two straight forward questions

puff_puff_hiss

Hi,

I have most bugs worked out of my 1 pipe steam system.  I just have two questions to trouble shoot the final radiator which i just can't seem to get to work correctly.  I have tried slow venting and fast venting,  but either way, I still get a lot of water (6-12 oz) that pushes out of the vent prior to the vent shutting and the radiator warming up. 





I have already tried pitching rad a little, pitching rad ALOT, and lifting the entire rad in order to pull the supply pipe up higher into the room, effectively adding pitch to the horizontal leg that is under the floor that takes me over to the wall to meet the riser.





my latest hypothesis leads me to two questions:



1) can a supply valve go bad BUT still have the following characteristics.



1.a    Valve will prevent air/steam from passing when in the closed position.



1.b    Valve will allow air/steam to pass into radiator when in the open position



1.c.   when in the open position,  valve will allow air/steam to pass by the valve, but will not allow condensate to pass back through on its way back to the horizontal leg, and ultimately back to the radiator.





what happens that leads me to these questions is a hot supply pipe and hot supply valve,  and a cold connection and bottom of the radiator nearest the supply valve on the rad side for a very long time during the heating cycle when all other radiators are warmed up.  I am wondering if water can be pooling up there because it can not pass the supply vavle on its return trip to the boiler, so it stays there until enough pressure builds to push it across the bottom of my radiator, up to the vent and out the vent. 



 

Second question,  Can 12 oz of water be pushed up a 12 foot high vertical riser realistically speaking?  It 1.75 inch pipe and my simple brain is having trouble understanding how that would happen.   If the answer to this is NO,  I know that my problem exists at or near the radiator and I am on or near the right track with question #1. 







Thanks so much to anyone offering their knowledge.  

Rod

Answers to Questions

Hi-

Answers-  Even a good valve can pass a tiny bit of steam when closed. In this situation usually it won't allow condensate to return so that after a period of time (a week or so)  water will build up in the closed radiator. If you want to shut off a radiator it is better to turn the vent upside down as then gravity closes the vent and the trapped air stops steam entering the radiator but condensate can still drain if it needs to do so.

If the valve only partially open,s it is possible for steam to get into the radiator but condensate can't return until it has built up enough head of water to force its way out of the radiator against the incoming steam stream. This is usually quite noisy.  Valves can still be turned and seem to be working okay but still not be fully functional.

   To check whether the radiator valve is fully operational you'll need to loosen the spud nut on the valve and slide the radiator back a bit so you can visually check the internal operation of the valve. If you need a replacement radiator valve be sure to get one for steam. Some hot water radiator valves don't work well with steam,



Second question-  12 oz of water is the quantity of a can of coke. It won't come vertical as a slug of water but from wet steam and condensate accumulation that can build especially in a pooling area caused by a sagging pipe.

- Rod

nicholas bonham-carter

checking a steam valve

alternatively, you can unscrew the bonnet of the valve, and get a good idea of its condition, without the heavy lifting,

what sort of main venting is on this system?--nbc

puff_puff_hiss

Type-o

Question 1.c should have read "ultimately back to the boiler"...... Not radiator

puff_puff_hiss

Answers

My main vents are gorton 1.



The system was installed 80 yrs ago and this portion of the house has likely not been renovated. All walls i've opened have shown properly insulated pipes which leads me to believe most or all of the horizontal leg has insulation. I dont believe the horizontal leg feeding the rad is my issue because i can lift the rad 4 inches into the room and add what i believe to be a tremendous pitch on this 6 to 8 foot leg and it did not really help (maybe there was a little less water).



I already disconnected the radiator once and didnt observe any debris in the bottom of it.



Supply gets hot on boiler side of the valve and not on rad side...



Water in my sight glass bounces 1/2 inch during cycle, rest of system works quietly and nicely.



I think my valve is the next check. Any reason to think there is something more i should be looking at with the radiator itself? It does rock quietly back and forth while warming when i have the pitch minimized, no movement while i have rad pitched to max

Rod

Radiator Questions

Hi-  You should have very little slope on the radiator, just enough to "encourage" the condensate to leave the radiator. Too much pitch will cause the condensate to pool at the intake and then steam trying to enter the radiator has to push its way through the pool of water. Usually it then collapses before entering the radiator.

  If you remove the radiator get someone to steady it for you. Disconnected they are top heavy and can tip over easily.

- Rod

puff_puff_hiss

In rod I trust

Hi rod,



Yes, slope is now just enough to encourage condensate. Same as all other rads in the house that all operate quietly.



Any other thoughts?

nicholas bonham-carter

12 feet of water

It only takes 5+ psi to move water up 12 feet in a solid collumn. What is your pressure seen with an accurate gauge?

If your main vents are not adequate enough, then the result will be wet steam going up the risers chasing the air out, with a radiator filling with water droplets.

Lower the pressure, and verify it. Add more venting on the mains, and put slow, dependable hoffman #40's on the radiators as a start.--NBC

clammy

1 Question

What is the location of the the promblem raditor.The reason i ask is ,i have encounter issues like yours and found on occasion where the last rad on a main would not heat but all other rads would it ended up being that the other mains raditor and main vent vented the air out so well that the last rad rad that would not was really not getting enough steam .I removed the main vent from the other main and plugged it and long behold the promblem rad heated.The issue was  the  added vent capacity of all the rads and main vent on the good main as compared to the promblem rads main .The promblem main if i remenber had only 3 and the other 5 or 6  and a much shorter main.Removing the main vent from the good main did not really effect amount of time it took for it to heat but made a world of difference for that promblem one on the first floor and if i remenber correctly it was alarge rad under a double window .Peace and good luck clammy 

puff_puff_hiss

Response

I have a pressure gauge that used to read at about 3psi during the cycle, but very early on in my troubleshooting i dialed it back and now the system does not run over 1 psi. All other radiators work great.

puff_puff_hiss

Problem radiator

It is on a mian and it is the first leg off the main, the radiator is on the second floor almost directly above the boiler. The other main definitely is the one that outperforms.