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Joined on September 15, 2010

Last Post on August 23, 2014

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@ January 23, 2011 10:01 AM in have i runined my air vents?

Do you know what your steam pressure is? What does the gauge read when the system is cold or cool and what does it read when it's been making steam for a while (just before it turns off).

What is the pressuretrol set to, the front tab should be set at 0.5PSI while the white dial behind the front cover should be set at 1.


Insulation doesn't have to be pretty

@ January 23, 2011 9:56 AM in Cycle Times - Help?


Insulation doesn't have to be pretty, it just has to keep the heat in; pretty can come later. When you have time start doing the same to all the piping you can reach in the basement.

You really want to keep the pressure down on these systems, 1.5 to 2 PSI is all you need. More pressure just makes the gas company happier. Also consider cutting that setback down to 3-4 degrees, so you don't have to bring everything up so much.

The steam mains are the large (2-2.5-3") pipes that feed steam to all the radiator takeoff pipes (1-1.25-1.5). Let us know about how long each of those large main pipes is. If the total length is 80 ft and it looks like it might be 2-1/2" pipe (about 9" in circumference) then you have about 2.7 cubic feet of air to expel from the mains alone; you want to vent those mains quickly. The existing Hoffman 75 air vents are too small for that, if the mains are roughly the same length you probably need a Gorton #2 on each return. The Hoffmans are rated at 0.75cfm while the Gorton's are rated at 1.7cfm - both at 2oz of pressure. The Gorton #2's are large vents so you may have to use a slightly shorter nipple below the vent to accomodate them, measure the room you have to work with before buying anything.

Since yours is a 2 pipe system radiator vents are not used, except for that single radiator - is that one radiator piped as a one pipe? Are there any steam traps and are they working? The high pressure may have damaged them.

Once you have all the piping insulated your pickup factor will shrink even more; your boiler will be capable of producing even more steam than you can use. In fact that boiler rating is NET which means it has already discounted the 1.33 pickup factor. Even if it produces more steam than you can use, with correct venting and insulated pipes, all that heat will be upstairs keeping you warm and cutting the fuel bills.

Most of us have boilers that are capable of producing more steam than we need, especially on "normal" days, if everything were perfect then the boiler would run almost all the time on a design day.

My own boiler is too large, on a zero degree day the thermostat calls for heat about once every 45 minutes. It fires for about 6 minutes to make steam and 2-3 times more (cycles on pressure) for about 60 seconds each. I'll fix that when the boiler has to be replaced and hopefully that won't be for a while yet.

Once everything is working correctly you might be able to get a technician to lower the firing rate of the boiler so you aren't producing so much steam.


Reduce nozzle size

@ January 22, 2011 8:34 PM in Sizing up STEAM

I'm not a pro but my understanding is down firing  (reducing the nozzle size) by more than 25% is not productive. The burner has to be adjusted to run correctly at the reduced rate.

My small boiler (a Burnham V75) has been down fired by 30% and I'm beginning to think I may have to go back up a bit.

good luck,


new boiler worth it?

@ January 22, 2011 2:32 PM in Oil boiler rapidly cycling

Changing a boiler for increased efficiency can take an awful long time to pay off, assuming it's not 40 years old. If your boiler is grossly oversized I would make sure I've done everything else I can to optimise it (venting, pipe insulation, downfire it to the extent possible, etc).

In Boston right now oil is about $3.00 a gallon and the equivalent amount of natural gas is about $2.71. How many therms of gas are you going to have to burn to make it a good proposition? Gas might be cheaper in your area so it might be a faster payback in your case.

I've been wrestling with this for a few years now and have decided to go with what i have (oil fired 15 year old Burnham V75) until it has to be replaced. That could be tomorrow or it could be 10 years out.


Korean central heating (traditional)

@ January 22, 2011 12:23 PM in Iranian heating

That's a very modern setup.

When I was serving in S Korea in the late 60's, I was posted to a remote microwave site on top of a mountain. Let me tell you it gets VERY cold in the wintertime.

There was a small farming village a few hundred feet below our site and the small houses were thatched huts built on an earthen mounds with partial packed mud walls. The mounds were probably 16" high and they had a tunnel that ran under them. A small fire is built in one side and the heat travels under the floor and warms the entire floor. Charcoal was the fuel of choice.

This is probably one of the earlier forms of radiant heat.



@ January 22, 2011 10:36 AM in Cycle Times - Help?


That's a good sized house so i assume your steam mains are pretty long. You show two Hoffman 75 main air vents in one picture, you may need a more venting so your not using your gas to compress the air in the steam mains. Also 3PSI is the highest pressure those air vents should ever see, most residential boilers run at less than 2PSI, mine runs at 12 oz.

Your near boiler piping may not be optimal, do you have a hartford loop? Does the water in the gauge glass move up and down much?

How long are the steam mains and what size pipe?
How long (from a cool start) does it take each main vent to get hot?
Is this single pipe steam?
Are all the radiator vents working and what kind of vents are they?

