The beer engine project

Necessity is the mother of invention. MacGyver is the father.

I have been missing the real ale in London (among with other things I miss in London), pulled from the cellar on hand pump beer engines. I looked into buying one for the Thoor but they cost about $500 for an authentic one. I decided to try to build one first.

Most of the progress, however, came as an accident when I took the Hagal Stout down to my family’s bar for St. Padraig’s Day. I had it in a 2.5 gallon keg that I had not yet used, and when I got there, I found that the piece that attaches the CO2 to the keg was broken. In order to get beer out, I had to unscrew the two sides of the keg and just pour it out. This meant that the beer was exposed to air and had to be consumed, so when I got it home the next day I set out to hook it up to the prototype beer engine I had already begun.

The pump:

photo(15)Looking on the web, it looks like many others have had similar thoughts, and there are a few sites with instructions on how they built them. Mostly it is all about the housing for the pump, not so much the mechanism itself. Most of them use the same RV water pump as the base unit, and this is the one I am using for the first go as well.

The housing, which is what most of the sites talk about, is really not the point. I wanted to see if the thing was going to work first, so I made a basic platform with some plywood and drilled a hold for the pump to sit in and the tubes to come through.

Main issues:

The main issues in building the thing are not the obvious ones, the pump and housing. The main issues as I see them now are:

  1. The attachment at the keg and how beer is to come out of the keg and air get in
  2. The dispense at the glass. Because the beer will not be heavily carbonated, some sort of mechanism for air to mix in is necessary at the dispensing point. Usually this consists of some sort of sparkler. This puts a head on the beer, but also the air mixing in brings out the flavors in a way that will not happen if it is poured flat.

At the keg:

Essentially what needs to happen here is that beer needs to leave the keg, preferably without bringing all the yeasty goodness with it, and air needs to get into the keg to replace it and prevent a vacuum from forming (nature supposedly abhors a vacuum, despite the fact that only a tiny fraction of the universe is anything but vacuum). I have seen videos online showing modifications to a Corny keg for using it to dispense beer from an engine. The main issue is that the Corny tube for drawing beer goes all the way to the bottom of the keg. This means that if the keg is naturally carbonated, the tube will sit in the yeast sediment and make it difficult to draw off a clear beer. The solution shown in the videos is to reverse the uses of the openings, bending the beer outlet tube and turning it toward the side of the keg so that when the keg is laid on its side, the end of the tube sits in an air pocket to let air in. Then the beer is dispensed from what would normally be the CO2 inlet tube.

This seems like a lot of work, especially when I would rather stand the keg up than turn it on its side. The air inlet side of the keg only has a ball lock mechanism that pushes a valve open. So, all that is required here is to unscrew the ball lock mechanism and let air in as necessary. I love it when a plan comes together.

On the outlet side, the keg has a tube that descends to the bottom and the middle of the keg in order to draw beer from the bottom. This does mean that for a naturally carbonated cask-conditioned ale, it will probably be drawing up the yeast sediment. This was not an issue with the stout, but possibly because it had been poured from the side first. This will be something to look at. No reason really that the tube could not be cut a little above the bottom, though this may miss some beer I guess. For now, I simply removed the pouring spout from the end of the beer line, and attached it to the bottom of the pump. This gives a nice convenient ball lock connection to the pump.


The keg connections

The business end:

The first few pints, I poured just from the pump as it comes out of the But it was clear that some sort of sparkler was needed. Since I was in a pinch, and grew up watching MacGyver, I improvised. I found that the rubber caps that we all have for our rubber carboy tops to attach airlocks fit perfectly on the end of the spout from the pump. I drilled holes around the perimeter to force the beer through. I used a 5/32 drill bit I believe, but I would go smaller next time. Use 3/32 or 1/16.


photo(18)I did not consider the angle of the spout. Preferably, the spout coming into the glass would be vertical and go right into the bottom of the glass. The spout tube on this pump ends at an angle. So, with my sparkler, beer tries to shoot in all directions. I need to either make an extension to the tube so that it hangs vertically, or next time I would drill holes only on the bottom side of the sparkler cap.Of course, the pressure of the beer would blow the sparkler off, so I used electrical tape to fix it to the tubing.

The prototype:

That was about all there was to creating something functional. It did a serviceable job at dispensing the stout, even though it had been treated pretty roughly the previous day. It does not have a large capacity. A standard British engine will pull between 1/4 and 1/2 pint per pull. This one only pulls about 1.5 oz or so with each pull. That does affect the head and does not give the nice cascading effect of the pour. I have looked online for a higher quality, more capacious pump, but no luck yet. Building the pump unit itself would be a bigger project.


Of course, what is really needed to test the setup is a proper English bitter. So, I have brewed one and will update the performance of the engine when it is ready.

Next steps:

Aside from a higher quality on the pump itself, my main question at this point is whether the setup is going to draw in too much yeast off the bottom of the keg. If so, I could shorten the tube from the beer outlet so that it does not reach the bottom. Then, I am not sure I would be able to get all the beer out though. The modification shown in the videos online is an option, but let’s see how it goes first.



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