2 Pipe Steam Radiators Without Individual Valves

Daventry

Hi All - I need help. I have an old home (1865) that is 2 story with a basement. I have a steam boiler in the basement. The radiators are 2 pipe but do not have individual pressure valves. There are 4 large valves in the basement at different points along the return lines. These valves do release steam but it is somewhat misty. The don’t leak water but moisture can accumulate on the wall next to the valves.  The system heats pretty well but does knock quite a bit. 

I’m certainly no expert but do have a reasonable experience(in previous homes) with single pipe steam radiators with individual release valves. I have historically tuned these room by room to have a well balanced system. 

I haven’t been able to find much information about how my new system is situated or what potential changes I should be making. I am attaching pictures of the type radiators I have. Any input or help would be much appreciated. 

JohnNY

Post a few wide pictures of the boiler and boiler area, please.

mattmia2

2 pipe steam is balanced by adjusting the valve on the supply, unlike 1 pipe where that would trap condensate.

2 pipe radiators are vented from the return. If there is steam in the return you have bad steam traps somewhere.(or pressure or piping issues)

There should be a steam trap under each convector at the return and probably a few between the mains and returns.

I assume you took it off for the picture but those convectors need the cover on them to act as a chimney to pull air through them

Daventry

Will post basement pics soon. Yes, there are covers for all - removed for the pic. What are you calling a steam trap?

mattmia2

Take a picture under the return end of the convector, it is usually there. That lump in the pipe may be it. Sometimes they are in the basement under the emitter.

Steamhead

mattmia2 said:

Take a picture under the return end of the convector, it is usually there. That lump in the pipe may be it. Sometimes they are in the basement under the emitter.

That's right. The lump in the return pipe is a vertical trap, probably a Trane.

This is probably a Trane Vapor system. It is newer than the house. Looking forward to pics. Also, where are you located?

Jamie Hall

The valves on the inlet side of those convectors can be used to adjust the output of the convector, although most convector housings also have dampers which are a good deal more convenient.

Be sure your pressure is low enough -- it should never go over 2, and 1.7 would be better.

There will be traps on the outlets for the convectors -- each one has its own trap. If you feel the outlet from the trap near where it joins the return, it may be very warm but it shouldn't be steam hot -- that would indicate a trap which has failed open.

There may also be traps connecting the steam mains to the dry returns. Those traps are essential to good operation. If they don't exist, there may be vents on the steam mains. There MUST be functioning vents on the dry returns, however.

Daventry

Pics of boiler room. 

On the left there are 2 pressure release valves 

On the right side of boiler pic there is 1 pressure release valve. 

There are 3 more pressure release valves scattered along the return line

Here are pics of the radiators. Most have a damper you can control with a pull chain but some, like this one, are missing it. 

Close ups of input and output of radiator


I’m not sure I appreciate anything as a ‘trap’

Jamie, I’ll check temps on the return side in a bit as well as review system pressures. I can only appreciate one area (away from the boiler) where the supply line connects to the return. It’s hard to see in pics but the supply line is coming in overhead (above two by four and then continues to the right) and the vertical line, is a return. 

I know a lot of pics but this is what I’m working with.  What is the definition of a ‘trap?’

Jamie Hall

The common steam traps -- which is what we are referring -- contains an internal element which is a combination of a thermal sensing element and a float. It will open when there is water present, or when the thermal element is cooler. It will close when either there is no water or when the thermal element is near steam temperature.

They come in quite an array of shapes and sizes.

The device on your outlet may well be a trap -- but it is not one with which I am familiar.

As regards venting. You need to clearly identify which lines are steam mains (usually obvious enough!) and which are dry returns. The latter will NOT be directly connected to a steam main anywhere (they may connect through a trap or a water seal). They should never be much more than warm. They must be vented, and the more the merrier -- in a two pipe system, these are just as important as the "main" vents, if not more so, and I regard them as main vents. I have a suspicion that you do not, in fact, have any main vents -- certainly what is in the pictures wouldn't qualify.

mattmia2

That cast iron canister is the Trane device. If it is working properly it allows steam pressure to push the condensate back in to the boiler.

