increased capacity

[Mike in NY]

Adding a steam hood w/ preheater in it this yr to our 2x4 wood fired rig, home made 5 section raised flue pan. I copied the design of neighbors preheater and he gets 180* going into his back pan, I expect simmilar results. I picked up a blower today for a forced air induction.
last yr, our first yr w/ this rig, when everything was right we ran near 20 gph. If my upgrades do as I hope can I get close to 30+ gallons an hr on this little rig?

[Brent]

The guy that built my rig says a hood and preheater will get you a 10% increase. I can't argue as I have no before and after hood to compare.
And all the gph rates are next to impossible to compare because of so many other variables, so I took his number and went with it.

[WESTVIRGINIAMAPLER]

Mike,

I would guess around 25gph and hope for 30. 30gph out of a 2x4 is pretty hefty number and maybe attainable, but it will take some time to get it figured out as to what works best with firing and all the other variables.

[Teuchtar]

Mike:
The physics works approximately like this:
It takes 1 Btu to raise a pound of water (sap) by 1 degree. So if you pre-heat the sap by 100 degrees before entering the sap pan, you have made available 100 Btu to go into evaporation.
But it takes 1000 Btu to evaporate 1 lb water. So that 100 btu's can only evaporate 1/10 lb of water.
Hence the 100/1000 = 10% boost in evaporation rate.
Note, that if your preheater or steam hood allows drips of condensate to drop back into the pan, you have wasted your preheating effect, since those hundreds of condensed drops need to be re-evaporated again.
My guess is that those steam-heated pans that have preheater tanks suspended above them are a waste of money, unless they have gutters and troughs to drain off the condensate.
If you can raise the preheat all the way from 40 degrees (bulk tank) to 210 degrees, then maybe the efficiency boost could go as high as (210-40)/1000=17%. But steam pans can't preheat to 210.
By heating 40 degree sap to 180, you could see 14% performance boost, but thats the ideal maximum.
Adding an air injector to the preheater tank, using a regenerating blower and perforated stainless piping will further boost the preheating effect by evaporating more sap in the preheater. Google "Gast Tank Agitation" to find a design handbook on such sparging systems. The boost you get, depends on how much air you inject, and how much of the sap pan's steam you can effectively put to use in your preheater. You can buy a fuji or gast regen blower on ebay real cheap. People use them for big aquariums. I use a 1/6 hp blower on mine, and there's air to spare.
By taking those 3 steps ( preheat to 180, prevent condensate re-entry, and sparging) you can boost system very economically.
My own system is 2x6 will not yet reach 50% boost, although I think the commercial steam-away's claim they can. I can't see us doing that on a small rig. Small rigs are limited by heat exchanger surface area.
Good Luck. Let us know how you make out
Duncan

[KenWP]

Spoken like a true engineer. Now I can figure out my production boost with math.

[Mike in NY]

Mike:
The physics works approximately like this:
It takes 1 Btu to raise a pound of water (sap) by 1 degree. So if you pre-heat the sap by 100 degrees before entering the sap pan, you have made available 100 Btu to go into evaporation.
But it takes 1000 Btu to evaporate 1 lb water. So that 100 btu's can only evaporate 1/10 lb of water.
Hence the 100/1000 = 10% boost in evaporation rate.
Note, that if your preheater or steam hood allows drips of condensate to drop back into the pan, you have wasted your preheating effect, since those hundreds of condensed drops need to be re-evaporated again.
My guess is that those steam-heated pans that have preheater tanks suspended above them are a waste of money, unless they have gutters and troughs to drain off the condensate.
If you can raise the preheat all the way from 40 degrees (bulk tank) to 210 degrees, then maybe the efficiency boost could go as high as (210-40)/1000=17%. But steam pans can't preheat to 210.
By heating 40 degree sap to 180, you could see 14% performance boost, but thats the ideal maximum.
Adding an air injector to the preheater tank, using a regenerating blower and perforated stainless piping will further boost the preheating effect by evaporating more sap in the preheater. Google "Gast Tank Agitation" to find a design handbook on such sparging systems. The boost you get, depends on how much air you inject, and how much of the sap pan's steam you can effectively put to use in your preheater. You can buy a fuji or gast regen blower on ebay real cheap. People use them for big aquariums. I use a 1/6 hp blower on mine, and there's air to spare.
By taking those 3 steps ( preheat to 180, prevent condensate re-entry, and sparging) you can boost system very economically.
My own system is 2x6 will not yet reach 50% boost, although I think the commercial steam-away's claim they can. I can't see us doing that on a small rig. Small rigs are limited by heat exchanger surface area.
Good Luck. Let us know how you make out
Duncan

my preheater has a set of 2 layers of V shaped fins offset to recapture the condesate that would otherwise end up back in the flu pan.It should supply me 8-10 gallons of hot water per hr to use washing filters. The rest will go up the steam stack. the blower I have is 1 hp and will need a rheostat(sp?) to slow it down or it will blow the front doors of the arch open. aerating the sap prior to hitting the preheater is interesting to me.