Heating Help

The efficiency of distribution increases

@ October 27, 2010 10:01 PM in Paul system

under vacuum as well. A small flame can develop quite the plume of steam under vacuum and heat is very effectively distributed throughout as the latent heat content of steam (and its speed) increases with lower pressures.

The heat output of a radiator in such a system will be lower as it has a lower surface temperature, and the number of pounds (mass) of steam in the system is lower under smaller flame/vacuum conditions even though the volume of steam will be the same as under conventional conditions. Nice steam trick, that.

Latent heat is steam's defining characteristic yet it is routinely overlooked by many a heating engineer/technician as if the temperature of the medium tells the whole story.

water treatment

@ October 23, 2010 3:39 PM in water treatment chemicals

My recommendations for water treatment are based on the characteristics on your water supply. In NE Ohio, I see a lot of boiler scale that dramatically decreases the steam output of an old boiler, wasting tremendous energy. Many steam heating systems are inefficient because of this condition. Chemical descaling takes care of it. Preventing the buildup is a better choice. If your water is not very hard, you probably don't want to use anything, as using too much (increasing your pH or over-basing) can cause foaming.

Attached is a hardness map of the U.S. I picked it up from somewhere on the net but can't remember where. I'm sure it's still accurate.

I was thinking firing rate too.

@ October 15, 2010 6:18 PM in Noisy steam

That lennox looks ecr/dunkirk-esque and can be quite the wet steamer if the gas manifold pressure is too high. Also have had to resort to surface blow-off with the boiler running. Those 2" header lines may be what's in the manual, although we all know going at least one pipe size larger on the header would be better.

water hammer yes.

@ October 11, 2010 6:07 PM in I'm staring up from the bottom of the deep end with no idea how to swim.

Now, you might have legitimate issues like pipe pitch or poor return flow, etc that can cause water hammer, but yes, all that wet steam will cause it in places that would ordinarily operate quietly. Furthermore, wet steam can cause strange heat distribution issues. One clue is "panting" radiator vents, whereby the air is expelled and then pulled back into the vent. Air pushes out of the vent then is quickly drawn back, then a pause, and then a repeat. Usually there are two steps forward and one step back and eventually the radiator heats. This effect can be so bad that hardly any heat reaches the radiators on the line in question before the boiler shuts off. Uninsulated mains can create the same problem, as water moves in wave in the supply lines. If the waves get large enough to form complete "slugs" of water in the lines, then your problem transforms into water hammer.

I can't prove it, but I think when there are two branches to a main, that the panting alternates between them. Perhaps others have tried to determine if this happens, though there really isn't any point in finding out.

From what I can see so far...

@ October 9, 2010 1:55 PM in I'm staring up from the bottom of the deep end with no idea how to swim.

You need BoilerPro. Of course, I have no idea what authorization you need in order to retain his services. You are in the difficult situation of caring about the facility and viable historic structures / mechanicals when no one else seems to care. Everyone else just wants to "plug something in" and be done with it. Correct me if I'm reading too much into your situation.

From what I see, the near boiler piping is incorrect. What you have there is a situation where the steam bull-noses together at the center of the header. The EQ is outside the direction of the flow of steam. This arrangement offers no steam-drying ability. The rust stains at the radiator vents provide witness to this.

Furthermore, the amount of water line surging you observe is excessive for a W-M PEG boiler. New boiler piping work introduces contaminants to the water's surface and causes this condition. It would not surprise me in the least if this trouble existed to some extent since that boiler's installation, as surface contamination will not leave the boiler by itself.

The ceiling fin-tube is amusing. Originally, a radiator may have been hung from the ceiling. Radiators radiate! Fin-tube doesn't. It merely bakes the ceiling and throws no radiant energy downward. Amusing, but not your big problem here.

Also check that radiator valves are fully open, not partially.

As an advocate for preservation and conservation myself ( embodied energy and all), You are doing the right thing, as implementing the solutions you find here will get the system to function correctly and save a tremendous amount of fuel.

edit: PS start at the boiler room and then move up in altitude to valves and radiator vent placement.

and

@ October 5, 2010 8:44 PM in J R Reed Radiator EDR

Nason or Bundy. Worked on an 1895 church system with those. The Nason a/o Bundy figures worked out fine.

I might add, that those radiators throw an amazing radiant heat field around them. Nothing like coming in out of the bitter cold and being greeted by one of those kicking out the heat!

boiler temp and other thoughts

@ October 4, 2010 12:14 AM in Paul system

I like the idea of building vacuum at the end of the cycle if for nothing else than lowering the boiler temperature to reduce stand-by losses.

school steam, t-stats

@ October 1, 2010 6:44 PM in updated steam systems in commercial buildings.