Your boiler may be oversized, and that can lead to short cycling. The only way to determine that is to measure all the radiators to see how many sq ft of radiation (EDR) you have. Try printing out this form and figure out what your total EDR is - The EGH-85 is rated at 875 sq ft of steam so your radiators would add up to something close to that in a perfect world.

Compare the near boiler piping to that shown in the installation manual to see what the installer might have missed.


Make sure it's level

@ January 22, 2011 7:24 AM in problems with pressuretrol not coming on

A mercury bulb pressuretrol has to be level to work right. make sure the pigtail beneath the pressuretrol is oriented correctly, if it's not expansion on the pigtail (as it heats up) will throw it off. The pigtails loop should be parallel with the side of the pressuretrol.


Bad gauge

@ January 21, 2011 9:39 PM in Too much pressure? Or reading the wrong gauge?

The box in the upper left is called a pressuretrol and that front tab should be set low, about 0.5 PSI; taking off the front cover will reveal a wheel that should be set at 1. Thet tab hjas two scales the right habd scale is PSI.

The 30 PSI gauge should read zero when the boiler is cold or warm, when it has been steaming for a while it should read no more than 2. It sounds like your gauge never gets down to zero the way you describe it.

Those 30 PSI gauges really are not much good when your trying to see low pressure. A lot of people mount an auxiliary 0-3PSI gauge off the same pigtail that the pressuretrol sits on using a few fittings you can buy at the hardware store. All the fittings are 1/4".


A waste of time and effort

@ January 21, 2011 11:04 AM in New radiator fountain after new boiler

Hopefully you sill owe this knucklehead some money!

If a steam boiler isn't piped per the install manual it is not going to work. there is not one thing with that install that is correct. If he balks at repiping it correctly (in threaded steel pipe) per the install manual call up the boiler manufacturer and ask them to twist his arm.


A taste

@ January 21, 2011 10:30 AM in Steam a "Dying Art"?


This article will give you a small taste of what your new book will be like -

If you can figure out what your problems are someone on this board will come up with an answer. There is more accumulated steam  knowledge here than anyplace else i know of.

BTW I just shoveled 8" of snow but the good news is it was nice light snow, nothing like the 10-12' of cement we got last week. Temps are supposed to be near zero by Sunday night so the dragon will be busy.


Boiler cycling

@ January 21, 2011 9:25 AM in Steam a "Dying Art"?

A steam boiler will cycle on pressure until the thermostat is satisfied. If the system is sized just right it will run almost 100% of the time on a design day (Zero F in my case) because the radiators will condense the steam as fast as the boiler can make it.

My system usually fires initially for about 14 minutes before cutting out at 12 oz of pressure. It then cuts back in at 4 oz and that continues (60 sec on and 90-120 sec off) till the thermostat is satisfied. My boiler is oversized but I'll live with it till it's time to replace that 15 year old V75 because the fuesl savings would take a very long time to pay for the replacement costs.


Your right

@ January 21, 2011 9:16 AM in Steam a "Dying Art"?

Your absolutely right about that, I remember Dan's article from a couple of years back where he argued for matching the load as close as possible to the boilers rating.

My only concern in the Boston area is the gas companies habit of mixing air into the gas lines to keep the pressure up in really cold weather. Some of my neighbors have complained about low heat and the flames not being blue during really cold weather. I'm still on oil so it doesn't bother me until they fill the damn tank! Does anybody know if there is a limit to the amount of air they can mix in.

time to go out and shovel,


Pressure too high!

@ January 21, 2011 8:06 AM in Steam a "Dying Art"?

It is not easy to find good steam men anymore and that is why this board exists. People have realized they have to become knowledgeable so they can tell the plumbers what has to be done if they don't understand steam systems.

Converting a steam system to hot water can be an expensive proposition because steam works at 1-1/2 PSI and forced hot water runs 10X that. You might find some areas that don't like that pressure after 80 or 90 years of low pressure. If you do convert, be prepared to remove all the radiators and piping so you can install everything new.

You said the boiler was running at 5.5 PSI that is MUCH too high, it should be 1.5PSI. All steam systems have air vents and some have steam traps (2 pipe); these do not work at anything over 2-3PSI and that makes your gas company very happy because they get to sell you a lot of fuel. Turn that pressuretrol down (0.5 on the front tab and 1 on the dial inside the front cover). Post some pictures of the boiler and the piping around it from a few different angles, also a picture of your pressure gauge and pressuretrol.

A steam boiler is sized to supply the connected load (EDR). The boiler has a plate on it that tells you how many BTU's and how many square feet of steam it can supply at a given fuel rate. The boiler sq ft should be 15-20% higher than the sq ft of radiation you have attached. Any take offs for domestic hot water have to be considered as well as if the piping in the basement is insulated, etc.

You can figure out what each radiators sq ft by printing and filling out this chart. just figure out what kind of radiators you have and then how many columns they have. The chart will tell you how many sq ft each section of a radiator has according to it's height. Then count the number of sections (rows of 2 or 3 columns) and multiply that by the sq footage per section to arrive at the square footage of that radiator.

