PSG caddy low heat output

[bluecloud]

I recently installed a PSG Caddy wood-only furnace. I also have a 80,000 btu propane furnace that is 95% efficient. Both furnaces run through the same duct work, but I set them up so that they can't be run at the same time (I block off the ducts to the one I'm not using to prevent hot air from going into the return air ducts).

I installed the Caddy per the installation manual. The chimney connection is a double-wall tee on the back, then a barometric damper, then 35 feet of 6" Class A Supervent (insulated) chimney pipe. The hot air plenum is 24" high (per manual) and the return air plenum is about 32" high. The main duct line is 8" x 16".

My house is an older 2 story house 2,000 sq ft plus full basement. But the basement is not really heated. I know the house needs more insulation and some air leaks sealed up. I am only heating the main level right now.

My issue is that I estimate the heat output of the Caddy to only be about 20,000 btu's. The brochure says max output of 140,000 btu's and average output of around 76,000 btu's. When it was 30 degrees outside, I ran the Caddy all day with a full fire, and it only brought the house up to 58 degrees. The last couple of days, it has been close to zero outside, and the Caddy could only keep the house in the low 40's with a full fire going.

If I run my propane furnace, it would only cycle on about 25% of the time to get the same amount of heat that the Caddy produces. That is why I estimate the heat output at 20,000 btu (25% of 80,000).

The ductwork in my house is not very extensive, and I run the fan on the lowest setting, which is about the same fan speed that the propane furnace runs on.

The Caddy hogs though a lot of firewood. More than a wheel barrow a day, if I keep loading it up. Burn times are not very impressive (load it up and it's gone in 4 hours). My firewood is high quality and dry. It is all hardwood, cut 2.5 years ago, split over 1.5 years ago, and covered from the rain. It is not rotten at all. I have tried firewood from another source and same results. The fire will burn really hot, I just don't know where the heat is going. Obviously the thermostat that controls the inlet damper is worthless right now, since it would always be wide open due to being so cold inside. So I have been controlling the inlet damper manually by propping it open with something when I want the fire to burn hotter. I am getting the secondary burns (I think), meaning that I see flames shooting out of the little air pipes in the top. And everything is burning down to a nice fine white ash.

I have played with the fan limit control switch, all different settings. The best seems to be on around 160 deg and off at 110 deg. I had a problem with the switch sticking, it would run for hours blowing out cold air, then I go over and tap the limit switch and it would shut off. I think I have fixed that problem. I have my own probe thermometer in the plenum. It will go up to 160 deg, then when the fan comes on it cools down very quickly (less than a minute) to 100 deg, but the fan will keep running for a few more minutes. At night if I have a lower burning fire (mostly coals), it will never get hot enough to kick on the fan (it only gets to around 120 deg), so I have no heat in the registers all night.

I think my chimney pulls a good draft, because even when there is no fire going, I can feel a draft going through the chimney, just because of how tall it is. I have also played with the settings on the barometric damper, moving the weight back and forth. I have even tried taking the barometric damper out so that it is just a wide open hole into the chimney. I can stick my hand through there into the flue, and the flue gasses do not feel that hot. The chimney is hardly ever hot to the touch, on the Class A portion of it. I have not tested the draft on the chimney, but even if I did, I don't know what options I would have if there is too much draft. I can't make the chimney any shorter or narrower.

The manual says one cause of low heat might be that the return air is too cold. I understand it makes the furnace run inefficiently, but how am I supposed to get hotter return air when the thing won't put out of enough hot air from the registers???

So I don't know where the heat is going and I'm out of ideas. Tonight it is very cold out and I did not even bother making a fire, I am just using the propane furnace tonight so that the pipes don't freeze.

I have over $5k invested in this thing (including the chimney, ductwork, wiring, etc), and I'm very disappointed in it so far. Any advice on how to improve the performance of this thing would be greatly appreciated!

 

[sloeffle]

I have the same furnace that you have, but mine has the panels to take out for electric or oil. I heat around 2200sq ft in Central Ohio without any issues at all.

The ductwork in my house is not very extensive, and I run the fan on the lowest setting, which is about the same fan speed that the propane furnace runs on.

Do your wood burning furnace have the 4 speed fan ? I have mine set to medium low per the manual and I have no issues pushing heat around.

Have you checked your static pressure in your duct work ?

The Caddy hogs though a lot of firewood. More than a wheel barrow a day, if I keep loading it up.

On a normal day I burn through about half wheel barrow load. If it is really cold out like it has been we burn through a little more. Have you checked the static pressure in your chimney ?

