Steam pressure

ceksenior

Hi all i have a question concerning pressure in my steam boiler. I have a 1 pipe steam heating system fairly new. My question is if all steam vents are working properly and there are no leaks in the system should a steam boiler hold pressure for a certain amount of time after the pressuretrol shuts down the system. The reason i ask is the system will run for about 10 to 15 minutes until the pressure reaches 2psi. It will then shut off and come back on within a minute after the pressure reaches .5psi. It seems to lose pressure immediately after the pressuretrol shuts it down.

Brad White

What affects a pressure most?

Once a steam system is up to pressure (whatever that pressure may be), what affects that pressure the most is condensing.

A cubic foot of steam condenses to about a cubic inch of water in rough terms. Think of the loss in pressure when that happens.

Under-insulated or bare pipe is a certain contributor. If your mains are well-insulated and your vents are working well, what remains (absent jacket losses and insulation imperfection) are the radiators themselves.

In a cold room during start-up, cycling should be expected. The fact that you MAKE pressure is great. Once the rooms are warmed, this will lessen.

If your pressure holds then you have no heat loss- and your rooms would have to be at 215 degrees.

scrook_2

steam to condensate volume

goes down about 1600x at 0 psi (gauge pressure) and about 1410x at 2 psi, so yes, pressure drops FAST when the fire stops!

Also, every pound of condensate gives up 970 BTU of heat without changing temperature, just changing phase -- or 7250 BTU/gallon of condensate formed!

ceksenior

Info greatly appreciated!

I crave knowledge about my steam heating syatem and im constanly trying to learn new things. This website is awesome. So from what Ive learned its ok for a cold boiler to cycle repeatedly after pressure is met at pressuretrol until the thermostat is satisfied? The reason I ask is I havent been using nightime setback becuase I thought constant cycling was no good for a boiler. I keep the thermostat on 67 hold so it only cycles aprox 3 times(within 15minutes) every hour on even the coldest day.

Plumdog_2

V8toilet_3

Based on what I read from Dans books a properly running one pipe steam system that is properly vented should never build more than 2-3 ounces of pressure. My steam system has never short cycled once and the steam pressure gauge never gets near the 1 psi mark.

Brad White

Now you are really

bragging!

"My Pressure is lower than your pressure... nyeah nyeah!"

May_2

Can I use the handle on my steam radiator to shut it off?

I live in a rented older building with individual steam radiators in each apartment. The boiler in the basement is now controlled by a computer, and I believe I heard the super saying it was at the lowest pressure : 5. Yesterday morning when the heat came on it went crazy. The pressure seemed excessive and there was lots of banging. It was louder than what I associate with 'trapped air' in the system. Because it was shaking and banging (this is a new radiator of only three years old), I turned the heat off using the round screw handle near where the radiator is attached to the pipe. Later in the morning, I turned it back on and everything was fine. Heat, no leaks, etc. At 9PM, with an outside temp at about 27 degrees, it began leaking from near the steam valve, and finally I called the super - who is part time, and not in the building.

He fussed with it for awhile, took a few wrenches out, and suddenly the handle flew off and we had a major steam disaster here. Impossible to see and breath as the room filled with steam. He made it to the boiler room to shut down the system. After a half hour, things dripping with condensation and ruined papers, etc, he managed to put a new valve on (said that was not the problem), and the proceeded to cement the handle of the radiator into a permanent ON position. He said it was my fault for turning the heat on and off, and that I had made it weaker by doing that. He said one should NEVER turn a radiator off. Is this really true? In my many years living in apartments with steam radiators, I understood it was necessary to keep the radiator either ON or OFF. But given the sometimes excessive heat sometimes - when the outside temp is moderate or changing - I need to turn it off. He told me that the handle was only for emergency shut down, not every day use.

I need some feedback so I can call the landlord and ask for professional help, not just that of the part time super.

Bottom line - It IS made to turn the radiator on and off, yes?
thanks,
MH

John_173

a bump for May

so the experts can see you.

1. May - start a new thread so people will read your question. You'll have a far better chance of getting good advice - I just happened to look at this because it was about to fall off the bottom of my list of threads.

2. I'm no expert, just an clueless homeowner.

3. Valves aren't made to be used? Seems a stretch. Cementing the valve open? Sounds breath-takingly dumb to me. Minimum pressure is 5 (PSI?)? Almost certainly way too high.

3. One-pipe steam valves should be ON or OFF. I believe you can throttle two-pipe steam, but you would be affecting the overall load of the system in either case.

4. Supers & landlords don't usually like being corrected. You need to be diplomatic. Sounds like a visit from a REAL expert could save your landlord money and make your neighbors more comfortable. Probably your super still wouldn't be happy.

5. Again, I'm just a clueless homeowner.

Peace

Dale

pressure

Losing pressure immediately is perfect. It means the air vents are open. Boilers like yours start at 0 gauge and must return there when off.

Jon Held

> Losing pressure immediately is perfect. It means

> the air vents are open. Boilers like yours start

> at 0 gauge and must return there when off.

Jon Held

> Losing pressure immediately is perfect. It means

> the air vents are open. Boilers like yours start

> at 0 gauge and must return there when off.




If the vents are open, how would the system build pressure? The original poster has a system similar to mine. Boiler fires until pressuretrol cuts out at 1.5-2 psi and rapidly looses pressure, at least on the first burn. Mine does exactly the same thing and will short cycle until stat is satisfied.

By the time pressure builds to .25-.50 psi, all vents are closed and all rads are hot. The remainder of the firing time on my system I see as wasted oil. It would make sense to cut out at a lower pressure and add a time delay to utilize the latent heat in the system and avoid short cycling. Has anyone done this?? Pros/cons of such a design.