help with mclain boiler

I have a Mclain gas steam boiler, my best guess it is EG 40 or EG45. Friend came over for Xmas and we were just hanging around the house, when I told him I better go to the basement to add some water to the boiler. Anyway he thinks I have a leak because I add water to the boiler about every other day. I add water to about 3/4 up on the water sight glass, and i wait till it goes down to about 1/4 on the glass before adding.
To my best guess this boiler is close to 20years old. I can't find the serial number on the boiler. I searched the forum and checked everything and I only found 2 very small leak. I have a one pipe system and all the pipes are above ground. When the boiler first kicks in there is some banging on the pipes but goes away quickly. I don't see any leak, wet walls, on or around any of the 7 radiators. I checked each of the radiators vent valve on the side to make sure it does close after steam fills the radiator. All the radiators are hot and measures over 210F on my hand held laser temp gauge. I usually let to set the house to about 74F.
I live in New Jersey just west of New york city.

When the boiler is on, it will kick off at 4psi, and back on at 2.5psi. The water level does move up and down in the sight glass but no more than 1/4" in movement.
I see one very small leak if you can even call it that at the top of the brass nut that holds the water level sight glass, i only notice it because after a while some water will slowly move down on the outside of the glass. I didn't want to tight that down too much thinking I may crack the glass. I will replace that glass during the summer.
The other small leak is at the 1.25" radiator angle valve and I can hear a small amount of steam leaking from the valve stem, but I do not see steam or water on the stem or valve body. I will go to the store and buy a new valve anyway. Currently i have no way of measuring how much water i am adding to the boiler. Unless there are other small leaks inside of the walls that I don't see. I agree with him that it seems I am adding much more water than the 2 little leaks I found? Than again maybe those leaks will lose enough water over a day?

My next step is to go outside tomorrow and see if there is steam coming out of my chimney but i have never notice it pulling up to my house during the day time.

My friend has an oil boiler says he only add water about once per week, but he set his house to 68F, and his system is 2 years old, so i know its almost apples to oranges.

I never had any maintenance done on the boiler by a vendor, i just drain the water every 2 weeks till the black color is gone and fill it up with water.

Am I missing any maintenance? If so any ball park idea on how much it costs to have a company do such PM? Is it done once per season?
thanks for any suggestions.

4lbs is a whole lot of pressure for a residential system. Most operate at about .5 lbs. Try reducing the pressure.

thanks for the fast answer. I don't know how to set the kick in and off pressure. I just read it off of the gauge on the side of the box. I will go see if I can go download an owner manual to show me how to set it. I think I may even call a company to replace that pressure switch looks like a grey box and I am not sure if that is original but looks old, guess a new switch won't hurt.

got home early today wanted to make sure i can see clearly at the chimney and saw nothing. Got my big flash light and went back and re-check each of the angle steam valve to all 7 radiators. Found one more that leaked and i can see one water drop once per min or so.
It is a Matco 1.25" valve and it is leaking between the top cap (i am not really sure what it is called.) if i am looking at the valve body, there is a cap on the top, above the cap is the stem cap, than the stem, follow by the black round handle. I went to my local box store and of course they don't have any in stock. The plumber guy said just take the cap off and put some white Teflon tape that should stop the leak. I got home took out the big wrenches and remove the cap, to my surprise there is no o-ring or gasket, the cap just screws into the valve body. I put some white Teflon tape and it seems to hold till the store gets my valves.
Shouldn't there be a gasket between that cap and body?

I also took the time and looked over the Honeywell pressure sensor grey box, and i adjusted the top screw all the way down so the dial read 0.5psi as it can't get any lower. I also turned the differential down from #2 to #1. Now the boiler kicks in just little below 1psi, and off just little over 1.6" It is hard to read on a 30psi gauge, i am going to buy a 0-3psi gauge and install a tee next to the main gauge.
Any recommendation on a pressure switch? I am not sure if my switch is off or my gauge is off. If the normal kick in pressure is 0.5, what should i set the differential to if any?

You set the pressure switch and differential just about perfect.

Whenever you see the pressuretrol cranked up like that it's usually due to somebody monkeying with it trying to overcome some other problem or defect in the system, typically a sticking/clogged radiator vent or system vent. Unless your house is 500' tall you wouldn't need to crank it to 4psi.