The thermostats may well be pneumatic. If there is an air compressor near the boiler room, this is what it is for. I know many people dislike pneumatic thermostats, but what I like about them is that they can modulate the heat in incredibly small increments. In other words, the steam supply valves can be partially open with purely pneumatic thermostats. It seems that the real keys to pneumatic longevity is that the air tank has an automatic water drain, and that the air supply has good dryers.

Also, many schools with steam heat have vacuum return pumps.

And quite a summit it was

@ September 6, 2010 1:32 PM in Steam Mini-Summit in Cleveland

Well, it certainly was nice to finally meet you in person, Steamhead! And that Gerry guy-- he's really good, isn't he? (Hi Gerry!)

Of course, it felt a little clandestine without Steve or Gordo there, but it's a good start. This calls for a LARGE steam summit, although there may be regulations against such things, what with our plans to revolutionize and take over the heating industry and all...

Low hanging fruit, yes

@ August 18, 2010 12:38 AM in engineer

Hi guys-

I pick my steam heat battles carefully, so I usually get excellent results. I may have mentioned this particular case in the past but it bears repeating. Just because a steam system works doesn't mean that it isn't wasting fuel --and that it can't be quickly and competently rectified.

A most satisfying steam job I had two years ago still pays dividends. About a half dozen contractors were asked to an open house at a very old church to look over its 1885 steam system. Most everyone who actually bid on the job quoted a complete new hot water system. One quoted a conversion to hot water with the existing cast iron radiators even though they were steam only.

My bid was for a tune up/ descaling/ downfiring/ venting/ draft control/ zone sequencing. There were also a few errors in a partial conversion from two-pipe air vent arrangement to a vented main arrangement. However, no major equipment changes were necessary in my estimation. Consequently my bid was about 5% (not a typo) of the next bid. I absolutely guaranteed a 1/3 reduction in fuel costs. (Did I mention the system was clearly out of whack?) The result is a consistent 59% reduction in total fuel consumption per degree day. A hot water system that provides about 20% of the total heat load was untouched. Therefore, the steam system's fuel consumption was reduced more than 60%.

The payback period was a couple months. It also appears that this congregation's board of trustees is unanimously delighted in their decision to stick with the steam system.

Iron Fireman

@ August 16, 2010 9:13 PM in New steam mini tube system installed in my own house. (Iron Fireman style)

Iron Fireman was in my back yard (sort of). They were in Cleveland 11, which is where I am.

Interestingly, I mentioned this to my octogenarian mother in the context of Cleveland's manufacturing heyday and some of the cool stuff that was made here. Turns out, her father (my grandfather, who died in 1951) worked for Iron Fireman before he fell ill. Apparently, working in foundries throughout the 20's, 30's, and 40's along with the unfiltered cigarettes, eventually caught up with him.

And one more factoid: Rumor has it that all the tech info regarding the SelecTemp system is in the hands of Turbonics, Inc., which makes hydronic heaters.

steam to water

@ August 16, 2010 8:58 PM in New steam mini tube system installed in my own house. (Iron Fireman style)

and the steam to water heat exchanger is a really cool set up.

micro steam

@ August 16, 2010 4:28 PM in New steam mini tube system installed in my own house. (Iron Fireman style)

Nice work, Gerry!

To everyone else out there, Gerry was nice enough to invite me on a field trip to the home with the SelecTemp system last year. I couldn't get over how FAST the system heats. And quietly. Like Gerry said, the boiler at that home is downfired. If the proper boiler were in there, it sure would look small for a boiler that is supposed to heat that home!

I think part of the magic is that the refrigeration copper gives such a smooth route for the steam. Those lines are like peashooters so the water gets jettisoned out of the way of the steam- it can't flow back to create hammer and the lines don't have elbows.

BoilerPro's comment about the orifices is a good one. I think the original SelecTemp impulse turbine nozzle must have acted as an orifice. If you look at the dimensions of those original unit heaters, they had truly mind-bending output for their small size. along with the modulating thermostat, the whole thing, blower and all would modulate.
By also modulating Pressure (rather than Temperature) based on outdoor temperature, you could really get tight control over the amount of heat delivered- and still have petal-to-the-metal heat output available for setback recovery.

My mind has gone wild ever since seeing the system that Gerry showed me. You have no idea, really, how impressive the heat output of a convector or kickspace heater is when fed this way. What comes to mind is the amazing speed with which a room can recover temperature.

It seems to me that individual valves and occupancy-sensing room thermostats could be integrated into the system to provide a genuinely "green" approach to heating --where room temperature is dependent on occupancy but has a fast enough recovery to make it practical to have deep temperature setbacks. Energy savings would be quite good, I would think. In this way, we can use steam to advantage for all of its characteristics, both its high heat content per unit of mass and its high temperature.

So Gerry- it looks like I should plan another field trip!

