Excess Make-up Water Mystery

lizg

This fall we had a new Burnham steam boiler (Independence 280K input BTU) installed for the one-pipe system in our 1885 Victorian. It’s been running well in its first few months, but we’ve had to add make-up water twice over this period. Not a good situation in a boiler for which the manufacturer warns against adding more than 3 gallons/year.

Five weeks after our plumber did his final boiler cleaning/draining (est. 15 gallons) and refilled to the normal water line, I witnessed the automatic low water shutoff happen in real time. We turned off the boiler and waited 2 hours before adding water. The “resting” level in the sight glass before re-filling was 2.75 inches below the normal water level (and 4 inches above the “lowest permissible water level”).

Three weeks later (after a very cold period, temps as low as -34F, when the boiler was running with little downtime) we noticed the water was dropping close to the level that had caused the shutoff earlier, so we proactively filled back up to the normal water line before it shut off.

I’m trying to troubleshoot this before calling our plumber, since I’m sure he is busy with more urgent problems that the severe cold has brought on. I just spoke with technical assistance at US Boiler to find out how many gallons the 2.75” drop in water level is equal to. He didn’t have that answer, but he confirmed our suspicions that this was far too much make-up water to add twice over the course of 2 months.

We’re mystified about where all the water is going because:

--We do not hear water hammer at all. Occasionally a radiator gives one “clunk” which sounds like metal adjusting to temperature change.

--None of the radiator vents spit or throw off steam. None of the radiator valves show signs of leaking. None of the risers to first and second floors seem to be leaking.

--Our 2” main is fully visible (it hangs just below the basement ceiling)--but because it’s insulated we can’t see the pipes directly. We think a leak of several gallons over a month would make itself known (waterlogged wrapping or water dripping out the lower end of the wrapping). But we don’t see any evidence of leaks in the main. Could very low humidity (26%) plus the heat of the main dry up a leak before it is noticed?

--The pitch of the main is correct except for one pipe, which in the past hammered and then developed pinholes that spewed steam. That pipe was replaced several years ago and the pitch was improved somewhat, but that section still could collect water in its sag. If so, wouldn’t that cause hammering? It doesn’t seem like that 5-6 feet of pipe could account for several gallons of lost water.

--The newly-poured cement pad under the boiler is completely dry, so it’s unlikely the boiler block has a crack in it. (The boiler we replaced was leaking, so we know what that looks like!)

Here’s the only idea we have about the disappearing water:

Some of our radiators are not pitched correctly. However, they seem to heat just fine. For example, the first radiator off the main is pitched away from the valve and toward the vent. I just checked the new Hoffman vent and 4-5 drops of water came out of it. However, this radiator does not hammer and during the past week of very cold temps all its columns heated. But could it and a few other badly pitched radiators be storing the gallons of water we’ve had to refill over the past 2 months? Photos attached.

Here are some specific questions:
--Given that we haven’t found any leaks, do you have ideas on where the disappearing water is hiding or going to?

--Is there a way to estimate the amount of make-up water we’re adding, short of installing an auto-feeder that records recovery amounts?

--Is there a device for detecting where water could be lurking in our system (like a thermal camera that distinguishes water from steam)?

--Do you have any tips on how two 70-yr old people with bad back (husband) and little upper body strength (me) can re-pitch several radiators (small jack?) Or should we wait until our strong plumber can do this for us?

--What material is best for shimming (hardwood, plastic, metal)?

Many thanks in advance for any ideas you can suggest.

jesmed1

https://forum.heatinghelp.com/discussion/170313/need-a-tool-for-lifting-a-radiator

Lots of different options for lifting.

Jamie Hall

Are there any pipes in the basement which are at or below the normal water level in the boiler? That's the first place I'd look. Your system is old enough that if there are, I wouldn't be at all surprised if they were a bit leaky.

lizg

@jesmed1 - Thanks for the link about lifting. I'm sure one of those ideas will work for us.
@Jamie Hall - Thanks for that idea, but none of the pipes are at or below the normal water level (except for the new boiler piping that returns condensate to the bottom of the boiler). All basement pipes are at least 6" high.

EBEBRATT-Ed

@lizg

If you have pipes or radiators sagging or pitched the wrong way you should fix that. But that is NOT you issue with loosing water. Sagging pipe or back pitched rad will not continue to "store more water" they will collect a little water and the water will stay there until the pitch is fixed but they will not continuously collect or use water.

Steam can leak and not be seen to the eye. Take a mirror and go around to the air vents and radiator valves and look for leaks at the valve unions and at the packings around the valve stems. Use a flashlight the mirror will fog up if any steam hits it.

A few small leaks can ad up.

Is your boiler building pressure? If so how much?

lizg

@EBEBRATT-Ed - Thanks for the suggestion. We’ll do the flashlight & mirror check over the weekend.

I don’t have an answer re: pressure. The pressure gauge units are from 0-30, and the needle sits at near zero all the time. Our plumber said we wouldn’t be able to read small changes in very low pressure on this gauge. What would we notice if the boiler wasn’t building pressure?

dabrakeman

First step as mentioned before is to make sure your pigtail is cleared out so the pressuretrol is actually seeing the real pressure. Assuming it is then you don't want to generate more than 1.5 psi or so max and yes those 30psi gages are not really good enough to see that. You can pickup a 0-3psi or 0-5psi gage for not much and it is easy to plumb in yourself.

EBEBRATT-Ed

It's a new boiler so you don't need to worry about the pigtail. Sounds like your plumber sized it right. No pressure is a good thing.....you don't need it.

lizg

Thanks, @EBEBRATT-Ed. After reading the comment from @dabrakeman, I did some research, on this forum and elsewhere, about cleaning pigtails and calibrating pressuretrols, but I’m not sure how these issues relate to water loss. Our system's cycling and delivery of steam seems to be working fine. We don’t have problems with the heat in our radiators (except one), just have the excessive make-up water problem. You asked about pressure — can out-of-whack pressure lead to water loss?

lizg

Thanks, @dabrakeman, for the info about the 0-5 pressure gauges. I really would like to be able to see the change in pressure, so will work on that upgrade.

EBEBRATT-Ed

@lizg.

The lower the pressure you can run the less fuel you burn so your in good shape their. All old systems may have a small leak here or there. The higher the pressure the more leaks you get.

delcrossv

Drop the thermostat temp a few degrees, let the house cool, then set the thermostat back. That will give you some run time on the boiler. Then do the mirror test at every valve and vent (including the mains vents in the basement). Bet you find something.