One last issue in one-pipe steam....

Mark_125

Hi fellow steamers,

So I've been in my 1937 colonial with one-pipe steam for about 3 years now. Following great advice from the Wall here and through reading Dan's books I think I've made about as many improvements as I can to my system, working with what I've got. My last problem is that right at the end of the cycle, when my radiators are almost full of steam, the vents in some of the radiators gurgle and hiss - its the kind of noise that wakes you in the night. Radiators 1, 4, 9 and 12 from the diagram have this problem.

I have replaced the vents with difference sizes but the same radiators still start to gurgle/hiss at the end of the cycle - it seems to me like I have a wet steam problem that only manifests itself when the steam starts pushing on the floats in the vent.

I've attached photos of my near boiler piping as well as a plan of my radiation (not to scale) - it's the near boiler piping that leads me to believe I have wet steam. To be clear, changing the boiler and piping are not an option at this time - thats just too much money right now. My question is, can I alleviate this problem using a vaporstat that is set low for cut-out, like say 6oz? Would that cut the boiler before the radiators get full?

I have no other problems you usually associate with poor NBP and an oversize system. I have approx 360 SQ.FT. of radiation and my boiler is sized for 525.  The Hoffman #76s have their vacuum disc removed and the mains fill 2-3 mins after steam is made.

Any help or guidance appreciated.

-Mark

Abracadabra

wet steam

Unless I'm blind, I see no equalizer, no hartford loop. You probably have lots of wet steam.







Is this parallel flow or counterflow?

Mark_125

Counterflow with Hartfood Loop

There is a Hartfood loop at the rear of the boiler - you just can't see it in these photos - it is counterflow.

Abracadabra

add a drip?

Can you add a drip to the risers or the main?







Wet steam is especially bad for counterflow systems. You got condensate coming back while pushing more water back up.

Mike Kusiak_2

Shorter steam cycles

You could try setting your thermostat for more anticipation or cycles per hour. This would result in shorter steam cycles which might not completely fill the radiators to the end.



Certainly would be easy enough to try anyway...

Mark_125

More Cycles = more fuel?

Mike, would adding more cycles use a bit more fuel or is the venting fast enough to help alleviate that? I'm already at 2 cycles per hour.

Abracadabra, would adding a drip involve cutting into the main somewhere?

Mike Kusiak_2

CPH setting

You might lose a bit of efficiency going to say 3 CPH, but since you have such an oversized boiler it may not be significant. I have a feeling that you are cycling on pressure at the end of each thermostat cycle, which isn't very efficient either.



The oversize boiler certainly isn't helping, as you are generating steam a high rate and velocity, while condensate is trying to trickle back to the boiler in the same main.



Is there any possibility of downfiring the boiler? If it is an atmospheric gas boiler it may not be an option.



Why not try 3 CPH and see how it works?

Mark_125

40 yr old atmospheric natural gas

Thanks MIke, I will give the CPH setting a tweak and see how it works out.

jumper

check the slope

have you checked the slope of your radiators ?

Rod

Counterflow System

Hi- From what I've read all the suggestions are good and since the "problem " radiators are random on the system, the suggestion to check the individual radiator's slope might be a big help. Make sure to use a bubble level as the house may have settled a bit. I had a radiator that when you looked at it had obvious proper slope but when I checked it with a level was surprised that it actually sloped the wrong way due to the floor sagging.

     While I know you aren't going to tackle the boiler piping at this point I've attached a couple of pictures/drawing which may help you in the future.

- Rod

Mark_125

will check radiator pitch

OK, so I've been eye-balling the radiators - shame on me - I will check tonight with a level.

I've also added one more change to the diagram showing what I now understand to be drips in the corners of the mains. As I understand it, no condensate should be making it back to the header.

Thanks all for input.

Long Beach Ed

Vents

Gorton vents tend to cool and "drop off" or open rather quickly.  We love them, but in some applications we find other make vents perform differently. 



Try using a different brand on the problem radiators and your trouble will go away. 



The analysis of wet steam is probably correct.

ChrisJ

vent

Maybe its just the picture but something doesn't look right with the stack on the boiler.  It looks like its pitched down slightly no?

nicholas bonham-carter

Gurgle and hiss

We often forget the other hard job which must be done by the main vents-e.g. relieving the vacuum which forms after the flame is cut off. This job is harder for them because the pressure difference between the inside and outside of the system is much, much, much greater at the end of burn (14.2 psi); whereas the difference when venting during firing should only be 2 ounces.

This is yet another reason to have very generous main venting! The hoffmanns may not be enough to handle the relief of vacuum on your system, and may be responsible for the rude noises made by your radiators!--NBC