Air Flow- Heat Commander

[Carl_Bunyon]

This past weekend, I replaced my old Longwood furnace with a Heat Commander. My HVAC contractor helped tie into the existing ductwork with a custom made plenum. For various reasons, he had to leave without hooking up the R/A. We plan to next weekend. We are a little light on the duct clearance (8"x18") connected to existing ductwork. Would adding another 6" round duct help the overall airflow? Right now, I am underwhelmed. My house footprint requires wood furnace on end of basement vs centered. I got more airflow out of old Longwood furnace. I think Heat Commander has bigger fan.

 

[sloeffle]

New Furnace Day: Drolet Heat Commander

So the blower is off if the tstat is satisfied? If so, wouldn't care for that either... Kinda back to the wide open/ off except more precise:rolleyes:... not sure how well that would work in my house being I have a furnace on the same level and need the blower running to push heat into the...

www.hearth.com

You are currently at 144 square inches. According to @SBI_Nick recommendations you'd need to add one 6" duct ( 28.270 square inches ) to get you a little over the minimum square inches of ducting he recommended in his post. Round ducts move air "more cleanly" vs a square or rectangular duct so there is a possibility that one might be okay. I'd shoot for two or maybe even three 6" round ducts if possible. It might be easier to add one eight or ten inch duct too. You almost double your square inches when you jump up to the next size ( 6 -> 8 -> 10 -> etc ) round pipe.

If you have a manometer you could use it to take a reading inside of your furnace to see where you currently are at.

 

[brenndatomu]

I would be shocked if the HC has a bigger blower than the LW did...those old school wood furnaces would use a lot of wood, but also put out a ton of BTU's, so they usually had bigger blowers too...depending on your house, the HC may have its hands full.
What are you heating exactly?
Keep in mind that the HC blower will run on low 99% of the time, unless you are running it hard.

 

[Carl_Bunyon]

I would be shocked if the HC has a bigger blower than the LW did...those old school wood furnaces would use a lot of wood, but also put out a ton of BTU's, so they usually had bigger blowers too...depending on your house, the HC may have its hands full.
What are you heating exactly?
Keep in mind that the HC blower will run on low 99% of the time, unless you are running it hard.

Between 2200-2500 SF farm house built in 1989. Roughly 1200sf footprint. Half of which is open to second floor

 

[trx250r87]

Attached photo is the blower off my HC if you need to find the specs for that motor.

The way I have my HC set up now, I get more airflow into the house compared to when my previouse furnace (Drolet Tundra) was hooked up using two 8" take-offs.

What is the temperature of the basement return air entering the air box of the HC?

Eric

 

[Carl_Bunyon]

Attached photo is the blower off my HC if you need to find the specs for that motor.

The way I have my HC set up now, I get more airflow into the house compared to when my previouse furnace (Drolet Tundra) was hooked up using two 8" take-offs.

What is the temperature of the basement return air entering the air box of the HC?

Eric

The blower specs are in the manual... 875 cfm. The air temp in the basement is roughly 65 degrees

 

[brenndatomu]

The air temp in the basement is roughly 65 degrees

Getting the return air hooked up will no doubt give you a performance boost then...warmer air in = warmer air out.
Definitely hook that extra 6 or 8" return duct up too...minimum sq inches is minimum sq inches.

 

[Carl_Bunyon]

Getting the return air hooked up will no doubt give you a performance boost then...warmer air in = warmer air out.
Definitely hook that extra 6 or 8" return duct up too...minimum sq inches is minimum sq inches.

Agreed. See pic. The 8x18 dumps into the 24 x 8 main trunk line on the side of the basement near the chimney. I am thinking we redo the plenum so the 8 x 18 can vent out the side and then run a separate 6" round out the opposite side directly to the main living room supply. That would give me 144 + 28.26= 172.26 sf

 

[sloeffle]

Agreed. See pic. The 8x18 dumps into the 24 x 8 main trunk line on the side of the basement near the chimney. I am thinking we redo the plenum so the 8 x 18 can vent out the side and then run a separate 6" round out the opposite side directly to the main living room supply. That would give me 144 + 28.26= 172.26 sf

I’d put a bigger duct in then a 6”. A 6” duct barely gets you over the minimum. I’d go 8” or 10“ or multiple 6” ducts.

 

[Carl_Bunyon]

I’d put a bigger duct in then a 6”. A 6” duct barely gets you over the minimum. I’d go 8” or 10“ or multiple 6” ducts.

At what point am i losing air flow to main trunk of the house? I was going to run the 6" direct to my living room independent of the main trunk line. My issue is now I don't have much air flow going upstairs as it is vs the old Longwood

 

[brenndatomu]

At what point am i losing air flow to main trunk of the house?

Put a damper in the "extra" line then.

Agreed. See pic. The 8x18 dumps into the 24 x 8 main trunk line on the side of the basement near the chimney. I am thinking we redo the plenum so the 8 x 18 can vent out the side and then run a separate 6" round out the opposite side directly to the main living room supply. That would give me 144 + 28.26= 172.26 sf

Are we talking about supply ducts, or return air ducts? I see supply duct in the picture...

 

[Carl_Bunyon]

The sizes i referred to are supply ducts. My previous message said I am not yet hooked up to the house return air system. I hope that connecting to the R/A will increase the air flow

 

[brenndatomu]

I hope that connecting to the R/A will increase the air flow

It wont increase the flow much, if at all...but it will increase the supply temp some.
Do they send an air filter with the HC? If not, what MERV filter do you have in it? A high MERV filter can make a real difference in airflow (less) especially when it gets a little dirty

 

[Carl_Bunyon]

It wont increase the flow much, if at all...but it will increase the supply temp some.
Do they send an air filter with the HC? If not, what MERV filter do you have in it? A high MERV filter can make a real difference in airflow (less) especially when it gets a little dirty

Air filter is optional. 20 x 15 x 1. My guy is going to make one with final connections

 

[brenndatomu]

Air filter is optional. 20 x 15 x 1. My guy is going to make one with final connections

Air filter or not, will change airflow CFM for sure. I'd have him go bigger on the filter size if possible.

