Joined on May 22, 2006
Last Post on April 21, 2014
@ April 21, 2014 12:24 PM in Twin Steam Boilers - 4 Stages of Firing RatesIf there's been no tightening of the building then keeping the current EDR in play is a good choice. They way you've designed it, there's a lot of flexibility and resilience there. Getting control of air infiltration and introduction of attic insulation, storm windows or anything else that affects heat loss can be compensated for by simply changing an orifice. And it can be done on a room by room basis as changes to heat loss are made. A good situation.
Regarding the vacuum, I'm cheating. What I failed to reveal is that once upon a time this building had a Warren Webster Moderator system. The 8" Moderator modulation valve is still there and works perfectly, although I have to replace the diaphragm stem seal. The original operator is gone, but I'm going restore it with a modutrol motor with a linkage. I want a constant differential between supply and return but want it to slide up or down with respect to atmospheric pressure.
Still looking at control options. I've done my own relay-logic set ups before, but the world of vacuum modulating controls is radically different now. I'm afraid a simple solution no longer exists. Cost is a factor since the heating fuel consumption on the place is very low as it is, it makes it harder to justify a large expenditure for diminishing returns (no pun intended)
@ April 20, 2014 12:32 AM in Twin Steam Boilers - 4 Stages of Firing RatesBy installing the orifice plates, the effective EDR drops. Are the boilers sized to the total radiator EDR? Or did the orifice plates allow you to size closer to the heat loss of the structure? It may be irrelevant due to the firing rates available.
I've come to like orifices such that the effective EDR is on the slim side for the supposed heat loss, but boilers sized and modulated (or staged) over that amount so that the pick up factor is quite large but drops out quickly. In practice, this gives great distribution and very low fuel consumption per square foot per degree day. It appears that this is what you have done.
In other words, you've just done the ideal steam setup for comfort and efficiency.
I'd be wary of reducing the cold start available pick up factor in warmer weather via a multistage thermostat. The hot water mindset of half the boilers running being directly equivalent to half the heat is problematic with steam if distribution suffers. I've compared and it seems more effective to just let the whole shebang fire up and then drop out quickly, cold start pick up factor being the most demanding of all.
Unless you could alter the orifices based on outdoor temperature. :-)
I'm working up a design to allow one boiler of two to fire on a large system, but the wrinkle is that we'll be controlling the amount of vacuum applied to the system based on outdoor temp, once the new vacuum pumps arrive from Oak Services.
BTW, I wouldn't worry too much about the combustion numbers on low fire. Experience has shown that, for some reason or another, you should see excellent fuel usage that belies the combustion numbers. Ideally, fuel and air should be tightly controlled but low fire on atmospherics works better than it should.
@ April 20, 2014 12:01 AM in Steam Radiators???And one shouldn't underestimate how effective they are. Aside of the radiant heat emitted anywhere in direct view of the pipes, they also place a cushion of warm air at the ceiling which radically changes the mean radiant temperature of the ceiling, which can be quite cold on a top floor of those buildings. If suspended about 10 feet from factory windows and used alone without any perimeter radiators, the downward air current created by the windows pulls warm air from across the ceiling, indirectly tempering the chill of those windows and somewhat increasing the pipe coil's output due to increased "sideways" convection.
A very fine heat source.
@ February 11, 2014 7:47 PM in Meet The CozyThose of us who have balanced large steam systems know that the trash talk about steam heat's inherent wastefulness and unevenness is pure BS and ignorance.
Having said that, the potential to correct balance problems doesn't matter in many if not most situations where the tenant is powerless to change The Way The System Works. (You can take "System" to mean anything you want!)
In reality, when one actually encounters the owner or operator of a large, wasteful and inefficient steam system, they have that certain shrug with a "that's just the way steam heat is" attitude and look at you like you're a delusional thief if you suggest remedies. You learn (as the steam person or a hapless tenant) it's just one of their truths that they live by, and you don't want to upset that world of theirs. Sometimes it's just futile. Self fulfilling prophesy? Yes. They're in control of the heating system and you're not? Yes.
The $300 is worth not having that entanglement. Besides, you could sell it to the next tenant.
And while a TRV should have been provided by the landlord for units that overheat due to solar gain, at least you don't have to worry about snapping that poor bulky thing off at its 1/8" fitting while moving furniture. Or dancing at a wild party.
