Need help with my steam heating system

nicholas bonham-carter

when you replace those main air vents, get good quality hoffman or gorton, and mount them away from that elbow on a pitched branch of some sort to shield them from water hammer which could destroy them in 2 heating cycles [don't ask me how i know this].i put ball valves in that branch so i could swap out different sizes and see the effects they made without having to wait for things to cool down.
also keep that pressure down in the ounces range with a vaporstat and good low pressure gauge [gaugestore.com].mount the vaporstat and the new gauge well above the waterline on the SAME pigtail, so they are both on the same page.
just remember now is the best time to spend quality time with your boiler!good luck--nbc

Steve Raftopoulos

Need help with my steam heating system

Folks,

I'm sure glad I found this website. I'm the owner of a 1924, 2-story colonial with steam heat, and after reading through much of the information here, I believe that my heating system could be made to operate more efficiently. I'll give you as much detail on the house and heating system, and am hoping that I can get some opinions and some guidance on how to optimize performance.

The house is a 2 story colonial (22'x30' foundation) with two single-story bumpouts (10'x15' and 8'x7'), adding up to ~1500 sq.ft. The wall cavities are uninsulated, the second story ceiling has rockwool between the joists. We had vinyl siding installed 2 summers ago and the contractor installed a layer of 1/2" pink foam board insulation. We also had the old windows (single-pane with triple-track storms) replaced with double-pane modern units.

I have six, (original to the house) 5-tube radiators, 26" tall by 9" wide (23" tube height, 26" if measured to the floor), a total of 81 sections. The tubes are ~1.5" wide . I also have one, 4-tube (very slender, modern design), radiator in the remodeled bathroom that I estimate at 25 sq.ft. EDR. If I looked up the EDR correctly I have ~308 sq.ft. steam radiating surface. This equates to ~74MBH.

The boiler is a mid-1980's, Peerless JOT-TW/150, originally oil fired at 1.5 GPM (210 MBH input). At that firing rate, the boiler is designed to output 134MBH, or 558 sq.ft. steam. According to Peerless data sheets, this size boiler can also be fired at 1.75 gpm for 245MBH input. Unless I calculated my radiator EDR incorrectly, this boiler appears to be way oversized for the radiator area that I'm heating.

Here's where it gets interesting. I bought the house in 1990 and heated with oil for two winters. The system seemed to perform fine - no banging, gurgling, it made steam quickly, etc., but I chose to convert the boiler to gas because I was concerned over the 1000 gallon oil (of unknown age and condition) that was buried under my front yard. I also didn't like the frequent cleaning (I was cleaning the boiler myself twice duting the heating season), and the roar of the flame was loud and could be heard in the living room right above. In 1992, I purchased and installed a Midco E20B gas conversion burner. I figured that I was loosing some eficiency, but gas was relatively cheap and I liked the fact that it burned cleaner and quieter. The burner came with several spuds and could be set up to run from 75 to 225 MBH. Out of the box it was set up to fire at 150MBH, and I left it that way, mainly because my gas meter is rated for 275 MBH and I also have gas running the stove (45MBH), Water heater (32MBH) and Dryer (30MBH), so the larger spud would have put me over the meter rating. From the start I noticed that this gun would not make steam as quickly as the oil burner. I do get steam, but I never trip the pressuretrol, unless I close all the radiator valves. I probably had the pressuretrol set too high - I just lowered it last night to ~1 psi cut in and 1.5 psi differential, but I haven't run the system to see if it's made a difference. I takes longer for steam to make it's way to the radiators than what you folks have stated on this forum. I also suspect that my mains are not vented adequately. The first horizontal run from the boiler goes about 10 ft and tees out to 2 branches that each make make a loop around the basement. The vents are on the end of the condensate return of each loop, right on the elbow that turns the pipe downward. I've installed the largest vent valves that I could find at the big box home center, but I suspect that these vent valves are for radiators, not mains. I can add pictures and sketches to help describe my system if it helps.



To sum it up, I believe that I have an oversized boiler that being underfired by too much for the chamber size, which is resulting in inefficient production of steam. I'm tempted to install the 225MBH spud and fire the boiler closer to it's design rate and see what happens. I suppose that I've never had problems with gurgling, banging and wet steam because the system was being underfired, but these issues may show up if I fire at the higher rate.

I may be way off in my analysis, so please, please give me you opinions, comments, suggestions.


Thanks, Steve

Fred Harwood_2

Help

Pics would help, and, what make and model are those mains vents? And the rad vents?

Underfiring can be a good thing, but has its limits. First ensure that you have the best venting.

bill_36

Insulation/vents

Working on four storie building 2 pipe steam - return to hartford loop [ no traps] every radiator has vents. Question A. Should the supply and return piping be insulated? if yes is 1 1/2" fiberglass O.K.? B. I know vents should be different sizes depending on distance from boiler. How do you determine the sizes or is it a matter of just trying out different ones?

