Old high school 2 pipe steam boiler with trane fin blower units.

heating1234

heating1234

Have an old school "early 60's" all trane finned blower units shut off electorally except one running near the thermostat. Thermostat is on a cut back timer.

The issue is, with one finned radiator unit running I see steam coming out the vent to the outside of the building. Thermo scan shows steam going in the other units that are working but the blowers are not turned on and the temperature is around 200..

The condensate lines drop into a receiver and are being pumped back to a wet line entry for the boiler, some distance away with check valves installed at the boiler and after the receiver pump on the receiver end. The check valves are ok and the pump is putting water back into the boiler. I can see the receiver pump working and hear the check valves operate. Return water is around 190.

On a low demand day i see steam coming from the receiver vent which goes to the outside world.

There are 2 float traps of which one dumps to the 2ed float trap that dumps to the receiver unit.

The hall where the thermostat is takes some time to heat up, (old school building)

Do you think more units have to be turned on to heat the hall more quickly rather than one unit.

Hate to be pumping steam out side with the price of fuel.

IDEAS

Thanks

Big Ed_4

Kinda curious about the out side vent ,belching steam…

I assume your the Fireman during the holiday ?

heating1234

That old 1 in pipe is just an open pipe to the atmosphere with just a 90 on the end it rise about 8 ft.

That belching, well some condensate get to the bottom and yep we get a belch. Not the fireman, just a volunteer.

Big Ed_4

Is it a vent off the condensate tank ?

heating1234

Yep, comes off the tank up the wall and to the out side.

heating1234

PS When it is working you can feel air being pushed out to the atmosphere. Then when the pump reaches it turn on level you can feel the air being sucked back into the tank.

Jamie Hall

Nothing wrong with the vent — but at least one of your traps isn't working. Also it sounds as though maybe one of the lines is double trapped? That isn't right either.

heating1234

There is an old Sargo 2" ft-30 30# b82 that feeds the receiver, then I have a trane 602 that dumps to that sargo unit. I was thinking that the thermostat may not be working or the vent for the thermostat may be plugged.

heating1234

I think your right on the double tap. They seem to have used the main steam feed as a manifold and one branch feeds a Gym heater and a couple of class rooms. That branch uses the Trane FT , and that trap dumps down to the Sargo FT about 8 ft away. It has been that way from day one as far as I can figure.

mattmia2

the vent is to allow water to enter and exit the condensate tank. as @Jamie Hall said, a bad trap somewhere is letting steam in to the returns. that will kill the pump in the condensate tank among other things. obviously each univent and all other emitters have a trap on it and those all need to be good.

the 1960's section with the univents instead of radiators or convectors was the new section of the school…

EBEBRATT-Ed

You have bad traps in the building . The steam is getting into the returns and the condensate pump and going out the vent pipe.

In addition to that your condensate temp is way too high……another indication of bad traps.

What steam pressure are you running? I would lower the pressure (just make sure you can get heat to all areas) until you get the traps fixed.

heating1234

Mattmla2 no univents on system just finned radiators with a blower. One pipe steam other return to condensate.

Mad Dog_2

Sarco? Mad Dog

heating1234

EBEBRATT

I believe your right. The trane trap had it's thermostat changed in September and cleaned out. That Sarco trap may have a clogged thermostat vent.

I walked around the gym looking at the condensate pipes and see some smaller traps. They have been painted and the paint has not been disturbed on those traps. That paint job was more that 20 years ago.

Do you think if I do a cold start and thermo scan on those traps? Maybe I could see which one is passing steam on startup. I would think if one is stuck open it would heat up the fastest.

Any other thoughts to find the offending trap?

heating1234

Eberatt

Steam pressure just below 5 lbs.

EBEBRATT-Ed

I would suspect many traps are bad they can be rebuilt and it doesn't take long . Once you get the hang of it you can do a radiator trap in 15 min or so.

The cost of wasted steam and the damage to the condensate pump seals and damage to the boiler from excessive MU water means it best to do the traps. Some college campuses will chanke all the trap guts every 4-5 years. Why? Because if you can rebuild one in 15 min the labor saved chasing down bad traps is usually wasted labor. Just start rebuilding them all especially with 20 years of paint. Contact Tunstall associates or Barnes and Jones. Some trap companies will do a trap program but that is more $$$ and it is better to do this in the summer or when you can shut down.

If a trap is really bad and blowing steam you can probably hear it. You can try infrared gun or thermometers they also make ultrasonic and other types of testers.

heating1234

ED, may try the old hammer on a couple of those little traps to see if I can buy time. I was even thinking of pulling the plug at the bottom and screw in a nipple with a ball valve to see if i could blow something out of the trap.

I did find major crud in that Trane trap when I got into it this fall. I might open that one up again to see if anything else wash in it from the condensate line.

On that Sarco FT 30, This is what it looked like when I got into it. I found the bellows down by the float and I believe the vent passage is clogged.

