No steam pressure

Mlaz19

I have an old 3 story house with steam heat and a one pipe system. With the boiler running full blast the pressure gauge (0-30 psi) does not move.  All  8 radiators on the first floor have plenty of steam. On the second floor, 4 are fine and 4 have partial heat (2 or 3 fins) are hot. The 3rd floor has heat in one radiator and the other 5 get nothing or a few fins. I have removed some of the air vents on the radiators and do not feel any pressure. Why is the boiler not generating any steam pressure?

World Plumber

The causes could be many

Is this a new problem?

Are there leaky vents?

Are there vents that aren't opening?

Are the main line vents working?

Is there enough venting on the main lines?

Is there a leak someplace?

What's generating the steam? Is it oil? Did someone down size the nozzle?

Is the boiler sized for the amount of radiation?

Is there a sagging pipe filled with condensate?

Did someone add radiation?

Did someone turn the pressure up on the pressuretrol? Steam won't travel if the pressure is too high. Think ounces.

ryanr256

Yes, ounces

+1 on the ounces. It doesn't take much pressure for a steam system.



The 0-30 PSI gauge will not be accurate enough to reliably show the pressure. A 0-3 PSI gauge needs to be installed in addition to the 0-30. I believe it's code in most entities to have a 0-30 gauge.



-Bob

Mlaz19

Response to Questions

Is this a new problem? No and it is getting worse

Are there leaky vents? If they would leak steam then no

Are there vents that aren't opening? I dont think so because I removed suspect valves and did not feel air escaping from the radiatior 

Are the main line vents working? How can I check?

Is there enough venting on the main lines? There are 2 vents that I can see

Is there a leak someplace? No

What's generating the steam? Is it oil? Natural Gas

Did someone down size the nozzle? N/A

Is the boiler sized for the amount of radiation? Weil Mclain 300,000 BTU came with the house. Unit is 7 years old. Possibly oversized knowing the former owner.

Is there a sagging pipe filled with condensate? Possible How can I tell

Did someone add radiation? No

I heard the previous owner was away and the boiler shutdown during winter for unknown reasons. Don't know if that could create a problem but thought I should throw it out there

I read conflicting info on valve sizing. One article said to use smaller opening valves closer to the boiler and larger father away. Another said to size them to the radiatior.

Would insulating the basemant pipes make a difference?

ryanr256

Valve size and insulation

Yes, you want to insulate every exposed pipe you can find. 1 inch is preferable.



Radiator venting is usually done by radiator size, not location. But, it is an art more than a science. There is a good booklet in the "Shop" about balancing a steam system.



-Bob

BobC

balancing the system

Main vents on a lot of systems they are woefully undersized and that can cause the problem you are seeing. Look around and see if you can spot them, then tell us what brand and model # they are. To test a vent just hold a piece of tissue paper above it to tell if air is escaping as the boiler runs - don't use your had because you could get burned.



Also take some pictures of the boiler, the piping around and above the boiler (from a couple of different angles), and the steam main(s) showing the vents. That will let us see what you are dealing with.



All horizontal steam pipes have to slope so the condensing steam can find it's way back to the boiler. Over time as buildings settle sometimes that slope is reversed by the building settling or remodeling that did not take the specific needs of steam piping into mind. If that happens then water pools in that section of pipe and causes the passing steam to condense and can lead to water hammer. You can use a level to check the piping slope and make sure it is consistent.



radiator venting is somewhat tricky because it must take into account several things. how much air does each radiator contain, how much air does the pipe that feeds that radiator (from the main) contain, what is the relative need for warmth in that room? It's ofter easier to use adjustable vents like the Hoffman 1A so you don't end up having to buy a lot of various sized vents.



Bob

Jamie Hall

Are you sure

really 100% take it to the bank sure that you don't have a steam leak?  Like in the boiler, from the steam chest to the firebox?  The symptoms of that would be a nice big plume of steam out the chimney and using more makeup water in the boiler than you should.  I have seen a system with a hole in the steam chest you could put your fist through which still heated the house -- although with no pressure build up...

World Plumber

Crack

Jamie:

    I failed to think of that. When mine cracked it would steam all the water off in about 4 hours but heated the house as long as I kept water in it. That's where auto feeders without meters through you off track looking for problems or mask the fact that there is a problem.

   Another problem could be blocked returns. or if he has a short "B" demention. Before I got into heating and bought my first home. I would loose the heat to parts of the house. Till dummy tried connecting the vacuum to the boiler with it steaming and emptied the boiler on to the upstairs bedroom floor. (talk about hot water) Then I figured out that If I filled boiler to the correct operating level the return water rose and blocked the tee going to that section of the house. So I now understand well why some boilers sit in pits.

   That I failed to mention also. Is he filling the boiler to a higher level than in previous seasons?

Mlaz19

I think its the piping

When the boiler was replaced 7 years ago some of the original black pipe was replaced with copper and it does not look like it is pitched enough. I hear gurgling in a few areas. Also a pipe right at the boiler appears to be pitched the wrong way. There is corrosion on the outside of this pipe. I assume if it is pitched wrong I would get no heat at all. Thanks for your help

Photo 1 is main steam valve in basement

Photo 2 shows the same valve but the photo is inverted. The valve is vertical

Photo 3 is the same valve

Photo 4 is the boiler general view

Photo 5 is a picture of the pipe pitched heavily. The level is above. The shot is taken looking at the boiler face on with Water Heater on right

Photo 6 is pressuretrol and gauge

Photos 7-11 are part of the repiping that I find very confusing. It is very hard to piece together with the photos. The last shot is the 2nd main valve in the basement I need to remove some of the ceiling to get the model number

Charlie from wmass

Please check the find a pro section

Good news is the problem is common. Bad news is its a lousy installation. The piping is copper and undersized. Look for that leak. If no leak than it is simply the poor piping that is not allowing the steam to leave the boiler.

icesailor

It's the piping:

Wow. I'm not an expert on steam boiler piping but something looks different to me from anything I ever saw that worked. I'm waiting to learn from the authorities here.

I don't quite understand though, why it won't make pressure. Any return piping under a floor? What happens if you turn off the fill valve and run it? Does it run out of water?

What's the exhaust temperature in the boiler?

Charlie from wmass

Also that pressuretrol is set too high

Turn it down for starters as you try to save for the new piping and or boiler. Down to 0.5 on the gauge and inside is a differential turn that to 1. Do not expect pressure to read on gauge. Flooding the boiler when COLD is likely to show the leak

Mlaz19

Next step

I am calling in the experts. I will post when I have an answer.

Charlie from wmass

Where are you located?

I am sure there is a wall adviser near you,

World Plumber

Header

     Have you looked in the chimney or vent pipe for steam when the boiler is running? A copper header like that is a good way to crack a boiler.

      Start with turning the pressuretroll down. How long are your mains? Studying the venting charts, I formed a rule of thump of 1 number 1 main vent per 12 feet of 2 inch pipe. Over 12 feet start adding tee's and more vents. Talk about changing the characteristics of a system

Mlaz19

Main valve in wrong location?

The third picture shows the main valve properly The second picture is rotated 90 degrees.  I noticed that all the piping except the nipple and the main valve got hot. They were the last parts to get hot so I replaced the main valve. The valve is not the problem. Since it is not on the top of the main I assume it is in the wrong place.  I also have about 20 feet between the boiler and that valve