water going away

DaleW

I have a new steam boiler that has a water line going away. I replaced the boiler in this home 7 years ago the owner failed to get service and also failed to blow down his lwco. thus another new boiler. same series and size boiler as before. this problem did not happen 7 years ago. thus i am puzzled , i flushed out , used cleaner and put in conditioner, to no avail. has a time delay water feeder. this is a 2 pipe system, has 5 return drops with checks on each. When the system fires the water line drops until it cuts off on low water, stays off until waterline returns or feeder adds more water. thus over the cycle adds to much water and when system shuts down boiler floods. could one or more of the checks bad and allowing the water to load up in the returns ?
Thanks for some help. Dale Williams Asheville N.C.

Jamie Hall

You shouldn't need checks in any of the returns, assuming that they are -- as they should be -- below the water line of the boiler. That they are there indicates other problems.

So... to start, what is the cutout pressure set at? It should be no than 1.7 psi, and the cutin correspondingly at 0.7 ps. Check and fix that first. Then check and see that the pressure control can actually see the boiler pressure. Is the pigtail clogged? They do.

Since this is a two pipe system, there must be either traps on the radiator outlets or orifices or flow control valves on the inlets. If there are traps -- most likely, check and see that they are working. If they are failed closed, the radiator won't heat, or will heat very poorly. If one is failed open, the outlet going to the return will be steam hot.

Then we need to consider the near boiler piping -- a few pictures would help here.

Then we need to consider vents. Are there any? What kind, and where?

As a general thing, the water level in the sight glass should not fall more than a couple of inches from where it stands with the boiler cold to where it is with the boiler operating.

Fred

Have you skimmed this new boiler? What kind of cleaner did you put in it? New boilers have a lot of oil in them and need to be skimmed from a port above the boiler water line. Leaving those oils on the surface of the water will cause the steam bubbles to push water out into the wet returns and it will look like the boiler is low and the auto feed will add water causing the boiler to overfill.
Drain the boiler and flush out whatever chemicals you put into it. Refill the boiler and skim it, very slowly to get the oils off of the surface of the water. It may take a few skims to get the waterline to stabilize. Don't add any more cleaning chemicals.

DaleW

went back today flushed out , skimmed boiler again. the cleaner was 8 way by rectorseal. refilled the boiler and fired water level bounced and had shut off on low water. But another thing I saw was something I should have seen much sooner , this is a webster system. So this boiler and the last 2 have been 2lb boilers, not sure how this system worked for this many years without problems. im going to get a presuretrol for a vapor system.

Fred

You want a Vaporstat for a vapor system.

KC_Jones

DaleW said:

went back today flushed out , skimmed boiler again. the cleaner was 8 way by rectorseal. refilled the boiler and fired water level bounced and had shut off on low water. But another thing I saw was something I should have seen much sooner , this is a webster system. So this boiler and the last 2 have been 2lb boilers, not sure how this system worked for this many years without problems. im going to get a presuretrol for a vapor system.

How was the boiler sized? Pressure is a function of boiler sizing and system capacity, with venting adding in for good measure.

If it's running at 2lb it isn't the boiler "making" pressure, it's the system pushing back at 2lb.

Jamie Hall

Fred said:

You want a Vaporstat for a vapor system.

And set it for no more than 8 ounces per square inch cutout with a 4 to 6 ounce differential.

If the water level is still bouncing enough to trip the LWCO, you may have to repeat the skim. Several times. And make sure that all the additives are out of the system first -- complete drain and refill, then skim.

nicholas bonham-carter

Are all the wet returns under the waterline?
As pressure rises, the waterline in the wet return will rise 1.75 inches per ounce of pressure, and any horizontal return above the waterline can fill up, and “hide” the water until the boiler cuts out, and pressure drops to zero. Then the water returns.
That system could give good heat at 2 ounces, so a 0-16 ounce vaporstat would be best.—NBC

Jamie Hall

@nicholas bonham-carter has a very good point. You mention "new steam boiler". Did anyone match the water line in the new boiler to that in the old one? New boilers are often shorter than what they replace, and it is quite possible that one or more of the wet returns aren't wet anymore. This will cause exactly this kind of problem. Now that the boiler is in, if this is the case you have two choices: a false water line -- or lower all the wet returns to where they need to be.

Plan on doing that anyway, if that's the factor. Whether it solves this problem or not, it will prevent other squirrely problems.

EBEBRATT-Ed

Sounds like it needs to be skimmed