Old Moline vapor system boiler change out.

rws1443

The boiler has been changed out and a condensate pump boiler feed unit added. Steam is coming back to the pump. What now?
rws1443

Steamhead

I'd bet that condensate pump isn't needed. Many aren't. Steam is getting into the returns since they are no longer filled with water.

Post some pics of the boiler area so we can have a look. Also, where are you located?

rws1443

I don't have access to get pictures. I was called in after the job. Being an industrial steam guy I put a trap ahead of the inlet to the receiver, that helped that problem, but I think it is going to cause others. I am in Denver, CO.

Dave in QCA

Moline systems are supposed to run at a pressure not exceeding 8 oz. Many folks often state 6 oz., but Moline documents say 8 oz. In addition, restriction rings on radiator supply valves and outlet valves are critical to regulate the right amount of steam to the radiator, thus keeping it from blowing through and into the return piping. If original valves have been replaced, or the slotted cylindrical restrictors have been removed (I've seen it!), the steam will blow right through and into the return piping. If this is the case, the easiest fix is to measure the EDR and order correct orifice plates (sized at 8 oz) from Tunstall. If the pressure at the boiler is exceeding 8 oz, it is likely that the boiler is oversized. A vaporstat is necessary to prevent pressure from exceeding 8 oz.

One thing with Moline Systems, and any fully orificed system for that matter, is that you do NOT have to allow for 34% piping and pickup factor, only a 15% piping loss factor, assuming that the mains are insulated and the amount of piping typical.

What kind of boiler are you running.... some Weil McLain LGB models come out of the factory with 2 stage capability and work great on Moline systems.

rws1443

Thanks, for the information. The contractor is running the system at 4 to 5 psig. He tells me that is the lowest pressure pressuretrol he can find. Any suggestions for the proper one would be greatly appreciated.

Steamhead

Hatterasguy said:

rws1443 said:

The contractor is running the system at 4 to 5 psig. He tells me that is the lowest pressure pressuretrol he can find. Any suggestions .................

Remember the statement by Donald:

"You're fired"

Use it.

Obviously that guy never heard of a Vaporstat.

Dave in QCA

This is the device that is needed. http://www.supplyhouse.com/Honeywell-L408J1009-Vaporstat-Controller-Steam-0-to-16-oz-in2
Low pressure in this case, means atmospheric vapor. Pressure is SO low that it is almost nonexistent. The pressure is probably the main problem, perhaps its the only problem. If the contractor had installed a Vaporstat to start with, a condensate receiver and feedwater set up probably would not have been necessary as the condensate will flow back into the boiler by gravity at these low pressures.