I also have to wonder if this isn't a pretty good solution to single pipe system conversions as well, where you could run 3/8" OD to a single pipe radiator's vent tapping (drilled & retapped if necessary) and use the existing supply piping for return. No traps. Resize that boiler for the heat loss and away you go! Just a thought, since we're breaking the rules as it is.

Large scale steamers

@ July 9, 2010 11:55 AM in High Efficiency Steam Boilers

I'd also like your take on the Smith 28HE. Its numbers are in the 85% range. I've gotten quite a bit of positive feedback about these.

yes there are

@ April 28, 2010 3:17 PM in Low Pressure Wood/Biomass Steam Boilers?

Check it out- really clean wood gassification steam boiler. Some years back someone posted their installation on heatinghelp.

http://www.alternateheatingsystems.com/WoodGasification.aspx

Using the functionality already there is no problem.

@ April 24, 2010 1:56 PM in Adding a two stage gas valve

Some manufacturers of atmospheric boilers (like W-M, peerless, etc) utilize their two stage gas valves for this purpose, just the way multi-base designs can be used for similar effect. The only catch is, the manufacturers recommend it only for hot water heating systems since the heat distribution is not affected, being that the water is pumped. I think manufacturers don't want the hassle of offering it for steam boilers because the firing level and timing all affect distribution as well.

It is really easy to adjust lo fire properly, its just that manufacturers probably aren't confident it will be done properly in the field. [With the exception of peerless, who package a steam boiler with three firing rates. Mod-u-pak gives three rates, which handle most contingencies without diddling with gas manifold pressures.]

As such, enabling a function already provided by the manufacturer doesn't change the configuration of the gas train. Now, adding a maxitrol two stage regulator to the existing gas train components is a bit different. Its a good question, though, since we are not disabling or altering the existing active components in any way. Maximum fire and all safeties are fully functional.

IMO, all steam boilers should have and always should have had this function, if for no other reason than to let the pick-up factor figured into the I=B=R ratings for steam to drop out once the steam distribution is established.

I'm with Gerry on this, as introducing an extra regulator that lowers the firing level when triggered is so benign a change and so very useful.


Terry
P.S.
I won't address the bigger-than-life morass of legal and regulational implications of adding a small downfiring gas regulator to boiler as I'm liable to break into a tirade about knowledge, ability and principles being trumped by pathological manipulations of the law and our court system to serve an increasingly organized culture of legalized kleptomania. Won't go there. Nope. Not me...

---

Further reading for anyone interested, expanding on the theory of why the low fire set point is important:

Steam heating introduces the possibility of premature contraction of the volume of steam in the system if you turn down the fire too much or too soon, letting air back in --usually at the farthest reaches of the piping/radiation. The vacuum created by the condensing steam in the radiation already filled will keep the limited amount of "too-low-a-fire" steam going in their direction and maintaining a steam starved condition at the periphery of the system. Inadequate steam output at low fire will "lock" the heat distribution in its unbalanced state throughout the remainder of the cycle.

Theoretically you can so thoroughly balance the system so that a steam volume contraction is even and has no net effect on heat distribution. The real world tends to be different. So: the system should be well balanced, the mains vented really well, and the low fire gas input level and vaporstat trigger point adjusted to maintain the trigger pressure. See Gill and Pajek's article on balancing steam systems using a venting chart- it on the Shopping page.

Also, Boilerpro on this site has done a great article on using smaller boilers and even undersized boilers for steam- and how to get the distribution right. Its part of a larger issue of doing a "virtual downsizing" of existing oversized steam heating systems without touching or moving pipes or cast iron radiators. Good Stuff!

And, if you haven't read every post by Steamhead and Gordo on this subject, you really should.

cross posted at your original message

@ April 24, 2010 3:08 AM in Adding a two stage gas valve

Guess I should start reading at "strictly steam" before heading to the main wall!

They recommend it for hot water but not for steam. Steam benefits from hi/lo firing every bit as much as hot water if not more. The trick is that the low fire manifold pressure must be carefully adjusted to prevent sporadic cooling of some radiators if the steam pressure is allowed to fall for a long period of time before kicking back up to high fire.

Check out my reply at your original posting. I have more detail there.

Terry

P.S. If Gerry says to do it -- do it!

two and a half things

@ April 24, 2010 2:57 AM in Adding a two stage gas valve

Since you will use the vaporstat to control hi/lo firing, don't forget to keep the original pressuretrol as a high limit safety.

A very important thing to remember is that you will have to adjust the low fire level properly. I usually adjust the low for a "steady" steam pressure hold after coming off high fire. So if you are set at, say, 8 oz pressure to trigger low firing, the low fire should hold the pressure at 8 oz or a verrry slow creep up in steam pressure. You will need a low pressure gage to read this. Add one to the system, but retain the existing 0-30 psig gage to meet the letter of the law.

