General advice and checkup request (also water hammer)

kflory

I'm hoping some of you here are able to give me some advice. I've been renovating and am set to tune up my heating system (Oil-fired boiler, one-pipe steam heat). The home is a 1,220 sq. ft. two story living area (plus full basement (42' x 13' x 7') where the boiler is located) with cast iron radiators, built in 1928.

Radiator dimensions and pipe diameters attached at the very bottom.

I believe there are a few problems with the system:

• The 2nd floor is too hot. T-stat at 75f, the upstairs is 86f+.
  
• Loud water hammer in the early heating cycle.
  
• Lack of main vents.
  
• Lack of basement pipe insulation.
  
• Boiler may be oversized.
  

note: The radiators are pitched appropriately, and I've installed new Heat-Timer Vari-valves on them, and the supply valves are fully open.

The company I use for heating maintenance is claiming that the main vents are unnecessary as the air will leave via the radiator vents. They claim that the pipe insulation is unnecessary as it will just make the basement cold. They claim that water hammer is normal, but that it shouldn't be as loud as I describe.

I disagree with all of the above.

I requested they send their best expert on steam heating systems to speak with me and review the system with me... that appointment is set for Jan 26th. I'd like to see what you guys think before that date.

Pictures of system:

MilanD

Where is the hammering occurring? Everything you said above you disagree with you are correct to disagree with. 

kflory

Having trouble pinpointing it. Seems to be from the pipes themselves. I'm thinking there could be scale building in the pipes?

MilanD

From looking at your pictures, it seems the Hardford loop (the Y by the boiler) is slightly above the water, and your wet returns may start slightly above the waterlines. Both these locations may be causing the hammer.

MilanD

Next step is to check all your rads for pitch, then, your mains for a sag, including any sags in the swing joints on the radiator takeoff. These thingd can sometimes happen if the floors have been sanded or replaced, or radiators that have dug in the floor. 1/8 inch can make a difference. Good news is that all is mendable without much cost and can be done by yourself.

Jamie Hall

The hammer very early in the cycle? Like shortly after steam starts to be made, and the mains are warming up? Check the pitch of all those long mains, end to end, and make sure they drain properly.

With no insulation, those mains will be condensing like mad. Simply insulating them, which should be done as soon as you can, may help a great deal.

That said, there is at least two places you need to repipe the system. In the picture showing the oil tank, there is a white painted pipe which comes down, then angles off behind the water tank and presumably comes back to the boiler. That pipe must be lowered to the floor. Not a hard job, but it may be part of where your hammering is coming from. There should be a main vent both those steam line as well, which I don't see. The other is the similar line under the electrical panel; that needs to drop to the floor as well. That Burham has a much lower water line than whatever was there before, and those pipes were meant to be below the boiler water line -- and aren't any more.

kflory

Thanks. I can pass your comments along to the service tech when he arrives and let you know what they say.

As to the mains in the basement, they seem to be pitched properly and there is no visible sag. As far as I can tell, the rest of the piping branching from that is pitched and run ok... but it is likely VERY old and I wouldn't be shocked if they have significant scale buildup inside.

The radiators are all pitched properly and they all heat up as expected. In fact the ones upstairs heat up TOO well. I have the varivent valves set to closed and the radiators still get fully hot. I was considering reducing the pressurtrol from 2/-1 to 1.5/-1 to help reduce hammer and perhaps not heat up those rads so much. Any thoughts on that?

MilanD

You def want to try for as low of a pressuretrol setring as you can get while still getting adequate heat. However, that may lower the returns waterline and exacerbate the water hammer, but then again, it may help it too...

MilanD

Also, you won't find any scaling inside steam pipes. They are clean as a whistle. Wet returns may need flushing of the sludge, but they also won't have any scaling to cause hammering.

kflory

I ordered some Rectorseal 8-way boiler treatment. I'm hoping that will help to clear up any issues with buildup in the system and keep corrosion down. The water gets murky fast.

MilanD

kflory said:

I ordered some Rectorseal 8-way boiler treatment. I'm hoping that will help to clear up any issues with buildup in the system and keep corrosion down. The water gets murky fast.

8 way won't hurt for sure. Just watch how much you use as too much can make the boiler misbehave. However, flushing the returns will help much more with the murky water.

Jamie Hall

One thing I might add -- it's very unlikely that there is much scale, if any, in the steam mains. Any water which gets in there, after all, is distilled!

kflory

My assumption was that corrosion and sediment from the radiator would get flushed back into the pipes and eventually cause a build-up over decades. Is this not likely?