There's something attractive about a totally non-invasive approach to remedying temperature control issues. And that it is controllable by the user at any time whether they're there or not, just makes sense in this day and age.
Even though the idea of a cozy is not new, of course. nor is the idea of baffling the heat source and controlling air flow given all the thermostatically controlled cabinet heaters and convectors with dampers, a slip-on remote and thermostatically operated retrofit makes inherent sense to me. If the radiator's kept hot with a big muff, then it condenses less steam. It's that simple.
I think it'll fly. The reality of what people truly experience says so. BTW, people in these buildings should have noticed that opening a window to cool down an apartment or dorm room doesn't really help when the system's running. It's the corollary to the above statement. The cold air will cause the radiator to condense more steam, increasing it's output. It simply wastes more energy than covering the radiator. The Cozy solves this problem too.
I'm looking forward to the details on the thermal storage technique that can increase the temperature of a room whose radiator is inadequate for the heat loss. Anything that can sink the heat from the radiator will condense more steam in a given period of time. Sounds intriguing.
@ February 4, 2014 12:38 PM in A visual way to explain banging pipesCoincidentally, I was looking up "crushing steel drum with steam vacuum" videos over the weekend and saw these kinds of illustrations too. Slow-motion certainly shows with startling clarity at least one cause of water hammer.
But I was looking at the videos from the standpoint of steam's natural tendency for self-(re)distribution, extremely high thermal transfer efficiency at the radiator/fan coil and to illustrate the distributive power carried with the steam particularly where large temperature differentials exist. Powerful vacuum that occurs at the moment of the steam releasing latent heat and collapse into water is the mirror image of a force created within a steam boiler, a force that is *never* taken into account when measuring efficiency.
I'm going out on a limb to say that the measures of heating boiler efficiencies assume water at 212F or 215F or whatever and ignore a powerful dynamic that is occurring systemically with the phase change. It should be well known that heat is not the same thing as temperature, and that logic extends to the whole idea of condensing products of combustion. That simplification model works in water boiler world, but in steam world, the work of distribution is a primary characteristic of the medium itself. All other things being equal, steam will condense more in cooler environments than warm ones-- all without sensors, computers or any other active devices. The misunderstanding of these dynamics elicit the erroneous statements that "steam heat is difficult to control" and "steam boilers are less efficient and therefore steam heating systems are inefficient." Usually, it's a self fulfilling prophecy out in the field.
Crushing cans and drums illustrate the forces that should be considered when looking at system efficiencies. Further out on that limb, I'm going to say that a steam heating system that recognizes and utilizes this force will operate efficiently enough to warrant "handicap points" in the measure of boiler efficiency.
And fully off that limb, assuming full boiler modulation, that number should be as high as 10 percentage points.
Whew. I feel much better now.
Thanks for posting this!
@ January 21, 2014 11:21 PM in New main vents, but mains seem unbalancedI guess that's why I have still an affinity for the old Hoffman 75, they're pretty consistent and, despite their slower venting capacity, they have a positive "clink" sound as the snap bellows pops the vent closed. It also acts as a float should the system flood. Very soon after cool down they positively pop back open. There's no "sort of open" when everything's merely warm. Due to their slower vent rate compared to the gortons, I've had to put two on a "tree" to get the faster venting.
So I'll go out on a limb and recommend the hoffman 75 main vent instead. Having said that, I still prefer the Gorton radiator vents due to their use in proportioning steam systems based on radiator size, and that feature of being somewhat closed (or not fully open) on a very hot radiator actually serves to help equalize the heat that each radiator puts out from cycle to cycle. This feature only seems to backfire on steam mains. On radiator they're the best
@ January 21, 2014 6:55 PM in New main vents, but mains seem unbalancedIf you never see any pressure nor hear any hissing, you could be a bit over vented. (I know, that's a scandalous thing to say around here:-) )
You could put a wrap of tape around the holes on the fast main's vent and punch a small hole thru the tape and see if the mains heating time changes. I'd leave the big Gorton #2 on the slow main alone. Increase the size of the hole in the tape on (originally) fast main until they equalize. You might find you only need a Gorton 1 in this position.
