Thor Evaporator

[5iguy]

I have a new Thor 20x68 evaporator with 7" raised flues that is not boiling at a rate of 20-25 gal/hr as specified by manufacturer. Currently I am only getting 12-15 gal/hr. Does anyone out there have one of these machines in use and if so what kind of performance are you getting?

[ecolbeck]

I don’t have that evaporator but I do have one that’s a little smaller that I get 20gph on. I would check to be sure that you have finely split dry wood and that the arch ramp is properly constructed. I would assume that you would have to use a blower to get max gph. You will probably need to add wood every 5 min or so.

[mol1jb]

Describe your setup more. Blower? Stack height? Firing rate and amount? Sap depth in pans?

[5iguy]

I am not using a blower and have 13' of 8" stack including the base. I usually put in 5 sticks of wood about every 5 minutes. The wood is primarily cedar with some pine slabs, a mix of small and larger pieces. The front of the flue pan boils very strong especially when fired but only in the front half. occasionally the entire pan will foam. (I use canola oil as defoamer.) Depth in both pans is 1-1/4"

[mol1jb]

I am not using a blower and have 13' of 8" stack including the base. I usually put in 5 sticks of wood about every 5 minutes. The wood is primarily cedar with some pine slabs, a mix of small and larger pieces. The front of the flue pan boils very strong especially when fired but only in the front half. occasionally the entire pan will foam. (I use canola oil as defoamer.) Depth in both pans is 1-1/4"

How much space is under the flue pan? One thing I would say is the flue pan depth is a little deep. Most run 1/2 to 3/4 inch over the flues. I started running deeper and as I gained experience I lowered them a bit every boil. That helped my evap rate increase.

[5iguy]

ecolbeck Do you have any specs on how the ramp should be constructed?

[Wmmaple]

I have a new Thor 20x68 evaporator with 7" raised flues that is not boiling at a rate of 20-25 gal/hr as specified by manufacturer. Currently I am only getting 12-15 gal/hr. Does anyone out there have one of these machines in use and if so what kind of performance are you getting?

I had a 18 x 63 dropped flue from a different manufacturer. I added sand and firebrick in the arch to within 1/4" of the bottom of the drop flues and filled in the space under the stack opening, leaving 1 1/2" for the smoke to go up the stack. This unit came with a 4" spacer plate that was supposed to go between the flue pan and the smoke stack. I moved the pans back against a 1" spacer that I made and put a 3" in front of the syrup pan. I added a small squirrel cage blower. With the blower and the syrup pan moved back more over the ramp I got a decent boil on the syrup pan and a rolling boil over the length of the flue pan. I used dry softwood cut split into 1 1/2" pieces 16" long and fired every 7 minutes. I always had problems getting a gradient started in the pans due to the syrup pan taking so long to boil, it seemed more like I was batch boiling, so I pulled it off at near syrup (3 degrees over the boiling point for the day) and finished over propane. By doing that I was at about 12-15 gallons per hour, about 5 gallons per hr under what the salesman had suggested it would get. The AUF made the most difference. I know your unit is different but maybe some of this will help.

[GeneralStark]

ecolbeck Do you have any specs on how the ramp should be constructed?

Does the manufacturer not provide this information? Have you reached out to them for guidance?

[ecolbeck]

ecolbeck Do you have any specs on how the ramp should be constructed?

I can only supply a general rule if thumb which is that the ramp should force all flue gassed up against the bottom of the pan. There should only be a minimal clearance of 1/4 to a 1/2 inch between the ramp and the bottom of the flues. A blower is a must if you want to get the most out of your setup. If Thor is unable to help you with this the I would look at other manufacturers for information. CDL sells a similar setup.

[5iguy]

Thanks everyone for your input. I have been in contact with Thor and they told me some things to try. None of their suggestions made any difference. They are now going to make some modifications to my arch, I just have to return it to their shop. Hopefully I will see an improvement in performance next season!