Dave in QCA
Joined on May 6, 2010
Last Post on July 5, 2014
@ July 5, 2014 8:24 PM in Two pipe: concerned about one radiatorHowdy! The mental image of Waterbury Rd came into my mind when answering this thread, but didn't give it a second thought. Turns out that IS where you are. There is quire a bit of old steam in Des Moines but I really don't know who the qualified contractors are. So many opportunities to get it wrong with steam. Spent a year in DSM in 1976 then came back again in 1999 to direct work and operations at Terrace Hill. Had a background in high pressure institutional steam. Several years ago we bought a place in DAvenport with a 2-pipe vapor system and found out that everything I knew from pressure steam did not apply. Quite an animal to get your head around but very interesting and rewarding when you do. Our system had every band aid you could imagine and no correct repairs for the last 40 years. Finally got it working like a charm.
Let me know if there is any way I can help.
@ July 5, 2014 10:19 AM in Two pipe: concerned about one radiatorHere is another one.
While the photo does not make it completely clear, the section are NOT joined at the top. It is a steam only radiator. It has been moved from its original location, but the piping configuration is consistent with the whole house. A few have connections across the top but most do not. All have the supplies at the bottom and the outlet traps at the bottom.
@ July 4, 2014 11:47 AM in Two pipe: concerned about one radiatorI have a few radiators just like this in my 1910 2-pipe system. In proper practice, the outlet bushing that the trap nipple is threaded into should be an eccentric bushing. That is, the 1/2" opening as all the way down inline with the bottom of the radiator passageway. Usually, the inlet is also bushed, and if so, with a regular bushing, thus putting the inlet at a very slightly higher plane than the outlet.
I have one in the system that had a regular bushing on the outlet and so it actually only worked as a vent. Condensate flowed back out the inlet valve. It operated silently. However, I have since installed orifice plates on the inlets and that has raised the effective level of the inlet and so condensate now flows the proper direction. The plates were installed for another reason altogether.
This arrangement may cause the trap to momentarily close early, before the radiator is entirely heated, but it will reopen if condensate is present and the radiator should heat without issues.
If you do not have a eccentric bushing on the outlet, one way to compensate for that is to install the trap remotely as you have shown. If you do that, you should remove the bushing from the outlet of the radiator. The pipe it up with a short nipple, sized to match the full size of the radiator opening. Onto this nipple, use an adapter nipple, 1 1/2" (full size) x 1/2" . Then continue the piping to the trap located below the floor. This arrangement will allow the condensate in the bottom of the radiator to flow out of the outlet with no impediment. Make sure that you don't create any water seals in your piping because that will prevent venting.
I suspect that most of your hammering is coming from other faulty traps. What kind to you have. Some repair parts are easier to find than others.
@ May 29, 2014 8:37 PM in Boylston deviceit is a surge chamber. If you zoom in on the photo, you will see the PRV valve in the distance. The small pipe that exits the bottom of the surge chamber is connected to the control head of the PRV valve.
The Boylston valve is directly controlled by the pressure downstreem of the valve. However, the diaphragm in the PRV control head is a very heavy fiber rubber material. It is durable, but is not supposed to be directly exposed to steam. So, trapped air and/or condensate is the medium that operates the diaphragm in balance against two springs.
Often, the surger chamber is installed directly on top of the valve when installed in an upright position. In the picture, the PRV in the distance in installed upside down. Since the steam operating line will become filled with condensate, except for trapped air at the valve diaphragm, the surge chamber will fill with condensate and will be able to provide a reservoir of fluid necessary for the proper operation of the PRV through its control range without allowing steam into the control piping.
@ May 27, 2014 10:24 AM in Steam PRV StationFisher Controls make some excellent products. Check out the website, it has some good information that might help you. http://www2.emersonprocess.com/en-us/brands/fisherregulators/steam/pressurereducing/multi-purpose/92b/pages/92b.aspx
Back in my day as facilities mgr at a hospital facility, we had several PRV stations to reduce the boiler pressure (70 psi) to space heating pressure, 10 psi. The high pressure was necessary to operate sterilizers and a few other pieces of equipment.
