Changing inlet stem on a Micromatic PremiumPlus regulator

March 7, 2015

I’m looking to add a nitrogen stout tap to the keezer.  As a result I need to add another gas cylinder to the setup – a 30/70 blend of CO2 to nitrogen.

In Australia we have a couple of different cylinder threads.  Standard CO2 comes in a cylinder with a Type 30 connection.  The new blend I will be using has a Type 50 connection.

I bought another Micromatic regulator to go with the new cylinder.  The original model that I bought is no longer locally available and the PremiumPlus model has taken its place.  This model comes standard with a Type 30 connector so I need to swap out the inlet stem with one compatible with Type 50.

Older model Micromatic regs use right-hand threads on the low pressure side and left-hand threads on the high pressure side.  This would be a massive problem because all commercially available inlet stems I’ve seen are for right-hand threads (left-hand threads seem to be a Micromatic idiosyncrasy).  I was really hoping that left-hand threads wouldn’t be applicable to the PremiumPlus, otherwise my options would be down to a custom fabrication or buy yet another regulator from different manufacturer.  Having emailed Micromatic about this I can say that, in my experience, as a company you should not expect any sort of reply – I certainly didn’t get one.  Not even an acknowledgement.  So I thought I would document my findings here.

The first thing to note is that all the fittings are sealed with thread-lock and assembled by sumo wrestlers wielding spanners.  They are not easy to get off and due to the limited purchase on the body of the reg you have to be very careful not to damage dials, etc.  You really have to build a jig like I have below.


Grab a sturdy off-cut of wood, drill a hole in it so that the regulator can sit flush against the surface.  The low pressure dial and outlet treads are held in place by coat hanger wire that is twisted tight on the back side.  You will also need to cut a notch so that the captive nut of the existing inlet stem can drop down exposing the hexagonal end of the stem.  You will also need to pry off the nylon washer that sits on the end that seals with the cylinder.


Grab the appropriate sized socket (metric) and you’ll need a long length of pipe to turn the spanner into a large breaker-bar.  I used a 1m length of cast iron gas pipe.  The thread on the inlet stem is right-hand (yay!) so apply controlled gradual anticlockwise pressure until the thread-lock loosens.  It’ll take a fair amount of torque.  I also recommend getting a friend to hold the regulator and be ready to catch it should the jig snap to stop it all crashing to the floor.

Colour-coded manifold

October 29, 2012


I realise that for many this will be stating the bleeding obvious, but I have to admit that it took me a month or two to get around to making this 1 minute enhancement!

The problem arises from the fact that beer and gas lines don’t like going around sharp corners, and John Guest style fittings don’t like being stressed laterally (slow leaks result).  The upshot is that lines tend to be a little longer to make slow curves and mine plunge down into the deep recesses of the keezer.  Combine this with the reality of numerous identical gas lines (which unlike beer don’t get coloured by the presence of the beer style inside them) and that often kegs are swapped in and out while others are still in use, and you easily end up with a bit of a braided bird’s nest of anonymous tubes running here and there.

The simple solution is to put a ring of electrical tape at the gas disconnect end and a corresponding tab on the manifold.  Beer lines don’t need any treatment as they sit on top and are really obvious where they go.

Now when a keg is exhausted it’s really easy to look at the keg and think “turn off red”.  Or slot a new keg in, grab any old gas line, hook it up and flip the appropriate valve on the manifold.  I honestly don’t know why this wasn’t done earlier – I’m astounded by my own apparent laziness!

A sight no-one wants to see…

September 4, 2012

I did some brewing prior to nipping off on a month long holiday.  I came back, noticing that the fresh gas bottle was registering empty.  I naturally assumed I had a gas leak from one of my JG fittings.  I was wrong…

Opening the lid, I was greeted with a sight that no brewer wants to see – precious beer all the way up to the compressor hump.  One of the poppets had leaked and the gas cylinder had emptied a full keg of wonderous dry-hopped pale ale and then itself.  Bah.

I guess the only upshot of this is that a) my gas lines don’t leak after all; and b) I have proven the keezer to be water-tight.

Keezer – Plumbing

June 19, 2012

Throughout the keezer I have elected to minimise the number of barbed fittings and instead use John Guest-style push fittings.  Unlike barbs these fittings can have the hose lines easily removed and generally terminate to a 1/4″ flare thread (MFL/FFL).  For this reason I chose a gas manifold and liquid/gas disconnects that terminate to 1/4″ MFL for every connection.  Easy disconnection has distinct advantages for cleaning and system adaptability.

