Can you identify the Alien component in my central heating system

Discussion in 'Plumbers' Talk' started by Vic Truesdale, Jan 21, 2019.

  1. Vic Truesdale

    Vic Truesdale New Member

    I have a 60s house with an open central heating system, once powered by oil, now using gas. It has a component that I have never encountered before (see attached picture). The component is essentially a right angle bend in the plumbing, lying in the vertical plane, between the pipe that goes to the lower union of the hot-water tank heat-exchanger, and the main riser from the boiler. A grey, plastic 'screw-head adjuster' pokes out horizontally from the end of a tube that otherwise would be the right -angle bend. In effect, we have a Tee-piece. On the upper side of the horizontal tube there is a window, which presumably allows one to see the condition of the water in the system.

    My thoughts are that this is: 1. a control for the hot water/central heating balance; 2. a sludge indicator device. However, why have the window if its 1, and why have a controller if its 2??!!

    The name on the device is Rauchmann, or Raukmann.

    Any thoughts?

    Attached Files:

  2. dcox

    dcox Screwfix Select


    Thanks to Google (

    3/4" Differential Pressure Regulator
    Honeywell Braukmann D146M1032

    Used to eliminate excessive pump head pressure when most radiator valves are closed due to reduced demand.

    Includes: Built-in differential pressure indicator
    • Install between supply and return sides of a hydronic system to stabilize pressure differential and reduce the effects of demand changes.
    • Control maintains a constant differential between the two sides by opening a bypass whenever the difference between supply and return reaches the setpoint.
    • Provides silent, trouble-free service.
    • Easy installation; requires no electrical hookup.
    • Easy adjustment of pressure by turning regulating cap.
    • Brass valve body with thermoplastic and stainless steel parts.
    • Diaphragm of EPDM.
    • Pipe Size (inch): 3/4 in.
    • Pipe Size (DN): DN20
    • Pipe Connections: Angle type, female threaded NPT
    • Outlet Pressure Adjustment Range (psi): 0-17 psi
    • Max. Inlet Pressure Rating (psi): 85 Psi
    • Materials: Brass (body), Stainless steel and engineered thermoplastics. EPDM diaphragm.
    • Dimensions (in.): 6 1/4 in. high x 3 3/8 in. wide
    • Dimensions (mm): 160 mm high x 86 mm wide
    • Capacity: 120,000 Btu/hr
    • Capacity: 18 gpm
    • Temperature Range (F): 230 F
    • Temperature Range (C): 110 C
  3. Vic Truesdale

    Vic Truesdale New Member

    Fabulous!!!! I even get an additional bonus because my system is identified as hydronic! Better find out exactly what that implies!

    Thanks again!
  4. dcox

    dcox Screwfix Select

    I don't really understand what its purpose is in that position. Attached is how Honeywell show it in a heating layout:

    diff diagram.jpg
  5. Vic Truesdale

    Vic Truesdale New Member

    Hi again from Vic

    DCox makes an interesting point. Firstly though, the Boiler/Heat Exchanger at the bottom of the diagram is a bit weird! As I see it, the heat exchanger is not connected to the boiling system! Instead, the coil goes off downwards, somewhere else! Also, the system depicted is a pressured system,isn't it? (I think we can put that aside! Or maybe the cylinder depicted, IS THE BOILER!)

    My mystery device is across the output from the hot-water storage tank, and the main riser from the boiler, with the riser connected to the 'C' distance indicator on the accompanying diagram. The orifice 'B' is connected to what I presume to be the exhaust water from the hot-water tank. Given the diagram from dCox, it would seem to relieve any excess pressure created by the boiler, by lifting the internal valve off its seat. How does the indicator work, then?

    Thanks d, your contribution has taken me into understanding what goes on inside the 'mystery valve'!
  6. Vic Truesdale

    Vic Truesdale New Member

    Hi again, dCox
    Just a little more questionning! Is that diagram you supplied of a pressurised system really correct? It seems to me that the pump ought to be BELOW or to the RIGHT of the word pump, so that it is in the Return. Also, the domestic hot water is contaminated with the central heating fluid in the diagram!! As I said in our earlier exchange, that hot water tank is wired up incorrectly; isn't it? Ha, ha! And that's a Honeywell diagram, I take it?

  7. dcox

    dcox Screwfix Select

    Hot water tank looks like an unvented cylinder to me in their simplified illustration. It was taken from an American website so perhaps that would explain why things don't look quite right to us. I still don't fully understand its purpose.
  8. The Teach

    The Teach Screwfix Select

    As mentioned its a vintage central heating bypass valve with a sight glass section to show the differential pressure when in bypass mode. Braukmann made quality valves,pity honeywell swallowed them up.

    once it has been set correctly during installation then no other attention is required ;)
  9. Vic Truesdale

    Vic Truesdale New Member

    Thanks to 'The Teach': the reason I viewed it as alien must reflect its vintage quality, yes? But why then, were they fitted in the first place, and has that problem gone away in modern designs?
  10. The Teach

    The Teach Screwfix Select

    When your braukmann bypass was installed,it would have been for a reason,hopefully a legit technical reason and not a vintage diy idea.

    Braukmann was producing many different valve products for proper european & usa markets all excellent products directed to commercial markets including major domestic installations in europe (1970's) new build estates where the householder could manually turn radiators on and off at ease.

    Some products got to the uk,the fact they have internal 3/4 inch threaded connections its a clue to being foreign. Nowdays Uk spec plumbing has compression fittings as its only where diy plumbing fiddling is allowed. plastic plumbing has now taken over a lot of the uk market but even more defects are now being called out due to ***** install techniques where systems depressurise due to leaks in concealed (where no fitting is allowed) areas.

    Braukmann made some excellent heating products,some still available now but at a cost where diy fiddlers will buy cheaper import chinese look a like products.

    love diy-china :p
  11. Vic Truesdale

    Vic Truesdale New Member

    Thanks again, 'Teach'!

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