Spitting radiator air vents

foresthillsjd

Hi everyone,
I really appreciate the wealth of information on this board. I live in a 1925 house with one-pipe steam. This has been our first winter in the house, and within the span of a month, the vents on six radiators decided to start spitting (maybe the presidential election coverage has got them mad?) It's a mishmash of Maid-o-mist, vairvale, and hoffmans. And I have a mix of recessed, cast-iron column, and baseboard radiators. It seems like too many failures to be a coincidence. Any thoughts?

Also, I have one recessed radiator that has the air vent located in a corner. There is a little elbow coming out of the radiator, and straight varivalve is attached there. Is there a more durable brand that can replace the varivalve? It has to be tall and skinny, so no Gortons need to apply.

foresthillsjd

Actually, I should clarity. Only one is spitting (it is on the baseboard radiator, but pitch seems to be fine). The others are just hissing constantly. I tried soaking the vents in vinegar, but no improvement.

nicholas bonham-carter

Check the main vents, and pigtail under the pressuretrol for blockage.
Hoffman 40's are the most durable, for radiators, and are relatively slim, and tallish. Varivalves are too aggressive and spitty for use on radiators.
Generous main venting is needed to allow the air to escape from the pipes, which the radiator vents cannot do effectively, without paying extra for fuel.--NBC

BobC

If this all started at once it sounds like the pressure is too high. What is the steam pressure?

A plugged pigtail under the pressuretrol sounds likely.

Bob

Abracadabra

picture of said "baseboard" radiator. Is it a baseray or a fin-tube convector? Pics of near boiler piping?

Big Ed_4

Water too high ? Should be one third high . Boiler Water may need to be skimmed ? Lack of main pipe insulation ?

Fred

If this just started happening, all at the same time, and nothing was changed on the system, I would agree with the others and check to make sure the pigtail on the Pressuretrol is clean and that the pressure (Cut-in and Cut-out) is properly set. .5PSI Cut-in, Differential set at "1" for a Cut-out pressure of 1.5 PSI.

foresthillsjd

So that leads me to the next question. I had a plumber come out and mentioned that I wanted to install main vents (there are none. There is a plug on one main, and the other is boxed in, so we didn't have access) and to check the pressuretrol, but he said the main vents aren't necessary. He could install them, but the plugs are probably rusted shut and he would have to break off the union and replace it to install vents. As for the pressuretrol, he said if the gauge shows it isn't getting above 2 psi, it is fine. And then he said he could replace all my radiator vents to stop the hissing. (I declined, as that much I can do myself). For those that asked for pictures, I will take some tomorrow. Thanks for the responses!

STEAM DOCTOR

Watch water in glass while boiler is running. Shouldn't bounce all that much. Boiler may need cleaning. Main vents are a must have. The boiler is the heart and the main vents are the lungs of the system.

BobC

Your plumber may be very good at his trade be he does not understand steam, find someone who understands steam. Tell us where you live and maybe we can suggest a more knowledgeable contractor.

Bob

Abracadabra

foresthillsjd said:

he said the main vents aren't necessary. He could install them, but the plugs are probably rusted shut and he would have to break off the union and replace it to install vents. As for the pressuretrol, he said if the gauge shows it isn't getting above 2 psi, it is fine. And then he said he could replace all my radiator vents to stop the hissing. (I declined, as that much I can do myself). For those that asked for pictures, I will take some tomorrow. Thanks for the responses!

Tell him he's fired.
1 - Main vents are necessary.
2 - A real plumber should be able to remove a plug rusted or not.
3 - Gauges are notorious for being wrong and inaccurate especially if yours is a 0-30 psi gauge.
4 - Replacing the radiator valves will not necessarily stop the hissing.

foresthillsjd

I live in Queens (NY), so if anyone wants to send me the contact info for a real plumber, I'd be much obliged. The water is not bouncing around in the gauge glass very much when the boiler is on. Last night, I finally had some time to sit by the boiler while it pressured up, and the pressure gauge went to 6 psi before the thing turned off (and that might have just been because the temp upstairs was satisfied).

So either the pressuretrol or the the gauge is not right.

foresthillsjd

I forgot to add that the reason I decided to babysit the boiler was that I found a mysterious puddle underneath it (maybe a cup or so of water). I wonder if this was from the relief valve discharging...