The other thing I can't see from here is what the cumulative radiator venting capacity exists on the radiators of each branch. That will affect it too. As little total restriction as is practical for good distribution is what you're looking for and restricting the fast main just a touch might be the easiest thing to do and get the desired end result.
@ January 21, 2014 6:33 PM in rads very hot at top but stone cold below - low pressure arco systemSteam heats sequentially. Every steam radiator fills this way.
The real question is, "Is the room comfortable?" If so, there is no other concern. If not, then it is an issue of distribution of steam effected by venting of mains and/or returns or boiler steam capacity vs radiator condensing capacity.
EDIT: and I will add that this is the hallmark of a well calibrated vapor system if the total percentage of each radiator being heated this way is about the same. Furthermore, orifice vapor systems with no traps really should never heat the entire radiator as the last 10% or so of the radiator is actually a "post condenser" to prevent steam from ever hitting the returns.
@ January 17, 2014 12:28 AM in Another Look at Vapor Vacuum. . . unless you really want to. :-)
" It seems to me that the overwhelming majority of the heating process is going
to go on at atmospheric conditions anyway."
Very true. I think the gray area is that the ancients of steam heating used at least three different meanings of vacuum steam heating, one of which overlaps with vapor heating. The one that overlaps vapor heating is naturally induced vacuum. The others are vacuum return assistance and the third is true subatmospheric operation. The last two require pumps. And in particular, subatmospheric operation requires a fairly high HP liquid ring vacuum pump that can maintain below atmospheric pressure on supply and return under all conditions. You're not going to find subatmospheric in a home (nor just about anywhere else these days) so, nope, when the heating gets going, it'll be pretty much atmospheric.
I think mechanically assisted return can result in shorter run times during milder weather, where the heating industry seems to focus its attention. But my experiments have shown that a jet pump operating with a 1/25th HP motor can have great benefit for very little electrical use.
I'll defer to Nash Jennings' and Oak Services' case studies on vacuum return improving seasonal fuel consumption by 30%. If a 3 HP motor can reduce fuel consumption that much on a 5 million BTU heating plant, it seems worthwhile.
My own jet pump vacuum assist pumping station (using a cheap generic hydronic pump, 1/25th HP) has been working very well for 2 years, but the application is a 400 EDR area within a much MUCH larger heating system and all I was trying to achieve was even heating without a flooding subheader and violent water hammer in a problematic part of the system. Which it does. But any impact on fuel consumption is impossible to assess.
Currently, another such pumping station of similar design is about to be implemented in a 600 EDR two pipe system with undersized boiler and slow return problems. Nothing else will change and a 1/12th HP pump will be used to drive it. We have a much better chance of measuring fuel consumption differences this way. The design is such that the system will function with or without the pump and without affecting performance with the pump disabled. I really want to find out how this affects seasonal fuel usage.
"Last I checked that big boiler that I paid to heat up is still inside my house
with all its heat and warming the floor above it."
Yes. And the pipe too. That it's in the home is why that heat loss (if you can keep most of it from going up the chimney) is not really a loss. Steam is erroneously knocked for the issue of warm pipes and boiler. But still, if we can limit run times, then we're saving.
"When I really need heat steaming begins immediately at fire in the natural vacuum."
Actually, I find this true of atmospheric operation too. The larger systems I've dealt with actually will puff air out of the vented condensate receivers within moments of when the power burners light on low flame. I don't know where steam's detractors get away with implying that a boiler has to heat for 10 minutes ever single cycle.
The question becomes, whether mechanically assisted venting and return creates a net savings of energy between electricity and fuel and whether that combination exceeds the total efficiency of other heating media. We already know that steam's advantage is its latent heat, and the more the better per pound of steam generated.
Unless there are intractable problems, the simplest is what you are doing. And probably the best under many circumstances. There is value in a finely tuned yet simple system.
My last sentence on this thread
sums up where I stand on the fundamental issue.
@ January 16, 2014 5:43 PM in Another Look at Vapor VacuumLatent heat does increase. And it is delivered to the radiators, not lost. The steam also has less density at lower pressure thereby reducing the amount of total heat in the radiator, lower radiator temperature and reduced resistance to circulation. Mechanically induced vacuum return allows the reduction of boiler size due to the easing of "pick-up" factor requirements.
