Steam trap rebuild - diy?

motomars

Hi all. I am a volunteer with my church and we have a faulty Barnes and Jones steam trap (FT2015-4). This was confirmed by an HVAC contractor, who also wants what seems to be an ungodly (see what I did there?) amount to rebuild the trap. I'd like to tackle this myself, as it does not seem very difficult - buy a kit, pull off the old cover/float, clean up the gasket, install new cover/float. But one issue I'm concerned with is that there is an isolation valve on the output side, but not the input side (see pic). How much does this complicate the process? And while I am very experienced with plumbing, I am not a professional - so I want to make sure I'm not getting in over my head with this repair. Any feedback is appreciated.

Jamie Hall

Just don't reuse the old gasket. Bad practice.

JUGHNE

The top ports are the inlets......the lower ports are the outlets.

That looks to be a brass strainer above the F&T. Shut off the ball valve above.
You should remove the plug on the "wye" looking part of the strainer.

I put a short nipple, ball valve, short nipple and cap on the clean out port.
Then once a year I remove the cap and carefully open the small valve while under pressure,
this will blow out the strainer screen.

(With the system off and cool), then the bolts should be a fairly easy removal.
Some give them a little nudge tight and then loosen the bolts.

Cleaning the face of the body might be the most work.
I paint the surface of the gasket and iron bodies with "Never Seize" for the next time of repair.

Where does the left side pipe go to??

How does the F&T pass air to a vent or pump tank??

EBEBRATT-Ed

Just shut the boiler off when your rebuild it. There pretty easy to rebuild.

motomars

This is terrific - thank you very much. @JUGHNE - I appreciate the detailed info. I'm not able to get to the boiler room right now to answer your questions, but I'll post a picture if I can get there today or tomorrow

motomars

Okay, so I turned off the boiler and condensate pumps and installed the rebuild kit as directed. I turned the boiler and pumps back on, cranked up the thermostat, and let it run for a while - all seemed fine. When I turned the thermo down, the boiler shut off but I could hear the condensate pumps running. I looked at the condensate tank water level and it was near zero. Turned off the pumps and the tank began filling. I let it fill well past the low level mark and then turned pumps back on and fired up the boiler. Ran for a bit and then the condensate overflow started gushing water (see pic). 

Very confused by this! The only thing I did was fix the trap. Is there something else I should be doing on start up? Or maybe the faulty steam trap was masking another problem (note that there are 2 traps on the system)? The boiler water level remained stable throughout all of this. Thanks for any help.

JUGHNE

Back up for better pictures, show floor to ceiling piping, including boiler.

Where did that left pipe go to??

motomars

These are the best pics I have right now - I can go take others if need be. In the wide shot facing the boiler, the pipe you mention appears in the middle, to the left of the boiler (the repaired trap feeds into it).

motomars

One more...

JUGHNE

What prompted you to rebuild the trap to begin with?

When did the water stop running? Was it cold or hot water?

It is possible that the float in the feeder pump tank did not shut off the inlet water.
There is a pressure reducing valve in the cold water feed line to reduce the pressure as the float valve can be overcome by city pressure.

You could drain the tank down to about 2/3 on the sight glass, shut off the water inlet and run again.
But don't leave the water off unattended.

motomars

Excessive amounts of steam were being released through the condensate tank vent. Our contractor identified the trap as the culprit.

When the overflow started, I turned off the boiler and water flowed from the high overflow pipe for at least several more minutes. It was hot water. After it stopped, water continued to drain from the low overflow pipe (which goes outdoors) for a while longer. It eventually went down to a trickle (the glass still showed that the tank was full) and I tried firing up the system again. I watched the low overflow and, after 5-10 minutes, it went from a trickle to a stream of water, so I turned off the system - figuring the top overflow would soon start pouring water into the boiler room.

Pumpguy

That looks to be a boiler feed pump set, not condensate pumps.

The difference is condensate pumps run start - stop, controlled by a float switch.

Boiler feed pumps are similar, but instead of float switch, they operate on demand of low water boiler control. Also, boiler feed pump set has low water make up valve, which yours appears to have.

The overflow condition you have could be due to a leaking low water make up valve. Yours appears to be a mechanical float type, similar to that found in a toilet water tank.

Another way to control the make up water is to use a float switch and solenoid valve arrangement.

You may have a starve - then flood condition in your system where condensing steam creates a vacuum which prevents the condensate from returning to the boiler feed tank. When this happens the low water control opens and takes on more fresh feed water.

Then later when the vacuum bleeds off the excess condensate flows back to the feed tank where it overflows to the floor drain.

There are ways to equalize your system so condensate will always flow back, even when condensing steam creates a vacuum.

Being a pump guy, I will leave to others to advise on these changes, if you find they are needed.

JUGHNE

Do you have 1 or 2 pipe radiators and are they fed from the ceiling main with drop pipes?

Pictures showing both ends of the radiators please.

motomars

Two pipe and they are fed from below. This is the best picture I can provide at the moment.

Scottynot2hotti

Doesn’t seem like an ungodly price now does it 

EBEBRATT-Ed

As @pumpguy mentioned that is a boiler feed tank not a condensate tank. If you look at the boiler facing the burner the control on the right side is a Mcdonnell Miller #150 which operates the feed pumps.