I'm finding an air vent Sh1135 which looks like it replaces the bellows thermostat. I also ran into some stainless steel thermostat. I was wondering if these are replacements for those old bellows units. Cannot get hard information on that old unit.

Hey, thanks for your ideas.

EBEBRATT-Ed

Is that a "Master Trap" installed at the condensate pump inlet? If it is that is part of your issue.

When the buildings original traps start to fail instead of fixing them some install a trap on the condensate pump inlet thinking this will solve the problem. It may help but it causes other issues.

Steam backing up the returns through failed traps causing over heating

Condensate drainage slowed, hammering etc

It's just not the right fix

heating1234

ED That is the Sarco trap and as you can see in the picture the Hoffman Watchman condensate unit is fed by it. The pipe on the right is the inlet to the Hoffman and the small pipe between the 2'' is the vent pipe. You can see the copper return from the pump in the picture. The other inlet is capped. This is original equip as far as I know. I cannot get anyone to admit anything. You know the story it's broke can you take a look at it?

Your thoughts make sense. I wondered why those little traps have never been touched for years coming from those class room heaters.

I have to try and see if the vent tube in that trap is not plugged. I can hear the trap doing its thing when it is up to temperature. There is a ball valve on the bottom of the Trap that I open to clear any crud from the trap. When things are going ok I get the amount of condensate that you would expect the trap to hold with float closed. During operations when things are going good I get the water then the steam from the ball valve.

The other day like I said before that trap was scanning at about 200 and I was getting heavy steam and little condensate from that ball valve. That is when I saw the vent outside venting steam. That float may have stuck open.

EBEBRATT-Ed

Master trap is a common but wrong approach. You can read about it in many of @DanHolohan books including LAOSH and some others that I have forgotten. A LOT of buildings get screwed up by master trapping

mattmia2

there should be no steam in the returns. the steam getting to that trap is the result of failed traps elsewhere. when that trap is closed it will keep things from being able to vent and heat while the trap is closed. the vent on the condensate tank is also the vent for all of the emitters.

ratio

I don't know the details of your system, but it sounds similar to mine: two pipe with a combination of loooong radiators in the old part of the building and Nesbitt fan-powered unit ventilators in the newer part, controlled by pneumatic valves, for the classrooms and hand valves for the other areas . I'm sure that there are a good number of failed traps, but between the condensate running underground and my vaporstat settings of 20 oz cutout I don't get any steam in the receiver. I've added a few TRVs in the cafeteria to manage the overheating.

Anyway, unless you need to lift condensate, 5 lbs seems awfully high and certainly isn't helping you keep steam out of the returns. Try turning it down, maybe one lb a week, & see how low you can get it. You might want to invest in a vaporstat as well, to go even lower than you can reliably control to with a pressuretrol.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1830576#Comment_1830576

the 5psi might be an attempt to compress the air that can't vent out because of the extra trap at the condensate tank and the failed traps

heating1234

mattmia2 I agree that there should not be much steam in the condensate. Maybe some from worn valves, ect. but no pressure and definitely not running around 200 degrees like I found it.

What I was wondering about is that since they only have one blower unit that turns on and is running when the building thermostat calls for heat from a cold start. All the rest of the finned units are just doing convection heating with no blowers running in the building. Since the building is cold, due to the cut back thermostat setting and the amount of time it takes for that one running unit to bring up the heat in the school hall to satisfy the thermostat setting. All the time the thermostat is calling the boiler for heat.

I was thinking that the boiler is putting out steam but there is not enough cooling from the finned units that are not running to cool the steam back to condensate. I haven't checked their btu ratings or did the math to figure what they would be putting out. The boiler is a

That output is 947700 btu's I'm thinking that running it this way is part of their problem. While that one Trane unit that is running is not able to put out enough heat to bring the temperature in that hall up to have the thermostat to cut the call for heat from the boiler. I can almost understand why that outside vent is putting out steam.

I'm sure those small traps up line have issues.

Thanks for the reply. I take any ideas.

heating1234

ratio I've been thinking about bringing the pressure down. But I am trying to deal with one issue at a time. Just after start of heating season I got the news of water by the boiler. I worked on that, In old systems there is always another problem. They just neglected they system for years. Now that fuel cost are up it has there attention. Getting too old for this stuff.

heating1234

ED Thanks ED, I'll have to do more research on master trapping. It is always tough to figure out what the last guy was thinking of, let alone the thing of people that 20/30 years ago.

The poor young fellow that we called in from one of the areas heating shops seemed to be a bit overwhelmed. He was wanting to start ordering new traps and the like. I would like to get a real idea of the problem first. He said that he would talk to some of his older people for advice. We just don't want to throw money to see if this or that will fix the problem.

Volunteering sucks sometimes.

Jamie Hall

There's a missing point here, @heating1234 : you are entirely correct that the boiler is capable of putting out more steam than the system can absorb on its own. And also correct in thinking that this may be why steam is getting through those convectors (it probably is).

