The benefits of Pipe Insulation on steam systems.

dopey27177

For the past two years I have read about boiler change outs, good and bad. Also many home owners asked about replacing old steam mains but no one talks about insulating the steam main, near boiler piping. Saw many pictures of uninsulated pipe and the people speak about heating the basement while having steam system problems such as banging, uneven heating or no heating at all in some selected space or radiator.

Pipe insulation is not cheap, but it will save a lot of money and improve the heating systems operation markedly.

Pipe insulation can be installed by anyone with an old sharp knife, a razor blade knife,
a hacksaw and some duct tape.

See attachment

Jake

Jamie Hall

Absolutely. Insulating steam mains is simply not optional. There are a number of evils from uninsulated mains, not all of them obvious.

Just do it.

And, if you need heat in the basement, do it deliberately. Don't depend on stray heat from the mains! There are a number of options all of which work.

ChrisJ

While I insulated almost all of my steam piping including some dry returns (if you can even call them that) I do like to be as accurate as possible.

If a steam system is performing fairly well and balanced without any insulation and the majority of the piping is in the heated space. How could someone save money by insulating the piping?

dopey27177

Read the enclosure and see the heat loss of bare piping and compare it to the insulated pipe.
Because this is a large system the savings is much more in cash and BTUs than a small system.

In regards to a small one pipe steam system or two pipe steam systems many problems associated with large amounts of condensate generated by bare steam piping goes away, this includes main vent valve failures, water spitting, banging and other problems. Also it improves system operation.

One thing to remember is although the monetary savings to you is small in relation to cost of the insulation the savings goes on for years just like a bond at 5% the savings in cash is passive but it still is a savings.

On the maintenance front if you do not have to replace vent valves on a regular basis or listen to music of water hammer, or banging at the start, middle or end of each heating cycle I think besides saving money your quality of life in the home is a little better.

Jake

Jamie Hall

The problem, @ChrisJ , isn't actually so much the heat "loss" -- which as you note is going into a space which can use some heat, so loss isn't even the correct term -- as it is excess condensation in pipes which should be carrying dry steam. This has two consequences. First, and more obviously but probably less importantly, the excess condensate may not drain freely, especially in mains pitched to be counterflow. Somewhat less obviously, it will cause steam delivery along the length of the main to be slowed quite considerably when the system is warming up -- and no amount of venting will fix the problem.

ethicalpaul

The first 10 feet of my main is currently counterflow and uninsulated. As most of you know, I can see inside the main when it is vertical above the header. There is no condensate flow backwards toward the boiler after the first couple minutes of a heating cycle. Any condensation that forms in the main gets turned back into steam by the heavy steam flow from the boiler.

Steam delivery is no doubt slowed by cold pipes but it's pretty minimal. The pipes don't get that cold between heat cycles in the winter (one or two cycles per hour).

I think insulated main pipes are good, but they don't make a huge difference in my observations.

dopey27177

Hi, Ethicalpaul
Since you only have 10 feet of uninsulated counter flow pipe I can see that 10 feet of unisulated pipe will make no difference to any savings in cash or system efficiency,

Just for poo and giggles why don't you take the chart and calculate how much savings there will be in your home if all the pipe was not insulated. Apply that to 10 years of savings, After that the monetary savings is all yours, remember no water carry over, no spitting main vents, and if you are running at the right steam pressure no problems with radiator vent valves.

The example shown was from a condominium in N.Y.C. where my pay for the consulting job on the upgrade to the heating system was based on the monetary savings on fuel used for heating and domestic hot water production.

My payment was 50% of the savings for January and February of the year the work was done.

Jake

ethicalpaul

Yep I agree it's beneficial to insulate in order to make more heat go where it is most useful (I too hate wasted heat in the basement which is one reason why I hate indirect or tankless hot water). But I don't think in residential systems it will be a noticeable savings. It might pay for itself in many years.

