Boiler turning on and off intermittently, LWCO getting triggered -- why???

tomfrawley

Hi All,

I'm a newbie at steam heat but have read one of Holohan's books, so I know a little bit. I recently had a new Burnham gas fired boiler installed into my one-pipe system. Ran fine for a while until it got really cold out. When it is very cold and I guess the boiler has to work harder, the LWCO gets triggered and the boiler shuts off. It will stay off for about 15 seconds and then fire up again. It runs for about 30 seconds and then the LWCO gets triggered again. Eventually, after maybe hours of this, it stops happening and the boiler operates normally, but our house is cold in the meantime. When its malfunctioning, it seems like water is having a hard time returning to the boiler as the return pipe is cold and takes a long time to get hot.

We've had the company that installed the boiler come out three times. The last time they put some kind of chemical in the system ( I think he called it Swick?) and he said that would clean the water and might help. If that didn't work, he guessed it was a faulty LWCO. I don't know. Could it be something else going on? From reading the forums, I thought maybe dirty water but the guys insisted that it did not look bad from the sight glass. I'm hesitant to get the LWCO replaced without a second opinion. Seems kind of strange for a brand new piece of equipment to malfunction although I'm sure it happens. Anyone know of any experts in Rhode Island? No one's listed in the contractors section of this site.

One other thing that I'm not sure is relevant or not. One of the radiators that the return pipe connects too has not been heating properly for a long time. Only heats about a third of the way usually. Is it possible that the radiator is blocked somehow and prevent the water from returning?

Thanks for any help you can give me.

Tom

KC_Jones

Did they skim the boiler? If not it sounds like it needs skimmed. All new boilers need skimmed there is no chemical that can replace this. Is the sight glass completely clean...like brand new and is the water perfectly clear? If not it's dirty and needs skimmed. Also post some pictures of the install...sometimes there are other factors at work. Is this one pipe or 2 pipe system?

tomfrawley

It's one pipe. They did skim, but the water is not crystal clear. It's cloudy. They said this is normal.

KC_Jones

How long did they skim for? Just as a reference (and this time can vary depending on amount of work done) I skimmed mine for about 12 hours on 3 different occasions to get it completely clean. That is in addition to the wand cleaning I did before start up which totaled about 3 hours or so. Just because they skimmed it once doesn't mean it's clean yet. Take a picture of the sight glass and the boiler piping and post it here.

Mark N

Is the water dropping low enough to trigger the LWCO? How much is the water bouncing in the gauge glass? Is the boiler surging, do you see water spilling down the gauge glass from the top?

Fred

First, Post a picture of the piping around the Boiler. Does it look like the diagram in the owner's manual?
Skim the boiler. Hopefully they installed a skim port on the boiler. It should be a short capped pipe or maybe have a Ball Valve on it, somewhere above the Boiler Normal water line. It sounds like there are oils on the surface of the water and chemicals simply are't effective at removing it. The water may look OK but trust there are oils in there on a new boiler. Since oil sits on the surface of water, it can't be drained from the bottom boiler drain. It unusAlly takes multiple skims so don't be discouraged. Skim it run the boiler until the water in the sight glass becomes turbulent again and skim it again. Do that until the water stabalizes with about 1/2 to 3/4" bounce max.
As to that radiator, make sure the radiator has a little pitch back towards the steam supply pipe. You can use shims or even quarters to put under the legs of the radiator on the vent side of the radiator. Check the pipe that feeds that radiator in the basement and make sure it is pitched back towards the Main so it can empty out. Check the vent on that radiator. It may be a very small vent or maybe faulty. Take it off and see if you can blow through it (holding it upright). If not, replace it. If it is the type of vent that is adjustable, adjust it to the next setting. When you take it off, shake it out to make sure there is no water in it.

NOTE: I also have a Burnham. Many of them don't have the typical skim port and, if it has the pressure relief valve mounted on the side or back of the boiler (Not on top) you can replace the elbow the pressure relief valve is mounted on with a Tee and put the valve back onto the top outlet of the Tee and use the end outlet to skim. When you're done skimming, put a plug in the end and you're set for the next skim.
The skim process must be done very slowly to keep the oils on the syurface of the water. We can advise you on that process when you are ready.

tomfrawley

The water in the glass is not surging too much, less than an inch, and i'm making sure that there is enough water so it is not going below the LWCO line.

The piping has been looked at by an inspector and 3 different guys at the heating place including the manager. Everyone said it looked right but I hopefully can post pics here later.

I will look into skimming. They didnt skim that long. For some reason the guys at the company dont think that is part of the problem when I suggest it. I believe there is a skim port but i will have to make sure. Is it a fairly straightforward process that I can do myself?