The problem with low fire being too low is that if any radiators have not heated fully, decreasing steam pressure can mean a distant radiator could begin to run cold. So set the low fire to maintain pressure, at the very least.

The final thing is more of an extravagance, but it should be superior in controlling excess air at low fire. Assuming this is an atmospheric boiler and If your installer is willing (and I can understand him drawing the line at this point for liability purposes), he can close off the draft hood and install a barometric damper in the flue to control draft.

The damper must be of the bidirectional type, the kind that swings both inward and outward; It must be properly sized and installed in the proper position and orientation; and it must be adjusted with aid of a combustion analyzer.

With a damper you will gain some efficiency over using the draft hood at lower firing rates.

Terry

Observations from a different perspective

@ March 23, 2010 11:32 AM in Modulating is it efficient?

Most of my observations are from Steam World (yea, I'm a Vapor Head), where the boiler temperature never changes regardless of firing rate and that modulation is base not on outdoor temperature but steam demand (as measured by gage pressure at the boiler).


Q: "When we look at say a 100,000 BTU boiler or furnace that fires on every call at full input is that efficient? Taking into consideration proper cycling rate."

Proper cycling rate is critical. Assuming we're load matched to EDR and the system is well balanced, firing the boiler at full such that it satisfies the Tstat as the boiler approaches pressure cycling, we're golden. I don't think we can get better than that. It rarely occurs but it sure is ideal. Given that combustion time, temperature and turbulence are important factors, as are the Temp diff across the heat exchanger and the heat exchanger material/thickness, we have the temp difference and turbulence working in favor of efficiency at full fire, as is the likelihood that excess air will be at its lowest.

Q: "If we however cause that system to modulate based on outdoor reset is it more efficient?"

N/A to steam unless working a vacuum subatmospheric system; I would say yes to HW if a) the HX provides proper turbulence b) air/ fuel mixture is constant, c) we are utilizing condensing technology and d) the returning water temp is low enough to allow substantial condensing.

Q: "Now what about the combustion issue? When we fire at less than full input into a chamber designed for full input what is the trade off?"

More time, less turbulence. HX design important here, i.e. water side flow rate, fireside surface area and gas passageway design. Some steam boilers with good modulating burners measure about the same efficiency regardless of firing rate. Mostly seen in some of the flexi water tube boilers like the Bryan. The old W-M MGB atmospherics (a tall, narrow boiler of low water content) claimed equal efficiency down to 20% firing. Perhaps somewhat a fictitious claim, but the unusual height and HX design might introduce enough added time for the gasses to transfer heat.

Q: "If we are firing at a lower input is excess air still the same?" Certainly not on an atmospheric with a draft hood!

Q: "Is flame temperature affected by modulating?" Educated guess here- I think the flame temperature is the same, only there's less of it. This still leaves the question of transfer characteristics thru the HX.

Q: "Which has the bigger problem with the modulating concept as far as efficiency the boiler or the furnace?" Dunno for sure but I think the boiler would have the bigger problem since the return water temp changes dramatically throughout the cycle and between cycles (and variable temp gain through the HX), whereas the furnace has a pretty predicable and low return temp.

So here's the flip side: On atmospheric steam with taller boilers (e.g. Peerless, W-M JS series, etc.), I have achieved excellent fuel savings per DD by introducing hi/lo firing even though the excess air has increased. The JS in particular develops quite a bit of excess air at a 45% firing rate. At this firing rate (which occurs when only one of two large zones is open) you can barely hear the burners, yet you can hear the steam rushing through the 6" outlet into the 8" header and through the 4" motorized globe valve. And this with a boiler steam pressure of less than 1# psig.

I can only assume that the benefit derives from the lack of short cycling (with the resulting steadiness of the steam drive and evenness of heat distribution) and the boiler design itself. It seems to me the where the excess air travels is of some importance. I recall reading some literature by Exhausto where they show one way excess air can envelop the flame, providing an insulating cushion of air between the hot combustion gasses and the HX surface. The greater the turbulence a design gives (like a tall boiler with rectangular "pins") the less likely that cushion is to develop in the worst possible place.

I use tools like this:

Combustion Efficiency and Excess Air

re: google, via the ONION

@ March 18, 2010 6:03 PM in Is this what I think it is?

Google Responds To Privacy Concerns With Unsettlingly Specific Apology

If its good enough for Google

@ March 17, 2010 11:39 PM in Is this what I think it is?

maps.google street view, its good enough for me.

the contractors predicament here notwithstanding,

@ March 17, 2010 11:11 PM in Problems with a big vacuum system in Chicago

I really like this kind of question on The Wall. Gives us something to sink our teeth into. I'm really curious with this one, no matter what it is.

Not just steam heating, but Vacuum Steam Heating-- filled with Intrigue, Suspense, Money, Sex and Fame!

Of course, if its some stupid clogged strainer or clogged F&T, I'll scream.