 

[trx250r87]

Air filter or not, will change airflow CFM for sure. I'd have him go bigger on the filter size if possible.

I believe you have the option of installing a filter on left, rear or right side of the return air box. I put a filter on both left and right sides for better airflow.

Eric

 

[Carl_Bunyon]

Good morning, we are experiencing bitter cold weather in Missouri this week. While waiting for HVAC guy to come make changes to duct work discussed earlier, I went ahead and started a fire. I figured partial warmth was better than the straight electric furnace running nonstop. Now, mind you that i just bought this house and still needs some work. It is very drafty. I set the t-stat at 73 but the house never gets above 69. I am lucky to get 3 hours of constant blower time before I need to add wood. I am reading other folks post they are getting 7-9 hours. Is this due to needing the draft damper as suggested before? I have read mixed responses whether the draft damper was needed. I have two magnetic flue thermostats on the flue pipe. It typically reads around 150 degrees, reaching as high as 200 degrees immediately after refueling. So it does not look like i am losing a lot of heat out the flue. My plan was to make changes to the plenum and supply ductwork first, but should i go ahead and put in the flue damper? How will that react with the auto damper in the HC?
Thanks for the help.

 

[trx250r87]

Good morning, we are experiencing bitter cold weather in Missouri this week. While waiting for HVAC guy to come make changes to duct work discussed earlier, I went ahead and started a fire. I figured partial warmth was better than the straight electric furnace running nonstop. Now, mind you that i just bought this house and still needs some work. It is very drafty. I set the t-stat at 73 but the house never gets above 69. I am lucky to get 3 hours of constant blower time before I need to add wood. I am reading other folks post they are getting 7-9 hours. Is this due to needing the draft damper as suggested before? I have read mixed responses whether the draft damper was needed. I have two magnetic flue thermostats on the flue pipe. It typically reads around 150 degrees, reaching as high as 200 degrees immediately after refueling. So it does not look like i am losing a lot of heat out the flue. My plan was to make changes to the plenum and supply ductwork first, but should i go ahead and put in the flue damper? How will that react with the auto damper in the HC?
Thanks for the help.

How is the return air getting back into your basement? Do you leave a door open?

Your original statement mentions that the HC is on one side of the house and not centered. Mine is set up the same way. The 2 farthest rooms opposite the HC are a little cooler than the rest of the house but I also have cheap windows.

My footprint is about 1750 sq' basement with the same on the 1st floor. I have a ranch and the center of the house has 12' cathedral ceilings.

Eric

 

[Carl_Bunyon]

How is the return air getting back into your basement? Do you leave a door open?

Your original statement mentions that the HC is on one side of the house and not centered. Mine is set up the same way. The 2 farthest rooms opposite the HC are a little cooler than the rest of the house but I also have cheap windows.

My footprint is about 1750 sq' basement with the same on the 1st floor. I have a ranch and the center of the house has 12' cathedral ceilings.

Eric

My basement is roughly 1200 sf. The house is two levels, with roughly 1/3 open to the second story. Actually, the rooms farthest from the furnace stay warmer because the ceilings are 8' . Yes, right now I leave the door open at the top of the basement steps.

 

[FixedGearFlyer]

I suspect you have more going on than just opportunities in your heat duct connections.

How do you have your HC wired for a thermostat input? You mention you only get 3 hours of constant blower output before reloading - if you have a thermostat connected and it's satisfied (not calling for heat), thr blower will not be on constantly.

What does your firebox look like after 3 hours? Is it all coals? Are there still charred splits left? How much wood do you put in when you reload? What kind of wood are you using and what is the moisture content? What does your flue connection look like and what kind of chimney does it connect to?

If you're only getting 3 hours of burn off a full firebox of seasoned wood, something is definitely wrong.

 

[brenndatomu]

If you're only getting 3 hours of burn off a full firebox of seasoned DRY wood, something is definitely wrong.

Fixed it for ya
If the HC is anything like the Tundra, or the VF100, you CANNOT burn up a fully loaded firebox in 3 hours...you just can't....unless its all uber dry kindlin or something...

 

[JRHAWK9]

It is very drafty. I set the t-stat at 73 but the house never gets above 69

if you have a thermostat connected and it's satisfied (not calling for heat), the blower will not be on constantly.

If the HC is anything like the Tundra, or the VF100, you CANNOT burn up a fully loaded firebox in 3 hours...you just can't....unless its all uber dry kindlin or something...

His thermostat is -not- being satisfied though, so I'm guessing the furnace is running with the damper open the whole time trying to satisfy it....?

 

[brenndatomu]

His thermostat is -not- being satisfied though, so I'm guessing the furnace is running with the damper open the whole time trying to satisfy it....?

Yeah, probably not, but even so you can't need to reload in 3 hours...unless maybe you are loading a box 1/2 full of screamin hot coals...

 

[FixedGearFlyer]

His thermostat is -not- being satisfied though, so I'm guessing the furnace is running with the damper open the whole time trying to satisfy it....?

He was also talking about running his electric furnace in that post, so I'm not clear on whether the thermostat is for the electric or wood furnace, or whether he has the dual furnace interlock wired on the Heat Commander.

 

[JRHAWK9]

Maybe the HC is different, but I thought on those furnaces which are thermostatically controlled, when the thermostat is calling for heat the air damper opens in order to try to provide that extra heat needed.