Fred Harwood_2

Help

No traps in a two-pipe? Might the rad condensate el be a special one?
Supply should be insulated, as should mains. Buy insulation to fit the pipe.
You could try adjustable vents on the rads, but where and what are your mains vents?

Steve Raftopoulos

Help

I'm attaching pics of the boiler, near boiler piping, vents, etc. I forgot to mention in the original post that it is a single pipe system.

After looking at the main vents, I may have been wrong about them being radiator vents - they have a much larger pipe thread on the end than my radiators' vents. They are labeled as follows: Loop1 vent:Harp/USA No. 59, Loop2 vent:USAV 833. They are both almost identical in size and shape and have a rather small vent hole (~0.080").

The Radiator vents are Maid-o-Mist Jacobus angle vents with the all the orifices at #6(0.0935"), except for the room with the thermostat which has a #4(0.040"). I used the orifice sizes to balance the flow of heat to the radiators so that the distant rooms would warm up before the room with the thermostat got too hot. BTW, the thermostat is a Hunter programmable Set'n Save 1. I don't have central air, so I figured that I just need a unit that calls for heat and can be programmed to drop the set point when we sleep and are at work.

Steamhead (in transit)

You need

to have a pro set your burner up properly. It is not possible to do it by eye- a digital combustion analyzer is needed. This is probably why the boiler and system take a while to heat. You also may be making carbon monoxide, which is deadly.

Those main vents look too small. Measure the length and diameter of each steam main and we'll tell you what you need.

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Steamhead (in transit)

That's

a 2-pipe air-vent system. As long as you keep the steam pressure low, you shouldn't get any steam in the returns. But you should always insulate the supply mains.

Vent your steam mains properly and the radiator vents won't have so much to do. Measure the length and diameter of each steam main and we'll tell you what you need.

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Steve Raftopoulos

Need help with my steam heating system

Steamhead,

I had borrowed a gas analyzer from a co-worker when I initially installed and fired up the Midco. It was set at 9.1% CO2, 4% O2 and has been burning nicely with a blue flame and the correctly colored orange/yellow tips ever since. My friend has since retired and left the area, so I've lost ability to properly measure any adjustments. So yes, If I do change the settings on the burner, I will definitely get a PRO to adjust it.

Regarding the vents, the more I educate myself on this topic, the more I believe that the vents may be my biggest problem. I'm going to the plumbing supply house this morning to purchase a larger set of vents for the mains. I'm also thinking that I should balance the heat to my radiators with a larger set of vents. My radiators heat evenly throughout the house, but I may have accomplished this by chocking the airflow out of the radiators by too much.

I'm starting to understand why the folks here keep stressing the importance of properly venting of the system first - the faster I can vent, the faster the steam gets to the radiators (and with less pressure required to push it). The faster the steam gets to the radiators, the sooner the burner shuts off.

Steve Raftopoulos

Need help

Thanks nbc,

I did get a Gorton #1 for each branch. I questioned the sales clerk whether that would be enough venting - he though it was fine, so I just bought the one for each branch and will see how things operate. I also purchased a couple of Gorton "D" radiator vents for the furthest upstairs bedrooms that have always been a bit colder than the rest of the house. My Maid 'O Mist radiator vents have a screw in replaceable vent (and I have a bunch of extras from the last time I swapped out the vents), so I drilled out the vents to be either "C" size (0.125"), or a little smaller (0.109") and replaced the #4-#6 (0.040" to 0.0935") vents.

I ran the system with this new arrangement and made the following observations: Steam at the boiler output in 6-1/2 minutes; Steam at the Gorton main vents, at the ends of the 2 branches (25ft and 40ft from the boiler) in 14 minutes; Second floor radiators hot all the way across in 30 min, while the first floor radiators, which are much longer units were 1/2 to 2/3 hot; Five degree rise in temperature (in the room with the thermostat) in 35 minutes. The boiler never made enough pressure to trip the pressuretrol so the burner ran the entire time.

Does this sound like reasonable performance?

Steamhead (in transit)

I bet

the steam reached the end of the short main first. Add a second Gorton #1 to that main and they should both heat to the end at the same time.