Your point is well taken, however, since there are many ways of eliminating the pick up factor in steam heating. Off the top of my head, there's: Orifice vapor systems, Minitube with tiny piping, conversion to fin-tube (including cast iron fin) radiators, naturally induced vacuum on very tight systems, mechanically induced vacuum, and of course, any and all combinations of above.
I really like the vacuum operation where it's an existing installation with the requisite big pipes and radiators and with an undersized boiler that can't muster equal steam distribution since it lacks adequate headroom. We can then turn an energy pig of a system into a highly efficient one. That possibility alone makes the discussion worthwhile to me.
@ January 16, 2014 1:57 PM in Another Look at Vapor Vacuumand say "yes. it is obsolete."
Larger systems with separate boiler feed pumps do not utilize a hartford loop, only a check valve.
Electric controls have obviated that, and as you point out, the hartford connection doesn't prevent a "dry fire" condition should the controls fail.
I'll add that the hartford connection also tends to hold condensate back when the water level drops and exposes the return connection to equalizer steam pressure. So it works the other way too. The water can't return until the fire stops or is reduced. This is why a hartford connection that's above the normal water line can cause boiler flooding with float operated auto fills and can also exhibit hammering at the end of the cycle a minute after the fire stops.
After all that, I think they should still be properly installed. A little tradition never hurt anybody. And as D in QCA just pointed out before I could post this one, it's so simple and reliable it makes no sense to leave it out of the picture.
@ January 16, 2014 1:37 PM in Another Look at Vapor VacuumThat's so cute!
But it's the same instinct that's always drawn me to steam radiators too!
I think a primal need is satisfied when our heat sources are actually hot. ;-)
@ January 16, 2014 1:32 PM in Another Look at Vapor VacuumDave in QCA, you said, ".... of course until the vapor filled the system " and I think that's the key. My hunch is that if return temps are high enough for reboil, vapor will already have filled the system. And regardless, the highest temperature water in the system, as you also said, being at the top of the boiler would preferentially supply the vapor. It would boil off first and maintain the vapor flow in the preferred direction.
I suspect that return water boiling wouldn't be a significant issue, since that hot kettle of water can supply vapor faster than the returns could.
Of course, introduce a motorized zone valve with separate vacuum returns and all bets are off!
@ January 15, 2014 4:41 PM in Why hot water and not steam?Steam for central heating prevailed before there were gas and oil boilers. It was used when all we had were "alternative fuels." The same stuff as used in heating stoves.
Simply stated, larger scale Central Heating required efficient and effective distribution that gravity water and gravity air could not do. Notice that homes with gravity hot water are tall but narrow. Hot air and gravity water were not scaleable without electricity.
Steam heating boilers are also power boilers since distribution is fueled by expansion of water to steam about 1700x (and vacuum induced at radiators by the same factor). Nothing else can do this but a phase change. Electric pumps and blowers removed this advantage of steam, and this advantage has actually been used to knock steam since the motive force is removed from the efficiency equations relating to boilers and furnaces. Heating water under pressure at 215 degrees (and circulating tons of it) is not the same as heating water to steam at 215. The physics if different, but is gleefully ignored by the industry. This is how some steam systems like Gerry Gill's minitube system uses a small amount of fuel that belies the comparative ratings on the boiler.
So if we assume a continuous supply of free electricity, well, then I guess we don't need steam's motive force for self distribution. If we also assume that manual feeding of alternative fuels into heating devices is "easy" with water and air, but "difficult" only with steam, then I guess steam's completely out of the picture. And if complexity is simpler than simplicity, I'm moving to a parallel universe!
@ January 12, 2014 11:47 PM in Steam Mini Tube/hybrid/vacuum??The idea of running a single pipe radiator "backwards" from the vent line was discussed a couple o' years ago on the subject of Gerry's minitube system. Seems single pipe people felt left out! Seriously, the question was whether a virtual downsizing of a steam system was practical with a minitube arrangement (it was) but what to do about single pipe.
So Gerry is the first to implement it, and with great success. In retrofit, the thought was to run new mini lines to the radiator vent positions and utilize the existing supply lines as the return. Plenty of places for vacuum leaks, though, if converting to vacuum op as well.
