Heating the same boiler with either propane or electricity?

[Steve Broady]

I’ve seen a few older references to people bringing a boiler up to temperature with propane and then switching over to electricity, so I don’t think this is a completely insane idea. I do have some questions about it, though, so I’m hoping someone here has some real world experience or knowledge.

What I would like to do is to heat a keg boiler over propane for a stripping run, because that seems like the fastest way to dump lots of heat in and get the job done efficiently. At the moment, a 220V circuit is not easily available. I’m working on that, but I’m trying to focus here on what I can do right away.

For a spirit run, it seems that ~1500W is a common power input, maybe even less. That’s achievable on a 120V circuit, so I’d like to use the same boiler, with an element inside, for the spirit run. I have a keg with a 1.5” TC ferrule welded in, so that seems like the obvious choice. A with running on 220V, building two separate boilers isn’t really the most practical option at the moment.

I have two related safety concerns. With the keg as it stands now, I’d have to put a cap on the ferrule when firing on propane. I don’t think it would get too hot for the PTFE gasket to be damaged, but it would also be exposed, so maybe? Second, what if I added another ferrule at the bottom (or flipped the keg, same difference) as a drain port? That one would be directly above the fire, so would that be too much for the gasket? I’m assuming so, which is why most drains seem to be welded and bright out to the side, but I wanted to ask because I don’t know and I want to learn.

[HDNB]

i think the teflon would suffer if/when the flame gets to it. if you can avoid direct flame, i don't think the heat would be a problem, the mash will sink it fast enough.

otherwise, heat is heat... and being the cheap bastard i am i use natural gas. But on my last still i had 5000w/240vac immersion and 1500w/120vac hot plate and i used them both for heat up and then the hot plate was more than enough for a nice spirit run.

[Steve Broady]

i think the teflon would suffer if/when the flame gets to it.

That is my fear as well. On the side, I am thinking that the clamp would serve to protect the edges of the gasket for any stray flames. But I’m worried that it wouldn’t be enough on the bottom, so I’ll probably leave the bottom port out of the plan. A drain would be handy, but only if it’s not a hazard.

[jonnys_spirit]

Test it out with a blowtorch or something on a side port you might already have? It’s just a gasket

Cheers,
-j

[juana_b]

I use both concurrently (as I rarely have 220v) with no issues, but I do not expose the triclamp to direct flame.

[Salt Must Flow]

I have a boiler that I primarily use with electricity. The keg is properly upright, I like the handles on the top. I have a drain in the very bottom. I never use this boiler over fire.

I have another keg that I use over fire and I also have a 2" Tri-Clamp ferrule in the side as low as possible for heating with electricity. I cap that and use a PTFE gasket. I use one of those large 10" Banjo burners to heat it and there's a LOT of excess heat that spills out around the bottom of the keg. This has never harmed the gasket. The clamp covers the vast majority of the gasket so it is protected. I have absolutely no worries about harming the gasket. For this keg I have a 1" ball valve plumbed through the side as low as can be. I can tip the keg to aid in draining, but it cannot completely drain the keg like a bottom drain will. With this keg I always end up flipping it upside down to hose it out thoroughly. This is just a tradeoff to be able to heat with flame. I have never tried subjecting a PTFE gasketed joint to direct flame, but I assume it would damage it.

I collect kegs whenever I find a good deal so I don't mind having kegs for multiple purposes.

[subbrew]

From the experience of others here it sounds like a side port is fine. But as additional precaution you could wrap the port, cap and tri-clamp with tin foil. It would add an extra layer of protection.

[NZChris]

The temperature of the charge will protect the PTFE.

You can boil water in a paper bag over a flame. The bag won't burn until the water is gone because the water boils at 212F and protects the paper.

[NZChris]

If you are doing a lot of strips, a Charentais style preheater is the way to go, saving time, plus heating and cooling costs. It's an old invention that has been saving me money and time for decades.

[Dancing4dan]

I use propane to preheat the thumper when using the steam still. To protect the tri clamp and gasket I just place some flat sheet metal pieces between the burner and the bottom outer edge of the thumper pot so they stick out past the side of the pot about 6 inches. Have done this all the way around the pot edge and added a welders blanket around the pot which insulates and allows faster heat up of thump.

The steam boiler is 220 electric and is turned on and heating as the still gets assembled. Doing it this way the still is built and the boiler is close to boil and the thumper with wash is pre heated and ready to go almost at the same time.

The heat shield protects all of the tri clamp connections as well as the welder blanket.

Have had no issues with tri clamp or gaskets, but the blue plastic on drain valve handles won’t take the heat.

All connections are on the side on all my stills.

[Hoosier Shine9]

Hi Steve,

Maybe I misunderstood what you were asking....... (that happens a lot for me)

In the first paragraph I thought you were saying that you want to:
1} have the electric elements in the keg boiler.
2} Have the Keg Boiler on a gas burner.
3} when Boiler charge is up to temperature, or close, turn off Gas.
4} continue & finish the run on Electric.

If the above is the thought I would be concerned with the electric connections on the outside being exposed to flame & melting the insulation.

[Salt Must Flow]

^ ^ ^ I would too. There's a LOT of heat that spills out around the base of a keg. Many RTD sensor cables are heat resistant enough, but I doubt electric cables are. Some sort of heat shield could deflect the heat and protect the cable.

[Steve Broady]

Sorry for the confusion. I mentioned people doing that, because it’s the only reference I found to people running the same boiler on both heat sources. In my case, I want to be able to use either one, but not both simultaneously. Propane for stripping (with a cap over the bottom port), or electric for a spirit run (with an element in the port).

I like the suggestion of just torching a gasket and seeing what happens. When I get home, I’ll clamp one up between a couple ferrules and see how it does.

[bcook608]

Sorry for the confusion. I mentioned people doing that, because it’s the only reference I found to people running the same boiler on both heat sources. In my case, I want to be able to use either one, but not both simultaneously. Propane for stripping (with a cap over the bottom port), or electric for a spirit run (with an element in the port).

I like the suggestion of just torching a gasket and seeing what happens. When I get home, I’ll clamp one up between a couple ferrules and see how it does.

Make sure you take temp readings if you can! That way you know what temp the surrounding metal was at when failure occurred.

[jonnys_spirit]

Sorry for the confusion. I mentioned people doing that, because it’s the only reference I found to people running the same boiler on both heat sources. In my case, I want to be able to use either one, but not both simultaneously. Propane for stripping (with a cap over the bottom port), or electric for a spirit run (with an element in the port).

I like the suggestion of just torching a gasket and seeing what happens. When I get home, I’ll clamp one up between a couple ferrules and see how it does.

Make sure you take temp readings if you can! That way you know what temp the surrounding metal was at when failure occurred.

Please take and share some pics too for the record

Cheers,
Jonny

[Hoosier Shine9]

Hey Steve,

The keg that you have was used as a "Gin Basket" on a commercial still. They were trying to see if it would work.
After a couple of "trials" they decided they would go a different direction.
The Boiler that it was being used with was in a Registered Commercial Distillery & either 750 or 1000 gallon boiler.

hs9

[elbono]

I just tested my 15.5 gallon keg that I recently added a 2" ferrule for the heater element an 3/4" npt half nipple for the drain. Both are on the side just above the bottom chime.

I put a end cap with Teflon gasket on the heater port and left the Teflon tape sealed drain in place. Filled it with water and brought to a full boil with my banjo burner running close to wide open on the 5psi regulator.

The only issue I had was I forgot to remove the insulation from the bottom of the keg. Teflon wasn't affected at all.

Live and learn.