power will reset the gas furnace, but these days I'm guessing that is considered to be too much effort on the homeowner's part and so its not allowed. Personally, I don't really care about that. I know for a fact that a 10" duct can pump enough heat into the cold air return to cause this fault because I had it happen several times over the years with the old wood furnace. I'm not sure if a 6" line will feed enough heat to create this issue or not, but I intend on intestinally creating the scenario to see if it will or not just so that I know one way or another. I put a damper on that 6" line for a couple of reasons. One of those is so that on cold days when I expect the HC to run as designed, I can adjust that damper down to prevent this issue from being able to occur. Adding this 6" line will not likely have the desired effect of having 0.2" WC in the plenum when the HC blower is running, but I don't really give 2 rips about that. When it comes to moving a compressible gas, I'm not really concerned about back pressure. Even with the manual damper mostly closed, the line will create enough air flow to pull heat off of the fire box and allow the RTD to work like it should. So far, the additional 6" line seems to be working exactly as I intended. Now I just need to get the G draft working correctly. After that, I should be set.

I haven't done it yet, but I also agree that the RTD should be mounted as low as possible. IMHO, it really shouldn't be used to prevent the blower from running. It should only be used to kick the unit into high speed in an over temp scenario, but then again, I didn't design the controls on the unit. Having said that, if I end up not being able to get the unit to work the way I really want to, I will absolutely grab a PLC and HMI off of a scrapped machine at work, and design my own controls system for it. 3 analog inputs from thermocouples, 2 inputs from limit switches, 2 outputs to servos, and an output to a relay to turn the blower on. That's about as easy as it gets.

I did check the overhead baffles last night. They didn't look out of place, but I was able to push them back about 1/2". Not sure if that was enough to cause and issue, but its corrected now either way.

 

[brenndatomu]

I did check the overhead baffles last night. They didn't look out of place, but I was able to push them back about 1/2". Not sure if that was enough to cause and issue, but its corrected now either way.

Certainly won't help matters any, especially when its in "idle" mode.
As far as this RTD, if its going to be moved, IMO it needs to be moved UP...the plenum will be hottest at the top...regardless of if the blower is running or not...hot air rises, and you will definitely have convective currents moving around inside that big steel box!
Use a IR thermometer, the higher you go on the body//plenum, the warmer it will be.
I'm betting a new control board is going to fix 99% of the issues