Boiler Level

wildrage

Ah another heating season, another problem .

For those that don't remember me, 1 pipe system, 15 radiators, 6500 square foot victorian house. 250k btu Wells boiler.

Here is the scenerio:

Boiler is cold, water is 3/4 way up the sight glass (high, i know). While boiler is in the middle of the heat cycle, sight glass goes down almost to nothing. Water feed kicks on. This is before the heat cycle even ends. Water is not irradic, just slowly drops as steam is made. Putting more water in the boiler seems to make pipes loud (more water getting into the risers due to higher levels i suppose).

By the time the boiler is ready to cycle next, water is back to 3/4 of the way up, and we repeat the same scenerio. I turned the auto feed off for this reason. So far it hasn't been enough to trip the low water shutoff, but engouh to turn on the water feed - to the point that no water can be seen in the sight glass. I am not losing water.

I could understand if I had a slow return, and the water was low at the start of the cycle, but the water is 3/4 of the way up. Any ideas? I don't remember this happening before. Only change to the system was a chimney liner installed recently - which i can't imagine would cause this.

Thanks!

Fred

Hi @wildrage , Good to hear from you. Skim the Boiler. I know you had some piping fixed last season and the oils in that new pipe/fittings has made its way back to the surface of the boiler water. That oil sitting on the surface of the water makes it difficult for the steam bubbles to break through and it causes the boiler water to push out through the wet returns. Skimming is a slow process of removing the oil/water off of the surface of the water. Draining from the bottom won't work as the oils cling to the sides of the boiler as the water drops. Hopefully you have a skim port, above the normal water level.

EBEBRATT-Ed

@Fred is correct. try skiming

wildrage

Is that my skim port? It does not look very friendly . Just confirmed that my condensate pump is clicking on 2-3 times during a cycle, I believe water is backing up through the return. He fixed 1 elbow...I'm surprised that could cause an issue. I had the boiler serviced at the end of the season and they put in this purple stuff....could that cause a problem? My water is still an off-purplish / brownish color. Wonder if its worth doing a drain / refill.




PS - this is what the water still looks like after draining off 2 or so gallons.....

nicholas bonham-carter

I would do a drain, and refill. Make sure the boiler is not hot when refilling. Do you have a valve on the returns? Drain it all if you can.
They may have put in too much additive, causing more violent boiling, throwing water up into the mains, and taking a longer time to return to the boiler.—NBC

wildrage

Hmmm...I let the boiler cool down about 1.5-2 hours before draining and refilling...hopefully it was cooled down enough :-\. It's on its first heat cycle since, so I guess I'll know soon enough.

Got water down to a little less than clear. Clear to the naked eye when draining, but about a piss color when in the bucket. It was a brown sludge color formerly.

ImYoungxD

When you add fresh water, make sure you let it boil so it releases the oxygen.

wildrage

Yea I boiled it right away. Seems like i'm having the same issue though . I'm going to let it go a few cycles and see where it lands me.

Fred

@wildrage , that tapping could be used for a skim but check around the boiler and see if you have a larger pipe sticking out of the boiler, with a cap or plug or shut-off valve on it. That would be the normal skim port.

wildrage

Just checked the water, and now it looks just as dirty as before. Like this chocolate milk sort of color. It was purple when they put it in last year. I had assumed that the darker color was just the purple color breaking down. I'm wonder if they put in some sort of detergent in there thats pulling all the crap and gunk out of my pipes?

Fred

They probably did put a cleaning agent in there. The water is going to be dirty until you cycle all of it out of the wet returns. Drain and refill it again until the water is clear or a tea color. then, like it or not, you will likely still need to do a skim to get the oils out.

wildrage

Fred said:

They probably did put a cleaning agent in there. The water is going to be dirty until you cycle all of it out of the wet returns. Drain and refill it again until the water is clear or a tea color. then, like it or not, you will likely still need to do a skim to get the oils out.

How long do you think i should let it run and cycle before I drain it again?

I noticed that it looks like it only starts to push the water back into the returns towards the very end of the cycle (with maybe 10 mins left). I'm guessing thats what its doing because the level starts to drop and my condensate pump clicks on. Also sounds like a great way to kill your condesnate pump. I'm sure it loves 200 degree water.

Fred

Do you have any drains on the wet returns? If so, drain them from there to get the dirty water out of them and then flush them out (if you can) or drain and refill the boiler. If you have no drains on the wet returns, I'd drain and refill the boiler once a day until the water is clean. May take 3 or 4 days, depending on how long your wet returns are. Can you post some pictures of your boiler, the wet returns and that condensate pump set up? Are there any back flow/check valves between the condensate pump and boiler that may be stuck open?

wildrage

Returns are 40-50ft on one side, and about 15 feet on the other. Return goes under basement floor (there's a grate, so its accesable), over to the condensate pump. I think I see a check valve on the copper line going to pump. Pics below.

PS I know my header should be higher, but such is life

Fred

I bet that check valve might be stuck open, allowing boiler water to push back out into the return

JUGHNE

This check valve you speak of looks to be on the discharge of the cond pump....which seems as it should be?????

