PVC pipe pre-heater?

[Clan Delaney]

Has anyone here ever tried building a parallel flow pre-heater out of PVC pipe? N, more specifically, has anyone ever used one with any success?

And before you start (and I KNOW you will :lol:), yes yes yes I know I should be making it out of copper. But I don't have any copper. I DO have about 50 feet of 3/4" PVC. It won't conduct heat nearly as well as any metal, but it's certainly not an insulator either.

My biggest concern is in the catastrophic failure department. I fear that the constant exposure to around 200 degree steam will cause warping, sagging, etc.

Thoughts? Experiences?

[Thad Blaisdell]

There was a robot that said it best

Danger Will Robinson Danger

PVC will never work.

[Clan Delaney]

*sigh*

I just checked the technical specs for PVC schedule 40 pipe. It MELTS at 173 degrees. D@mmit. :mad:

[markct]

hmm didnt think it melted that low, but i know it gets real brittle after being exposed to hot, about 160 degree, water for long periods, found that out when in a hurry we patched in some hardware store pvc on a wash system for a powdercoat paint line, worked great for a few months till the fittings shattered like something just a touch tougher than gram crackers!

[moeh1]

What the limit on CPVC, I know it s higher....:confused:

[Bemis]

I believe it is 160C gentlemen. That's pretty darn hot.

I also thing this plan is doomed to failure.

[sweetwoodmaple]

Doesn't matter if it survives, plastic is an insulator. You will not get much preheating from this, hence the copper preheaters.

Sorry, guys...I know that copper is expensive...but start watching ebay and grab up some deals.

[Rossell's Sugar Camp]

Last year i was boiling and i used a plastic valve as a drawoff valve in a pinch. I tasted the syrup when i was done and it tasted like plastic. I dumped 2 gallons on the ground. Not worth buying the pvc if there is a chance it will not work.

[Beweller]

The maximum service temperature for PVC is 140 F. For CPVC it is 200F. The thermal conductivity is low, about 0.95 BTU/hr Ft^2 F/in, compared to 2600 for copper. At the heat fluxes used in preheaters, this is significant. You would need many more square feet of surface using plastics.

In favor of plastics is the lower weight, lower cost per unit surface area and simplified fabrication.

In all, I suspect the vote will be against plastic.

[collinsmapleman2012]

wow... i was just asking myself the same question 10 minutes ago... now my thought for good preheater and head tank is to use a 275 gal tank suspended in the air, and then run piping out over the arch and pan to make a preheater... will this work?
here is a diagram

[maple flats]

For a preheater to be of any significant net gain you must have a hood AND must catch the condensation and channel it away from the evaporator. I understand the most efficient one even use a damper in the steam stack, I do not.

[sugarmountain]

Pvc will droop and melt etc. I used pvc once to feed the preheater and it was trashed after one day. That ran next to the hood not even in it. Its now stainless milk pipe, no more worries.

[Clan Delaney]

Well, for the sake of argument, what about PEX? It's used for radiant floor heating, so I suppose it could take the heat.

I admit that if the choice was to buy PEX or copper, you should go with the copper. But if it's a question of using PEX you already have on hand versus buying new copper.... I'd do the PEX over no pre-heater at all.

[DRod2]

I ran copper around the flu, I baught a 50 ft roll of 5/8th roll and this makes the sap drop in around 100 degrees. It doesnt always have to be right above the hood

[kiegscustoms]

I have built a few preheaters based on Leader's design. If you know how to block solder (with an iron) you can make one for less than $200. I just built one for my 7' flue pan for $140 (1" copper pipe, unions, box manifolds, etc. Go to your local sheet metal shop and have them make up a drip tray and you're good to go. Besides why would you want to spend the time materials to make something that could melt or give the finished product an off flavor possibly?