Dirty Water From Steam Boiler

[dtlithonia1]

My question now would be--- if I skimmed and flushed and was fairly sure there was no oil or dirt in the boiler but everytime the boiler tried to make steam it was still pushing water up the pipes (and of course bringing down dirt and rust) what would I do next?

[Noel Murdough]

What are your actual symptoms? Have you checked a sample of the water that came off the top of the boiler? Is there oil on it?

What else have you checked, so far?

Noel

[bobby7388]

Originally posted by casturbo

Originally posted by dtlithonia1
I don't think it's a surface oil problem. I am still getting gallons of rust & sludge out of the system after I bring it up to steam.(running at 2.5 psi)

2.5 psi of steam?....remember, setting the pressure-trol to 2.5 is the cut-in pressure, the cut-out pressure is the differential setting plus the 2.5 psi. Typical pressure-trol setting on the diff is 1 psi, so in effect you could have 3.5 psi of steam pressure in the system....OUCH. That's ALOT of steam energy that is just aching to make noise and stir up alot of sludge. I'm no steam guru, so hopefully someone who is can proof read this. For a residential boiler I run maybe 1 psi of steam and set the diff really low, maybe .5 psi tops. Lower setting on the pressure-trol has got to save fuel too I would think.

The 2.5 would be the cut-out, minus differential for cut-in.
The problem with pressure controls is that there not very accurate, close though.


Noel is right about what-if's, without some certainty as to the water quality and the boiler internal condition it's speculation as to the issue.

One thing, if the water is hard it's most likly more on the acidic side.
A high PH will cause surging/foaming.
Oil will cause carryover, slight priming with lo pressures. The oil increases the water surface tension causing the steam bubbles to explode through the layer with much greater velocity. Oil in the water can be confused with a hi PH level and the two are often confused.

Also read that the guy is empting and re-filling with fresh water, a good idea, if possible, is to use not cold tap water but heated water. Cold water holds much more disolved oxygen than hotter water.
With residential this isn't always possible, but even 120 degrees from the hot water tank is better than cold tap water for a skimming.
The idea is to remove as much O2 as possible before steaming.

[Edited by bobby7388 on 10-31-2005 at 10:39 PM]

[tinman]

When you figure you're done skimming pour some water in a pan and boil it on your stove if it foams keep skimming.

[imgod]

Just to add a little to the discussion here: Remember that everytime you introduce fresh water into the system you are introducing air and contaminants. This adds to the crud in the water.

[dtlithonia1]

Hi thanks again Noel and to all who have helped. I spent two days surface skimming and the system is working much, much better. I skimmed untill the water looked clean enough to drink and a sample boiled quietly on the stove. But I'm still getting some surging and bringing new contaminents into the boiler and it looks like it will get worse after a period of use. I also set the pressuretrol to 2psi and the differential to one half pound. It says the differential is subtractive. That means the boiler should cut out at 2 lbs and back in at one half pound if I am still calling for heat. Is that right? Also someone suggested a boiler cleaning additive and someone else said never to use anything like that. All the radiators in the house now do get warm although I know I still have to do some balancing once I get rid of the surging. And I am still not sure the pressuretrol is set correctly. I can see by the pressure gauge that I am still getting a couple of pounds in the system even though the main vents and all the radiator vents are new.

[casturbo]

Originally posted by dtlithonia1
.... I also set the pressuretrol to 2psi and the differential to one half pound. It says the differential is subtractive. That means the boiler should cut out at 2 lbs and back in at one half pound if I am still calling for heat. Is that right?

I would still lower the setting further. The 'big' houses (10+ radiators) I routinely service have no more than 1 psi set on the pressuretrol and they heat easily, with no surging. It do suspect, however,there is still oils and/or crud in the system that makes steam production difficult.

[dtlithonia1]

I suspect you are right casturbo. It is a fairly big 9 room house with 10 radiators. How can I tell if it's a crud problem or a PH problem and how do you measure PH? I am still getting some surging although after several flushes (with just plain water) it's not as bad as it first was. I have not used any boiler cleaner or chemicals. It also builds to about 2 lbs of pressure. I have my work cut out for me.

[Noel Murdough]

You can use swimming pool test strips for the pH. Nobody does that on residential boilers, unless they've messed with the water.

It'll only be off if you use chemicals, instead of water.

Don't be bothered by the mud and crud coming back. If you pull off a little water each week to get the heavy stuff out, you'll find that it gets better and better as time goes by. Don't hurry it. New water makes new oxidation.

That you're finding mud when you look for it shows how well the system has been looked after in the past.

Think "steam cleaner" when you think about the inside of the pipes. It's like the vacuum cleaner; if you don't empty it regularly, it backs up the dirt into the piping.

If you take a little bit of mud out each week, it'll come back into it, the water will clear. Don't look for a drastic overnight cure for 50 years of nonchalant maintenance. It won't happen.

One other thing I learned, early in my career. Do your boiler maintenance on Monday morning. Every time. That way, when something comes off in your hand, and the water laps at your dancing toes, you won't have to pay overtime, or wait the weekend without heat for someone to come help. Believe me. It's your money that I'm concerned about.

Oh, by the way, don't worry about "air" coming in with the fresh water. Air refills the entire system after each run cycle. 3 times an hour, usually. NOT a problem.

Dissolved oxygen is another story, which goes away each time you heat the water.

Noel



[Edited by Noel Murdough on 11-01-2005 at 06:20 PM]

[bobby7388]

All good points Noel.

Some other points to consider for the original poster.

If you are having cold radiators around the house venting is typically the problem(but not always).

If your going to check the PH be sure that the watersample has cooled down, if it's hot it will give you a false hi reading.
Like Noel said and I agree, it's doubtfull that the PH is hi. but check anyway to be on the safe side. A litmus paper will do the job for now.


Water quality is your biggest enemy, or lack there-of.
Every attempt to control 02 and dis-solved minerals(solids) goes along way, even in a simple residential system.
Start with the proper techniques and avoid any bad habits.
The system does pull in air on the off cycle and this usually doesn't pose a problem, mainly because water at 212F will not absorb 02 readily as water at 70F will.
Now! in a perfect world you would only have to fill the unit once and never again worry about water treatment. We all know though that this doesn't happen.
The best investment you can make is a water softner.

If this is a cast-iron boiler and your still pulling out dis-colored water this could be due to the fact that cast is very pourous and it will take some time to clean the surface rust off the internal surfaces.
"Crud" in a new boiler isn't surprising, most don't clean the internals good enough after installation.
You could try a alkaline cleaner(boiler cleaner) but check with the manufacturer first, if you mess up you could void your warranty.
If you decide to go that route use very little and run multiple skims, too much alkaline cleaner will cause your residual PH to sky-rocket for a number of cycles(severe foaming) and you could possibly cause hairline cracking of the boiler internals.

[dtlithonia1]

I noticed that the installer used Vent-Rite #75 for the main vents. I can find information for Dole and Hoffman, but not Vent-Rite. I wonder if anyone has the pressure spec for this valve. I know for this boiler there should be low pressure (about 3psi) mains.