A properly configured steam system can be very efficient. If your going to live with steam heat you have to understand it, you can buy a copy of "The Lost Art of Steam Heating" under the shop banner of this site. That book will give you a better understanding of steam heat than most service people. It's well written and has a huge amount of information in it. It will pay for itself 10X over.


Turn the pressure down.

@ January 20, 2011 8:47 PM in 2 pipe system-banging noises

That pressure is much too high, if they can heat the Empire State Building with 2-3PSI an apartment building will do just fine with 1.5PSI maximum. Higher pressure makes everything worse but it makes the people supplying your fuel very happy.

Has this system been noisy forever or did it start after some work was done on it? Have they checked the main air vents to be sure they are working? A lot of main vents do not take kindly to anything above 3PSI - in fact they lock shut and they can't work as they were designed - and then you pay the fuel company in spades.


Run it back along that return

@ January 20, 2011 4:37 PM in Got Book Now need main vent!!

It would be nice to get a foot or more back from that drop down so the new vent lasts a good long time. Maybe a short nipple and an elbow so you can go back along that return, Come out of the elbow with a reducer to get down to a smaller pipe and then another elbow to screw the new vent into. The Gorton #2's are large so you want to make sure you have room for it and that #2 wants to go into a 1/2" fitting -

That book is going to pay for itself in spades!


degree days, radiator venting, tstat

@ January 20, 2011 2:26 PM in Steam Main Venting (Residential)

Here's a link to Boston degree day data -

Now that the mains venting has been addressed it's time to see how well the reast of the system is balanced. The goal is to have all the radiators start to heat at about the same time and for that to happen the venting on the radiators has to be proportionate to its EDR (square footage of radiation). larger radiators require more venting than small ones do. Just putting huge vents on all the radiators does not work.

Print and fill out this form for all your radiators and note the type of air vent and if it is 100, 50, 25, or 10% open. there are pictures and charts that should enable you to figure the EDR of each radiator.

Also what kind of thermostat do you have and is it set up for steam?


EDR seems small.

@ January 20, 2011 10:14 AM in Pressurtrol needs help

Those numbers look awfully small. A typical radiator in my single family 1920 house is a 38" tall, 3 column, and has 6 sections; per the chart each section (of 3 columns) for that height is 5 sq ft and since I have 6 sections that radiator is 30 sq ft - 5sq ft per section X 6 sections = 30 sq ft. In my 6 room house I have 190 sq ft of radiators (EDR), yours will be different. Please check your number again to be sure because a total EDR of about 75 sq ft seems very small.

make sure your thermostat is set up for steam, the newer digital ones need to be adjusted to 1 CPH (cycles per hour). You should also insulate as much of the piping in the basement as you can, start around the boiler and work your way outwards.


Pressure, calcium deposits

@ January 18, 2011 1:46 PM in Spitting Air Vents

First, do you know what pressure the boiler is running at?

It sounds like calcium deposits are probably preventing the Hoffmans from closing all the way. Knowing what the Hoffmans cost, I'd replace them with Gorton #1's and then try to reclaim the Hoffmans as spares by boiling them in white vinegar for 15-13 minutes.

Last year my Ventrite 35 did the same thing and the vinegar boil allowed me to reclaim it and use it as a spare after I replaced it. just make sure everything is relatively cool and shut the boiler off before getting out the wrench.

Take some pictures of the boiler, the piping around the boiler, and those vents from a couple of different angles and post them here so we can see what you have.



@ January 18, 2011 8:20 AM in Is this a crazy idea?


i agree with Dave that adjusting the radiator venting down might help this system a lot. Also his comment about venting the steam main fast should be followed.

Another item is insulating all the piping in the basement, any heat your losing in the basement is not available for use upstairs and that might just be enough to make it all work.

If you could post some pictures of the boiler and basement piping it might help us visualize what your dealing with.



@ January 17, 2011 7:54 PM in Steam Pipe Fiberglass Insulation versus Asbestos air cell insulation

I have no clue what R factor asbestos pipe insulation is. However I've removed it from pipes and installed 1" fiberglass pipe insulation in it's place,  and my intuition is that the fiberglass insulation is at least as good as an equivelent thickness of asbestos.

All the exposed piping in the basement should be insulated with a minimum of 1" fiberglass pipe insulation.


main vent location

@ January 17, 2011 10:59 AM in Removing air valves in one pipe system

On the steam main in the basement there should be a short pipe nipple and a main air vent near the end of the main (usually a long 2 or 2-1/2" pipe); it can also be near the end of the dry return which comes off the end of the steam main.

The main air valve may look like a larger version of your radiator vents or it may be a large copper or green in color. that is there to handle all the air in your steam main and the boiler, the radiator vents then just have to handle the ar in the radiator and the pipe that feeds them.


Main vent

@ January 17, 2011 9:04 AM in Removing air valves in one pipe system

Do you have an air vent on the steam main and is it large enough? It sounds like your radiator vents are venting the entire system, they are only supposed to vent the radiator and it's feed pipe.

Also if the thermostat has a selectable CPH setting, Select 1 or "Steam and gravity hot water". A lot of these come preprogrammed for hot air and that doesn't work at all well for steam.

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