There is no carryover due to uninsulated mains (I was able to see this when my entire main was uninsulated), and no spitting main vents, and no problem with radiator vents. This is because the amount of condensation created by uninsulated mains is very minor. The main carries way more water from the first radiator runout than it ever does from condensation generated in the main.

mikespipe

Every pipe is a radiator. I strongly recommend insulating every steam pipe in the furnace room and any uninhabited basement room, they where designed to be insulated. with the demonizing of asbestos much of it has been removed and not replaced. A short story. I had a customer who wanted to by bigger radiators for his house. those he had could not heat it properly. I asked did anyone live in the basement, are the pipes insulated . with no's to both I recommended 1" fiberglass insulation on the basement pipes he purchased 50 ' of 2inch by 1inch thick insulation right then and installed it that night . He came back the next day everything was perfect. he saved more than the cost of the insulation every year since then, I suspect he saved 15 to 25% on his heating bill. the over heated basement meant he lost to much steam before it got to the rest of the house. remember the old adage that every degree you heat a space is 3% of the heating cost for that space. so if the full basement of a house with 2 story's above it is 15 degree's hotter than it needs to be that can be 15% of your heating bill.
The reason I recommend 1 inch thick insulation is that with a little razor work you can run it right over and around the fittings and save on special covers and you get a little better than twice the insulating valve of 1/2 inch at only a 50% increase in cost of the insulation.
Even in a lived in basement the furnace room should have fully insulated pipes.

Zipper13

My main vent from the 1920's whistles as it starts to vent so I use that as an indication for when steam actually starts moving in the mains (that is, it's being produced faster than it condenses, I guess).
I've seen two winters here uninsulated and one winter with insulated mains.
My unscientific observation is that venting starts several minutes earlier with the mains insulated vs uninsulated. I did not notice any major improvement in balance/comfort, but I have to believe that a few minutes less run time per cycle, say 20 cycles per day for 2 or three months has to be cheaper. If my math is right, that could be 40 hours less run time per season.

ChrisJ

@DanHolohan When did they start using asbestos insulation on steam piping?

Larry Weingarten

Hi, I'm clearly not Dan, but found this article: https://historycooperative.org/the-history-of-asbestos/ It looks like commercial mining of asbestos started in 1879 in Canada.

Yours, Not Dan

dopey27177

As was said every pipe is a radiator,
Example: A 2" pipe radiates 1/2 a square foot of radiation per linear foot.
That is 120 BTUs per linear foot of 2" pipe. Most steam systems have at least 20 feet of 2" pipe plus some 3 or 4" pipe around the boiler piping, a lot of 1/12" and 11/4" pipe.

Just using the 2" pipe for this example the savings on heat loss is nearly 10 square feet of radiation, that is
nearly 2400 BTUs per heating cycle times how many times the boiler goes into a heating cycle.
Does not sound like much until you do the math.

Lets use a mild day when the boiler cycles 20 times in a 24 hour period, that is nearly 48,000 Btus or 2 to three radiators in the home.

In this example where therm is 100,000 Btus on the mild day you are saving about 1/2 a therm per day.

Therms add up pretty quickly especially when you get into the cold weather.

Jake

ChrisJ

dopey27177 said:

As was said every pipe is a radiator,
Example: A 2" pipe radiates 1/2 a square foot of radiation per linear foot.
That is 120 BTUs per linear foot of 2" pipe. Most steam systems have at least 20 feet of 2" pipe plus some 3 or 4" pipe around the boiler piping, a lot of 1/12" and 11/4" pipe.

Just using the 2" pipe for this example the savings on heat loss is nearly 10 square feet of radiation, that is
nearly 2400 BTUs per heating cycle times how many times the boiler goes into a heating cycle.
Does not sound like much until you do the math.

Lets use a mild day when the boiler cycles 20 times in a 24 hour period, that is nearly 48,000 Btus or 2 to three radiators in the home.

In this example where therm is 100,000 Btus on the mild day you are saving about 1/2 a therm per day.

Therms add up pretty quickly especially when you get into the cold weather.

Jake

Except that steam piping is usually located in, or under the space being heated so it's not nearly that simple to calculate actual loss.

dopey27177

Typically a basement without in it usually has a temp. of 50 to 60 degrees. The temperature differential between the surface of the pipe is generally about 145 degrees.
That is a lot of heat. No matter what you calculate the the 2" pipe still radiates 120 btus per hour.
Many people think by heating the basement from pipe with no insulation tat they are saving money.