There were three building sections that were fed steam at lower pressures. Two of these areas utilized a 2 valve parallel flow Fisher Pressure reducing valves. They were set up as 1/3 -2/3 capacity and when finely adjusted would maintain a downstream pressure within 0.5 psi of the 1 psi set point. The valves were not new when I arrived and functioned perfectly during my 17 years on the job, without any failure or difficulty.
There was also a building that had a Boyleston brand PRV. It was a one stage valve and while it funciton satifactorily, it was prone to drift of 1-2 psi. In our case it did not cause a problem, providing steam for coils in air handlers as well as a few unit heaters. There also was a smaller Boyleston PRV that provided 25 psi steam to the kitchen for steam kettles, steam ovens, etc.
My experience in our midwest area, you can't beat Fisher Control.
@ May 16, 2014 6:42 PM in Steam to Hot waterIt actually is possible to convert a good tight steam system to hot water. I have seen several done, and of those, they were not done well, didn't work well, didn't save any money, and cost a LOT to do the conversion.
I have heard of some conversions that actually worked out well, so it's not to say that it can't be done. But, the conversion that was very successful, the work was done by one of the best steam contractors around there. They didn't design it or recommend it, an engineer did that. (they don't teach steam anymore in engineering school) But, through the craftsmanship of the contractor, the thing actually worked.
@ May 16, 2014 6:34 PM in Replacing existing steam system- hoping t get some opinions and adviceYou see a lot of feed tanks installed for multiple reasons.
1. Many contractors don't understand gravity return, the think in terms of 2 psi and the water won't go back into the boiler.
2. Low water content on some boilers combined with large systems in large building sometimes cause a delay in condensate returning to the boiler. A feed tank rectifies that problem by keeping the boiler water at the right level. Your little residential system would not have that problem unless you got clogged up return pipes, in which they need to be cleaned out anyway.
3. Adding in a feed tank raises the price and profit of the install. They will have a markup on the tank, and they make a profit margin an the labor as well. Little motivation to sell you less when they can sell you more. Let's see.... we could propose a feed tank or a vaporstat. (you gotta have one or the other). Let's propose the feed tank at about 10 times the cost.
4. Most of all, contractors tend to do things they way they have done in the past. We are all creatures of habit. So easy to do some thing that you've done before and so hard to do anything for the first time. This could be an opportunity for your contractor to learn a new trick!
JStar's suggestion for a 2-stage set up is very wise advice. It will make the system run very smooth. I also strongly recommend that.
@ May 16, 2014 6:16 PM in Sunrad Radiator - Loud banging problemPretty sure that it is the supply pipe that is causing the problem. When steam is first going into a cold radiator, there is a huge amount of condensate flowing back out, and the steam and condensate will hammer up a storm if they cant get past each other.
Here are the size ratings from TLAOSH
1" inlet 20 EDR Max
1.25" 55 EDR Max
1.5" 81 EDR Max
2" 165 EDR Max
As you can see, there is no size where 3/4 pipe is specified. It's just too small for 1-pipe steam.
Also, the air vent on the rad should be no higher than the middle of the rad. Yours is in a port that is intended for hot water use. Those screw plugs a little more than have way down are where the steam vent goes. And, the vent should be on the opposite end as the steam inlet.
@ May 15, 2014 10:39 AM in Pneumatic controlled univentBack in 1981 I was responsible for a building with about 32 uni-vents. One section of the building was on hot water and the 1960 part of the building ran on steam. Night set back consisted of turning off fans and outdoor air only. This was accomplished by a series of pneumatic switches located in the boiler room that applied control air (20 psi) to pressure switches located in the vicinity of the group of uni-vents being controlled. When pressure was applied, it activated a normally open switch, which in turn powered a normally closed contactor, to disconnect the power supply to the uni-vent fans.
Individual Uni-vent control was consistent to the schematic I have attached. This is a very typical setup for steam uni-vents. One of the most complicated, yet usually very reliable components is the damper actuator, which usually is designed to operated in two stages. With control pressures less than 4 Psi, the dampers are closed. In the range of 4-8 psi, the damper is in the normal minimum position to deliver the required amount of fresh air to the space. In the range of 9-13 psi, the dampers will index open to provide cooling with up to 100% outdoor air. The steam valve operates in the control range of 4-8 psi, with 4 being open and 8 being closed.
