Lowering the pressure of a boiler with 2 pressuretrols

Stephenderski

I bought a house with an old gas fired Peerless steam boiler.  I knew nothing about steam boilers at the time so I bought “The Lost Art of Steam Heating”.  It a nutshell, to stop my pipes from banging and the radiators from whistling, I followed the recommendations of insulating all the pipes I could, and since I don’t know how old the air vents are on the radiators and the main vents, I replaced all of them.  However, the whistling continued so I figured it must be a pressure thing.  My boiler doesnt have a pressure gauge on it, just an “internal syphon” gauge.  It does have two pressuretrol switches, which confuses me.  Is that normal?  The one switch was set at .5 cut in and a differential of 2 - which I then changed to .5 and cut in of 1.  The second switch was set at a cut in for about 7 or 8 (no actual lines where the gauge was set) with a differential of 3.  I lowered this to the minimum as well.  Is that correct?

 

I tried googling the answer for this a number of times but I was unsuccessful in finding the answer to this particular question and I ask now because even with adjusting the pressuretrol switches, I still hear the same whistling as before.  And since I am easily to be paranoid, I hope for reassurance than I haven’t done something stupid.

 

Thank you.

Stephenderski

Sorry

I bought a house with an old gas fired Peerless steam boiler.  I knew nothing about steam boilers at the time so I bought “The Lost Art of Steam Heating”.  It a nutshell, to stop my pipes from banging and the radiators from whistling, I followed the recommendations of insulating all the pipes I could, and since I don’t know how old the air vents are on the radiators and the main vents, I replaced all of them.  However, the whistling continued so I figured it must be a pressure thing.  My boiler doesnt have a pressure gauge on it, just an “internal syphon” gauge.  It does have two pressuretrol switches, which confuses me.  Is that normal?  The one switch was set at .5 cut in and a differential of 2 - which I then changed to .5 and cut in of 1.  The second switch was set at a cut in for about 7 or 8 (no actual lines where the gauge was set) with a differential of 3.  I lowered this to the minimum as well.  Is that correct?

 

I tried googling the answer for this a number of times but I was unsuccessful in finding the answer to this particular question and I ask now because even with adjusting the pressuretrol switches, I still hear the same whistling as before.  And since I am easily to be paranoid, I hope for reassurance than I haven’t done something stupid.

 

Thank you.

BobC

Second pressuretrol

The second one is probably a safety backup that will stop the fire if the first pressuretrol (or pigtail) fails to operate to do a mechanical failure or a plugged pigtail. It is normal for the safety unit to be set significantly higher than the primary pressuretrol.



What kind of main vents are on the system and does the gauge ever read anything when the system is producing steam?



Bob

Stephenderski

Re:

Thanks for the response Bob.

I don't believe the gauge is functional as it is always reading 10, that I have noticed.



As far as the main vents are concerned, I wasn't entirely sure how to answer you so I took a picture of them, along with taking a picture of the pressuretrols.

BobC

May be too small

Those look like a Ventrite 35 type of vent that is sold in big box stoes under the Durst name. They are low capacity vents that may not have enough capacity for your system.



Can you tell me the length of your steam mains and what size pipe they are (pipe circumference would be fine). From that I can calculate the volume of air the pipes contain and what kind of venting you should have.



With larger main vents the radiator vents would have less air to handle and should make less noise. Does the boiler ever shut off and then restart a couple of minutes later when it is making steam? I'm asking because it's possible you have a blockage in a pigtail that is not letting the pressuretrol see the actual pressure in the boiler. Steam systems usually work just fine at low pressre - one to two pounds is more than enough.



Bob