The drawback of this plan is that an awful lot of FFL to hose connectors are required and this pushes the price up.  The standard line used in home beer dispensing is 5/16″ OD (3/16″ ID).  The internal diameter is important because appropriate flow resistance is critical for ensuring that carbonation stays in suspension while the beer is in the lines.  Failure to do so causes a foamy pour.

5/16″ connectors in Australia (like everything niche) are very expensive.  A $2.30 connector in the US is $7 here in a brew shop (who are pretty much the only people that stock this size).  Yet 1/4″ line is extensively used for water filter systems here and is very reasonably priced ($3-4 a connector).  1/4″ hose is obviously narrower causing higher resistance, lower flow rate and be harder to fit to flared fittings.  So basically I have a couple of options:

  1. Buy all in 5/16″ locally and pay 2-3 times as much [aka The Chump’s Option]
  2. Buy all in the US, pay international shipping and wait for 2 weeks for it to arrive (and this option leaves no room for finding out I’m short by one connector) [aka The Trader’s Option]
  3. Buy all in 1/4″ and run the risk of flow issues [aka The Pioneer’s Option]
  4. Buy all the gas, where resistance doesn’t matter  and most of the fittings are used, in 1/4″ and only do the liquid side in 5/16″ [aka The Heath Robinson Option]
  5. Try and talk a water filter shop into ordering in the 5/16″ gear from their supplier and not charge me massive brew-shop prices [aka The Wheeler-Dealer Option]

The two approaches that appeal to me are 4 and 5 – I would prefer to have the liquid lines in proper 5/16″ but I would like to avoid where possible giving my money to the graspy brew-shop owners that know they have their customers over a barrel.

So the option that I finally went with was the local water filter shop.  Chris at truwater got the bits ordered in – while not as cheap as an overseas order, still pretty good.  For comparison, a $7 John Guest 1/4″FFL fitting at a brew shop was $4.50.  I estimate that I saved at least 35% by buying through him.  And didn’t have to wait for anything.

Once all the bits arrived it was all pretty much plug and play thanks to all the John Guest fittings I was using.  After getting truwater to price up the bits I went the extra mile and ordered in some JG fittings for my tap shanks.  This made installation a breeze and will allow greater disassembly should I need to.

One of the challenges was working out how to make the connection between the keezer and an external gas cylinder (so that I can run the full complement of 4 kegs).  My solution was to use 5/16″ grommets and some spare plastic (old ipod box, I believe!).  I have this arrangement sealing both the inside and outside walls of the collar.

And finally, here’s a look at the inside of the keezer. You can see my JG shank fittings at the top; the black is a sheet of coreflute with yoga mat behind it for lid insulation; and on the left is my 4-way gas manifold.

Keezer – Digital Thermostat

May 20, 2012

A chest freezer has many advantages over a standard refrigerator.  One of them being the thermal efficiencies gained by avoiding a front-opening door that spills all the cold air out every time it’s opened.  Indeed I have recently tested my keezer and a digital thermometer placed inside, halfway down, doesn’t even move by 0.1C when the lid is opened (carefully) for a short period of time.

Unlike a refrigerator, however, a freezer must be run with some form of thermostat.  People routinely store normal bottled beer in their home fridges but uncontrolled a freezer will (obviously) freeze them.  I don’t see this as an encumbrance at all – I don’t like my beer at household fridge (food preserving) temperature anyway, so I would have to run a thermostat regardless.

I already run a digital thermostat on my fermenting fridge.  And another one on my HLT.  These are both STC-1000 thermostats, which provide both heating and cooling circuits.  The thermostat that I have ordered for the keezer only has one switched output – it’s a Willhi WH7016C (again bought on ebay and cheap: $15).  I don’t like the interface on this unit as much as the STC, but that might just be a familiarity issue at this point in time.

Just like my previous thermostats I placed this one in a black project box and wired it up by cutting an extension cord in half to provide the power connections.  Some people like to install these units into their keezers but I didn’t for a number of reasons: I think that a visible display ruins the look of a full-wood keezer; I don’t intend to change the temperature very much so what’s the point?; this keezer is going to live in a domestic space (do I really want to be watching a movie with the room lit up by the keezer display?); if I installed it inside the keezer it would be subject to temperature fluctuation and presumably condensation.

Just like the HLT temperature controller I wired this one up with an RCA plug for the NTC temperature probe.  This meant that I could use a bulkhead fitting RCA socket on the back of the keezer, making it easy to seal any holes that pass through the wall of the keezer collar.  It also means that the thermostat box is completely removable, which is clearly useful if the keezer ever needs to be moved.

The probe itself sits inside the keezer.  I’ve just left it dangling about halfway down so that it’s measuring the temperature of the mass of air in the center of the keezer.  I figure this is probably a sensible location for it and will prevent it from fluctuating if the lid is ever opened.