So, in a condition where the room temperature is well below the set point, say during a warm-up period, the thermostat might be sending out a pressure less than 4 psi. At this point, the dampers would be closed and the steam valve 100% open. As the room temperature rises, the thermostat output will also rise. AS the thermostat reaches a 4 psi output, the dampers will open to the minimum position, and the uni-vent will continue to heat, as the steam valve is 100% open. As the room temperature continues to approach the set point, the thermostat output will decrease, causing the steam valve to modulate toward the closed position. The thermostat and uni-vent will modulate to a point where the output temperature from the uni-vent is sufficient to maintain the room temperature at the set point of the thermostat. Now, if room conditions change, say the room has been empty and now 30 hot sweaty kids return from recess, this will have an effect on the room. As the room warms up, the thermostat will increase it's output signal causing the steam valve to index closed. If the room temperature continues to increase, the increase in thermostat output signal will cause the fresh air dampers to index open. If it is cold outside, the low limit thermostat, located in the output air stream of the uni-vent, will cause the steam valve to index open to a position to maintain an output temperature of no less than 60F.
It should also be noted that there is always an interlock device, usually a 2 position solenoid valve wired into the fan circuit. When there is no power being supplied to the fan, air connection to the air damper is cut off, causing he Outdoor air dampers to remain closed. As is always the case in pneumatic controls, lost of control air will cause the system and all components to go into full heat mode.
@ April 19, 2014 11:42 PM in Steam Radiators???Here is a handy table. Look on table 5, it will give you what you're looking for.
@ April 16, 2014 11:57 AM in lowering steam pressure in a industrial buildingThis is not a simple situation but it sounds like there would certainly be an opportunity for huge savings and your engineer is wise to want to proceed with a plan to reduce the building pressure.
You used to require high pressure steam not only because the load was higher, but because much of the power or process equipment required that pressure to operate. You no longer have that requirement. You only have the heating load which has been described to be 12 psi. While most system can operate on pressure as low as 2 psi, others are designed at 5 psi or 10 psi. Control valve sizing, steam/air coil sizing, etc., may have all been calculated at the 10-12 psi range, so keeping that pressure may be necessary if that is the case. Also, may buildings with higher pressure systems (5 psi) have condensate lines that rise above the steam device, and therefore need enough pressure to accomplish that lift.
The critical factors for this project would be to calculate the full steam load of the building heat load and line losses in the building. Then, it should be a simple calculation to determine the capacity of the steam main, operating at 12 psi. Can it deliver the needed quantity of steam. There will likely be a little line loss under full load conditions, but I would guess that 1-2 psi loss between the boiler and the building being heated would not present a problem. 10 Psi will probably work just fine.
As for your feed pumps, you indeed bring up an important issue. Those pumps are designed to push feed water from a tank at atmospheric pressure into a boiler at 90 psi. If the pressure is dropped to 12 psi, they will operate much differently. They will pump water much faster. While the operation will probably be no longer on the performance curve, it will be above the curve not below. Cavitation tends to be a greater problem either at high temperatures or at very high heads where the pump is barely able to move the water. You will have the opposite condition. However, if the pumps in use are still being manufactured, it might be worth getting a manufacturer's rep to run the proposed operation of the pumps by the engineers in their home office and see whether a problem would be anticipated.
Good luck as this moves forward.
@ April 16, 2014 11:24 AM in Am I venting my mains too fast?With the combination of Main and Radiator vents that you have on your system, One would expect the steam to reach the end of the short main quickly, at which time it will close. Steam will continue flowing down the long main and will actually speed up when the short main is heated. Before the steam gets to the end of the long main, flow into the radiators should be minimal. After the steam has reached the end of the long main, those vents will close, causing a slight increase in pressure, at which time flow into the radiators should be begin. For the most part, the flow into the radiators would be expected to be fairly even. THIS is what would be expected, bit obviously, its NOT what you're experiencing.
