2 PIPE STEAM BANGING

PTTG40

Thanks for all the great insights. I have an large old 3 story home in Westchester County NY that originally had oil hot water heat. Have since updated to a Dunkirk Gas fired Steam System. Pics attached. I drain some dirty water out once a week. There is an automatic flow on it as well.

The risers to the third floor  bang by far the most often and far more loudly. The basement is cooler but by no means cold. I have lowered the cut in to 2psi.  Some radiators have air vents some don't.  It seems when I release the cold air as the boiler fires that the radiators heat much faster and warmer.  There are all different types and sizes some have Milvaco traps some don't have anything. One radiator seems to sound like water girgling in it at times

Any assistance as to whether air vents or main vents in the basement will help. It also seems there is a wet return pipe that is capped off and I drain it every few weeks. Unsure if there is anything that helps there.

thank you

Jamie Hall

A few thoughts

and I'm sure that others will have more...



First thing that comes to mind is that your near boiler piping probably isn't helping you much.  It may just be the perspective, but it looks to me as though the horizontal line -- which might be called a header if it were bigger -- slopes back to one of the risers, rather than over to the equalizer.  Not so good.  That is not helping you with good steam quality.



There shouldn't be a need for vents on the radiators.  If there is, it suggests that something was or is wrong with the trap on that radiator -- which might also cause condensate to go back to the steam riser, where it should not be.  Which could cause some of the banging.



You do need venting on the steam mains.  Lots of it.



The pressure is still too high.  This system will run best on less than a pound, and the only way to get there is with a vapourstat, not a pressuretrol.  Until you get the pressure down, though, checking the traps for blowing by, or the radiators without them, which may be controlled by orifices, for steam in the returns, is futile.



That cold return looks very much to me like a simple water trap separating a steam main from a dry return.  It should not need draining, if that is the case.



The banging is caused by water pooling where it shouldn't.  It is very much worth the effort to go through the whole system, literally inch by inch, to make sure that water which might collect in every single pipe everywhere (unless it is a trap, like the one in the picture) can drain back to the boiler wet return fitting.  Check for proper pitch, end to end, of any horizontals, but also check for any sags.



It would probably help if you could come up with a diagram of the whole system -- it doesn't have to be a work of art.

Pipedope_2

Thermostatic traps

Looking at your pictures, I see a relatively new Hoffman cross over trap, and a very old Weber? trap. If the thermostatic traps in your house haven't been serviced in a long time, safe bet is they don't work. Do the cross over traps first, and then move to the individual radiators. Increased venting at the ends of the dry return can't be stressed enough. A 1/2" tapping literally blows air at you when these systems are running. The valves let the air move around, and the water go where it's supposed to. Keep an eye out for bellies in pipes while you're working, but I always look for the moving parts first.

PTTG40

Venting

Thank you for your response. You are correct that the piping over the boiler does slope to a riser. Not sure I can do a larger plumbing job right now.

As far as venting in the basement. the vertical one above the boiler seems the newest and I do hear air exiting. The thermostatic on the side of the house looks newer but an't tell if it works or doesnt. The oldest one in the third pic probably needs to be replaced. I will try to draw up a diagram.

PTTG40

Traps

Thanks fo rthe response. So I am clear, the Hoffman crossover if the vertical one  above the boiler ?  The very old I will just replace. When you mention having them serviced is there a process to help them be more efficient or just buy new ones ? thanks again

Steamhead

The piping around the boiler is a mess

not only is it pitched wrong, but it looks too small. I bet if you look at where the steam pipes come out of the boiler, you find they have been reduced from 2-1/2" to 2". This increases the steam's velocity which makes it pull water along with it as it leaves the boiler. This results in "wet steam" which can be a major cause of banging.



These Dunkirk steamers are very sensitive to improper piping, since they don't separate water from steam internally very well. Every one we've encountered has had its piping reduced, which proves time and again that you can't fix stupid. This boiler needs both 2-1/2" risers, and I'd use a 3" drop header which would feed both steam mains. This will dry out the steam so the system will heat faster and more efficiently.



You have a Vapor system, which was the Cadillac of heating in its day. When you get everything straightened out, you'll love the way it works.

Jamie Hall

One crossover trap

is the brass body looking one in the third picture, connected between a steam main and a dry return (two pipes).  It does look newish.  If the inlet from the steam main gets hot, but the outlet to the dry return doesn't get as hot, it's probably just fine.  The other trap -- connected to two pipes -- looks pretty tired to me, but it's hard to tell.  Same test -- inlet from the steam main gets hot, outlet doesn't get as hot, it's good to go.  Otherwise it needs to either have the innards replaced or the whole thing replaced.



The main vent -- one pipe in at the bottom -- is probably OK, since you note air coming out of it.  It probably wouldn't hurt to have more main venting, but...



As I said in my first reply, check your pressure on the boiler and make sure it is cranked as low as it will go (be careful not to try to set it too low -- they fall apart in a most annoying way if you do).  Better yet, replace the pressuretrol with a vapourstat, and set it at about 12 to 14 ounces cut out with a 6 ounce differential.  Your system will be a lot happier.



Unfortunately, all of that is unlikely to stop the banging.  That's from water lying where it shouldn't.  Your near boiler piping is bound to be throwing a lot of water into the steam mains, and isn't helping at all.  In the meantime, while getting up the courage to fix all that, check everywhere for places in the steam mains and runouts and dry returns where the pitch is wrong or where there are sags in the pipe and fix those.

PTTG40

Pitching/ reduced

Thank you. I will def look into.

PTTG40

Crossover Trap

Thank you very much. I will do my best to look into and if not see what my plumber says or can do.

Pipedope_2

Radiator gurgling

Gurgling in the radiator is a pretty good sign that the trap on the return side is closed, or the radiator is back pitched. Rad vents on a 2 pipe system point to non working traps, and or not enough main venting. Keep in mind the cross over traps are like main air vents, they just direct air out of the steam mains and into your dry returns. There are replacement "cages" available for probably all of the various brands of traps in your house. Much easier, and cheaper than replacing all of the traps.

As a home owner, you may be able to tackle the thermo traps, and adding vents yourself. You'll probably want a pro to tackle the near boiler piping. In the pic of the radiator with the air vent, is that a Dunham trap?

PTTG40

Radiator gurgling

Thank you..

Some of the traps on the radiator are Milvaco. I will look into the cages.Seems to be multiple problem and have to be dealt with one by one.

PTTG40

BOILER PRESSURE

Thank you. I did lower the pressure on the cut in to .5 from a little under and the pressuretrol from 10 to 5 but when i turned the heat on the boiler didnt fire? Not sure why. I then reset it and raised the pressure and it fired right away.

Also, It seems that the riser that leads up to the third floor is warm or hot for the first 20 feet from the boiler and then goes cold after an elbow turning it upwards and thats where a lot of banging is. The other banging is from a larger pipe about 12 feet from the boiler as it connects and is reduced to a smaller pipe leading up to the first floor radiator.