st croix scf 050 has me fustrated

[ridered333]

Hi I am new to this forum I have done some searching around and found a lot of very good info. I purchased a used scf050 this past spring and it seems to run pretty good mechanically. The problems I have been having is it doesn't seem to keep up very good when the outside temps get below 30 and I also seem to be using a lot of pellets 2 bags a day. My house is new to me as I bought it over this past summer and its about 1100 sq ft I believe this furnace should have no problem heating it. I have cleaned it a few times thinking that could be the problem, every time i do i find another crevasse that i didn't realize was there the last time. At this point however I am pretty confident that it is very clean and there are no blockages. Still the furnace doesn't seem to be putting out enough heat. I am now thinking that maybe the door gasket needs to be replaced because when I play with the damper I can shut it all the way and def see a change in the flame if i open it to about 1/4 the flame seems better but still pretty tall as I open it more it doesn't seem to change at all. Burning pellets is new to me and I'm not exactly confident in my ability to read the flame. I was hoping to maybe get some more ideas and suggestions out of you guys that have more experience. thanks for any help I can get

 

[SmokeyTheBear]

Please describe your installation in detail, pictures will help tremendously.

Also do a search on leaf blower trick.

 

[DexterDay]

What is your venting? Starting from furnace, all the way to termination cap (including vent size 3" or 4" vent)

Also describe how the Duct work is supplied? Do you get good flow from the registers?

How is the burn? Is it black and sooty? Or do you have a nice grey ash (ranging from light brown to white/depending on pellet quality)

 

[slangtruth]

Hi I am new to this forum I have done some searching around and found a lot of very good info. I purchased a used scf050 this past spring and it seems to run pretty good mechanically. The problems I have been having is it doesn't seem to keep up very good when the outside temps get below 30 and I also seem to be using a lot of pellets 2 bags a day. My house is new to me as I bought it over this past summer and its about 1100 sq ft I believe this furnace should have no problem heating it. I have cleaned it a few times thinking that could be the problem, every time i do i find another crevasse that i didn't realize was there the last time. At this point however I am pretty confident that it is very clean and there are no blockages. Still the furnace doesn't seem to be putting out enough heat. I am now thinking that maybe the door gasket needs to be replaced because when I play with the damper I can shut it all the way and def see a change in the flame if i open it to about 1/4 the flame seems better but still pretty tall as I open it more it doesn't seem to change at all. Burning pellets is new to me and I'm not exactly confident in my ability to read the flame. I was hoping to maybe get some more ideas and suggestions out of you guys that have more experience. thanks for any help I can get

Pellets = about 8000 BTU per hour (input - less comes out as no method of turning them into heat is 100% efficient)
2 * 40 lb bags = 80 lbs * 8000 = 640000 BTU
640000 BTU / 24 hrs = about 26,500 BTU input, and less than that delivered to the heated area.

Your furnace is rated up to 45,000 BTU input, so you still have a way to go, and are not burning too many pellets. To give you a (very very) rough estimate of what you're in for, we're in the green zone on the map here

(broken link removed)

which doesn't take into account home insulation, loss in the ductwork in your installation and many other factors. They're talking 45-50 BTU per square foot, so you'd be looking at about the right area with the SCF-050 if it's running flat out (which is more like 3 1/2 bags of pellets a day) if you're using good pellets and there aren't a lot of other losses. I have a St. Croix Revolution, much the same as the SCF-050 with a higher input (up to 65,000) and a little faster blower, and am barely able to squeak out warming (to 60-65 degrees) a space twice as large as yours, badly insulated and with 10' ceilings, when I'm burning about 3 bags a day. But it hasn't gotten really cold yet. I think you should plan on buying the best pellets you can find, running the furnace at high much of the time, and working on increasing your insulation as much as you can afford.

My damper is almost closed, maybe 3/8" open. I found the best place for it by suspending a thermometer a few inches above a heat register and dicking with it in small increments until the air coming out was at it's highest temperature. More details on your installation will help the folks here come up with other suggestions for you. Tell us more!

 

[jtakeman]

If the stove is squeaky clean, The one question I have is Is the duct work insulated?

Duct heat loss is a killer!

 

[ridered333]

The furnace is installed in my basement it is vented through the sill and then up above my roof line has a total rise of 13 ft. It is ducted into the plenum of the existing oil furnace which is just blocked off with a piece of heavy cardboard. The cold air return is just open for right now but I opened the cold air duct work for the oil furnace up to the basement. The intake air is just open to the basement also as of right now I will change that eventually to pull in outside air. There are a few openings around basement windows that i will eventually seal up once get it setup to pull the air in from the outside.

 

[ridered333]

What is your venting? Starting from furnace, all the way to termination cap (including vent size 3" or 4" vent)

Also describe how the Duct work is supplied? Do you get good flow from the registers?