You indicate that you hear swishing in the long main. That is an indication of a huge problem. Water in the main will prevent steam from passing and when it does whoosh through, much of the steam will be condensed by the water. It would be similar to having a gate valve in the pipe and having is mostly closed. The system just cannot work correctly with water in that main.
You indicate that the boiler is over-sized, yet you do not mention that it short cycles. Does it? I am also unclear in your description of 5 minutes for the short main and 30 minutes for the long one. Is that the amount of time it takes for the steam to get to the end of the main, or the time it takes for the radiators to be fully hot?
You probably should also check the firing rate of the boiler. Many times, for various reasons, they do not fire at the rate on the rating plate. Make sure everything else that burns gas in your house is NOT running, operate the boiler, and count the usage in a minute by watching the needle on the meter that turns the fastest. The dial will tell you how many cubic feet of gas pass per revolution.
Also, I'm wondering how often your boiler cycles. Once per hour? More often? Less often? When the boiler starts a new cycle, how hot is that long main? Do you have a way to measure its temperature? Or, perhaps the air coming out of the main?
Reason being, while Gorton #2 main vents are incredibly fast when they're cold, the begin to close in the 130-140 range. If the air coming through them is 150 or above, you can be sure that they are completely closed. In my system, cycling once per hour, the mains with 1" insulation on them, even on cold rooms, never cool down to below 150 degrees F. So, in one of the trial setups in my system, I found the Gortons just didn't do the job the were supposed to, except on a cold start.
@ April 16, 2014 10:16 AM in Is my steam boiler way oversized?I operated a pair of large dual fuel boilers 25 years ago. At that time, the dual fuel option was not set up properly and I set out to make corrections and set it up so that the firing fuel could be changed with the flick of a switch, the way it was supposed to be. At that same time, we changed from firm service gas to interrupt-able, which saved 25,000 a year. These boilers were 238 HP Kewanee Scotch marine type, firing at around 9 Million BTU on high fire.
Set up and adjustment was a pretty complicated process as the the burners were fully modulating, not a simple hi-low operation. The first step required getting the oil firing correctly adjusted at hi fire, then at the low end of the modulating range. Second step was to adjust the air shutter linkage to provide the correct mixture of air through the full range of oil firing. The third step was to switch to gas and then adjust the gas firing rate to match the air shutter so that proper mixture was obtained all through the firing range.
While it does not sound too complicated, the process required a considerable amount of time. But, once it was done, fuel switching merely required a few steps to the boiler, turning the boiler off, turning the selector switch to the desired fuel, and turning the operating switch back to "on".
In your case, a dual fuel burner might be unnecessarily complicated and expensive. You could just save the old burner and of fuel oil prices ever get lower than natural gas, (not likely), you could simply install the old burner and you probably could change the nozzle and make it fire at the lower rate you need.
As for the option of 1 stage or 2 stage, I would opt for 2-stage, but there will definitely be a price difference. 2-stage firing would provide a benefit if your load varies from time to time because of some of the radiators being turned off and at other times, all of them being turned on. Also, if you frequently fire the system long enough to fully heat the radiators, this will cause the boiler to cycle off and on. This can be minimized in single stage firing by having a low pickup factor. But, if you do this, you will need to make sure that your main venting is good and fast and your radiator venting is slow, for example, no faster than a Hoffman #40. This arrangement will make your system slow to heat up, but it should be even and in most cases, on off cycling when fully heated will be minimized and may not occur at all.
Gas pipe size: You probably need 1 1/4" if running house pressure from the meter. 1" is too small.
When we bought our building, the boiler was a 1,050,000 BTU firing rate. We are on low pressure and there is a 2" main coming in from the street. The meter is a 2" meter, but the piping reduces to 1 1/2 to the boiler which is about 40 ft away. This piping was actually a little under sized. In addition to the 2" meter, there are 9 more meters connected to the incoming main, most are for kitchen stoves by 2 of them have forced air furnaces on them. It all works just fine and the pressures are adequate to deliver the required amount of gas.
@ April 16, 2014 9:39 AM in Dunahm Air Eliminator replacement availableI found a substitute for the Dunham Air Eliminator and wanted to post the information for all to see. Of course, it would also work for any system that used a float type air eliminator on the return piping of a 2-pipe vapor system, such as ARCO, etc.