KC_Jones

I don’t know what the EDR is for your radiators, but based on the size of your house I’d suggest that boiler is most likely oversized.  You could, for informational purposes, measure the rads and figure up the system EDR to see how oversized.  I just noticed you posted a pic with your rad measurements.  If you post a pic of what style radiators you have I could run the numbers for you.  That said, shooting from the hip, I’d say you are 75-100% oversized, but the numbers will tell the story.

That boiler looks fairly new, is the contractor you are dealing with the same one that installed it?

I feel that knowing the EDR can help give realistic expectations for system performance and how low of pressure you can run and still heat properly.

I also suggest as part of this you absolutely need main vents, that’s a cornerstone of keeping pressure down and heating efficiently.  A good low pressure gauge is never a bad idea either.

kflory

Keep in mind that the insulation on this 1928 built home is poor. I have blown-in wall insulation on the bottom level, but the 2nd story has uninsulated walls. The attic has blown-in insulation, and I put rockwool bats in between the floor joists of the basement to insulate the living space from the basement. But overall, the house still leaks air like a sieve.

The original boiler was coal-fired... that wood panel on the wall is a boarded over coal chute. The oil tank sits on top of what was the coal pit. Before I owned the house, it was replaced with an oil-fired boiler... the older model of what I have now. The older boiler was replaced years ago with this one in the pictures above. The boiler was installed by the same company that does the maintenance and servicing and told me all of the above in the first post.

PICS OF RADS

The exact # of sections for each rad is in the notes in the first post.

Most of the rads are this style... two (out of four) of this style on 1st floor, three (out of 4) of them on the 2nd floor:


Two of the four rads on the 1st floor are this style:


The 2nd floor bathroom has this dinky little one:



edit:
The 2 short, wide rads on the first floor are 20.5" tall and 12 and 15 sections long.
The 2 tall rads on the first floor are 38" tall and are 8 and 9 sections long.
The 3 tall rads on the second floor are 38" tall and have 6, 7, and 8 sections.
The 1 dinky rad in the 2nd floor bathroom is 25" tall with 4 sections.

KC_Jones

I’m getting a system EDR of 257, the boiler you have is rated for 513.  That puts you at almost exactly 100% oversized.  That boiler is available in a size rated for 288, 2 sizes smaller than what you have and much more appropriate.

Those can be doe fired some, but not enough to get you in the ballpark of where you want to be.

I’d suggest maximizing the main venting and keeping the pressuretrol as low as you can, unless you can’t get even heat due to dramatic short cycling.  If that happens you may have to bump up the setting to get proper run times.

As far as the banging I agree with all the previous suggestions.  For me I’d start measuring heights, the Hartford loop looks suspect as well as the overall height of the wet return.

I noticed Harrisburg on the service tag, I’m in Hanover so probably not too far from you.

kflory

Thanks KC, I measured from the floor joists above down to the waterline of the sight glass, then did the same for the hartford loop. It looks like the waterline of the hartford loop would be in the dead center of the inverted-Y fitting... if my floor joists are level.

I'll post pictures of where I think the current water level is in the loop, and where it COULD be if I fill the tank closer to the top of the sight glass... if you think that could help until it can be re-piped?

This is where I believe the water-line is:

If I fill the tank so 4/5ths of the sight glass is full, it could be here:

KC_Jones

The wye fitting is to be 2” below the normal water line.  Normal water line on that boiler is 31 1/8”-31 7/8” from the bottom of the boiler/floor.  So the wye should be ~29 1/8” from the bottom of the boiler/floor.  I believe that measurement should be to the top of the wye.  That fitting being too high can cause banging, along with the wet return sloping through the water line like that.

Return piping is supposed to be either always filled with water or “dry”.  When it crosses from “dry” to wet it should be in a vertical pipe which eliminates the possibility of the steam and water causing banging.

BobC

I agree the wye has to be lowered to keep it 2" below the normal waterline and that wet retuns have to be lowered so they are well below the waterline.

Heat timer varivents are hard to adjust properly on almost any steam system, I would replace them with Gorton'n. Maid O Mist or Hoffmans and Have main stem vents added near the end of each steam main in the basement.

Are you getting significant bouncing in the sight glass and has that boiler been skimmed? Water treatments help but they are not a substitute for proper skimming. Hss the skim port been piped so it can easily be used?

Bob

kflory

There is some bouncing in the sight glass and the water becomes very murky while the boiler is running (but then clears after settling). According to the boiler manual, the surface blowoff tapping should not be permanently piped, and the plug replaced after skimming. However, I do not currently have the proper equipment and piping to use it, which is something I have on my to-do list.

kflory

Oh, and before I forget to ask... What do you all think of that T-fitting for the steam mains in the very first picture at the top of the page? I was watching some of Dan H.'s webinars and he stated that a T like that could cause significant turbulence to the steam flow and that it would be better to have two separate steam mains that have 90 degree elbows instead of one T.