Scott

 

[laynes69]

There's no way your burning a load in 4 hours, and only putting out 20,000 btus. You need to set your draft with a manometer and check your static pressure. Our home is so drafty, I can smell the fresh air from outdoors. Not proud of it, but it is what it is. Even then we have no problems keeping warm. The temperature of the air from the woodfurnace will not be that of the gas. If it was, the home would be a 100 degrees. Either your home isn't as tight as it could be, or there's something wrong with the installation, or operation of the furnace. Going from 160 degrees in the plenum to 100 within a minute tells me something is wrong. I watch our limit control and when there's a good fire, the temps read between 130-140. At 1 degree the other night, we had a solid 6.5 hour burn overnight with a very heavy call for heat, holding the home at 72* and our home isn't small. In the mid 20's to 30's we can see 8-10 hours overnight. Above that it's half loads overnight. At 30 degrees we easily could have it 80.

 

[bluecloud]

Thank you for the replies. I hope to do some more testing on it this evening. sloeffle, I probably have the same furnace that you do. Mine has a panel that can be removed to add electric heating element (and maybe oil...not sure). Which I think would be really dumb to heat with electric on one of these, even if it was working right, I think a lot of the electric heat produced would go out the chimney, even if there was no fire. Just my thinking.

I will try to get the static pressure in the ductwork checked. But I don't really think it would make too much difference. I have the fan on the lowest setting, and it is cooling off the plenum pretty quickly. Going to a higher speed setting would just cool it off even faster. And the propane furnace is basically on the same ductwork, and it works fine, and the air coming out of the registers is much hotter.

 

[laynes69]

You need pressure in the ductwork, the slower the air, the less pressure. Bump up your fan speed to med-low to med-hi, your not putting enough heat from the furnace into the home. My ductwork size is 8x18 off my plenum. If I set my fan to low, I would never heat the home. You will not see the output temps from the Caddy that you see from your central furnace, it's not designed that way. Also make sure the exchanger is clean for maximum heat transfer. The electric add-on has nothing to do with the chimney, neither are tied to each other. 100% of the electric heat would be put into the home. Your propane furnace is an off-on system, that's not how a wood furnace operates.

 

[laynes69]

I'll also add, running with the damper open isn't going to put more heat into the home, but push it out the chimney. Get ahold of a manometer and set the barometric damper to the manual (.04"-.06").

 

[mackat]

I'll also add, running with the damper open isn't going to put more heat into the home, but push it out the chimney. Get ahold of a manometer and set the barometric damper to the manual (.04"-.06").

I recently installed a PSG Caddy wood-only furnace. I also have a 80,000 btu propane furnace that is 95% efficient. Both furnaces run through the same duct work, but I set them up so that they can't be run at the same time (I block off the ducts to the one I'm not using to prevent hot air from going into the return air ducts).

I installed the Caddy per the installation manual. The chimney connection is a double-wall tee on the back, then a barometric damper, then 35 feet of 6" Class A Supervent (insulated) chimney pipe. The hot air plenum is 24" high (per manual) and the return air plenum is about 32" high. The main duct line is 8" x 16".

My house is an older 2 story house 2,000 sq ft plus full basement. But the basement is not really heated. I know the house needs more insulation and some air leaks sealed up. I am only heating the main level right now.

My issue is that I estimate the heat output of the Caddy to only be about 20,000 btu's. The brochure says max output of 140,000 btu's and average output of around 76,000 btu's. When it was 30 degrees outside, I ran the Caddy all day with a full fire, and it only brought the house up to 58 degrees. The last couple of days, it has been close to zero outside, and the Caddy could only keep the house in the low 40's with a full fire going.

If I run my propane furnace, it would only cycle on about 25% of the time to get the same amount of heat that the Caddy produces. That is why I estimate the heat output at 20,000 btu (25% of 80,000).

The ductwork in my house is not very extensive, and I run the fan on the lowest setting, which is about the same fan speed that the propane furnace runs on.

The Caddy hogs though a lot of firewood. More than a wheel barrow a day, if I keep loading it up. Burn times are not very impressive (load it up and it's gone in 4 hours). My firewood is high quality and dry. It is all hardwood, cut 2.5 years ago, split over 1.5 years ago, and covered from the rain. It is not rotten at all. I have tried firewood from another source and same results. The fire will burn really hot, I just don't know where the heat is going. Obviously the thermostat that controls the inlet damper is worthless right now, since it would always be wide open due to being so cold inside. So I have been controlling the inlet damper manually by propping it open with something when I want the fire to burn hotter. I am getting the secondary burns (I think), meaning that I see flames shooting out of the little air pipes in the top. And everything is burning down to a nice fine white ash.

I have played with the fan limit control switch, all different settings. The best seems to be on around 160 deg and off at 110 deg. I had a problem with the switch sticking, it would run for hours blowing out cold air, then I go over and tap the limit switch and it would shut off. I think I have fixed that problem. I have my own probe thermometer in the plenum. It will go up to 160 deg, then when the fan comes on it cools down very quickly (less than a minute) to 100 deg, but the fan will keep running for a few more minutes. At night if I have a lower burning fire (mostly coals), it will never get hot enough to kick on the fan (it only gets to around 120 deg), so I have no heat in the registers all night.