The device is made by Spirax-Sarco, and is intended for use in hydronic systems to let air out of places where it might be trapped, but then closes via the float valve when water is present.
I do not know the diameter for the valve port passage and if it is too small, it might not provide for enough venting. However, if operated in vacuum by adding a swing check valve, venting becomes less of a concern.
@ April 16, 2014 8:46 AM in Replacement Dunham trapsNicholas, you have touched on a subject that mystified me for quiet some time. Does a thermostatic trap operate properly on vacuum and if so, how the heck does it do it?
First, your observations that the early Dunham systems did not use the 1E trap for crossover. That is correct, they used the the Dunham Air Line Valve. That device was actually a small version of a 1E type trap and the same thing as a paul type trap. In addition of it being used as a crossover trap at the end of steam mains, it was used on vacuum one-pipe systems as a retrofit, just like Paul systems. I supposed it worked fine because often in coal fired systems, steam was slow to build. Whatever the case, my guess is that Dunham discovered that they had a real big problem with unbalanced distribution, especially on partial steaming cycles. Thus, they started using "balancing plates" or orifices to even out and regulate the steam at the entry point of the radiators. They still used traps so the orifice openings must have been larger than they would be on an truly orificed system. About the same time, according to my reference books, they stopped using the air line valve as a crossover trap and instead started using the 1E. Of course, a 2E would be even faster.
VACUUM ? If you look at the cap on a 1E trap, you will see that it is rated from 25" vacuum to 10 psi steam, actually some early Dunham 1E traps are marked to 25 psi steam. How does it work? That steam at 25" vacuum is not very hot at all!
It took a long time for me to wrap my head around it, but eventually found an explanation somewhere in one of the Dunham books, or at least I think that is where I found it. Here it is. You have to realize that the thermal disc in the dunham trap is flexible, somewhat like a balloon. When the temp of the disc is hot enough, around 180 or 190 at atmospheric pressure, the alcohol will vaporize, causing an increase in pressure inside the disc, therefor expanding the disc and closing the trap. Now, if the the system pressure is 10" Hg vacuum, the flexible capsule will expanded because of the low ambient pressure, transferring the forces of the vacuum to the contents of the disc as well, and lowering the flash point of the alcohol inside the disc. Thus, the closing temperature of the trap adjusts according to the surrounding pressure/vacuum so that the closing temperature is lower than the actual temperature of the steam at that same temperature.
Nicholas, I forget about the detail of the Dunham system you're working on. Does it have an air eliminator? a return trap? any other original boiler room apparatus, such as a differential controller, etc?
@ April 11, 2014 5:11 PM in Radiator air vent preference?Here is a diagram of the Hoffman #40
Here is a view of the insides of the Gorton
Note: They both have a float. The Hoffman closes suddenly when steam is present in the vent. The Gorton closes more slowly but at much cooler temperatures, generally as stem is getting close the vent, the last air coming out of the radiator is probably warm enough to close the vent.
@ April 11, 2014 1:32 PM in Radiator air vent preference?I prefer the Hoffman #40 because they are nice and slow and because of that, tend to help a system heat up smoothly with balanced steam distribution.
The varivalves are just way too fast and don't have any provision for dealing with condensation in the valve body. As Chris said, the Hoffman 1A adjustment mechanism is so poorly designed it is difficult to get any kind of adjustment set correctly, and on many system, they perform the best if their set as close as possible to the rating of a #40.
I have observed that most systems, if piped properly in the first place, the radiators will heat up proportionately with #40 vents. That is, both small and large radiators will heat the same percentage on a partial steam cycle, even though they are using the same sized vent.
@ April 11, 2014 1:23 PM in Is my steam boiler way oversized?Just wanted to let you know that I have an oversized boiler similar to yours, except mine is a Weil-McLain 680. I really only needed a 580, which will allow for future restoration of parts of the steam system that are not currently connected. Because I wanted a 2 stage burner, and WM had only approved a 2-stage burner on a 680 and larger, that is what I ended up with. At the present time, it is firing on Low Fire, a little less that 50% of its full rating. It works great! 82-83% efficiency and 34% less than my old gas boiler.