Almost all valves all have some sort of packing wound around valve stem under the compression to prevent seepage. The traditional tried & true is a heavy cotton string, but on steam systems high temps eventually break down the cotton over decades, reducing it to dust, which is probably what's going on here. Teflon has a much higher operating temp, and should go the distance. There is no pressure on the system to speak of (as compared to pumped hot water heating or potable water), so if it's not leaking, don't "fix" it by replacing the valve, lest you want to seize defeat from the jaws of victory here. When it has gotten to the point where the valve won't open or close replacement would be in order, but if the only problem is the packing, give it a bunch of wraps of teflon tape and call it a day. (It doesn't take much to hold 1.6psi steam, even if the valve stem and nut are pitted.)

well after 3 days the water level in the sight glass is about the same. I am surprised that one drop every one min equals my adding that much water every other day. I usually change out the radiator air vent every other year. I know you can clean them, but they are so cheap I just replace them. All the radiators are working and the house is at 74F.

I have never replaced the "system vent". I assume it works just like the air vents on the radiators to let the cold air escape and close when steam hits it.
Where do i find this system vent? Is it right next to the boiler? How often should the system vent to replaced?

hids2000 said:

well after 3 days the water level in the sight glass is about the same. I am surprised that one drop every one min equals my adding that much water every other day. I usually change out the radiator air vent every other year. I know you can clean them, but they are so cheap I just replace them. All the radiators are working and the house is at 74F.

I have never replaced the "system vent". I assume it works just like the air vents on the radiators to let the cold air escape and close when steam hits it.
Where do i find this system vent? Is it right next to the boiler? How often should the system vent to replaced?

Click to expand...

Cut in plus differential equals cut out.

You should replace the main vents if they leak or.......you don't hear steam coming out when the boiler 1st makes steam.

BTW, most steam vents do not have o rings or seals. They rely on brass to brass fine threads.

The main system vent is usually located after the last of the branches off to radiators, at the end of the main steam distribution plumbing, or partly into the dry return. That allows the air in the main distribution pipe to be purged first rather than forcing 100% of the plumbing air volume through the radiator vents. That way the radiator vents only have to deal with the much smaller branch-plumbing and local radiator volume.





If the main vent is stuck closed or clogged some radiators will get more steam (and more quickly) than designed for while others may end up being a bit starved for steam and run cooler than the other radiators under some load conditions, even if it's local radiator vent is working fine. You want the main steam pipe to behave like a manifold feeding steam or or less equally to all of the radiator branches, and that doesn't happen if the main vent isn't sufficiently open. If it's stuck open, you'll be adding water a lot more frequently.

thanks for the drawing. I found the main vent, as it been painted over once i sanded the paint off it is a Hoffman #45. It seems to still be working as i can feel air coming out of it when the boiler first kick in. I found replacement for about $30 online so I will replace it just in case.

So in theory the bigger the main vent, the faster the steam? what would be the negative for over size the main vent?

An oversized vent may not close off when it should

So far things seems to be working but one of the 2nd fl radiator vent spit waters from time to time. (boiler is in basement) So I went to the store and picked up a new #45 for the main and a new Maid-O-Mist #6. I couldn't find the post where how to test the air vents to see if they are good or bad, i did blow on the old one (about 1yr old) and i can blow air in from both direction.
Installed the new #6 vent and I can hear it working as it opens and closes, till about 12hrs later. Around 2am i can hear that vent hissing and spit water. turned on the light and I can see little steam coming off of the top so for what ever reason the vent is not closing again. Took the vent off, and put a cap in its place for now, till I go to the store and buy another vent. This vent seems to be working as I can blow air from both directions, except i can hear water inside of it when i shake it. I already checked and the radiator slopped and my boiler water level is no more than 1/2 on the sight glass.

Most have a cork like media in there that swells up when it gets saturated with steam.

Would have never thought of this. Came home with the new vent, and i know the radiator is higher on one side because it got shims so I never even checked it with a level. Well to my surprise after i put my level on top of the radiator it is dead center! guess the house must have settled over time and what ever pitch it had evened out. I added another small piece of shim under the radiator to make one side little higher, i didn't want to put too much shim to force the pipe. my level bubble moved so small that it looked like it is still in the middle. Took out my iphone and use the level app, and it showed it is angle at 1 degree. Guess that is better than nothing. Only time will tell if the vent spits again.

hids2000 said:

Would have never thought of this. Came home with the new vent, and i know the radiator is higher on one side because it got shims so I never even checked it with a level. Well to my surprise after i put my level on top of the radiator it is dead center! guess the house must have settled over time and what ever pitch it had evened out. I added another small piece of shim under the radiator to make one side little higher, i didn't want to put too much shim to force the pipe. my level bubble moved so small that it looked like it is still in the middle. Took out my iphone and use the level app, and it showed it is angle at 1 degree. Guess that is better than nothing. Only time will tell if the vent spits again.

Click to expand...

Normally, shims are not required especially if the floor is level. Radiators have built in pitch.