hammer after reconfiguration

skippersteam

Maybe you can help me. I have a small 2 story house (1200 sq. ft.) with a single pipe steam system. After reconfiguring part of system to fix a head room problem, I created a new one...severe hammering. The "fix" increased the length (from the main line) of two runs from 15' to 20' (1" pipe,horizontal). Do you think scaling them up from 1" to 1-1/4" pipe would allow more room for the condensate and steam to pass by each other with out conflict (my guess is that the condensate using enough of the diameter of the pipe to restrict the steam traveling towards the radiators but what do I know). I can actually feel the location of the hammering on these pipes which is about 15' from the main and 5' before they go vertical. Pictures attached show the new work...1st pic. shows 1" lines going left, main steam line in the fore ground. 2nd picture is from the other side...return line in foreground, 1" pipes going to radiators going off to the right. And thank you in advance for putting some expert eyes to the problem I created....
-Parker Heath

skippersteam

2nd picture shows up by clicking "steam #4" jpg. box

Fred

Is the Main or return line sloped towards the boiler so condensate will flow back to the boiler? It is hard to tell where the boiler is relative to those pipes but if the return/Main is sloped the wrong direction or if there is no slope, wter will sit in the pipe and cause hammer when steam hits it.

Fred

The horizontal runs to the radiators need to be pitched back towards the Main as well.

skippersteam

The main, after exiting the top of the boiler was/still is pitched down toward the returns. 7/8 of the main (and return) is pitched exactly as it was when installed originally. I essentially shortened the far end of the loop 5' and added 5' to two lines to reconnect them back into the system. I was perhaps unwise to change the original set up...but I kept most of it as/per original. And yes, the lines all are pitched back to the main with no sags or "traps" along the way.

Fred

It looks like you changed the Main to swing up between the floor joists (in the Background) If that's the case, condensate is probably dropping down that severe slope so fast that it gets in the way of steam trying to move down the Main. Is that the area where you hear the Hammer? You may be able to put a drip leg at the base of that drop and take that back to a wet return, below the boiler water line

Captain Who

Sounds like you made the "horizontal" runners to a couple radiators 5 ft longer than they were. That's quite a lot, especially if they are 2nd floor or above radiators. I believe the rule of thumb is a pitch of 1" per foot in that situation. Other Wallies can correct me if that is in error.

Fred

Fred said:

It looks like you changed the Main to swing up between the floor joists (in the Background) If that's the case, condensate is probably dropping down that severe slope so fast that it gets in the way of steam trying to move down the Main. Is that the area where you hear the Hammer? You may be able to put a drip leg at the base of that drop and take that back to a wet return, below the boiler water line

The fact that none of those pipes are insulated will also create additional condensation as the steam moves down those lines which just adds to the volume of water tring to return to the boiler.

BobC

I think that is 1 inch for 10 feet of running length.

Bob

skippersteam

Right now, those lines are pitched at 1/4" per foot (they now run 20' instead of the original 15). Sounds like I need to look at increasing as much as possible...may be able to change things to get as much as 3/4" per foot pitch. Would increasing the size of the pipe (from 1" to 1-1/4" ) help the problem (more "breathing room" between the condensate and steam)?

Captain Who

@skipperstream - are the radiators being served by those 2 runners on 1st floor, 2nd floor......? I believe if they are on the 1st floor 1" per 10 ft is OK (but maybe not for a 20 ft run....pretty long), but if they are on 2nd floor or above I thought the rule was 1" per foot and takeoff should be at 45deg (which it looks like you have).

Captain Who

Increasing the size will absolutely help.

skippersteam

The entire system, excepting the short steeper pipes connecting into the main, is pitched very close to 1" in 10'...even the the lines which I lengthened (to reconnect to the shortened main loop). Virtually all the radiator lines (10 in all) have a short/steep section (running down at 45 degrees) where they connect into the main. I certainly can insulate the pipes which are hammering to help them retain their heat during each heating cycle...will have to report back on that.

BobC

On page 89 of LAOSH there is a note about the pitch of the horizontal runout to a one pipe up feed riser being 1/2 inch per foot if the run is over 8 ft long. If you can't get that pitch you should go to the next larger pipe size.

Bob

skippersteam

Captain Who...the line which (as far as I can tell) is the one doing the hammering does in fact go up to the second floor. The one right next to it runs just about as far horizontally (nearly 20') but just passes through the floor to a 1st floor radiator. It doesn't seem to be hammering.

Captain Who

If you eliminate those short steep sections near the mains, you can maximize your pitch over the whole runners. You will have even pitching the whole length then.

Captain Who

@ skipperstream - that's what I figured. You need to get the 1" per foot on that one, I believe and/or increase the pipe size.

skippersteam

Thank you all. I really appreciate your thoughts and suggestions. At this point, I'll throw a all the darts at it (try to pick up some pitch, increase the pipe size, and insulate the run.) May do them one at a time to actually learn what (if anything) works...will report back. Thanks again, you guys are great.
-Parker

Captain Who

Sounds like a good plan. Good luck. One thing I'd say is that I'd be leery of using any reducers to increase the pipe diameter coming out of those Tees that are at a 45 deg upward angle out of the main. Could cause water to pool up there if it isn't done right.

skippersteam

Well here's the low down. My oil guy came by to look things over. And while the system was heating up, the furnace stopped for a few seconds (low water) then restarted...The problem was a surge situation due to impurities in the boiler water. Although we were careful with the pipe joint compound, some probably got to the inside of some pipes/joints. We could see gooey water running down the glass as the boiler water over flowed during each surge "event". After a thorough flush of the boiler water (twice), all is now working as before...good reaction time, no hammering, heat to all 10 radiators. We have lived in this house 17 years now. I still gain a little better understanding of how these (terrific) steam systems work...am just a carpenter, but keep trying to learn a little more every day. Thanks again to Fred, BobC, Captain Who, and Dan Holohan. You guys taught me a lot.
-Parker

Fred

Because you added new piping, there are oils in tht pipe from the manufacturing process and threading. Those oils will work there way back to the boiler and cause the water to surge a lot. You probably just got some of it out and you need to watch the sight glass over the next few weeks as you will probably see the water bouce erratically. The water can bounce so much that it shuts the boiler down on low water or it trips the auto water feeder (if you have one) causing the boiler to over fill. When that happens, you (or your oil guy) will need to skim the boiler. That process is easy but time consuming as you will need to use the skim port (should be located on the boiler above the water line and may have a valve on it or it may just be a 1-1/2 inch pipe with a cap or plug on it. If you don't have one (many installers fail to put them in) if you have a pressure relief valve mounted on the side of the boiler, that can be used as an alternative. If that pressure relief valve is mounted on top of the boiler, we may need to see a picture of the boiler to identify another location where skimming can occur.
You will hve to skim from above the water line because simply draining water out of the boiler through the lower drain valve will just let the oils cling to the side walls of the boiler block and when you fill the boiler, those oils will float on the surface again. keep an eye on it and if you need instructions on skimming, come back to this site and almost anyone can guide you through the process.