As a general rule of thumb, most power burner boilers can fire at 50% with little loss in efficiency and sometimes, actually more efficient that firing at 100% of capacity.
As second benefit, it doesn't work the boiler near as hard and you'll probably find that it will have a longer life as a result.
If it were my boiler, I'd convert to gas and tune the thing at 50% of it's full rating ASAP. I would not bother taking sections out, it's too much bother and cost (new jacket panels) and not really necessary.
@ March 25, 2014 5:56 PM in Vaporstat sticking / biasing after vacuumI have two vaporstats on my system. One is an old style and the other is a new type. The vaporstats are subjected to pressure occasionally as high as 14 oz and vacuum as high as 9" Hg. It has not had any effect on either device.
@ February 28, 2014 9:36 PM in Pickup factor. Help me understandThis is a somewhat difficult subject to understand and its an even more difficult subject to explain. I have to bow to Jamie for his analogy to the accelerating car, it is excellent!!! I had never thought of it in that way before, but it's spot on!
I'm going to jump in and give my 2 cents too and see if I can help to make it easier to understand too.
The "pickup" factor is actually two separate factors that have separate purposes. First, the piping loss factor takes into consideration that piping will give off heat and in doing so will condense steam, even after it is fully heated up. So, in order for a boiler to be able to maintain a fully heated system of radiators and piping at full temperature and and maximum output, the heat losses or emission of the radiators and the heat losses of the piping must be matched by the output of the boiler. The amount of heat loss from an average piping system that is insulated is estimated at 10% of the capacity of the radiators. So, if the radiators on a system add up to 200 Sq Ft, the piping losses can be estimated to be equal to an additional 20 Sq Ft of radiation.
But, the piping loss factor only takes into consideration the piping losses of a fully heated system. Steam systems by their nature are difficult to heat up in an even manner. By comparison, a hot water system uses a 15% piping loss and pickup factor, or only 5% pickup. The result is that old gravity hot water systems with huge cast iron radiators are very slow to heat up, but they do eventually heat up. In the heating process, all of the radiator will heat up gradually and all at the same time. Starting from stone cold, to luke-warm to warmer, and eventually hot, if the boiler has been firing continuously. The key point is that the radiators throughout a well designed system will heat uniformly.
This is not the case with a typical steam system. On a steam system, an additional pickup factor of 24% on insulated piping is needed. On a typical steam system what would happen with a boiler sized too small to give adequate pick-up, some radiators will heat first, and others later, sometimes not getting any steam at all until other radiators are blazing hot. The negative effects of unbalanced steam distribution are especially undesirable in mild weather when steaming cycles are short and only partially heat the radiators. Undersized boilers in these situation will often leave some of the radiators with no steam at all.
Fast vents on steam mains will improve the likelihood that steam will arrive at the radiators at the same time. Slow, make that VERY slow radiator vents will further improve even distribution. Actually, I have seen some cases where marginally sized boiler worked just fine, but the size of the mains were small, reducing the amount of heat loss and the vents were all Hoffman #40s, which are pretty slow.
The negative aspect of using the 34% piping and pickup factor for insulated mains or the 50% piping and pickup factor for uninsulated mains, is that on long cycles, when the system becomes fully heated, the boiler will start cycling off and on because of pressure. It is just a part of the beast. Of course, as has been mentioned, two stage firing is a great benefit in this situation.
It should be noted that in two pipe systems, when inlet orifices are installed on the radiator, since they separate the radiator from the boiler and main pressure, the pickup factor can be omitted. Only the piping loss needs to be factored. Also, according to writing by Dave Bunnell, aka, the Steam Whisperer, if very slow vents are used on one pipe systems, the pickup factor can sometimes be omitted as well.
Hope this is helpful. on some level.
@ February 6, 2014 9:54 AM in An Epic Tale: I hear the Trane a comin'!Colleen, Now you're really having fun! And, staying warm too! I don't know how you have tolerated not having heat for so long!
Regarding your main vent. That little vent on top of your return trap is not the ONLY vent is it? I was thinking that you had a mercury pot on your system. If so, the venting is running through that pot.