3 Steam heating problems - need help

Mike Szanto

I have a 4 unit investment property I purchased a year and a half ago and have a couple of steam heat issues, some old, some new.

Ever since I bought the place, the tenants have complained about the noise (water hammer). It sounds like someone's rapping the pipes with a 22 oz. framing hammer. Needless to say, they aren't too happy because it is affecting their ability to get a good night's sleep. I guess I can't blame them for being upset, and I've read every single suggestion on this web site (fantastic resource by the way!) and I think I may have some ideas why the hammer is occuring but I wanted to toss it by someone before proceeding with the work.

Before continuing, it would be helpful if you referred to a steam piping diagram I found at www.hoffmanspecialty.com. I've attached the file to this message, but you can also download it from:
http://www.hoffmanspecialty.com/pdf/submittals/hs-901a.pdf
(You'll need Adobe's Acrobat Reader in order to view this diagram) If you don't/can't open this diagram, you still should be able to follow my description of the problem.

I have 4 steam boilers all installed in 1995, each one supplying steam to a one pipe steam system, 3 of which have a dry return and 1 having a wet return (due to height constraints). The steam running to the first floor apartments works perfectly. It's the steam that runs to the second floor apartments thats causing me grief.

Issue 1:

The system that is causing the most noise is using a dry return. In the steam piping diagram (mentioned above) I noticed that there are two types of designs for a one pipe system, parallel flow (supply main slopes down from supply riser so that condensate flows in the same direction as the steam and the dry return starts at the end of the supply main) and counter flow (supply main slopes up from the supply riser so that condensate flows in the reverse direction as the steam and the dry return starts near the beginning of the supply main). Problem is that my layout doesn't match either of these designs. It's piped as if it's a parallel flow layout but the slope of the supply main is pitched in the wrong direction as if it was a counter flow layout. Based on this observation, it is my belief that the dry return is doing absolutely nothing because it starts at the highest point in the run and since condensate doesn't run uphill, it would never return thru the dry return. In addition, because there is no dry return to intercept the condensate near the boiler, the condensate is returning to the boiler via the supply riser. I'm 90% sure that this is very very bad for a number of reasons but the ultimate question is what is the best/easiest solution: 1. reverse the slope of the supply main or 2. move the dry return so that it starts close to the boiler? I'm thinking that option 1 would be the best choice because my supply main is only 1 1/4" and is not adequately sized to handle a counterflow layout. This leads me to another question. From what I've read, the supply main should be the same size as the supply riser but for some reason my supply riser is reduced from 2" to 1 1/4" at a point 12" above the top of the boiler. Can someone confirm whether this is appropriate and whether I should replace my supply main with 2" pipe?

Issue 2:

The next problem I'm experiencing with this boiler is that the pressuretrol cut-in is set to 0.5 psi with the differential set to 1 so that the cut-out should be at 1.5 psi yet the pressure in the boiler is rising extremely high (as much as 15 psi at times. I had a reputable heating specialist come in and take a look at it and he was only able to resolve part of the problem. He found that the pigtail pipe connecting the pressuretrol to the furnace was blocked and there was too much water in the boiler. By unblocking the pigtail and lowering the water to the correct level it helped the problem somewhat, but not completely.When I was visiting my building earlier this evening I noticed that the pressure was running at 5 psi using the same cut-in/cut-out settings mentioned above. Theoretically, the boiler should have shut down as soon as the pressure reached 1.5 psi. My first thought was that the pigtail was plugged again, so I disconnected it and it was fine. I could blow air throught it with no resistance. While I was doing this, noticed that even though I had taken the pigtail off, the pressure gauge was still registering 5 psi inside the boiler. This was very perplexing to me because my assumption would be that if there was any pressure, water would be blowing out of the opening for the pigtail until it equalized. Based on this observation, I waited for the pressure to drop back down and then inspected the pigtail opening and made sure it was clear. Next, I reattached the pigtail but did not reattach the pressuretrol so that I could observe how many psi it would take before liquid spouted from the pigtail. In order to do this, I shorted the wires that normally connect to the pressuretrol and restarted the boiler. What I found was that steam/liquid would not emerge from the pigtail until the pressure guage displayed 5 psi. I then performed the same exact experiment on another boiler and found that liquid would emerge from the pigtail before any reading would even register on the pressure guage. Based on this experiment, I'm assuming that there are no problems with my pressuretrol, and that the cause of the problem could be one of two things: 1. The pressure guage is bad and displaying incorrect readings. 2. There is something wrong inside the boiler is causing the pressure to build up on only one side of the boiler. This leads me to my next question: What do you think the cause of my pressure problem is?
One other point I should note is that after the boiler shuts down, it takes an extremely long time for the pressure to drop down. It seems to sit at 5psi forever but it eventually does drop down. On the other boiler it drops all the way down in a very short time.

Issue 3:

The other boiler that is causing me problems also supplies heat to a second floor apartment, but this one uses a wet return. In addition, this one also appears to be piped incorrectly (same as issue 1) because it's laid out like a parallel system but the slope is incorrect. Weird thing is that there is no water hammer when the system first heats up. Instead, the water hammer occurs after the boiler shuts down and the condensate returns to the boiler. I'm wondering why the water hammer occurs at the end of the cycle instead of the beginning, but the same question applies as issue 1 should I correct the slope so that the condensate flows in parallel with the steam.

Issue 4:

Same boiler as issue 3. I noticed that the boiler was short-cycling and never running long enough for the radiators to warm up. In this case, the pressuretrol is working properly and shutting down the boiler because the pressure was too high (same settings as issue 1 on the pressuretrol) After some experimentation and cranking up the psi on the cut-in, I eventually found that setting the pressuretrol cut-in to 2.5 with the differential set to 1 was the ideal setting. During this experiment, I tried leaving the cut-in set to 0.5 and increasing the differential to 3 assuming that this would allow the pressure to build to 3.5 psi before cutting out, but instead, the boiler kept cutting out at 0.5 psi. Can someone explain why setting the cut-in to 0.5 with the differential set to 3 did not work as I expected? Also, can anyone tell me why this system needs the cut-out set so high? From what I've read, the system should run fine with steam pressure between 0.5 and 2 psi.


Final question:

I noticed in the steam system diagram mentioned above that the parallel flow wet return design also includes a Hartford loop. My wet return system does not include a Hartford loop. Is a Hartford loop necessary in my wet return system. My wet return does include what looks to be a reverse P trap just before the return pipe enters the boiler.

Same question for my dry return system. Does my dry return system require a Hartford loop?


Regards,

Mike

Long Beach Ed

Problems

Mike,

You certainly do have some problems there.

First of all, a 2" riser that is bushed down to 1-1/2" is probably piped incorrectly. So I suspect you have other piping problems as well.

Water hammer is caused by water laying around somewhere and being hit by steam. Usually improper pitch or mains that are not properly dripped will cause this.

The system has the be looked at by someone who knows what he is doing. Or you've got lots of studying to do to learn this stuff. You can buy Dan's book and sepend some serious time learning about the beast and tackle it yourself. Just prepare for some real work getting that piping to where it should be.

Low pressure boiler guages are very often incorrect. Keep your pressures very low on the pressuretrol -- that will help. Also, look for places where water could lay in steam mains or where boiler pressure can push water up the riser from return to invade the mains.

Good luck.

Long Beach Ed

Steamhead

Mike, I think you're on the right track

but you need a real good steam man. Try the Find a Professional page of this site to locate one near you. If you're in the Baltimore area, e-mail me.

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