Effects of missing traps on rads

guzzinerd

Five of the 30 radiators in my building were replaced with these things by the local plumbing company before I bought the place, no traps, just valves.  Two of them are on one end of the main, another two on the opposite end and another in-between.

My plan was to just replace them with new cast steam radiators with proper traps this summer...BUT

Are the effects of the steam flowing into the returns from these 5 radiators hurting my system enough where i should be adding traps now or can it wait for the summer?

Thanks

Jamie Hall

"Are the effects of the steam flowing into the returns from these 5 radiators hurting my system enough where i should be adding traps now or can it wait for the summer?"

Yes. The steam flowing into the returns from these may cause the other radiators on those returns to heat poorly, if at all.

guzzinerd

Ok.  Is it possible to put a trap a foot or two below the rad in the crawlspace?  I ask because there's no room right next to them. 

EBEBRATT-Ed

Yes, you can put the trap in the basement in fact it will work better down there..

Keep the steam pressure low or the traps you already fix may be ruined by steam in the returns.

Baseboard must have been installed by a hot water guy

guzzinerd

EBEBRATT-Ed said:

Yes, you can put the trap in the basement in fact it will work better down there.. Keep the steam pressure low or the traps you already fix may be ruined by steam in the returns. Baseboard must have been installed by a hot water guy

The trol is set at 1.5 - 0.5 although it was set at 5 before i got there.  Dunham rebuild kits are on the way already.

I have unlimited space in the basement and won't need to coordinate with 3 different tenants this way.

mattmia2

I'd leave the traps down there with the new radiators. Easier to service if access is an issue. The ability of the condensate to form a column to get some pressure behind it also helps the condensate flow in to the return.

ChicagoCooperator

Looks like they were recessed convectors at one time?

guzzinerd

ChicagoCooperator said:

Looks like they were recessed convectors at one time?

They were.  There are still 20 originals in the building.  Sure wish they didnt hire knuckleheads who threw them out as they went cold

guzzinerd

mattmia2 said:

I'd leave the traps down there with the new radiators. Easier to service if access is an issue. The ability of the condensate to form a column to get some pressure behind it also helps the condensate flow in to the return.

You don't know how happy that makes me.  I think it also reduces chances of floor damage if they leak.

GBC_illinois

I know the conventional knowledge is that all radiators in 2-type steam should have steam traps, but I have an unusual setup in my condo building where *none* of the radiators have steam traps. It was built in 1920 as a 2-pipe, very low pressure vapor system. (Before you ask, yes I know what a Richardson orifice trap is, and we don't have those either in the returns; we've opened some of the return lines to see). We run at about 0.75 psi now, but I suspect I could run lower, if the boiler wasn't so dramatically oversized. Steam does flow into the condensate returns (and back into the other radiators through the condensate line), but its so low pressure it doesn't seem to matter. Our basement has no radiators or other heat, so it is a beneficial side effect of this setup that the condensate line, which is uninsulated, heats the basement.

JUGHNE

Fdarby82, what type of inlet valves are on your rads, could there be an orifice in the union of the valve?

GBC_illinois

JUGHNE said:

Fdarby82, what type of inlet valves are on your rads, could there be an orifice in the union of the valve?

All the radiators have Danfoss RA2000 thermostatic valves on the steam inlet. It's a 15 unit coop building, so these valves allow each resident effective control over their own radiator heat. On one hand, I bet we are losing a decent amount of money in steam loss to the condensate line, but if we need it to heat the basement, it seems like a wash to me. Also, without steam traps on any of the ~65 radiators, there's virtually no reason to have a pro enter each residence to maintain the radiators. The RA2000's do go bad, but they are easy to change out even for a layman. 

guzzinerd

Fdarby82 said:

JUGHNE said:

Fdarby82, what type of inlet valves are on your rads, could there be an orifice in the union of the valve?

All the radiators have Danfoss RA2000 thermostatic valves on the steam inlet. It's a 15 unit coop building, so these valves allow each resident effective control over their own radiator heat. On one hand, I bet we are losing a decent amount of money in steam loss to the condensate line, but if we need it to heat the basement, it seems like a wash to me. Also, without steam traps on any of the ~65 radiators, there's virtually no reason to have a pro enter each residence to maintain the radiators. The RA2000's do go bad, but they are easy to change out even for a layman. 

Appreciate the feedback.  There are no pros in our part (if not all) of the State so I don't mind learning to do this stuff thanks to this forum.  My lines run through too much crawl space to make your system work for me, trying to get my gas bill down.

Jamie Hall

I would bet good money that the original system had either orifices or controlled valves on the radiators to limit the steam flow to what they could condense. Without them, you will -- as you have discovered -- get steam in the returns, and that is NOT a wash. That is limiting, in a quite unpredictable way, the performance of other radiators on the same return. Further, while it may seem that it's nice to have a warm basement, there are better -- and much more efficient -- ways to do that.

How much efficiency are you losing? Hard to say. Probably upwards of 25%, maybe more. Once any given radiator is full and passing steam into a return, all that extra steam is essentially completely wasted.

Mad Dog_2

Having some working traps and some non working traps is a recipe for some cold rads
Uneven heating and poor comfort
Levels. Migrating steam in the wrong zones can act like a plug or air lock that stops flow.   U change all or none. Clean sweep...unless u want to spends days fiddling around.   Mad Dog

jumper

Duck,Duck "Fin Tube" by Noel Murdoch. Why spend money on those baseboards if you're going to replace them?

Mad Dog_2

Jumper...please elaborate...not following. Mad Dog

guzzinerd

jumper said:

Duck,Duck "Fin Tube" by Noel Murdoch. Why spend money on those baseboards if you're going to replace them?

