Replacing Hoffmans, Stuck

drewbert41

Hello,
I am replacing my Hoffmans that do not work at all with some Big Mouths. I cannot get them off. I am unable to get a large wrench on the Hoffman because of the cone above the fitting. Should I hacksaw it off right at the bottom of the cone and then put a big wrench on it? I have used a lot of PB blaster on it. I have not tried the fittings below, just the Hoffman. Have not tried heat or breaker bar.

drewbert41

ethicalpaul

I think I see two bushings below the vent. Try to see if one of those will break loose for you.

I think cutting off the vent would be fine...but you are rather committed at that point

You could also put a pipe wrench on the vent on the shoulder above the hex part, but that could crush it.

drewbert41

I was wondering if the hoffman took an oil filter wrench (kinda looks like it) but I know those probably arent strong enough.

I guess I assumed the two bushings would be more difficult as they may be 100+ years old. Hard tellin.

JUGHNE

I would put a smaller pipe wrench (something that has jaws that will fit in there) on the hex and then cheater pipe on the wrench.
A second wrench for backup on the lower bushings or tee.

ethicalpaul

They may require more torque, but you can put a much larger pipe wrench on them and not be constrained by the vent, right?

drewbert41

That makes sense. I am also trying not to rip down everything hanging from the ceiling by going ham on it.

Jamie Hall

Before you go gorilla on those vents -- are you quite sure the Hoffmans aren't functioning? How have you tested them? Those things are pretty sturdy.

And... I'd substitute a Gorton #2 rather than a Big Mouth, as the Gorton has a float in case water gets there for some reason, and the Big Mouth doesn't.

drewbert41

I have had a few techs tell me they are not working at all. Rusted\clogged. I bought 2 big mouths. I have a large system heating 4,000 sqft. Gorton #2 sounds like a good idea, everyone just swears by big mouth so I bought them.

ethicalpaul

drewbert41 said:

That makes sense. I am also trying not to rip down everything hanging from the ceiling by going ham on it.

It's always good to provide opposing force with another wrench so the pipes don't have to take it.

Zipper13

This is not a recommendation, but rather a question I have myself about a similar situation for pipes above the waterline...
Would the judicious application of heat from a propane soldering torch help loosen things up or could that cause more damage (not sure it's wise either way after the PB Blaster though)?

ethicalpaul

The judicious (or even non-judicious) application of heat may help and won't hurt. Don't catch your house on fire.

Don't worry about the PB Blaster. It will either already have evaporated, or it will burn away soon enough after you torch it.

acwagner

@drewbert41 I'd recommend getting a crescent wrench or open ended wrench and try that on the hex portion before using heat. From your photo, it doesn't look like it's threaded that far in. Applying the force right at the bottom with good contact should help. Using a pipe wrench on the body will probably just deform the vent vs unthread it.

acwagner

Also, if the vent failed it's for a reason. The vent doesn't look that old. Water hammer might have damaged it. You don't want to put your new vents on just so they can get damaged too.

Do you have room to put a section of pipe on to raise the vent higher off the main line?

Jamie Hall

I'm stubborn. I'd still want to know why those Hoffmans failed -- if they did. How did the tech determine that they weren't working? They can only fail in two ways -- stuck open or stuck closed. Stuck closed and your system pressure will rise remarkably fast, and the main will be slow to heat. It's almost impossible to tell if they are stuck closed by feeling the air coming out of them -- someone suggested incense a while back; a very light sheet of tissue paper might be sensitive enough... your hand is not. If they are stuck open, however, it's a lot easier -- you will be losing water from the boiler, and a mirror or piece of cold metal held up to the vent opening will fog.

But... let's assume for the moment that the tech. is right. The first thing to do is to find out why they failed. First place, I take it from you post that both of them have failed at more or less the same time. That just doesn't happen without another cause -- and if you don't find and fix the other cause (over pressure?) it will happen to your new ones as well. Not what you want.

Now you've done that -- I'd be very surprised indeed if you couldn't get them off as @acwagner suggested: a big crescent wrench on the hex, and a backup wrench on the bushing or T. Use a cheater on the crescent wrench.

Do NOT wrench on the vent itself (if you haven't already) -- that will surely wreck it.

SteamHeat

I have had better luck with homemade penetrating lubricant than stuff in a can.

1 oz. power steering oil + 1 oz. acetone
Mix in a 2 oz. glass dropper bottle you can get at any "health food" store.

Shake up like crazy before you use it.
Saturate the area and leave it soak in for minutes or hours.

I have broken free pipes rusted together for decades with this.

Store this safely. Acetone is pretty flammable.

HTH.

STEAM DOCTOR

Interesting. What types of pipes have you loosened with your mixture? Sizes? Enquiring minds want to know. 

SteamHeat

Yellow Brass and Black Steel.
Smallest was 1/8 inch (radiator vent).
Largest was 1 inch.
Also, screws and bolts (steel) up to car wheel stud sizes.
Haven't tried it yet on Red Brass or pipes larger than 1 inch.

Formula came from old magazine article that I found on web, April 2007 "Machinist's Workshop". There was a later correction that it was power steering oil mixed with acetone not transmission fluid which was shown in a picture with the article.

HTH

drewbert41

Jamie Hall said:

I'm stubborn. I'd still want to know why those Hoffmans failed -- if they did. How did the tech determine that they weren't working? They can only fail in two ways -- stuck open or stuck closed. Stuck closed and your system pressure will rise remarkably fast, and the main will be slow to heat. It's almost impossible to tell if they are stuck closed by feeling the air coming out of them -- someone suggested incense a while back; a very light sheet of tissue paper might be sensitive enough... your hand is not. If they are stuck open, however, it's a lot easier -- you will be losing water from the boiler, and a mirror or piece of cold metal held up to the vent opening will fog.

But... let's assume for the moment that the tech. is right. The first thing to do is to find out why they failed. First place, I take it from you post that both of them have failed at more or less the same time. That just doesn't happen without another cause -- and if you don't find and fix the other cause (over pressure?) it will happen to your new ones as well. Not what you want.

Now you've done that -- I'd be very surprised indeed if you couldn't get them off as @acwagner suggested: a big crescent wrench on the hex, and a backup wrench on the bushing or T. Use a cheater on the crescent wrench.

Do NOT wrench on the vent itself (if you haven't already) -- that will surely wreck it.

I have wet steam from having a header that is way too low. So this will probably just happen again, but at least the big mouths are rebuild able. If anyone knows someone in the central, IL region who could install a drop header for me that would be awesome.

drewbert41

acwagner said:

Also, if the vent failed it's for a reason. The vent doesn't look that old. Water hammer might have damaged it. You don't want to put your new vents on just so they can get damaged too.

Do you have room to put a section of pipe on to raise the vent higher off the main line?

I have about 6" or so I can go up.

drewbert41

acwagner said:

@drewbert41 I'd recommend getting a crescent wrench or open ended wrench and try that on the hex portion before using heat. From your photo, it doesn't look like it's threaded that far in. Applying the force right at the bottom with good contact should help. Using a pipe wrench on the body will probably just deform the vent vs unthread it.

I should have thought to use a crescent wrench. I have 3 different sized pipe wrenches I have been trying to use. You are right, it does not look like it is threaded too far in.

SteamHeat

If you have not already done so, I would take a wire brush and brush away as much of the crud in the threads right next to the fitting (as close as possible) and then use a syringe with a fine needle to try to inject whatever penetrating lubricant you choose to use right down into the fitting. Simply spraying PBlaster on top of crud will not help you much.