I think my chimney pulls a good draft, because even when there is no fire going, I can feel a draft going through the chimney, just because of how tall it is. I have also played with the settings on the barometric damper, moving the weight back and forth. I have even tried taking the barometric damper out so that it is just a wide open hole into the chimney. I can stick my hand through there into the flue, and the flue gasses do not feel that hot. The chimney is hardly ever hot to the touch, on the Class A portion of it. I have not tested the draft on the chimney, but even if I did, I don't know what options I would have if there is too much draft. I can't make the chimney any shorter or narrower.

The manual says one cause of low heat might be that the return air is too cold. I understand it makes the furnace run inefficiently, but how am I supposed to get hotter return air when the thing won't put out of enough hot air from the registers???

So I don't know where the heat is going and I'm out of ideas. Tonight it is very cold out and I did not even bother making a fire, I am just using the propane furnace tonight so that the pipes don't freeze.

I have over $5k invested in this thing (including the chimney, ductwork, wiring, etc), and I'm very disappointed in it so far. Any advice on how to improve the performance of this thing would be greatly appreciated!

 

[mackat]

Blue cloud - have your Caddy furnace problems been solved?( I just saw your post at 2015 03 25). You relate so much in your comments. Your chimney and experiences are very similar to mine only I paid, 5 years ago, over $14 000 Canadian for the system change over from a Duomatic Olsen wood oil to the Caddy wood oil. It also included the installation of a 7 inch stainless steel chimney liner. The fire box in the Caddy is so hot but I couldn't get the heat into the house. ........We have tired a number of possible solutions and got results from each one to a varying degree of success......we are trying to heat a 2800 sq foot home.......first the installer played with the fan speeds and then checked the plenium pressure and it was adequate........then the flue pressure on the 44 foot chimney...it was acceptable. He returned the fan speeds to the manual recommended ones. Some trouble shooters have suggested that the furnace is not adequate in size to heat this house. I was shocked to discover that after I bought the
140 000 BTU Caddy unit it was explained to me by a government official that the furnace efficiency is now measured using its efficiency number and its output. I replaced a 112 000 BTU Olsen with a 140 000 Caddy. The Caddy is rated as 140 000 but that is multiplied times its efficiency which is around 75% so its real out put is only 105 000 BTU on the best wood. He went on to say that on a pine wood fire it would only put out about 65 000 BTU in a prefect running situation! I was appalled to learn this! {However with the solution I give below, pine wood makes a great daily fire and I save the hard wood for my overnight fires now}.
Our home would be quite comfortable on the oil side of the furnace with the fan running quite differently on the oil than on the wood......then he put baffles in all my ducts to slow down the air moving through my heating system because the air was moving too fast through the hot air plenium.( He explained it's like the cool you feel when you stick your arm out the car window on a hot day. Your arm feels cool because it doesn't take up any of the heat in the air.)...the air was moving too fast to collect the heat there and it can't preheat the air coming in to be heated up at the base of the cold air plenium where the chimney base runs through for this purpose. This prompted me to remove the outdoor fresh air fed that ran directly into the cold air plenium. Result 10 -15% improvement in heat to the house - 45 F to 55F. It was replaced by an insulated J line just outside the front door of the furnace. I can't see why I should be using my heated air to allow the fire to burn. We have been freezing in our home over the past 4 years with the Caddy in, UNTIL THIS YEAR when we have had record breaking cold here for most of the winter. I too played with the fan limit control (which ran for hours pushing cold air).....and got some improvement there - 5%. I ahd to tapped it to satrt it and stopp it many times. Eventually the installer replaced my fan limit control. The manufacturer said my wood was too wet - it wasn't! Smoke coming out the door on mine was solved by cleaning the unit AND the chimney more regularly at least twice a winter...........instant results and the smoking goes away! We started installing more energy efficient windows( triple glazed and some special gases) and got some heating improvements 3 top 5 % because the furnace didn't have to work so hard. (Old windows were installed in 1983).
My final solution, and this has taken our home from the 50's F to 70's/80's F with it minus 10 F outside for weeks, was to move the fan limit control in the hot air plenium.......moved it 2 inches and only 2 inches closer to the front of the furnace. Left it on the same level plane but moved it 2 inches and no more.......it takes about 15 minutes to cut the hole in the hot air plenium, reattach the wires safety to the side of the furnace and properly seal the old hole with metal tape. We've seen our wood consumption drop by 30 % and our heat improve by at least 15% more - 50 F to 80F if we want it. The logic behind this modification is that like 'the arm out the car window', moving air is cooler. In the old position, the sensor is exposed to too much moving air inside the plenium which keeps the sensor "cooler" than it should be so it doesn't operate in the correct range that you have it set at.
Accompanying this solution for us was that the furnace starts to cycle the air damper properly and hence wood is saved. Before the limit control move, the air damper on the front of the furnace was open all the time because the demand for heat was never met at the thermostat in the living area. There was always a demand for more heat so the damper was wide open all the time. Now when it closes down I can sit in front of the furnace and watch the blue flames dance over the wood like other owners told me that they had seen in their Caddies. The fire takes on a whole new characteristic. (and so does a warm wife). Hope this wasn't too late and that it helps. Mac