If you need to heat a basement you can do that with a hot water loop from the boiler with thermostatic control.
Most basements that I have seen unless finished for office or family use are used s a storage area laundry room that requires little or no heat.

So calculating heat loss in an empty basement is not to hard to do.

There are many benefits besides saving btus to the piping system.

Jake

gfrbrookline

When I added insulation to the mains the basement went from 85 to 70 and the rooms above became more even and reduced my boiler run time which also reduced my gas bill. I am not a professional but real world results should count for something.

PMJ

The variable I watch the most now is time to steam at the most remote location from the start of a burn.

Steam will not travel down a pipe that isn't hot enough period. Uninsulated pipes obviously cool much more between cycles than insulated ones so delivery time is dramatically affected. I chart it every cycle and I've observed that pipes cool quickly below steam transport support temperature - even insulated ones.

The heat lost by uninsulated pipes in the basement stays in the house, but it is in the wrong place. Getting enough heat to more remote locations then requires overheating the core 1st floor. You must run longer each cycle to actually deliver to remote areas. All that extra time bare pipes would continue to put heat where you don't want it while you wait the extra minutes for it to get to where you do. All the heat is still in the house so the cost is not so much in $$ but it would be in comfort.

I've written it many times but I doubt it will ever be fully appreciated without actual experience. The heat is the most even when steam delivery at the most remote radiator is happening the highest percentage of the actual fire time. With a coal fire it was essentially 100%. With intermittent fire you lose all the reheat time and all the potential delivery after fire if open vented every cycle. The after fire heat delivered in vacuum must be replaced on next fire too, but all that heat went where you need it instead of staying in the boiler room between cycles. Vacuum does reduce the pipe temperature required to support steam flow too. I know single digit minutes of net delivery every cycle difference doesn't seem like much. But when you consider how many cycles we do these minutes add up to a lot of targeted delivery and a much more even result.

Bottom line I wouldn't consider running my system without insulated piping. It would work and the house would be heated. It wouldn't be anywhere near as even as the heat could be, not close.

clammy

The largest positive effect of insulating pipes comes apparent when dealing w older structures which have zero insulation or any weather sealing done on any part of the basement . In the way past I ve insulated steam mains which where un insulated for ever and the HO would complain of un even heat and over heatedly basements and high fuel bills . After insulating no more over heated basements no more drastically uneven distribution and in a few cases excellent fuel savings w some staying 30 to 40 % drop in fuel and drastically increased performance . In most homes the saving are marginal but they all state better heat and more even distrubition. I have always felt that if insulation on steam mains was not important then they would have never insulated it in the first place . As always you can lead a horse to water but can’t make it drink . It s usually a pay me now pay me later . Most systems that are not insulated are hopefully piped correctly ,there’s nothing worse then a mis piped boiler throwing wet steam into a un insulated mains it’s a great recipe for condensate grooving in steam-mains and creating pin hole leaks add mim main venting to the picture and that’s what gives a bad name to steam system . Cause and effect buddhism at its best just because every body wants to save a penny and no one see the purpose and reasoning behind it until there replacing the same section of piping repeatedly and no one knows why . Cause and effect and remembering there’s a reason for why things are done not just because . Peace and good luck clammy

The Steam Whisperer

One advantage not yet pointed out is that condensate returns faster with insulated ( and well vented) steam mains. Basically the steam gets much further out in the system faster, so the last radiators start producing condensate sooner. This in turn starts returning water to the boiler sooner. I've had several systems where the boiler was overfilling due to slow condensate return and modern low water content. Once we sped up the steam distribution speed, the boiler no longer overfilled. This is a much simpler, effective way of dealing with the problem than adding tanks or boiler feed pumps.