The float control in the feed tank is supposed to maintain a constant minimum water level in the tank

motomars

Thanks so much guys. @Pumpguy, you mentioned the possibility of a leaking low water make-up valve - by that you mean that the float is stuck or broken and so it's holding the tank's feed valve in a continuous open position?

You also mention the possibility of a vacuum condition - that makes sense, as the tank completely drained and then after a short period of time, flooded. In talking with someone else at the church it sounds like a similar flooding condition happened late last year. But the boiler has been operating normally (with the exception of excessive steam, likely from the faulty trap) for months. Would it make sense that this vacuum condition would only happen sporadically? Are there particular conditions that might cause it to happen?

Sylvain

motomars said:

When I turned the thermo down, the boiler shut off but I could hear the condensate pumps running. I looked at the condensate tank water level and it was near zero.

So
- the boiler was still asking for water after shut-off.
- The condensate was still not coming back and the fresh water feed wasn't compensating rapidly enough.

Now that the trap is functioning, it is possible that a vacuum is forming. Previously the return was venting through the tank vent. Then under vacuum, water could continue to vaporize even if the burner is off.

Would it produce enough steam under vacuum to need more water (pump was running)?

When shuting off, all the steam including any "extra vacuum steam" wil condensate and finally come back.

Try to see if there is a (failed) vacuum breaker somewhere.

Now, apparently you didn't let it run long enough to see if it would come to some equilibrium.

Ebebratt-ed has an interesting story about cold start with an undersized boiler.

then there is this unresolved case:
https://forum.heatinghelp.com/discussion/180306/steam-boiler-seems-to-be-pulling-a-vacuum-causing-it-to-shut-down-on-low-water

motomars

@Sylvain - I just noticed this breaker is missing its plastic cap. Could this be the culprit? It doesn’t seem like the cap would actually affect the breaker’s ability to do its job, but maybe so?
 

JUGHNE

What was the condition of the F&T you changed?
Is there a pressure gauge that shows vacuum on the boiler?

It looks like both F&T's have vac breakers.
The F&T to the right looks to be for a drip on the steam riser.
Is that what the Left (repaired) one does also?

Twice I have had a large amount of water return because of vacuum.
One was a single pipe sys with TRV's that lacked a vac breaker.

The other was 2 pipe that somehow held water in what should have been a dry return.


In your boiler room there is a water trap for the dry return that drops down to near the floor and then back up. I am not sure of it's function as you have a pumped return.
Has that horizontal section, 3-4' long, ever been flushed?
It is an ideal sediment connector and could be partially plugged holding back water.

motomars

Okay, I lowered the tank water supply to 2/3rds and ran the system both with the supply turned off and with it turned on. Everything seemed to operate correctly - after a while the tank level began to slowly rise and when it hit the high mark, the pumps kicked on and brought the level back down. I ran it for a solid hour without issue. So is it fair to think that the incident yesterday with the water loss and then overflow was probably a one-off occurrence and that I should let it run as normal and just monitor? 

motomars

@JUGHNE - I believe both of the F&Ts serve the same purpose. I think one is connected to section of radiators in the old part of the church and the other goes to a newer (though still 60+ years old) part.

The repaired trap had a fair amount of gunk in the body - I cleaned it up as best I could - and the float and thermostat were rusty.

I don't think there is a pressure gauge on the boiler, but I'll look more closely when I'm there next. And I'm not sure if that lower section of pipe has been cleaned out - I'll look back at the records.

As I mentioned, the system seems to be operating correctly now. Would it make sense to go ahead and replace the two vacuum breakers on the traps as a precautionary measure?

JUGHNE

To clarify the operation: you have a feeder pump controlled by the LWCO switch located on the boiler.

The tank level would rise slowly by returning condensate water. It hitting the high mark would not start the pump, the boiler LWCO would make that call. It would bring the level down.
The boiler does not know what is going on with the water level in the tank

If too low then the tank float valve would add more water....hopefully it shuts off correctly at the right level.

Feeder pumps are often confused with "Condensate Pumps".....they receive water and when full a float in the tank starts the pump and sends the water into the boiler....regardless of whether it needs it or not.

You might let this run a few days and observe. Please let us know what happens.

Pumpguy

You may have a starve - then - flood condition caused by collapsing steam induced vacuum on the boiler and steam header. This is common in the shoulder seasons when the boiler is only making steam on a part time basis.

Your boiler should have a compound gauge showing if there is either a positive pressure or a vacuum (negative pressure) .

When the boiler is at vacuum, and you have a boiler feed receiver tank that is open to atmosphere, atmospheric pressure will push the feed water into the boiler and steam header causing a flooded condition.

When this happens, your boiler feed tank is low on water so the low water make up opens to restore the tank level.

When the building calls for heat again, the system now has too much water so it all goes down to the boiler feed tank where it overflows as shown in your videos.

If this is indeed what's happening, I can think of 2 solutions.

First is a vacuum relief valve on the steam header. This may require special piping arrangements which I will leave to others to elaborate on.

The second is a positive closing (motorized or solenoid type) valve on the discharge of the boiler feed pumps. A simple check valve won't solve this problem since it allows flow toward the boiler which is what we don't want in this situation.

This second arrangement is what I recommend for vacuum return systems with feed water supplied from a vented feed water tank.