How is the burn? Is it black and sooty? Or do you have a nice grey ash (ranging from light brown to white/depending on pellet quality)

The vent is 4" it goes from the furnace to a t cleanout then 5 ft at a 30* angle to a 90 3ft trough the sill to a 90 then up 8ft to a rain cap. The flow through the registers seems very good moves a towel hanging on the rack in the bathroom which it one of the longest runs. The ash seems like a nice fluffy grey ash. the soot on the window is light and wipes off real easy.


This is the flame on setting 1 pilot setting

 

[jtakeman]

What is your venting? Starting from furnace, all the way to termination cap (including vent size 3" or 4" vent)

Also describe how the Duct work is supplied? Do you get good flow from the registers?

How is the burn? Is it black and sooty? Or do you have a nice grey ash (ranging from light brown to white/depending on pellet quality)

The vent is 4" it goes from the furnace to a t cleanout then 5 ft at a 30* angle to a 90 3ft trough the sill to a 90 then up 8ft to a rain cap. The flow through the registers seems very good moves a towel hanging on the rack in the bathroom which it one of the longest runs. The ash seems like a nice fluffy grey ash. the soot on the window is light and wipes off real easy.


This is the flame on setting 1 pilot setting

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Your pictures will not post because you have a space in the folders name. This site breaks links with spaces in them, Rename the folder Mobile Uploads to Mobile_Uploads and it will work!

 

[ridered333]

Thanks I was just wondering why they wouldn't show up as you can see the duct work is not insulated maybe that will be my next step.

 

[DexterDay]

Hooking the cold air return up will help a lot. I do not have mine hooked up, but I have a huge woodstove thats 20' away and heats the basement to the 80*-85* range. So the furnace helps distribute that Hot air upstairs.

What setting are tou running on?? (3, 4, or 5?) Also can you measure the air temp coming from the registers?

I just measured mine last night and got 157* (1 ft up from furnace) and 140*-146* (at registers). Ran it on level 5 for an hour (1st time). Took the house from 70* to 76* in one hr. There was a Forum member that calculated my static pressure (within spec) for me. I had to supply him with all duct size and length, along with some flow #'s. Maybe he will see this and help. I dont want to call him out, as there is some work involved. But my fastest flowing register has an 8 mph wind speed. Flows pretty good. I also have all needed dampers installed on both furnaces.

Pellet quality will help a lot. Also pulling the air from upstairs (cold air return) will help. You are essentially trying to heat the basement area by not having a cold air return. With one, you will pull warmer air from upstairs, instead of trying to heat colder basement air. Efficiency will be increased. IMO.

I only used one side of my house (2 main duct runs). Is there rooms you can close off? Or vents that can be closed? To help the flow through others.

 

[jtakeman]

Thanks I was just wondering why they wouldn't show up as you can see the duct work is not insulated maybe that will be my next step.

I see 3 issues with the duct.

1.) it's not insulated

2.) Its 2 small

3.) Hook the pellet furnace to the cold air return. Also need proper dampers added.

If you reduced the ducting size from the pellet furnace you killed its air circulation ability's!

 

[ridered333]

Its 8 inch duct which the manual does call for min. 10 inch. I thought this could be a problem however 8 inch was the biggest I could find. Any suggestions on where to get bigger? Or maybe it would just be worth the money to have a guy come in an do the duct work over for me. Not sure what that would end up costing me I don't have a ton of extra money hence why I did the install myself. Ill also look into getting some insulation for the duct work.

 

[turbulator]

I have the exact same pellet furnace. It appears you are venting into the oil furnace plenum... Did you baffle the cold air return on the oil furnace since you arent using it?

My install is pulling from the main cold air return, with a slide baffle... When the pellet furnace is running, the baffle is slid over so it pulls from the house....when the heat pump is running, I slide it over so the heat pump can pull....

My St Croix struggles to keep up with my approx 2300 sq ft. home....I am in the same green zone as you....my problem is static pressure....and the SCF-050 only has 800CFM on high setting.... Heat doesn't get distributed well, so I get hot rooms and cold rooms....

 

[ridered333]

For right now I have a piece of heavy cardboard slid into the bottom of the plenum on the oil furnace blocking off completely. Does it sound like the furnace it running right and it could just be a distribution problem? Ill have to go get a thermometer and check some temperatures at the furnaces and at different registers.

 

[turbulator]

I am a bit of a noob myself, but I can tell you that if the furnace is malfunctioning, you will see it in the quality of the burn... My biggest issue is black glass due to ash clogs or clinker plugging up the gasification process....

Once a week the furnace gets a complete cleanout.... I made an extension for my shop vac with a garden hose, and it goes up into the ash covers... I also take off the cover where the heat exchanger scraper is....and clean out on top of the tubes....

