Spitting radiators, loud banging

SteamStuck

Hello All,

We have a one pipe steam system in a 1900 two story house. We recently had some remodeling performed (rooms re-arranged and radiators changed and moved around )which resulted in some nasty behavior, where two radiators at the end of the main are spitting and spurting and banging like a thingamajigger, and I had to shut off the valves.

I'm attaching three pictures: first shows the piping as is today. Based on my understanding of steam heat (I'm no plumber) I see two major problems: a) end of main is not drained properly, thus steam to radiators 4 and 5 hits standing water at the end of main; and b) horizontal feeder pipe to radiator 5 is not large enough and does not have proper slope. Anybody can confirm/infirm this?

Second attached picture shows how I think the condensate line from the main should be, and the new feeder pipe up-sized. Anybody has an opinion on this?

Last picture shows how my plumber proposed to fix the system. I personally see some issues with his proposed solution (beside a tag of 7.5 K) since condensate from radiator 3 will still not be drained properly and will continue to cause problems. He argues that since radiator 3 currently runs properly, there is no reason to drain it differently.

An additional note which might be of help: steam main is in a warm basement for most of its run, but the last 2-3 feet (including the take-offs for radiators 3, 4, and 5 ) are in a COLD crawl space. Steam lines, main, feeders, and risers are insulated though (1" fiberglass jacket insulation) both in the basement and the crawl space.

Also, the spitting and spurting and banging seems to happen mostly on cold nights. When it is warm outside (like 50 dgrees) and I crank up the thermostat, all the radiators seem to heat OK.



Any clues on these issues? Sorry for the long post...

SteamStuck

Pictures

I uploaded the pics but they did not show up; I'll try to upload again.

Jamie Hall

Not surprised it bangs...

your second drawing, with the drain (drip) moved will help a lot.  But you need to do it.  You should also consider figuring out a way to put a good vent -- say a Gorton #2 -- at the end of that main.

Phil_17

my 2¢

I'm not a plumber either, but I have spent a few years lurking here and working with my 1-pipe steam system.



You mention some work being done. How much new pipe was involved, and has the boiler been skimmed since that work was done? Wet steam can cause the problems you mention, and if the system was working okay before (maybe the original system was close to the limits on some parameters) then skimming may help.



Your first point about the 2.5 ft run of main that is still sloping downhill is a problem, and your second picture showing a new drip from the end of that is something that definitely should help.



The sizes of the runouts are determined by the connected load on them. We need to know the sizes of the radiators (3,4,5) in order to know if those pipes are correctly sized. Unless the runout to #5 has gotten significantly longer or you swapped a larger radiator to that line during the renovation it's likely okay at the current size.



It should be relatively simple to just move the drip to the end of the line and see what effect that has. If it does not sufficiently address the problems, then I would look again at the runouts, but I wouldn't rush into changing that stuff until trying the simpler solutions first.

ChrisJ

header

If the drawing is correct that header is built incorrectly and will trap water.

SteamStuck

diagram of the system before renovations

Hi All,



Thanks for the quick reply, I appreciate your interest in and knowledge of the subject.

Attached is a scheme of the system before the renovations. I also updated (slightly) the drawing of the near-boiler piping to reflect more correctly the reality.

Basically, before the renovation radiator 5 was located between radiator 1 and 2, its takeoff was before the condensate drip, and was heating properly; its runout to riser was very short (~10 inches) and both runout and riser were in 1-1/4 pipe. As a result of shuffling some living space around at 2nd floor, GC had to have the plumber move the radiator further, with a long runout (12ft), in a cold crawl space, and with little slope due to little available space under the floor. Also radiator no 3 was a cast iron baseboard with a separate wet-return in copper pipe as in the picture.

One serious concern I have is whether runout to radiator 5 will be large enough in 1 inch given that the run is pretty long, little slope and cold space. The load on that pipe is relatively small as in small radiator 4 sections 4 columns 24".

I would prefer not to open and repipe the end of the main multiple times when I move the drip pipe to the end of main, hence I would rather change all these pipes at once if I had to, rather than do incremental work...



Any ideas on the size and slant of the runout pipe to radiator 5? From Dan's book it seems that I have to have at least 1" in 10 feet , or/and switch to the next pipe size.



Also can anybody clarify how the connection between the end of the main and the drip should be? I.e. just an elbow reduced to 1-1/4?

Is there a minimum length for the vertical drip pipe at the end of the main?