RayWohlfarth

There are some great points and I am believer in steam pipe insulation. One of the reasons I like to see the steam pipes insulated is so the steam traps do not get overwhelmed and stop working. As you can guess my background is mostly commercial and have seen system lock up when the insulation was removed and not replaced. I am a bit hesitant about insulating the condensate pipes. I know @DanHolohan says to do so to lower the carbonic acid produced but I have found if the condensate is too warm, it will flash to steam in the boiler feed or condensate pump. This could slow the feed water to the boiler and cause nuisance trips

The Steam Whisperer

Ray, I've been told the same thing... don't insulate the returns. Also, if you have traps going bad and the returns are insulated, I would expect the damage to spread through the system much faster with insulated return lines. Nearly all of the two pipe systems we work on we have been converted to supply valve orifices, so the returns almost never get above room temperature. Return temps might get into the low 80s's in extreme cold when the rads are about 65% full of steam, but that's about it. Too bad the condensate volume is so low, it would be great for condensing steam boilers.

RayWohlfarth

@The Steam Whisperer (Formerly Boilerpro) I saw this on a boiler feed pump installation manual and wider if they are all the same

JohnNY

I hate pipe insulation. It makes my thermal imaging camera not work so good.

The Steam Whisperer

Ray, I think they all are except for some special ones that use a 2 stage pump set up. We're putting in a condensate transfer pump on a one pipe system later this week to eliminate some leaking underground returns. We'll be building in about 30 feet of 2inch cooling piping to help cool the condensate before it gets to the tank. Thanks go out to Denny Molloy (enjoying his retirement) for teaching me this and other tricks of the trade to make pumps work the best.

John, I agree....it makes it really hard to find bad traps when the pipes are insulated.

dopey27177

Thanks Ray:

You finally agreed with something I have preaching for about 2 years.

As far steam traps getting overwhelmed because pipe is not insulated that is a false premise.
If a steam trap is sized correctly , with proper safety factor and installed correctly cold condensate will npt affect the operation r longevity of the trap.

What kills a steam trap is water hammer and under normal operating conditions you won"t get water hammer.

Normally water hammer occurs when some one opens a valve to quickly, when a boiler is shut down for a long period of time and the operators send steam into the system without a proper warm up period. Not only that steam can kill, I consulted at Princeton University 28 years ago where a maintenance worker was killed in a high pressure steam transfer station because he or someone opened a valve to quickly.
Fault was never determined because of conflicts between consultants.

Pipe insulation in small systems as I said and others have said is beneficial as it helps a system (steam or water heating) operate more efficiently and helps in seam systems to prevent banging.

Insulating steam returns in any Vacuum or Variable Vacuum System is a no no. Condensate returning to to the vacuum pump set needs to be 160 degrees or less for the pumps to produce the desired vacuum in inches and that can be any where from 2"- 24" Hg depending on the operating steam pressure or zone valve opening.

Any commercial or industrial steam system operating above 5 psi can benefit from insulating the return lines in saved energy. Some people think that very hot condensate (at or near steam temperature) cannot enter the boiler. If dimension "A" or "B" is correct for that system the weight of the water in those water columns will push the water back into the boiler.

High pressure (15 lbs steam pressure and above) can really benefit in saved energy by insulating the return lines and the temperature of the water does not matter. Super heated condensate water typically goes to a flash tank where the flash steam and or water is piped to an economizer to produce hot water, heat a zone or another process in the plant.

Additionally the hot condensate will enter a de-aerator or very large condensate receiver where the temperature of the returned condensate matters little be the feed pumps will have the proper NPSH to pump that ht water into the boiler or boilers.

Remember the hotter the return water the less btus the boilers have to make up when the cooler a is put back into the boiler.

Additionally, there may safety issues where some returns are left bare.

To my friends that complain about not being able to use their infer red guns because the pipe is covered
You can peel back a small amount of covering to read the steam side and return side of the piping or do it like i did it before these toys came down in price, use a stethoscope, the clicking can be informative.

Jake

JohnNY

dopey27177 said:

To my friends that complain about not being able to use their infer red guns because the pipe is covered
You can peel back a small amount of covering to read the steam side and return side of the piping or do it like i did it before these toys came down in price, use a stethoscope, the clicking can be informative.

Jake

I have read this and have no idea what to say.