do I need to replace main vents?

1928steam

I have two mains coming off the furnace ... one is about 22 feet long and 2.5 inch pipe with 4 radiators coming off it, the other about 55 feet long and 3.0 inch pipe with 5 radiators coming off it. The 22 foot main has a 5 Ideal Quick Vent and the 55 foot main has a Quck vent air valve no 4 from the dole valve co. I insulated the mains with 1 inch fiberglass and cleaned the main vents, as well as radiator vents, in boiling vinegar. I timed the flow of heat from the furnace ... it takes approximately 16 minutes to travel down the short main so that pipes coming off the main are too hot to touch. The long main is another matter ... it travels maybe half way in that time and because the thermometer is in the part of the house that heats up early, doesn't make it to the end of the main unless I crank the heat to 75. Something else I noticed is that the furnace runs for 9 minutes, shuts off for a few minutes, runs for about 9 minutes, shuts off for a few minutes, etc. -- is this supposed to happen? I am thinking that the fatter pipe on the long main is not enough to move the steam faster and I need a better vent than the no 4 quick vent. I also thought the numbers generally meant more venting, so would switching them help, moving the 5 to the longer fatter pipe and the 4 to the shorter thinner pipe? any help much appreciated.

BobC

No data on Dole vents

I found a PDF on the Dole air vents but I can't find any data for the venting rates of the Dole air vents so I have no idea of how many of them it would take to meet your requirements. Do you know how old those vents are and are all of them working?



What pressure is the boiler operating at now? It should not be more than 1.5 to 2PSI and hopefully less. High pressure can damage vents. Check the mains to be sure the slope is consistent along the length (use a level - don't trust your eye), if there are any dips that will have to be fixed.



You mentioned that the boiler fires up for 9 minutes and then shuts down, The boiler is probably reaching it's high limit pressure setpoint because it can't expel the air fast enough (inadequate venting). Does the boiler have a pressuretrol or a vaporstat for controlling the pressure? What is the boiler pressure when it shuts down and what is it when the boiler fires back up? The 0-30 stock pressure gauge will be difficult to read at the low end but do the best you can. You could install an auxiliary 0-3PSI gauge to see what is going on.



We know that we want to vent the air out of the mains just as fast as possible, you cannot over vent a steam main BUT you can over vent a radiator. Assuming your pipe measurements are ID and not OD, your 22ft 2.5" main has 0.75 cubic feet of air that has to be vented and the 55ft 3" main has 2.6 cubic feet of air in it. The near boiler piping and the mains should all be insulated with a minimum of 1" fiberglass pipe insulation.



If we used Gorton #2 air vents my best guess would be 1ea for the 22 ft main and  4ea for the 55 ft main. These Gortons are large (almost 6" in diameter) vents so make sure you have room for them, also the fit a 1/2" threaded fitting so you might need to use reducers on what you have now and that will take more height.



Pictures of the boiler and the piping around it would help us see what your dealing with, pictures of the vents would help also.



Bob

Steamhead

Those Doles are way too small

I can't remember how many I've removed but it's quite a lot.



Gorton #2 vents are the way to go. Don't know if you'd need four on the longer main, I'd start with three and add the fourth one if needed.



You're looking for the steam to travel to the end of the mains first, in a couple minutes' time, before it starts to go into any of the radiators.

Jamie Hall

It's possible

given the size of those Doles -- as Steamhead says, they are way too small -- that the 9 minutes on 1 minute off bit long before the thermostat is happy is related to slow venting causing pressure to build.  Which shouldn't happen until way down at the end of a cycle, when all the pipes and radiators are good and hot.



But if the air can't get out fast enough...



Fix the vents and see what happens.



Also, check what the pressurestat (probably) is set at -- it shouldn't be more than 1.5 psi at cutout and .5 at cutin.

Mark N

LWCO

What type of LWCO do you have on this boiler? Is it a Cyclegard. The cyclegard will shut the boiler down at regular intervals to check to see if the water level is good. 9 minutes on and 1 off sounds to me like the cyclegard. Also I would replace those main vents with some Gortons.

1928steam

not enough room

There is only an inch or two of space above the dole on the larger main vent and only an inch on the side of the smaller main vent. I am not sure how the size of the thread is measured but both are approximately 1 inch diameter on the outside. The pressure is set as low as I can set it. Do I need to worry about elevation above the main with the gorton? The current valves are elevated 6-7 inches above the mains through a 1 inch OD pipe. Thank you.

1928steam

not enough room

There is only an inch or two of space above the dole on the larger main vent and only an inch on the side of the smaller main vent. I am not sure how the size of the thread is measured but both are approximately 1 inch diameter on the outside. The pressure is set as low as I can set it. Do I need to worry about elevation above the main with the gorton? The current valves are elevated 6-7 inches above the mains through a 1 inch OD pipe. Thank you.

1928steam

not enough room

The picture which you posted suggests I need to put 2-4 Gorton number 2s on a pipe which is then attached to either the small pipe coming off the main or the main itself or does it matter? Is elevation a consideration? and is this something I should have a pro do or can I do it myself? Thanks.

nicholas bonham-carter

venting improvements

this would be the place for a venting antler. as long as there are a couple of 90degree bends in it the possibility of water-hammer damage will be reduced. the joist space will give you the headroom you need for a few inches of rise before the first elbow. rod and brad white's excellent diagram for an antler is in this link.

 http://www.heatinghelp.com/forum-thread/138004/Main-line-steam-vent#p1241453

just put the piping together with a riser, elbow and then a union, joined to the rest of the tee's spaced so the vents protrude up into empty joist spaces. the union makes it easier to assemble the whole thing on a bench, instead of on a ladder. i think you have 3/4 in piping, and that diameter used for the antler will give you the flow capacity needed.

use a tee on the end to accomodate an extra vent, if needed later.--nbc

1928steam

Cyclegard

Pressuretrol and cylcegard. The cyclegard shuts it off every ten minutes or so. The pressure gauge reads 0, always as far as I can tell. I don't know if the pigtail needs to be cleaned or not. I ordered the gorton valves today as I could not find them anywhere. I need to get iron pipe to make the antlers so maybe it is because they aren't venting enough? Still have to crank it to 73 to get the last radiator to heat. Also, furnace cleaner came and there was a lot of gunk in the exhaust pipe which goes up the chimney. He said it was wash and that we needed a cap or cover. But we have one. Could there be another reason? Thank you.

Junster

Boiler shutting on and off every 9 minutes

You have to see what kind of low water cut off device you have. I have a hydrolevel cycleguard and when the boiler is operating the low water cut off shuts down the boiler every 10 minutes for 30 seconds to read the water level when it is not boiling water to get an accurate read of the the waterlevel. My lwco device has a led light that indicates when it is shutting of the boiler to test water level. Yours should be located next to the low water led indicator. It also might the pressuretrol shutting of the boiler too if your internal pressure gets above the set pressure, doubt it though. Next time you fire up your boiler make sure your reading the pressure gauge and see what the pressure is when the boiler cuts off. If it reads a pressure near your pressuretrol setting than you might have to adjust the pressuretrol. Good luck