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World Plumber

Pig tail

I noticed you have a black pipe pigtail, it doesn't look like it's been off for some time. Have you checked and cleaned it lately? If the pressure can't get to the pressuretrol the system won't shut down. (the black ones are notorious for blocking especialy when low fired.) 2.) It didn't appear the pannel above your burner has been removed (the one with the peerless emblem on it. Were you removing the clean out plate behind it when you cleaned the boiler? I find the ports clogged all the time that has a major effect on the boilers output. Venting does make a difference. I just drilled and tapped my mains to add vents now the back of the house is nice and toasty.

nicholas bonham-carter

pressure gauge

when you change the pigtail to brass or copper get a good low pressure gauge [0-3 psi] and put it on a tee with the pressuretrol so you know definitely what your system is producing.if your present pigtail is in the wrong orientation, or is plugged you could be way over pressurised preventing your vents from working as they should.!keep your present 0-30 psi gauge for code requirements.--nbc

Steve Raftopoulos

vents and pigtail

Steamhead, surprisingly the steam reached both vents about the same time. I suspect that it's because the radiators on loop2 are mostly on the second story (a longer more restrictive path) so the steam just kept traveling down the pipe to the end of the loop. Anyway, I bought a second set of Gorton #1s and doubled the venting on each loop. Picture of new venting arrangement attached.


World Plumber, funny you mentioned this. In December of '97, I was in Miami for a 5-day business trip when I received a frantic call from my wife that the heat wasn't working and she was freezing - We live in Northern New Jersey. Fortunately we had a couple of unseasonably warm days before I returned, so she survived. When I looked at the boiler, it had me stumped for a while, until I realized that the pressuretrol was tripped open even when the boiler wasn't running. The pigtail was clogged in such a manner to allow steam into the pressuretrol, but the clog would not allow the pressure to relieve itself when the boiler stopped firing. I removed and cleaned the pigtail, and it's been working fine for 10 years, but yesterday when I bought the Gortons, I also picked up a new brass pigtail. Picture of new pigtail attached

I did remove the front panel access plate when I cleaned out the boiler. I had not cleaned the boiler since converting to gas in 1992 and am amazed at how little buildup was in there - especially compared to how fast it would soot up with oil. The panels look like cr*p, because the round black flange had leaked at one time (before we bought the house) and stained/corroded all the front panels of this boiler. Next summer, replacing that plate is on my "to-do" list.


nbc, I'll definitely implement this suggestion. I'm having trouble finding a low pressure gauge that's rated for steam temps. Most of the gauges are rated up to 140 degrees F, not 212+. Can anyone recommend a model #?

Question to all. Would I benefit from installing a vent on the first horizontal run from the boiler, before it tees into the 2 loops? The tee at the right side in the picture called "main horiz run.jpg" is where I'm referring to.

David Nadle

Regular gauge on pigtail should be ok

Steve, the water in the pigtail should protect a regular gauge from steam temps.

Steamhead (in transit)

Nice work

bet the system heats faster now! I wouldn't put a vent on the horizontal main before the split, you want all your vent capacity at the ends so all radiators will benefit.

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Steve Raftopoulos

Not much faster

No, the extra venting has not made an appreciable difference - at least in the time that it takes for the steam to reach the mains' vents. Yesterday, it took 8 minutes to make steam at the riser off the boiler, 12 minutes to reach all the inlet valves on the first floor radiators and ~16 minutes to reach the second story radiators. Of course it takes a lot longer for the full length of the radiators to heat up. The mains seem to heat up at a rate of ~5ft/minute.

BTW, I timed the gas meter a more accurately and measured the input at 141MBH. This is being fired into a boiler chamber designed for 210 MBH oil.


I have no basis to compare whether this is good or poor performance. If this is considered sluggish, then what else could be hindering performance? Restricted lines? Boiler underfired by too much?? What else.

Steamhead (in transit)

It's underfired

have the firing rate increased to at least 168 MBH, which is 80% of the boiler's maximum rate. And most importantly, have it tuned properly using a digital combustion analyzer. No installation of combustion equipment is safe unless it has been tested and found to be burning properly.

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Steve Raftopoulos

Pipes bangning now

So, I've made several venting improvements which I'm sure have helped efficiency, but the system is still slow and the consensus is that I'm underfired by too much. Before I increase the firing rate, I want to make sure that all else is in order. The main for the "west" branch now bangs loudly with every heating cycle. It used to bang the first time the boiler was fired at the start of the heating season, and would only "tick" with heating cycles after that. BTW, I've also removed the insulation from these pipes (am planning to replace with 1" thick fiberglass), but it's still bare for now.

Is this banging related to the venting improvements, the uninsulated pipes or both? Could a restriction in the main be causing this?

nicholas bonham-carter

banging

put a good magnetic pipe level on the line every few feet to see if there is a sag which is collecting codensate.if you think there is a blockage you could use fittings to connect a garden hose to the vent tapping in the far end while cool and gently pressurize to blow it out the return drain.--nbc

stevel

Should I flush the system?

In the 18 years that I've owned this house, I've always blown down the boiler from the LWCO, but have never drained/flushed from the bottom. Could I possibly have a layer of muck at the bottom of the boiler and the wet returns?

If I do need to flush, are there any special precautions since I've neglected this for sooo long?

BTW, I just ordered $400 of fiberglass pipe insulation so that I can fully insulate all the pipes and be finally rid of the asbestos.

Steve