calling Boiler Pro

Timco

I have a thread in the main Wall. (ID this system) Moline. Are parts available such as the main air trap / vent? Are the rad traps serviceable? I would love to make this baby fly....piped EXACTLY like the example in Lost Art with the condensing line making a loop in the basement. Vents on like 5 rads.



Thanks. 

The Steam Whisperer (Formerly Boilerpro)

Hey...

I would install a couple of Gorton #2's at the main vent location and see how that works.  There are no traps on the system.   These systems are designed to run at a maximum of 8 ounces of pressure.  The original supply valves are orificed to meter steam to the radiators and at 8 ounces of pressure should fill the radiator only about 80%, so traps or other outlet devices are unecessary.  Get rid of the one pipe steam vents as unce there is proper venting at the end of the system you may be pulling a vacumn on the system by the venturi action of the venturi tee at the ends of the mains.   When sizing the boiler, size to a maximum of 805 of the radiation capacity plus the piping losses.  If the structure has been upgraded thermally, you can downsize the boiler to the heat load and balance the heating by adjusting the radiator supply valves.....they were designed to be throttled effectively. 

It's been awhile since I worked or saw one of these.   It looks like the vacumn diaphragm is gone ( the spaceship looking device at the end of the cooling pipe) so just add you venting there.  Take a look back at the beginning of the cooling pipe or end of steam mains and you should find the venturi tee located right there.

Timco

Thanks!

Is this pictured item the vacuum diaphragm? Is this where the venting would go? No other mechanical devises. What would balance the system? Why the funny valves on the returns? They appear to have a key operated stem in them. Do the venturi fittings just stay?



Thanks again,  Tim

The Steam Whisperer (Formerly Boilerpro)

More info.....

I had to brush up again on the system.  That thing in your picture is the air vent.  Since it is at the end of the condenser, steam vapor should never reach it if the pressure is controlled under 8 ounces  (install a vaporstat and set it accordingly).  If it is still working, you could just leave it open to the atmosphere to vent the air from the system. If pressure is properly controlled you could just leave an open pipe there, but a vent acts as back up to overpressure.  Just making sure that there is free ventilation from this vent should balance the system pretty nicely (while removing the radiator vents).   The radiator valves can be adjusted to provide additional balancing.  The funny valves on the returns are simply service valves so the radiators could be removed for decorating etc. I have never seen anymore than just one venturi (Ejector in "Molinese")  on the systems I've seen and you definitely want to keep it.  The ejector is a steam powered venturi that creates a vacuum on the system returns to very quickly remove the air from the system when the boiler is steaming.  If you follow the system piping you will discover that the system is piped reverse return.....the first radiator off the supply is also the last on the return.  With the boiler pushing on the supply and the venturi ejector pulling on the return, steam arrives at all the radiators at about the same time because the pressure drop is equalized across all the radiators.

If you want to get creative, I suspect if you were to install a modulating burner steam boiler with a modulating thermostat and install a ( or a couple) of Hoffman main vacumn vents, you just might be able to run the system on vacumn again.  It would be interesting.

Timco

Thanks yet again

A couple more questions if you don't mind. First, if the main vent is not working, can it be disassembled and cleaned or replaced with any sort of similar item? How would this be checked for proper operation? Last, since a new Dunkirk was installed in '99, I will be working with what is there. Should it still run at less than 1lb? Still use vaporstat?



Nothing like working on steam boilers in rooms with white floors......



Tim

The Steam Whisperer (Formerly Boilerpro)

Main vent, et el

I haven't been fortunate enough to actually have a Moline system with the vent still in place, so I haven't had one apart.  It is a main vent that performs the same purpose as any other, so air should be felt coming out of its exit when the boiler begins steaming.  It only comes into play if the system reaches 8 ounces or more, since the condenser loop will condense all the steam that makes is through the Ejector at lower pressures...an open pipe will serve the same purpose below this pressure....just giving the air some place big to exit.  The Ejector itself also acts as a orifice, limiting the amount of steam that passes through to the condenser pipe.  If the pressure gets above 8 ounces then steam reaches the vent and it will close.   If you want to check its operation, shut off a bunch of radiators and start building pressure.  You should feel air exiting the vent opening as the pressure builds  When the condenser pipe is steam hot all the way to end let the boiler run some more.   If no steam is exiting then it still closes properly. 



 These systems need a vapor stat installed to prevent steam from entering the returns, since there are no traps on the radiators.    This may be the reason for the uneven heating, because if steam gets into the returns, the pressure equalizes across the radiators and steam flow stops.   I would mount the vaporstat either on the boiler header or near the end of the steam main, as the boiler has too much violent surging going on inside usually and causes the vaporstat to short cycle.



 I would also look for any non- Moline supply valves on the system.  Most likely these are standard valves that do not have the required orifices. You can contact Tunstall to get orifice plates that fit in the supply valve unions, or you can replace the valves with new orifice type supply valves by Barnes and Jones or Mepco.  If the system has been extended into additions, etc with added piping and radiators, usually the new radiators are equipped with standard supply valves and traps and typically do not heat well.  As previously, get the right supply valves or orifice plates and then check the return line to be sure that it is tied into the original return lines before they reach the Ejector.  If the new returns just drop into the wet return, you'll need to at least run a pipe up from the new return and over into the old returns to allow the ejector to place  vacuum on the new return.  If the new return drops into a condensate pump,  you will with need to reroute it back into a wet return or run the end of the return over into the old returns so both water and air can travel into the old piping from the new.  If you have a condensate pump, you can typically just get rid of it, as, is typically the case, they are unnecessary and can interfere with proper operation of the system.  

Timco

A million thanks!

This will all come together great. All valves are the original Trane. I really like the idea of mounting the vaporstat on the main. Would anyone else just tap into the pipe or should I weld a nut onto the pipe? I will post updates on what is done with this.

The Steam Whisperer (Formerly Boilerpro)

Trane valves...

I am a concerned about the Trane supply valves.   I would double check to see if they are an orifice type.....seems to me some were.  Without those orifices you're dead in the water.