MilanD

Oh, and before I forget to ask... What do you all think of that T-fitting for the steam mains in the very first picture at the top of the page? I was watching some of Dan H.'s webinars and he stated that a T like that could cause significant turbulence to the steam flow and that it would be better to have two separate steam mains that have 90 degree elbows instead of one T.

Yes, those mains should be separated with individual take offs from the header. However, that's most likely not your cause of water hammer. 

kflory

Thanks, missed that.

EBEBRATT-Ed

@Kflorey

As others have mentioned, you should have 2 supply risers coming off the steam header. Not one. A bullhead tee like you have is not good. The steam mains should be pitched down away from the boiler. you cannot do that with a bull head tee, it's impossible .......unless you just allow the pipes to sag which will put strain on the piping......Not good

I would have the boiler combustion down fired with a smaller nozzle and it must be done with a combustion check.

Main vents should be installed not only to vent the air but to let air in when the boiler shuts down preventing a vacuum in the system


Looks to me that some of your return piping has some horizontal piping the is probably just above the boiler water line. That's not good

Return lines need to be submerged below the water line or up as high as the steam mains.

Inbetween doesn't work`. That's where you get water hammer

kflory

Alright, the service manager was out to review my system with me today. I explained everything I thought might be contributing (to the hammering and uneven heating) as you folks helped me out with and he largely agreed with most of it. He still thinks that main vents aren't going to help much though as he felt the mains were filling with steam quickly.

His thoughts were that the most likely culprit in my list was the returns being sludged up (there is no valve on the return for flushing so it never gets drained... and as was mentioned here, they need to be dropped down below the water line. He wants to drop down the returns and replace the remaining steel return with a copper one which he thinks will help keep the return cleaner for longer. He is also going to drop the wye down to where the boiler specs state it should be while they are doing the returns. Some suggestions were made for balancing the radiators to keep the 2nd floor cooler and even out heat on the first floor which I'm going to give a shot.

After that is done, they're going to skim the boiler, drain it, and run some 8-way in it.

If the hammering and uneven heating is still a problem after the returns and Hartford loop are corrected we can move onto main vents, insulating the pipes, and replacing the bull-head tee with two proper take-offs.

kflory

So the HVAC guys were in today to drop and repipe the condensate returns and add Hoffman #75 main vents as well as a drain for the condensate returns.

I'm glad to say that the dramatic water hammer seems to be gone now and the radiators are heating more evenly as well. Refer to the first post for pictures of the old piping.















And the inside of the many decades old steam main...

Jamie Hall

Steam is, in many ways remarkably forgiving. In others -- such as those wet returns -- remarkably fussy. I'm glad things seem to be working better!

SteamingatMohawk

You said, "In fact the ones upstairs heat up TOO well. I have the varivent valves set to closed and the radiators still get fully hot. "

One comment mentions replacing the Heat Timers (for good reason in my opinion).

Heat Timer valves have a lot of capacity. At the CLOSED setting, It still allows about a #5 capacity. If they are on the second floor, you probably have too much vent capacity and need to reduce it compared to the rest of the radiators. The attached chart provides a comparison of some common vents. Also, read the comments on the chart to get a better understanding about them.

There is my favorite report here, that you can look at.

https://heatinghelp.com/systems-help-center/balancing-steam-systems-using-a-vent-capacity-chart/

It provides a lot of information comparing the vent capacities of lots of vents.

luketheplumber

I would stay away from Hoffman #5 vents, I had to flatten out the top plates in order to get them to be able to be adjusted properly. I'm going to go with the Vent-Rite 1 next time.

SteamingatMohawk

In general my preference, if you are not sure of the right setting is VentRite#1 for up to a #5, then Heat Timer for greater than a #5 on the radiators.

SteamingatMohawk

I did a bunch of tweaking with MoMs and have a slew of orifices, so I can swap them, but the two I mentioned above don't require taking anything apart.

kflory

SteamingatMohawk said:

One comment mentions replacing the Heat Timers (for good reason in my opinion).

I replaced the Heat-timer Vari-vents with Vent-rite model 1s set to about #3 on the scale

The upstairs is comfortable now, and since the new returns and piping was done, no more floor shaking bangs at 3am.

SteamingatMohawk

Awesome!

kflory

So I just had an interesting problem.

My sight-glass has been kept mostly full with about 1.5" of free space at the top. Today when the boiler fired, a few minutes in the mains starting PINGING and the water was rapidly siphoned out of the sight-glass down to almost the LWCO level. I flicked the cut-off switch for the boiler when I went investigating the loud pinging sounds and saw what was happening. With the boiler off, the water rushed back into the sight-glass and it refilled to nearly full.