 

[David_QC]

Thank you for this information, I will certainly try it with my Max Caddy tonight, I have the same kind of problem, it have a digital controller that can set the KIP (kick in temp) from 107 to 132F, maximum KIP is 132F, it is what I set it to... fan stop at 122F.
When fan start, it kills the process by cooling it too much ! Always cycle On/Off and the damper is always open and won't reach the best effiency point (manual says 160F)
I know this could improve my heating because when I have time to, I disconnect the 120v furnace plug for a few minutes, then I reconnect it and it usually shows somewhere around 160F when the controller come back and the fan start, and then the process is much much much better !

 

[mackat]

Thank you for this information, I will certainly try it with my Max Caddy tonight, I have the same kind of problem, it have a digital controller that can set the KIP (kick in temp) from 107 to 132F, maximum KIP is 132F, it is what I set it to... fan stop at 122F.
When fan start, it kills the process by cooling it too much ! Always cycle On/Off and the damper is always open and won't reach the best effiency point (manual says 160F)
I know this could improve my heating because when I have time to, I disconnect the 120v furnace plug for a few minutes, then I reconnect it and it usually shows somewhere around 160F when the controller come back and the fan start, and then the process is much much much better !

Yes I have done the same -turned off the power to the blower and let the fire box heat up (but not too much) and then turn it back on again and you get the heat you want for that fire!. Then moving the fan limit control solved it all for me...be careful taking the fan limit control out that you do not adjust your settings. I wish I could include a picture of my repair.....the new hole is not even the thickness of the limit control box away from the old hole in the hot air plenium. ( 2 inches is not a long way but what a difference in heat out put) Metal snips with a point can make the cut after you drill a 3/8 inch hole. I tried to do the hole all as one with a large metal bit and it is not possible ...it jumps around too much. Do not make your hole too big...the old hole will show you the size. Good luck and let me know your results.

It sure is strange how some Caddies work fine and about 2 in 10 seem to have this problem of no heat but the fire box is scorching hot. Mac

 

[mackat]

Yes I have done the same -turned off the power to the blower and let the fire box heat up (but not too much) and then turn it back on again and you get the heat you want for that fire!. Then moving the fan limit control solved it all for me...be careful taking the fan limit control out that you do not adjust your settings. I wish I could include a picture of my repair.....the new hole is not even the thickness of the limit control box away from the old hole in the hot air plenium. ( 2 inches is not a long way but what a difference in heat out put) Metal snips with a point can make the cut after you drill a 3/8 inch hole. I tried to do the hole all as one with a large metal bit and it is not possible ...it jumps around too much. Do not make your hole too big...the old hole will show you the size. Good luck and let me know your results.

It sure is strange how some Caddies work fine and about 2 in 10 seem to have this problem of no heat but the fire box is scorching hot. Mac

I just checked my fan limit control and it is presently set at 110 and 260.....that's on the rotatory type dial with the pins and this is working well for us and this winter has been cold!
Our house is presently at 25C and that's too warm. Mac

 

[David_QC]

Do not make your hole too big...the old hole will show you the size.

Max Caddy has a 1/4 diameter RTD probe, it will take me 2 minutes to drill another hole and move the probe 2 inch closer to the front door. I will see the difference as the probe temp is shown on the controller LCD.
If I see a colder temp than I guess it's want we want, because it will take a few more degree inside the firebox to get that controller start the fan...
I wrote an email to SBI just to make sure that I cannot set the KIP higher on the controller (kind of a hidden programmer mode?) or what they think about moving the probe...

 

[mackat]

Max Caddy has a 1/4 diameter RTD probe, it will take me 2 minutes to drill another hole and move the probe 2 inch closer to the front door. I will see the difference as the probe temp is shown on the controller LCD.
If I see a colder temp than I guess it's want we want, because it will take a few more degree inside the firebox to get that controller start the fan...
I wrote an email to SBI just to make sure that I cannot set the KIP higher on the controller (kind of a hidden programmer mode?) or what they think about moving the probe...

Good idea to contact them as it sounds like your control is quite different than mine........I am still interested to see how it turns out for you. Mac