Paul System to One-Pipe with TRV Conversion

grichmond

I have been tasked to convert a Paul System to a One-Pipe TRV system.

The Paul System has been dismantled over the years and only a few devices are still connected. Only a few Paul vents are still in place. The vacuum lines have all been cut and removed and air vents have been installed. The staff have been manually controlling the capacity by manually closing the supply valves which is not recommended. There are 37 cast iron radiators on this system. The supply mains run horizontal in the basement and feed vertically to risers serving 5 stories.

Can anyone provide me some recommendations on converting this system?

The pitch of the piping does not seam to have been installed with the recommended 1" per 10'. Was this required with a Paul System?

The facility is now on a district steam system so the steam capacity is endless which may be filling the system to quickly. I have lowered the PRV setting to 1/2 psig.

As a test I have installed a few TRV's and have a little bit of spitting occurring.

Any help would be appreciated.

nicholas bonham-carter

This is an interesting project!
Without the vacuum of the Paul system, and its air removal properties, you will need some Main vents, possibly at the top of the main risers, as well as at the ends of the dry returns.
Put a good low-pressure gauge on the supply, so you can be sure of maintaining a few ounces of pressure in the system.--NBC

Dave in QCA

grichmond, you mention something that could be critical. You say the system is now on district steam. As an overall building control, is there a main steam valve that opens and closes so that the building system only has steam to the radiators on an intermittent basis? If the setup furnishes steam to the radiators 100% of the time, the TRV vents will not work for you.

If you do have intermittent steam, and choose to go with the TRVs, there are quite a few on here that have experience with models that work well. They will chime in soon I am sure.

KC_Jones

Since you say this will go to a one pipe system with TRV's I assume you are using the vent side TRV's? Is that a correct assumption? If that's the case the function of this system on a district steam connection could be problematic. The air vent TRV's need to "breathe" periodically or they will never open. In other words they open let in steam, room warms then it closes. It can not open again unless the steam pressure goes to zero. If you are using TRV on the supply piping to the rad I think you will need to provide some method to drain condensate from in front of the valve. If the TRV closes and then the steam still left in the rad condenses, then it opens again it's going to bang since there will be a build up of condensate ahead of that valve. Just a couple things to think about.

KC_Jones

Dave we must have been typing at the same time!

KC_Jones

Here is an article that discusses the pressure issue with respect to TRV's.
http://www.fiainc.com/documents/10-08Canyoureallycontrolaone-pipesteamsystem.pdf

Steamhead

This might be a good application for vacuum, since by varying the vacuum we can vary the steam temperature. Wonder if Igor's system could be applied here?

grichmond

Thank you for all you comments and suggestions to date!
The system had two pneumatic valves on each of the two horizontal mains at one time, but they are no longer functional. These would be replaced the new valves used to cycle the steam. The TRV we used for our test was the MACON OPSK with the VM Series actuator. The TRV's are installed in the vents and controlled electronically by the automation system. The thought was to open the main valve if a group of radiators on that line were calling for heat then close it when they were satisfied.
I will look into adding main air vents on the risers and getting a good low pressure gauge installed.
We only are experiencing a small amount of spitting but it is in a historic building with wood floors so no amount is acceptable.
I have a couple more questions.
Was pipe pitch important for the Paul System to function properly?
The other thing I thought of with the District Steam was that we have an unlimited instantaneous steam supply. This would act like an oversized boiler. If we were to choke back the steam with some gate valves in the mains do you think this would help?