 

[jtakeman]

The vent is sketchie but not much else you can do with a basement install. And its 4" so something you'll have to live with. Ash gives a good clue to burning decent. A dirty stove would be more of a black sooty color. So if the fire is brisk when on the high burn, I'd say its distribution.

Increasing the duct size will send more volume upstairs and connecting the return air will get the basement out of the heat loop. The pellet furnace should radiate enough to warm the basement. Getting the basement out of the loop will reduce the square-footage your heating with the ducted air. This will also increase the efficiency of the furnace!

I'll see if I can find some links to post for 10 inch vent. But looking in the local yellow pages you should be able to find a supply house that carries something. Most HD and Lowes only go so large. They should also have some info on insulation for you. You increase the heat loss by a lot(could be over 30%) just by insulating the ducting.

Another thing is that cardboard for the damper. Cardboard is flamable and shouldn't be in the ducting system. Get yourself a piece of metal or cement board to use as a damper. Don't need any fires in the ducting! Safety first!

 

[SmokeyTheBear]

You are sending basement air through the system.

The proper way to install a hot air furnace is to use both the cold air return and the hot air distribution system that forms a closed loop for the furnace's blower and stops shoving basement air and likely mold spores throughout your house. You need proper block off plates on both the hot and cold air sides to stop sending any of the air the pellet unit is trying to heat back trough the other furnace's heat exchanger where a large fraction of the heat will be removed and sent up the other furnaces flue.

Having it set up the way you do requires that the furnace also heats the basement air as well as what your really are trying to heat.

The observation about lack of insulation is spot on just be sure to tape all of the joints before insulating, also the observation about the hot air side is spot on, you are causing unneeded stress on the convection blower by restricting its output side.

You need to also check the temperatures at the registers to prevent the burned toes outcome.

 

[jtakeman]

My advice comes from my own trial and error's in heating from the basement. It's a been there and done that thing! ;-)

 

[ridered333]

Thanks for all the advise i really appreciate it. I went and grabbed an infared thermometer from a friend to see what was going on with the duct work. Low and behold when I checked the temp at the base of the plenum I had 116 degrees and by the time i reached the top where the 90 is it was already cooled to 95 degrees I have 90 degrees at every register in the house when the fan is running. Once the fan shuts off the registers cool to 75-80 degrees in about 2 min. So my next step will be to get some insulation on the ducting and hookup the return and then I will go from there. Thanks again

 

[jtakeman]

Your actually measuring the duct surface temp. If you measured the actual air temp the loss will be slightly higher. If you insulate you still get initial some loss due to warming up the ducts, But once its warm you will see the temps rise on the registers. You will see some imediate results with the insulation, But this is only the start, You still need to improve the whole system. The damper first for safety sake! Larger ducting and getting the loop closed by connecting the return air to the pellet furnace. You also reduce you fuel usage in the long run so this has a payback along with a warmer house! Your not just throwing money at it! ;-)

 

[SmokeyTheBear]

Be certain to test the register temps because they should rise after you seal and insulate. You don't want any roasted piggies. But seriously you should tie the cold air return in and have the proper block offs installed.

 

[Freddels]

I'd suggest disconnecting it from your furnace system and just installing a register or two in the floor and running it directly.

I have the same furnace and I have it hooked into my furnace system. There's a short run to one of the bedrooms and when I don't have the damper closed, there's a ton of heat that goes into that bedroom. I then run a fan that distributes it to the rest of the house. When I close the damper to that room, there is definitely less output of heat being distributed to the house. I'll be disconnecting mine from the main system and installing a new register.

There's an HVAC supply place on Piedmont St. in Worcester that has all different sizes, including 10" ducts. It's also better quality than the stuff you can get at HD or Lowes.

 

[Wachusett]

Another thing to look into before you insulate the duct work is seal all the seams and joints with sealer.
You can buy a tub of it and apply with a paint brush. It may sound trivial but losses through these
seams and cracks adds up.

 

[ridered333]

Since Saturday I have done some insulating and taping just the main sections for now. I also hooked up the cold air return which I feel made a big difference. For safety sake I also replaced the cardboard with a piece of sheet metal. I feel like I still need to do some more sealing up of the ducting. Once I tied in the return my convection fan was staying on constantly and It feels like I am getting nice warm air out of the registers feels like pretty good flow too. I think tonight I'll play with the fan off temp so I can get the fan to shut off so the furnace has a chance to come back up to the on temp. To get me through this winter I'm gonna try to utilize my current duct work. In the spring I will redo the whole system as it will be a good time to install a central air unit at that time. I would just like to say thank you to all of you for the help and suggestions I really appreciate it alot.