Thanks

SteamStuck

Radiator 5

Phil, thanks for your advice. As I mentioned in the other answer, radiator 5 was moved in a different location (see picture before renovation.) Its takeoff was moved further down the main, the runout is much longer (I'm afraid not enough slope) and pipe is smaller in size. Also, it now runs in a cold crawl space (albeit it is insulated). That radiator was running fine before the move. (former baseboard radiator 3 was not heating properly before,and was banging loudly, now it is a regular radiator and runs relatively fine.)



If I had to change it, I would prefer to change when installing the drip at the end of main, rather than open the pipes multiple times.



Also, the plumber did not skim the boiler after installing a bunch of new pipes, changing few valves and replacing 4 radiators. (no 5 in the drawing plus other 3 radiators on the other main, not shown in drawing.) I skimmed the boiler myself couple weeks ago , once for about 2 hours. It was a pain, since my boiler does not have a skimming tap: I removed the LWC and the sight glass and skimmed through the upper copper pipe of the sight glass. I suspect that the boiler does need a lot more skimming than what I did since I still see surge when the boiler first fires, and I get water dripping from the top of sight glass. It's just too damn long process and I don't have the time to do it repeatedly.



Thanks

SteamStuck

Vent

Jamie, Thanks for your answer. As per the picture below, there is a Gorton no 1 vent right after the drip line about 10"-12" from the main. I believe this is enough as the steam hits the end of the main about 1 minute after the start of main gets hot.



Regarding the move of the drip to the end of the main, is there any special connection and piping that I should do, beside three elbows (down, lateral, and slightly angled down), and the reduction to 1-1/4"?



Is 1-1/4" inch return pipe enough for the condensate from all these 5 radiators?



Also, I'm thinking about leaving the Gorton vent on the return pipe about where it is (it will hence be about 3 ft from the end of main and elbows.)



Any thoughts on the long runout to radiator 5?



Thanks.

SteamStuck

Near boiler piping

Hi Chris, thanks for pointing out the near boiler piping. I uploaded a new drawing with the piping before renovations (picture is somewhere below), and it shows the near boiler piping more accurately (these pipes were installed when the boiler was installed 20+ years ago and were not touched meanwhile. )

The distance between the water line and the bottom of header is 12" (I thought it should be 24")



In any event, it is unlikely that I will change the near-boiler pipes before I change the boiler itself; given the age of the beast, I don't think it's gonna run for many more years.



Another question, what is usually the strategy for replacing the boiler? Wait until it breaks or develops leaks, or change proactively based on the age?



Thanks

Enreynolds

It looks like

The main was never dripped correctly. Prior to your renovation, you had less steam crossing the puddle at the end of the main. Dripping the end of the main instead of the current location should solve the retention of condensate that is causing your water hammer. What I would do is bullhead a tee on the end of the main, bush the top for a vent nipple, and pipe in the condensate return to the bottom of the tee.

Hap_Hazzard

Repiping the return

While you're repiping the return, you should try to keep the dry portion above the "A" dimension, then drop vertically to below the water line before joining the Hartford loop.

Phil_17

Should read more carefully before I post...

Since you have The Lost Art of Steam Heating, you have the resources to resolve the problem. It covers everything you need to know to fix this...



Horizontal run outs need to be one or two sizes larger in order to allow condensate and steam to pass without inducing hammer. Vertical risers can be smaller. There is a table in his book which details pipe sizes based upon the EDR of the attached radiators. I think your #5 radiator needs larger pipe for the 12 ft. horizontal run in the cold space, and may need a larger riser depending upon the EDR (1" pipe doesn't handle much at all... I've got one radiator with only 8 sq. ft. of radiation and it's still connected with 1 1/4" pipe). My approach would be to run 1 1/2" pipe in the horizontal and 1 1/4" for the riser to address the problems with #5.



As stated elsewhere you definitely should relocate the return line to the end of the main to avoid the puddles that are certainly in there. A reducing elbow to the return size (pointed straight down) would be typical. You can also reduce the size later, but keep the main full-sized before making the drop.



IMO the vent location is okay, and based upon your analysis it seems to be sized adequately. I definitely would not put a T at the end with the vent at that location (vents need to be away from sharp turns to avoid having water slam into them and damage them.



Good luck!

SteamStuck

repiping the return

Hap_Hazard, thanks for your advice.



Currently my "A" dimension is 24" (I believe it should have been 28",) but the portion of the dry return before the vertical drop is somewhat steep, and the end of the main/vent are definitely more than 4 feet above the water line. I don't think this will cause major problems. Besides, I don't plan to touch that part of the system (near boiler piping), this is definitely something more that I can bite. I will have to keep this in mind for when the boiler gets replaced, though.



Thanks