Pre Heater question.

[Maritimer]

I'm building a preheater for my small evaporator. After looking all through this forum, I found one that I like and would fit great in my hood. I'll have one feed line and 6 parallel 3/4 copper pipes. The question that I have is about the drip pan. I would like to make individual drip tray's for each length of pipe but I have seen some with just one tray under the whole thing.this would be a lot easier to make so would this still be ok? , would this allow enough steam to preheat the pipes even though the steam will be somewhat "blocked" by the drip pan,hence I think the individual tray's would be better. Any thoughts from anyone?

Mike

[Greenwich Maple Man]

I built a couple as well as bought my current one. The factory one I now have has a solid SS tray under the copper pipes. Works great , the sap gets very hot. The pipes are close together within a inch. The ones I built I made a drip tray using Alm. angle iron. cut a notch in the bottom pice and then set the ones that ran under each pipe into the bottom angle in the notch . Ran the one bottom angle right out of the hood. That worked very well to but was a little more crude than my current setup. My 2 cents is that I would never run a evaporater without a pre heater of some sort. Makes everything faster.

[NH Maplemaker]

I built my own and used the V shapes drip trays under each pipe. I think it makes more sence to have the steam hitting each pipe as hot as posible. I also put a temp gage on the exit line and we get temps of 200+ degrees. Now before anyone says your crazy! There are other traders on here that have seen it.LOL Don't forget the damper in the steam pipe leaveing the hood. Thats is as important as the preheater! JimL.

[Hop Kiln Road]

I have a factory preheater with a single drip pan. Last thing you want is condensate sneaking back into the flue pan. But like JimL says, as long as you have a damper in the steam vent pipe and a fairly tight hood, there is actually steam pressure under the hood. Be sure and have a vent to release any air lock because the sap will produce gas in the heater tubes and even with the vent you'll hear gas in the float box!

[Bucket Head]

Just like the Ford vs. Chevy debate. Either way works. I have a tray and i can get 190 degree sap with my damper wide open. Any preheater is always surrounded by steam in any well fitted hood. They have no choice! Go with whatever style is easier and/or least expensive for you to build.

Steve

[killingworthmaple]

I am about to make a preheater and have been considering the v shape style the only thing that has me wondering is will I be able to catch the drips the fall from the roof of the hood and from the steam stack pipe. Any oppions I would love to hear them?

Nathan

[heus]

My hood has built-in trays under each stack pipe exit. This then drains into the built-in channels around the inside base of the hood.

[Dennis H.]

I have a preheater and drip tray built by Jim S. of Smokey Lake Maple.
The drip tray is similar to what you want to make. It is V shaped bottom but it is made from sheet SS that was bent and has stamped out opens for the steam to go thru.

As for the hood it needs to have a drip channel around the bottom where it sits on the flue pan. This is where any condensate that runs down the sides of the hood will end up and then flow out a drain hole at a corner. My preheater drip tray also drains into this channel.
You should try as much as possible to make a tight fitting hood. This keeps cold air from being sucked in and causing the steam from cooling too fast.
Now as for the damper. I have used on and have found that on my setup anyway that there is a fine line as to how much to damp'en off the steam stack. With it wide open I get sap coming out around 180, if I close it completely off I found that yes the sap temp goes up to about 200 I also found that it sort of slowed the boilk rate down. I think this is from all the steam condesate staying in the hood and what doesn't go out the drain must end up in the flue pan. Not a good thing.
I found that I close it off about 1/2 , the sap going into the float box runs right at 195-198. I can live with that.

As for building up pressure in the hood. There should be no concern of that. Even if you closed the damper off all the way the hood is not completely sealed so steam will come up any crack that isn't sealed, like the doors. That is how I found that the damper 1/2 open is the best. I closed it off and watched the steam coming out any crack or opening. I then slowely opened the damper till no more steam came out of the cracks.

[Maplebrook]

I built the "one big tray" option. Like Hop Kiln says, the hood becomes somewhat of a pressure vessel, so the steam is surrounding the pipes anyway.
Maritimer, depending on the volume of sap you boil, 1/2" copper for your parallel tubes may be all you need.
Killingworth, design your hood so the horizontal part of the hood is narrower than the drip pan. Include a drip channel around the inside perimeter of the bottom of the hood. For my steam stack, the condensate from it collects in an area at the base of the stack which is then plumbed with a piece of sap tubing to the drip pan.
You guys are on the right track!
Darren

[wiam]

As for building up pressure in the hood. There should be no concern of that. Even if you closed the damper off all the way the hood is not completely sealed so steam will come up any crack that isn't sealed, like the doors. That is how I found that the damper 1/2 open is the best. I closed it off and watched the steam coming out any crack or opening. I then slowely opened the damper till no more steam came out of the cracks.


I have seen a 5x16 completely ruin both pans because the damper was closed all the way. The pressure pushed most of the sap to the front pan and when the front needed more there was none. Randy Gaudette from Leader told us he had seen it in another sugar house also. If you can run with damper closed all the way good for you but beware.