There are no traps on the baseboards, they are needed there. 

The replacements (real radiators) will also need traps, no?   I'll be installing the missing 5 traps on the returns below each unit in the crawlspace.  This will make swapping out the baseboards for rads a little easier this summer.

I'm also rebuilding all the original Dunham traps in the building.  Can't wait to see/feel the difference next winter.

jumper

Mad Dog_2 said:

Jumper...please elaborate...not following. Mad Dog

duckduckgo is an alternative to google. The article doesn't seem to come up in searches. I don't know if Erin will approve of me posting it here. Murdoch posted helpful stuff on the internet. Note what he writes below about two pipe fin tube steam terminals. They can work okay when steam is metered in slowly. Will an orifice on outlet suffice instead of a trap?

Noel Murdough wrote & posted the following somewhere:

 The basic design for a fin-tube steam system follows the same principles as other steam systems, special attention being given to the prescribed maximum limits for the lengths of elements and the slope of the fin tube.
 
   Special care must be taken to ensure that the supply piping can deliver the rated amount of steam for the size and length of the fin tube to be installed. As an example, 30 feet of two inch steel element can be connected to a one pipe system. It is rated at 5.7 sq. ft. EDR per foot, and 30 feet is 171 sq. ft. EDR. . Multiply by 1.33 (typically) to add for piping and pick-up losses, and we need 228 sq ft of capacity to the baseboard inlet valve. A 2’ steel run-out from the main to the fin tube can support only 169 sq. ft., which is below the capacity of the fin tube. A 2 ½” run-out will carry 260 sq ft. Add to this the vent that lets the air out of the fin tube at a measured rate, which can be too fast for the water that tries to travel under the steam as it returns to the boiler. The net effect of pushing the pipe size to the max, and of over sizing the vent is that the water that condenses in the cold piping gets pushed ahead of the steam. It can’t drain back underneath because of the velocity of the steam coming in.
 
   Pipe pitch is another concern with steam fin tube. If the fin tube is near the top end of the lengths allowed, a full ½” per ten feet of pitch is required. In those 30’ in the example, the pitch over the whole run will be 1½” of rise. If you are at 50% of the limit, ¼” in ten feet is enough. Do NOT vent too fast, though. Figure the volume of space in the run-out and the fin tube, and  the total length, and select a vent that limits the air venting and steam speed to about 10-15 feet per second MAX. Faster than that, and the water will hammer the vents to death, and spit water onto the floor.
 
   It is easier to apply fin tube to a two-pipe system, as the inlet valve can be modulated to control the output. Thermostatic Radiator Valves (TRVs) work wonderfully with two pipe steam systems. Orifices at the fin tubes, or steam traps at the ends of the fin tubes keep steam out of the return piping. Multi tier fin tube systems can be piped as commonly manifolded units with a single trap, or can be trapped on each tier, to stretch the length limits, as long as the run out and riser are large enough to support the load.
 
   Fin tube doesn’t mix well with iron radiators in the same system. The time to heat up, and the time to give up all of it’s heat is different between fin tube and standing iron radiators. The fin tube heated rooms will tend to be cooler before the radiator heated rooms are finished giving up the heat from the previous cycle. The temperature swings will be very wide in the fin tube heated rooms.
 
   When sizing for steam systems, the chart offers different pressure drops. On a system that has 100’ of pipe or less, the lowest operating pressure will be double the design pressure, as this is the way to ensure that the pressure will always be above what is required. Most systems are designed from the 1 ounce pressure drop column on the chart, and the minimum operating pressure will be 2 ounces of pressure PER HUNDRED FEET. Only measure the longest run in the system, to find this number. It is not all of the piping combined together; only the longest run. The cut-in setting will happen at this pressure, and the cut-out setting will be above that pressure.
 
   The steam pressure control should be set as low as possible, while still heating every piece of radiation. The steam air vents and some steam traps have a “drop away pressure” rating. This is the pressure that the steam must be kept below in order for the vents to reopen after closing. As the system design pressure is 2 ounces per 100 feet of piping, usually the steam system will run very well at a half pound (8 ounces) of steam pressure. The high limit pressuretrol that comes with most boilers is not a very fine-tunable control. Set the cut out very low, with a small differential, and test it. Make sure that it shuts off near the point where all of the radiators are hot, and comes back on before any of them are cool. If you set it too low, one or two rooms will be cool. If you set the cut out too high, the burner will short cycle. Sometimes, a vaporstat can be added to the system to give finer control.
 
   If you have a two pipe steam system, the dimension between the boiler water line, and the lowest horizontal pipe connected to the RETURN is called a “B” dimension. It determines the boiler pressure, because the water rises in the returns 28” for every one pound per square inch of steam pressure. If you only have 28 inches of height, the water in the boiler will fill the mains at 1 PSI or more, and the boiler will run out of water. Keep the cut out pressure low.
 
   If you decide to use a setback thermostat with your steam system, get the system up and running and balanced without using any setback. Set the day and night temperature settings to the same number. Let the system become stable, balanced, and quiet when running. This way, when you introduce the setback feature, the banging and hammering and vent spitting that occurs can be considered normal for your system.
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The Steam Whisperer

If you look at the TRV you will quickly see that they act as an orifice, so I would suspect that there is not much steam getting into returns if the system is run to maintain steady temperatures. Also, the imbalance issues that relate to no or inoperative steam traps are probably being counteracted by the modulating effect of the TRV's. Once an area gets warm enough the trv will throttle the steam, so if other areas are cold due to steam getting into returns, the steam flow into the returns is beings throttled or eliminated by the TRV's. I would still get properly sized orifices on every thing, but you're probably in not that bad of shape.