I can blow through vent on that radiator fine and there's no water. Will try shimming it.

Fred

Skimming is pretty easy, just time consuming. Don't accept the fact that an inspector looked at it. Many of them are lost when it comes to how a steam system should be plumbed. They check the fuel supply lines and after that you're pretty much on your own. Also, don't assume because 3 people from the same company looked at the install and felt it was good. If they don't know what they are doing, they will not know what they did was wrong. Do post some pictures.

Mark N

The installation manual for the Burham Indendence is available on line at usboiler.net. Download the manual and compare what you have to the manual. What size is it and how many risers from the boiler were used?

mahoney

Do you have an auto feed for the water? also did the installer remove any insulation from the near boiler piping. I knew someone who had a boiler installed, and removed all the asbestos insulation from the basement at the same time, the boiler could not keep up with the new demand that the uninsulated pipes presented. Low water would trip. auto feed would kick in, condensate would eventually return and the boiler would be flooded. insulation solved the problem.

vaporvac

I will second what everyone else wrote, but addto what @mahoney said about the insulation. I have a section of uninsulated pipe that runs through my unheated garage. The rads leading off from it never heat up fully as the steam condenses too quickly.
Regarding the LW shut-off... did they CLEAN or replace your wet returns Mine were clogged with thick, HEAVY sludge. It's a miracle anything got through before, but the old boiler had a much larger water capacity. These new boiler have much less so clean returns, (as well as clean water, and proper piping) is much more importan. Post some pics and let's see what you have.

tomfrawley

Here are a bunch of pictures. Let me know if you want to see anything else. Do you see a skim port?

BobC

I think the skim port for that boiler is on the back side behind a knockout, the manual identifies it.

Bob

wmtandson

install looks better than i expected

Fred

The near boiler piping looks pretty decent except it looks like 3 Mains are tied together there where the new pipe connects to the old pipes. That has to be an issue for even distribution of steam but, for the moment, should not be causing the cycling on Low water that you are seeing. Should be corrected at some point with each of those Mains tied into the New Header.
What is the Pressuretrol set at? From one of the pictures, a side view, it looks like it may be really high but it is hard to see. The Main scale should be no more than 1.5PSI with a 1 Differential if it is a subtractive Pressuretrol, making Cut -IN at .5PSI and Cut-out around 1.5PSI.
Are you sure the Boiler is shutting down on Low Water? Could it be shutting down on Pressure?
Have you checked all the low voltage wiring for the controls to make sure all wires are secure to their terminals at the Pressuretrol, the Low Water cut-off, the Thermostat, the flue safety switch, the Flame roll -out switch and the Gas Valve?

nicholas bonham-carter

What sort of boiler was there before the replacement? If it had been an old, tall boiler, now replaced with a shorty, then maybe some wet returns are above the new waterline. This situation can cause large amounts of water to be hidden for a while, causing regular shutdowns. Look around the wet returns, and measure their height above/below the height of the new boiler waterline. If you see a part of the return which is close to that height, then that could be a problem with hidden water.
A competent steam pro would have then raised the new boiler up to the old boiler level, or lowered the wet retuns down to compensate.--NBC

tomfrawley

Main is at 1.5 psi and diff is at .5. It is subtractive. Should I change diff to 1? would that make much difference? I think it is a low water problem because the lwco light comes on when it shuts down

It is a shorter boiler than the old one but the wet returns are below the water line

Fred

Skim it and see if that fixes the problem. My Burnham will push all the water (almost all) out of the boiler if there is any oil on the surface of the water. A good skim works wonders. If that fixes it for a week or two, you may need to skim several more times to get all the oils out.

mahoney

I am pretty sure you want to skim it when it is cold so the oils are not in suspension. Just let the water trickle out so the surface of the water is only halfway up whatever opening you are using. I clamped a funnel to a garden hose and ran it into a floor drain. skimmed for a few hours. I installed the same boiler about 10 yrs ago, and installed a skim port on the same side as the drain. there was a knock out up high and kind of closer to the front. removing the fact. installed plug was a bear.

tomfrawley

No skim port or obvious place to skim that I can see. I'm not about to rig something up, so I'm going to have someone come do it and watch what they do. Thanks for all the feedback. Hopefully skimming solves the problem.

Does anyone think there is a chance that the brand new LWCO is faulty? Or is that a super long shot?

Fred

Did they put teflon tape on the probe when they screwed it into the boiler? If it has teflon tape on it, that will prevent the probe from grounding and cause it not to work. If that's not the case, it's always possible that it was faulty out of the box but rare.
You also mention that one radiator that ties into the return pipe is not heating. Radiators should not be tied into return pipes on a 1 pipe system. That radiator may get a little steam but not what it should. It needs to be tied to the Main.