I like how the header from the previous boiler is still there and causing the risers out of the boiler to be of questionable length.

mattmia2

Also means the water line is probably a lot lower than it used to be so if the seal between the mains and the returns is just a water seal, it may no longer be deep enough.

Daventry

Matia, can you elaborate on the height/depth issues of the mains?  Is the canister you are referring to the large one above and to the left of the boiler in the ‘global pic?’

steamhead - can you elaborate on the Trane Vapor System. Yes, certainly not original. I was guessing 1930s or 40s?  I’m in Rhode Island 

Jamie, I guess I need to clean up my terminology. I was calling the ‘main’ what I view as the supply lines coming off the boiler snd going to their various locations. The returns are what I understood to be returning condensate back to boiler. I’ll need to dive deeper in my knowledge to understand the difference between a regular return and a ‘dry return?’

Steamhead

Daventry said:

.......steamhead - can you elaborate on the Trane Vapor System. Yes, certainly not original. I was guessing 1930s or 40s? I’m in Rhode Island......

Go here:

https://heatinghelp.com/heating-museum/trane-heating-specialties-for-vapor-and-vacuum-systems/

The vents on the steam mains and dry (overhead) returns on your system are pathetically small. Replace them with Gorton #2 vents and the system will heat much faster.

Daventry

Wow, that is the motherload of information. Thanks for the link. I’m going to pour a beer tonight and dig into this. 

Good to know about the vents. Some look rather spent as well. Was thinking of replacing them. Will look at Gorton #2s

JUGHNE

mattmia2 said:

Also means the water line is probably a lot lower than it used to be so if the seal between the mains and the returns is just a water seal, it may no longer be deep enough.

It does look like the wet return manifold at the boiler could be pretty close to the BWL.

Don't know if that contributes to the problem or not.
Perhaps steam comes down one drop and goes up another to hit the vents?


Would not be a major re pipe if needed.
Also, assuming that is the LWCO stuck in the return pipe, it looks like you would be very low on water before it cut out.

Daventry

Reviewed things in the basement. 3 of the vents are relatively close to the boiler and are on dry returns. The other 3 vents connect to where a horizontal return pipe elbows to a vertical pipe that drains to the lower wet return line. These 3 lines that are vented, don’t have a dry return going back to boiler area. Attached is a picture of one such elbow. The return is coming horizontally out of the wall, elbowing  to the vertical, then connecting to the wet return line about 30 feet from boiler (with the vent at this elbow). The other 2 vents are the same as above with a vent at the elbow but connect to the wet drain line ~50 feet from boiler.  

At the vents 50 feet from boiler (Pic below), the horizontal drain pipe comes out of the wall (which you cant really see in the pic) and does a T. One part of the T goes upward and connects to the steam supply line and the other side of T goes vertical down to the wet return with the vent hanging off the side Toward the left side of the pic. 

With regard to LWCO. My boiler has 2. 

One is on the return side. The other is over on the supply side. 

JUGHNE

The LWCO on the return side is actually at the return of the return pipe inlet.
This is usually near the very bottom of the boiler.
The secondary LWCO is usually just a little below the primary (Cyclegard LWCO)

Where it is now if the primary failed then you would have nearly a dry boiler before the second safety kicked in.

Also it is not in the boiler itself. I believe that may be required.
If you have ever opened some older boiler inlet pipes, you could imagine that long return pipe plugged up right at the boiler inlet, and the bottom of the boiler full of mud, but the LWCO probe still sitting in enough water to keep the boiler firing.

Many will say, well that can only happen in old neglected boilers etc......you are hoping that your boiler will grow old....but not neglected.
FWIW

Jamie Hall

The vents seem to be in reasonable places -- but in my opinion they aren't big enough. However, if the boiler doesn't shut off on pressure within 10 to 15 mnutes of firing, leave them.

Daventry

So I’ve certainly appreciated everyone’s comments so far - thank you. I guess from a practical standpoint, in my system, what is the best strategy to reduce the knocking?  

mattmia2

So the higher the boiler pressure, the lower those loop seals have to be below the water line. They rely on the weight of the water to prevent the steam from pushing through the wet return in to another main/dry return. It looks like you have a vaporstat, what is it set at?

Daventry