However.

It shouldn't. There are two ways in a two pipe system like yours to avoid that. Either there are traps on every single last one of those convectors and other steam using units, or there are orifices which control the amount of steam entering. Either one will work — but the orifices will only work if the pressure is controlled at a very low level (typically less than one psig, and often less than that). Traps, on the other hand, will work with less exacting control of pressure (though anything much over 2 to 3 psig shortens their life).

Now you also note — quite correctly — that the boiler can put more steam than that. Assuming that you can't modulate the firing rate — probably not — you have only one other choice to control the pressure: turn the boiler off when the pressure gets to the upper limit, and turn it back on if there is still a demand for heat and the pressure falls to a lower limit.

There must be a pressure control on that boiler. In fact, I sincerely hope that there are three of them. One, set high — perhaps 7 psig — should be a manual reset as a safety backup. Another would be what you might call a normal safety, and should be at around 3 psig as a guess. Then the third is your firing control, and is set to maintain the pressure range in the system. I'd suggest setting that one to cut out at around 2 psig to start with and to cut back in at around 1 psig.

If in examining the various units you discover that they use orifices rather than traps, you may need to lower the firing control cutout pressure to what will keep steam from getting to the returns. The Trane unit may conflict with that — but we'll cross that bridge when we get to it.

If the convectors have traps — as I suspect they do — fix them.

I will reiterate what I and others above have said: there should never, ever be steam in the returns at any location in the system. Any steam. Even a little bit. Until you get that straightened out, there's no point in chasing other things.

ratio

If the traps are failed, they must be replaced/repaired, or convert the system to a different type, usually orifices; there really isn't any other choice.

One of the steps to convert to orifices involves lowering the boiler pressure. Lowering the pressure will reduce the steam blowing by the failed traps, so when by itself it will help. In my instance, most of the returns are underground, where the ground temperature causes any steam to condense before it makes its way back to the condensate pump. It was a lot cheaper than testing & repairing 100+ steam traps. I would like to make the repairs, but it really isn't in the budget & since the system heats fine I'm going to have to live with it.

Lower the pressure, see if your problems just get less, or go away completely. 😉

bburd

If the owners do not plan to put those blowers back into service, orifices won't solve the problem. The steam control valves will remain open because the thermostat isn't satisfied, but without the blowers the coils will not condense anywhere near their rated amount of steam.

Remember that univents are designed to heat large volumes of outside air. The coil capacity will be considerably above that needed to offset the building's skin losses.

Jamie Hall

I'm betting there are traps on the system — and that at least half of them have failed.

heating1234

bburd These are trane units and not using outside air. I do believe that they have traps on each of the units as I have looked around and see some traps in the gym of this school. Like I said before they all seem to have been painted. As far as I can gather the last time they painted that gym was 20-25 years ago. The traps I have found the paint on them has not been disturbed.

Jamie Hall

Time to start disturbing some paint…

mattmia2

you did check that the blowers aren't just shut off, right? there is usually a switch in that type of unit heater that turns the blower off. (are they univents or not, usually in a school they bring in outside air either directly or from a duct system)

retiredguy

Let me give you a little insight on how a schools heating system operates. Since I am not there I can only tell you what I know to be a normal operating steam system since I worked on these beasts for 35 years. Most steam systems in Pennsylvania schools operate at an operating steam pressure between 3 and 6 psig. The normal operating pressure was set by the systems design engineering company but could have been changed by any condition that would require that change. In a school building, there are standards for the amount of air changes per hour that must be adhered to based on the estimated number of occupants to provide for a safe environment. These required air changes have changed over the years and I do not know what is required today. Uni-vents. as the are called, that are mounted on the outside wall should have an outside air vent to allow for the required air changes. Buildings that do not have outside air intakes must have another system to introduce outside fresh air into the building. Schools and other commercial buildings are notorious for not providing good maintenance due to the overall cost. The fact that you seem to have a master trap or traps on that system does not surprise me since that was the norm to keeping the cost low. Doing the repair the correct way by replacing all the steam traps cost way too much.. The saying was "why should I/we correct the steam in the return system the right way when we can do it the wrong cheap way".

heating1234

mattmia2 The blowers have been shut off and only turned on when people are using the room. Those classroom thermostats that used to regulate the heat in the classroom must have been bypassed and are out of the circuit. This is part of the problem. When people leave the classrooms they forget to turn off the units and the just run, no control on them.

The one Trane unit in the hall was operated just by a wall switch. I put in a regular outlet and wired that unit to a unit that turns on the heat at 99 and turns it off at 72. I'm thinking about doing the same to the classrooms.

heating1234

retiredguy Seems about the same at this place. Did you ever take the plug out of those smaller traps and install a nipple with a valve and flush those small traps?

To get to those traps in the gym I'll have to use a trestle ladder an fight them that way with a bucket ect. You know the story. Guys close to 80 should not be doing this crap. Never was too bright.

Thanks for the info.