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Need help with E8 boiler cascade controller!!


I have 2 wall hung Alkon50 boilers hanging on a wall and want to integrate a E8 boiler cascade controller -- the documentation is a bit weak for a non HVAC guy like me.  Specifically, can I hook up a traditional make or break thermostat to the E8??? Or do I wire-OR the thermostat leads to both boilers?  E8 has some FBR{1} abd FBR2 pins... can FBR pins take a make or break thermostat?  And if so, they mention 2+M  what the heck is that?    And do I set my max water temps way high and E8 will try not to go high fire unless needed?  Do I use the included FLOW sensor os is that for a fancy system with solar and DHW etc??  The E8 controller seems to be sold with a number of brands of mod-con boilers... I figured maybe someone has used  a E8 and could give me a few pointers??  The Alkons are slick, I can hold my hand on the metal flue pipe exiting the exchanger and it's just warm = condensing.  Tis install is replacing an ANCIENT 2-pipe steam boiler by GE... warm water should be lots less spastic and I will save a fortune in gas!  BUT, I am in the dark about the E8 -- and my system circulator pumps are wire-nutted ON, I'd like to get them controlled, and get the outside reset going...and the REAL cascading. 


  • Zman
    Zman Member Posts: 6,994
    Tough one!

    The E8 looks like a very powerful and versatile controller. It is also very European. I do not believe that you can wire T-stats directly to it.

    What happens if you wire the t-stat to one of the boilers?

    As far as sensors go, The E8 will need an outdoor sensor and a manifold supply temp sensor. The others are probably for other applications.

    The good news is that the boilers are capable of being controlled via 0-10vdc signals.

    If you become fed up with the E8 you could go to a well supported North American company like Tekmar. I would call them before purchasing.

    Did JohnnyNY respond? He seemed to like the product.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Armadillo
    Armadillo Member Posts: 8
    E8 Cascade controller thermostat controls inputs

    Johnny did reply but not with 100% concrete "I did this and it worked out like this"  but there again his recent install is very complex [to his credit].  I saw in the picture he shot that he was using the E8 controller and if he managed to do battle with it and WIN, OMG.  I certainly am not jumping on The Wall to bad-mouth anything or groan too much...  the E8 and it's docs are simply not intuitive and the documentation is so-so and then translated.  Boiler companies sell the controller but in my case have not spelled it out: "if you hook it up this way you have a working cascade with turn-down and outside reset and good old room thermostat and one zone". 

    I have 2 Unical Alkon 50 hanging on the wall, I got them via in Cedar Rapids Iowa.  I am a firm firm believer in these, I have them making heat forced down below the condensing point, I can touch the exchanger and or flue pipe and hold my hand on it -- a far cry from my ancient steamer belching out 350F flue gas into 8" chimney port. 

    However the pair bundled with the elusive E8 cascade controller?  There are some missing facts and simple ones.    It seems like if I buy sensors and thermostats made for the E8 I'm good.    Yah the boilers have terminals for the traditional make or break thermostat or even a toggle switch or wire jumper...  clearly, when flipping to Canbus control from the E8. all that's out the window.  The Unical Alkon 50, 70, 90..they have onboard controllers that are designed with the E8 in mind, but, can take a thermostat and plunk into an old lady's basement for an old school replacement.  Thus I have the pair running wire-or'd to a 2-wire thermostat with nominal water temps set at 120F [hoping the flue gas is below say 131F = full condensing, per my supplier].  It's pretty silly to have two boilers kicking on when it's, well I saw them on today when it was 60F here.    The system pumps are wired ON...lots of loose ends. 

    I have been watching public TV and see the show on Bentley... they  made aircraft engines with aluminum/magnesium/silicon just like Unical has  done with my wall-hung boilers.  Low-fired most of their lives I think they will last a long long while.  I think ALu has had a bad rap in the USA from some big snafus..dissimilar metal problems

    I read of...  

    Frustrated as I am now, I think I threaded the needle and WILL figure this all out.  The Europeans have been thinking about this green stuff seemingly longer.  I decided to be my own general contractor much like another guy on The Wall lately -- people in the biz quoted solutions that were costly [that's not unexpected] but that didn't answer the need for either a 40+ foot flue liner or a different H2O heater and a water-softener...which is fine but...when the quotes hit pushing $17K and didn't MENTION the loose ends... or the wisdom of implementing a counter-flow return system...  I took my own control and hired a master fitter and a guy to help under him, that I have known for decades.      My building is 3000Sqft 2-flat but the piping is now one "zone".  2-pipe steam rads we converted to warm water by yanking any vents, plugging those holes with plugs, we sawed off the plugs at top of 110YO rads flush, center-punched, drilled with 4-5 sizes of bits then tapped to 1/8" for bleeders. We yanked teh rad's steak traps guts and drilled the seats out.    The new awesome counter-flow return piping I designed with PEx-AL-PEX at 1" ID per side of the old mains, 2 sides of the basement but fed as one zone.   Being new to PEX in general I just did what I was told.  inside cut edges of the 1" ID pex-al sheered the PEx-AL fittings O-rings...everything leaked.  I yanked it all apart and used a simple burr-grinder bit to mill the insides of the PEX-AL ends to a taper/flare, replaced the sheered O-rings...  no leaks!  If I had to do it again I'd add anaerobic Permatex gasket goop to the formula, just about everywhere.  

    The posting is in the controls thread.  Back to topic, the e8 seems AWESOME and yet documented with some holes in the logic.  I turned to The Wall because it's majorly confusing.  My veteran fitter and I are in a holding pattern, brute force on but...  I am on the edge of caving in and third-party sourcing the FBR2 noted in the E8 docs... or the full-featured remote controller [not so great for tenants]. 

    The boilers?  They are spark -lit and will probably not have ignition failure for ages!  The flame-sensor is  bent steel rod.  Modulating gas valves... unicast ALU...counter-flow water vs gas.....  I would and will buy more, they are slick!  PROPERLY controlled they can low- fire most often and save the owner a huge amount of gas.  E8 controller?  Well, I have a few...ANY insights welcome!!
  • Armadillo
    Armadillo Member Posts: 8
    More E8 Trivia

    is a source for the 3-wire official  E8 controller thermostats.  FBR1 or FBR2 

    [email protected]  seems to be able to handle sales queries from folks like me; their SITE only wants to ship to Ireland by default.  Brian seems very responsive and like he knows the product.

    This page shows much of the E8 accessories I have been wondering about:

    and for documentation a great place is:[docname]=fbr&suche[keywords]=&suche[klass]=-1&suche[klassname]=All&suche[sprache]=-1&suche[sprachename]=All&suche[datum]=&suche[ordner]=-1&suche[ordnername]=All&suchen=true

    seek the PDFs with GB or Great Britain in the name if you are an English speaker?

    Since I plan to cascade I am gonna try to stay with the E8 -- for a single boiler I might think otherwise [Honeywell?  Techmar??] -- I have already made my E8 into a "used" item so...might as well keep learning and using!!  Outstaning questions I have are about using the included flow or other sensors with the E8 kit, and if they are needed for cascade management specifically?  [I have 2) Alkon 50s on the wall]  I opted NOT to do DHW on advice from another local wizard; he figured I'd have to fire at 145-150+ to get 125 degree F indirect hot water, that would be outside the full condensing region of the Alkon 50 boilers...he figured that WITHout the DHW task, the Alkons would be low-firing most of their lives.
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