ALSO, one of the mains vents (brand new Hoffman #75) is ringing like a bell whenever the boiler runs and the sound is being carried up to ALL of the radiators and is extremely irritating and noticeable. I'm not sure if this is considered normal or a defective vent. It seems to be the vibration from the boiler getting transferred into the mains which causes the internals of the Hoffman to rattle.

Help me out here.

ethicalpaul

There are only two ways I know that can cause the water level to suddenly drop in your boiler.

The first is poor near-boiler piping causing water to "carry over" into your mains which is very very common, but yours seems OK especially if this behavior has never happened before.

The second is high pressure building up in the boiler (possibly exacerbated by a non-working main vent?) which will push water back out the return and up to the mains and even radiators. Could your pigtail be blocked? This causes the pressuretrol not to "see" the pressure in the boiler. Do you have a low-pressure (0-5psi) gauge on your boiler that you can watch?

I'm sorry you bought a brand-new Hoffman 75. They are crazy expensive for how much venting they offer.

nicholas bonham-carter

Too much water treatment, (8-way), can cause more violent boiling, and blowing the water up into the mains.
However it is a good cleaner, so I would drain the boiler, and refill. That should remove the murky sediment and the water should be more clear from now on.—NBC

kflory

I drained the boiler and refilled with clear water and it hasn't siphoned out again. I had gone easy on the 8-way (about 3/4 quart) and the water color was a very light violet as the bottle said was normal. Guess I'll just use it for annual cleaning instead of as a boiler water treatment.

Mains vent recommendation for quiet operation?

ethicalpaul

I used to think so too, until I tried this experiment: https://www.youtube.com/watch?v=_JFfO_VgvNQ

The video is quite boring but the result was I put almost twice the amount that 8-way recommends into my boiler and it was fine.

but I did start with a clean boiler and water. Results might be different in a sludgy old boiler.

kflory

ethicalpaul said:

I used to think so too, until I tried this experiment:

The video is quite boring but the result was I put almost twice the amount that 8-way recommends into my boiler and it was fine.

but I did start with a clean boiler and water. Results might be different in a sludgy old boiler.

I did this after the new piping was installed on April 1st:

1. Drained the boiler, filled it with clear water and boiled it, then drained it.
   
2. Partially filled the boiler, added a teaspoon of Dawn (premixed into a quart of water) and filled the boiler, and then filled and flushed it twice more without boiling.
   
3. Added the cleaning dose of 8-way and steamed for 3 hours.
   
4. Drained the boiler, filled it with clear water and boiled it.
   
5. Drained the boiler again and added a little less than the recommended maintenance dose of 8-way and let it steam.
   

It had been running fine since April 1st, this was the first time I've had this problem.

ethicalpaul

kflory said:

I drained the boiler and refilled with clear water and it hasn't siphoned out again. I had gone easy on the 8-way (about 3/4 quart) and the water color was a very light violet as the bottle said was normal. Guess I'll just use it for annual cleaning instead of as a boiler water treatment.

Mains vent recommendation for quiet operation?

I would recommend that you put some 8-way back in there. Use ph test strips and get the ph up to 10 or 11 (after this issue is no longer occurring).

It sounds like you think the 8-way caused your problem, but I wouldn't agree with that. 8-way won't cause your water to carry over after weeks of it working fine.

I failed to look up in the thread to see that you had new piping done. New piping is the third reason that water can carry over into the mains (due to the oil from the new pipes)

I did this after the new piping was installed on April 1st:
Drained the boiler, filled it with clear water and boiled it, then drained it.
Partially filled the boiler, added a teaspoon of Dawn (premixed into a quart of water) and filled the boiler, and then filled and flushed it twice more without boiling.
Added the cleaning dose of 8-way and steamed for 3 hours.
Drained the boiler, filled it with clear water and boiled it.
Drained the boiler again and added a little less than the recommended maintenance dose of 8-way and let it steam.
It had been running fine since April 1st, this was the first time I've had this problem.

The first time you had the problem, or the first time you saw it? It's possible that it took some days for enough of the oils from the new pipes to collect in the boiler.

Your cleaning process although filled with many steps, may have been performed before the oil from your new pipes made its way to the boiler. But even if all the oils were already in the boiler, your process does not include skimming which may be required to get all the oil out. (edit: I read the whole thread and I thought you said the contractor was going to skim...did they come back and skim a week or two after their work?)

For nice venting I always recommend one or two Maid O Mist #1's unless you have a really large volume in your mains in which case I would say Gorton #2. But hold off because it's possible that the vent is making noise due to all the water in your mains. Maybe you can clean it, or maybe it will quiet down on its own.

nicholas bonham-carter

I am a proponent of generous main venting on each return, such as a Gorton #2, coupled with smaller radiator vents.—NBC