JUGHNE

Did you check the pigtail loop under the control & gauge?

foresthillsjd

I didn't check the pigtail, because anything that involves pressure gauges and controls seems to have the potential of me messing something up and you hearing about it on the evening news. I've seen posts on how to check the pigtail, but is it something a mere mortal can do?

Fred

It looks like the Cut-in (scale on the front of the Pressuretrol is set at about 3 PSI. There is a screw on the top. Turn that to turn the Cut-in down to .5 PSI. Take the screw off the center bottom front of the Pressuretrol and make sure the white wheel inside is set at "1" The '1" should face the front of the Pressuretrol. That will give you a differential of 1 PSI for a Cut_out of 1.5 PSI. Checking the pigtail is simple. Turn the power off to the boiler so that it doesn't come on. Take the Pressuretrol off and see if you can blow into the pigtail. If you can, it's open. If you can't, take the pigtail off and clean it out.

JUGHNE

If you can change rad vents, then you can clean the pigtail.
Shut the power off to the boiler, open the control and disconnect the two wires and the flex conduit.
The control unscrews with a wrench......do not remove it by the 4 screws on the bottom. Hold the pigtail from moving by inserting a small hammer handle or such into the curly loop of the pigtail. Or a small pliers or pipe wrench to hold it will work.

Remove the gauge with 2 wrenches. Both of these items have a very small opening where the steam pressure enters, make sure those are clear.

As Fred said you should be able to blow into the top of the pigtail and you should hear a little water drop into the boiler.
If plugged then maybe a long fat cable tie might clear the blockage. If that fails you can unscrew it to flush it with water pressure or replace it with a brass one. The piping that feeds that must be clear all the way into the boiler.
Before putting the control back on you should pour water into the pigtail to prime the loop, you should hear water going into the boiler when the loop over fills.

Does your gauge read zero when the boiler is off and cool?

STEAM DOCTOR

Feel free to give me a buzz. I am based right around the corner

Fred

STEAM DOCTOR said:

Feel free to give me a buzz. I am based right around the corner

That's great! You've got a Steam Pro right in the neighborhood! Have the Steam Doctor check out that small leak as well.

foresthillsjd

I did it! Thanks for all the encouragement and tips. It really wasn't as scary as I thought. The pigtail had some sludge in it, but was not clogged.

I had to raid my daughter's crafting stash and steal a pipe cleaner. She was surprised that they can actually be used to clean pipe.

Now my question, I lowered the cutoff a bit and watched how the pressure gage responded. It looks like even at a cut in less than 2 and a differential of 2, it is actually firing at 3 and going up to 5. It looks like the gauge reads the pressure as 1 0si higher than the pressuretrol. (Gage does go to zero when heat is off) Does this matter?

And is it okay for me to lower it to the .5 with differential of 1 if I don't have any main vents installed yet?

Fred

Yes, Set the Pressuretrol to .5 PSI Cut-In with a Differential of "1".
You really need to install a 0-3 PSI Gauge on the pigtail with the Pressuretrol. That 0 - 30 PSI gauge is required by local codes but they are not accurate at all and useless as it relates to determining the accuracy of the Pressuretrol or the actual pressure in the system. Once you get that new gauge on there, if the Pressuretrol needs to be calibrated to make it more accurate to the actual operating pressure, here is the procedure to re-calibrate it:
Inside the Pressuretrol, right below the micro switch, there is a pivot arm. At the end of that arm you will see a screw pin that is activated by the diaphragm at the bottom of the Pressuretrol. If you look very carefully at that screw pin, you will see it actually has a tiny (I mean tiny) hex head on it. It takes a .050 hex wrench and you can turn it clockwise (Towards the bottom of the Pressuretrol to decrease the Cut-out pressure or counter clockwise to increase the cut-out pressure (which none of us want to do but who knows, your Pressuretrol may be really screwed up!). Turn the power to the unit off first. You may find the first attempt to turn that screw a little bit stubborn (relatively speaking) because it has some Locktite on it but it does turn. Don't turn too much, a tiny fraction of a turn goes a long way towards getting it adjusted where you want it (maybe 1/32 inch turn to start with) . You may need to play with it to get it exactly where you want cut out to be.

Get some Main vents on there too.