[Woody]

For what's it's worth.....I cobbled up a hood and pre-heater last year and found that a drip channel around the bottom edge wasn't that necessary because when the hood itself gets hot it doesn't seem to produce much condensate. There's a lot generated from the stack due to the temperature differential and of course a lot generated off the pre-heater but that seemed to be about it. Interested in what you guys think about that.

The stack damper is a big deal I found and I'm glad to hear other guys are using a single pan. I tried one last year but was going to switch to individual v's but I don't think I will now. The pressurized hood should take care of assuring there's steam around the tubes.

Thanks and here's hoping for normal winter and spring weather.

[Maritimer]

Thanks guy's for all the input. I forgot that I had posted this and I just competed a new post!!!!! I had one of those blonde moments. You all say how important it is to have a well sealed hood. Well, mine is....up to a point. I have a 18x60 which includes the syrup pan in front. Its all sealed well up till the syrup pan. It continues over the front pan (18in square) and drops down 8in, with a space of about 12 inches that is open. Should I seal the whole hood all the way around my syrup pan as well?

[Maritimer]

Thanks maplebrook. I only tap 200, so far anyway. I was just going to go with the 3/4 because I was worried about the vapor lock with the 1/2. Does the hood have to cover the whole pan or just the sap pan. I have a hood over the whole evaporator but the sides are open over my syrup pan. About a 12in gap. Maybe I should take some pictures and post them on here. Its always easier to look at a pic than to try to decifer it from the way I try to expain it anyway.

[Maplebrook]

The way you describe your hood should work fine. My evaporator doesn't have a hood over the front pan at all.
Regarding pipe size, if you plan to build a manifold by butting 3/4" tees together with a stub of pipe, there won't be much room for the heat exchange pipes (width wise) as you only have 18" wide to work with. You want the preheater to be compact in width so the steam can get up around it. I soldered 1/2" copper directly into (at 90*) 3/4" to make my manifolds.
6247
6246

[Maritimer]

I can't quite make out your picture of your preheater. I.m not quite computer savey enough. At first I didn't now what the copper pipe was that went around the perimeter of your pan. I think its a drip channel to direct the condensate right? Your front pan is exposed but your hood is all sealed all around. Mine is open to the front around the syrup pan. I'll take some pics tomorrow and post them for you and you can see what I am talking about. But looking today at mine, if I get a peice of stainless to match the hood.......71/2 X 54in I can make it work and have both pans sealed. How about a damper in your steam flue? Do you have one. Some say it is a must. Did you ever take a temp reading on how hot your sap is?

[BoarsNest]

I notice that most preheaters are made with a manifold design. I have a lot of 2ft 3/4" copper drops. I was thinking to just solder elbows on the ends and make an S shaped preheater for about 30". I would tilt it with a vent on the high end. Other than maybe more soldering do you guys think I will get some good temps?

[wiam]

That would probably be fine for your evaporator. More flow can be obtained with parallel than going through one long pipe.

[Maritimer]

OK, I took some pictures. I'll see if I can get them imported to this thread. Originally I was going to go with one 3/4 feed line to a manifold then from there traveling up the pipes from the manifold(6of them) to the next manifold and exiting to the float box. Since I only have a 18x64 evaporator, I think I'll go with 1/2 pipe entering to a manifold sloping down (4in) then elbowing back up to another manifold and exiting to the float box. It would be something like the one Maplebrook had built. What kind of temps were you getting Maplebrook? As you can see in the pics, I'll have to close off the hood around my syrup pan. Will I have to install a damper also in my steam pipe?62516252625362546255

[BoarsNest]

That would probably be fine for your evaporator. More flow can be obtained with parallel than going through one long pipe.

I assume that more flow would lead to more heat transfer so hotter sap. If that's the case then I might rethink this. I want to get as much increase even if it is 10% that would be another 2-1/2 gph.

[Maritimer]

Well , I see your point. I could use 3/4 and still go with a stack instead of just the one set of pipes. Decisions Decisions.Do I need a damper in the steam stack?

[Maplebrook]

Here's answers to a couple of questions...I can get 160-185 degrees entering the float box. I have a thermometer from a commercial dishwasher in the outlet manifold.
The copper pipe around the perimeter of the flue pan supports the preheater and drip pan. No sap flows through this.
I do not have a damper in the steam stack.
Darren

[Hop Kiln Road]

6263

Don't skimp on your diameters, when the float calls for sap, it needs sap!

[Maritimer]

Ok, well you guy's talked me into it. I'll go with the 3/4 with a stacked type. By the way...do you know a place I can purchase a 5" dial Thermometer? Being from NS everything is mailed in and shipping is expensive.Just looking for a few different options.

[Pibster]

Where in Nova Scotia are you?

[bowtie]

where can i see plans for homemade pre-heaters, would like to look into building one and a hood but need plans, copper,ss and or aluminum are quite expensive to experiment with. thanks

[vernon]

Maplebrook Do you have any plans on paper of yor preheater? I took pictures of it but my phone went throuh the washer and lost my pics.....Thanks Vernon

[Pibster]

I had planned to use a 3/4" manifold on each end with 8 runs of 1/2" pipe between each one. If I use 3/4" pipe for everything, the capacity of sap in the preheater doubles. My preheater will be 18" wide and 26" long. With 3/4" pipe, there will be a 1-1/2" space between each pipe. Would that mean that the sap would move slower thru the pipes resulting in hotter sap?