Fred

JUGHNE said:

This check valve you speak of looks to be on the discharge of the cond pump....which seems as it should be?????

Yes, that's as it should be but, if you can get that cap off of it you might find that the swing check inside may be stuck in the open position, maybe from crud that keeps it from properly closing. That will allow water to be pushed back into the tank/returns.

JUGHNE

Is this a float operated condensate pump or a boiler feeder controlled feed pump.
If a cond pump and the check fails the float would return the water quickly and often. Doubt it would get into the returns.

Fred

https://forum.heatinghelp.com/discussion/167220/1-pipe-steam#latest

wildrage

JUGHNE said:

Is this a float operated condensate pump or a boiler feeder controlled feed pump.
If a cond pump and the check fails the float would return the water quickly and often. Doubt it would get into the returns.

It's float operated and does return the condensate quickly. During a typical cycle it returns condensate 2-3 times. So I'm guessing there's a bad check valve. Question is - does water only go back to the returns if there is a bad check valve, or do I also have a skimming issue on my hands?

nicholas bonham-carter

I would think the pump should be operated only by the LWCO, and not by a float in the tank-how will the float know the boiler needs more water?.—NBC

wildrage

nicholas bonham-carter said:

I would think the pump should be operated only by the LWCO, and not by a float in the tank-how will the float know the boiler needs more water?.—NBC

You're right - it should be. The auto fill and the pump are on separate sensors, which has created problems in the past, and discussed on here. It's on my list of things to do for obvious reasons.

JUGHNE

Does all of the condensate water have to go thru the pump?
(I had a heating hell job where part was attempting gravity and the remainder thru the pump.)

If the check valve is leaking the pump would short cycle even during the summer if the normal boiler water level was maintained.

If you throttle the discharge of the pump it will give longer operating cycles and not kill the steam in the boiler.

You say the pump runs 2-3 times during a cycle, isn't that normal operation to return water to the boiler? And all that I see will cycle after the burner is off as condensate continues to return.

I have several condensate pumps that work well in the field.
Those are large old boilers (over 1 million btu) that have plenty of water in them, a lot to work with.

If you cannot get more cond back quicker then changing to a boiler feeder pump with boiler mounted feed control might solve the problem......gives more reserve water to work with...like having more boiler water available.

Converting an existing condensate pump to a feed pump system seems fairly involved.
You could put on the boiler feeder control to call the pump to run.
But getting the fresh water if needed into the tank could be challenging.
Cond tanks are usually smaller than feeder pump tanks.

wildrage

@JUGHNE

Everything goes through the pump. I have 2 return lines (one either side of the basement). One more or less goes right into the pump, the other under a grate in the basement floor. I had steamhead over here 2 years ago, and he suggested that I just completely convert everything to gravity - but it's one of my many projects on an old house, and it's working for now . I thought I would leave it until when I get a new boiler.

My original quesiton was - Even with the site glass to the top, its going down to almost the very bottom and calling for more water. At around that time the condensate pump turns on. This is near the end of the cycle. Could the boiler be losing THAT MUCH water to steam? And could the system already be getting that much condensate back before the cycle has even completed? I suppose so. Some radiators ARE getting cold before the furthest radiators (near the thermostat) are getting warm. I just don't remember it working that way in years past. Typically the condenstate pump would turn on 20 mins or so after the cycle was already over.

Only changes have been - metal liner installed last month, and towards the end of the last season, boiler was maintnenced with some sort of purple stuff, and then ran for about a month after that.

Fred

You clearly need to skim that boiler. What you see happening in your sight glass is a clear symptom that the steam bubbles can't break through the layer of oil on the surface of the water and that pushes the water back into the returns. Given the age of that boiler and the fact that it doesn't even have a skim port, the oils have finally caught up with the boiler. I know you had a leaking fitting in your dining room ceiling last year that you had fixed. That new piping may have tipped the scales with enough new oil to cause this problem. It costs nothing for you to do a skim, except time. Do that and I am pretty certain the problem will go away. heat the water in the boiler, turn the power to the boiler off, Take that plug out of that tankless Hot water cover, put a 3/4" nipple in that opening, raise the water level up until the water comes out of the nipple and adjust the water flow down to a trickle and put a garden hose on that nipple and run it over to a floor drain. Let it trickle for several hours, over night if you can. After skimming, put a cap on the nipple you installed so that it can be used again if needed.

JUGHNE

Is your boiler floor at the same level of the basement floor with the wet return?

I agree with Fred, you must have a wet steam carry over issue.
If your pump did not run that much in the past then that must be the problem.

I am used of the cond pumps starting to run about half way thru the heating cycle.

Gravity would be great. You could get rid of the steam trap on the dry return and add more venting there.
How is the under grate vented? I assume it is a wet return.

Note: Not sure about Fred's theory of pushing water back into the returns...the check valve should stop that. If it was leaking then the pump would continuously shuttle water back and forth.