[Maritimer]

Hi Pib. Nice to see you on here as well. You and I are going through the same delema. I was going to go with one the same as maple brook. It seams pretty good. Think I'll put my own little thing on it to try to tweak it a bit. I still have that float box here if you are looking for one. I won't ask much for it....just your first born!!! Can you get copper cheaper than I can? one length of 3/4 I can get for 23$. We should have a preheater building meeting. you can supply the wobbly pops.

[Maplebrook]

Hey Maritimer & Pibster...can I come to the meeting? I'm in Elmsdale, and both of of you are welcome to come see my sugar camp.
On the 1/2" vs 3/4" discussion, here's my experience: I used to boil using a flat pan and 2 lobster pot burners side by side. I made a preheater using 3/4" copper looped back and forth for 4 or 5 runs suspended over the pan. It wouldn't heat worth a darn. I changed it to 1/2" copper and got it at least warm. This is why I support large manifolds/small heater tubes. As I said earlier this week on here, the flow of two and one quarter 1/2" copper pipes equals the flow of one 3/4" copper pipe. If your supply line and manifolds are 3/4", you won't starve your evaporator as long as you have at least 3 heater tubes. I support you building as you wish, but with 3/4" copper selling for $23/length....
Vernon, I don't have plans on paper, but I'm getting my preheater out this weekend to take some pictures for Lakeview Maple. Pm me your email and I'll cc you the same. Good thing you didn't drop your phone in the evaporator, it would ruin the syrup!
Maritimer, there is a D&G dealer in Bass River (Gordon Fisher) and a LaPierre dealer in Springhill(Kevin McCormick).
MPANS AGM is next Saturday in Truro. I joined last year...lots of info there and you get to rub shoulders with the big guys!
Darren

[Pibster]

Hey Maritimer & Maplebrook, it's great to see lots of locals on here. Thanks for dropping off that float box Maritimer, you can have Dawn's and my first born.
I ended up using 3/4" manifolds with 8 rows of 1/2" copper. It's very compact and uses every bit of the drip pan. Now I just have to figure out how to mount it inside the hood.

[lakeview maple]

Thanks Maplebrook for the pictures it was a great help62976298629963006301

[Maritimer]

Yes, all great pics. I pretty much got mine completed also. Just have to clean and solder it. I went with 1"inflow , 3/4 manifold , 1/2 inch pipes, and 1" outflow. They are 34" long and there are 7 of them. Which makes it 19.8 feet. I read a study on it and they say if you boil 50gal an hour you should have 20feet in total. Don't know if they meant all pipe including the manifolds or just your runners,anyway I only boil about 20gal an hour with my little one so I think I'll have a little overkill. I guess we will see what will happen.. After you get yours all finished Pibster, are you going to do a trial run with water to see what kind of temps you will have? I'd like to see it.

[Pibster]

I will for sure. I might be a few more weeks getting everything else geared up though.

[clw]

The small hobby guys may be interested in my preheater. I run a copper pipe thru my fire box and into one of my steam pans. When the sap runs out I pull out the copper preheater pipe.
643664376438

[Paul VT]

Has anyone used there preheaters they built yet? I am getting ready to build one and wondering what results people had. They all look pretty good wondering who has got the hottest temps?

[BoarsNest]

My preheater is giving me 180+ sap temp coming in to the float box. I think I've gained about 3 to 4 gallons per hour in evaporation and about 3 gallons per hour in warm condensate out of the hood.

[jrgagne99]

I built one a few years ago. It didn't work very well because I didn't build it right. I hung thin tin angle stock (used for exterior corners in sheet-rocking) from the pipes using zip ties. The condensate mostly hugged the zip ties and the tin angle stocks and then dripped right back into the evaporator. It made my syrup pick up a tinny taste too. Plus, I didn't have a steam hood at the time.

All those problems went away when I built my own steam-away.

[TheMapleMoose]

We built a parallel flow for our 2x4 flue pan. Used all 3/4" copper, 6 parallel tubes. I do have some plans for it in .pdf format. We changes a few things from the plan, mainly just the inlet and outlet heights to fit the hood. Ran it today for the first time and heated the sap from 40F to 130F with no damper. Could I increase my outlet temp with a damper? What are you guys using for a damper?

[BoarsNest]

I put a damper in mine and I am going from sap in the mid 30's to 190+ degrees. I just welded a plate in my stack with about 1/2" opening all around and it seems to work great.

[Pibster]

I'm getting up to 170 degrees with my preheater and hood. Sure makes a huge difference, especially with the steam reduction in the sugar shack.

[Paul VT]

781078107811
These are the pics of the preheater I built. It works great! I have seen 197 degrees and when drawing off only drops to upper 170's! Fills a five gallon bucket with water so hot you can't touch it in about an hour! Never thought it would work this good. And for much less then I could buy one for.
Only got to use it on the last two boils. Can't wait to try it next year!
Sorry about the sideways pictures. Haven't figured that out yet. 78127813