I currently have in service an experimental vacuum return station that provides mild vacuum return and 2' condensate lift for a steam sub header that serves about 410 EDR. The lift is into a former vacuum return. It sits a couple feet below the return, at the end of about 200 feet of undripped 3" main. You can just imagine how well that was working out. The original Webster lift fitting was gone.. Until such time that a new vacuum return is restored for 17,500 EDR, I had to come up with something. The arrangement uses generic hydronic components of VERY economical cost. Basically an immersed recirculating but open loop jet pump powered by a cheap cartridge circulator. The single piece cartridge circ's been working fine since it operates on the "clean side," condensate only. It's been running 2 years without flaw.
In the next week or two, a two pipe system nearby is going to get the same treatment, but this time the vacuum pumping station is not required to lift condensate into the boiler return, so it's going to be arranged a little differently but with the same ingredients. Orifice plates will be installed. Originally I looked at the system due to some water hammer on start up and a long lag for return, causing boiler flooding. The supplies and returns are nearly the same level and the end-of-main drip trap has little static height above the return. The returns are dry and ceiling level up to the boiler room. "A HA!" i thought. "Perfect place to experiment!" The owner is excited about it too. The active vac return should solve all the basic problems of uneven heating, start up hammer and slow return. The question will be if passive vacuum can be induced without causing cartridge pump cavitation under higher temps AND vacuum. (And whether cartridge pump seals will be destroyed under vacuum conditions. A two piece may be necessary).
The same arrangement could also be a suitable substitute for a Paul system return.
It could easily be put together as an inexpensive packaged unit, field installed in a number of configurations, including standard two pipe to vapor conversions, minitube construction and Paul operation. The idea is to eliminate the pick up factor among other benefits. I'd guess a conversion would save 30% on fuel consumption even without deep vacuum operation. This is based on vacuum return system installation studies by Oak Services (the people who do the Nash Jennings heating systems).
I'll look for the photos of the experimental pumping station currently in "beta test" and the basic diagram a little later.
Links to Gerry's excellent stuff!
@ January 12, 2014 10:55 PM in Anyone near Detroit?On the window subject, it's worth noting Fenestra steel windows are direct descendants of the Crittal window of the UK.
I gasketed my Truscon steel windows and stormed them up. Not drafty anymore. They seal tight and are very quiet now. But still, at -13 degrees a good drapery is nice to have!
Scroll down to the comment on casement window tricks to see as description of gaskets I made for mine. http://www.bobyapp.com/blog/2010/01/stell-casement-windows
Scroll down to Appropriate Types of Weather Stripping for Metal Windows. This is from US Department of the Interior, Preservation Brief 13. http://www.nps.gov/tps/how-to-preserve/briefs/13-steel-windows.htm
And I'm not associated in any way with these people, but I may give these a closer look, as an alternative to the gaskets I made. http://metalstrips.accurateweatherstrip.com/viewitems/window-weatherstrips/windows-series-no-100-all-types-of-metal-casemen-2?
I know it's off the boiler subject but it's on the heating demand subject! Since I did the attic insulation and rehabbed the windows, the drafts are gone even in high winds (even during Sandy last year) and the proof is that the heat used to run nearly continuously at 0 degrees outside, but this year at -13 it was still cycling off.
@ January 7, 2014 7:47 PM in Clow gasteam radI've been going to the wrong junkyards!
I have a larger version of that but it was missing parts. I found another that was freeze cracked and got all the appropriate parts. I've done nothing with it yet, probably because I really would prefer to have the ever elusive vented version. I simply don't like unvented stuff including fireplaces. I even vented my ancient Servel gas fridge even though I dialed in the combustion to about 0 ppm CO. Ya never know when those things might change!
@ January 7, 2014 7:37 PM in Incorrect Installation QuestionsOne of the things I've seen go wrong with a hartford connection that's too high is that condensate gets held back in the system. If the water rises to too high a level, distant supply lines can flood and create water hammer. This is why A and B dimensions are so important.
So I see two problems. One, the "air born" parts of the system (above the water line) can't deliver dry steam thereby creating a percolator effect and sending too much water into the mains; and two, the high hartford connection puts the top of the return into steam pressure territory since it is so high above the water line, causing the return condensate to stack up in the returns.
Either could cause your trouble. Both? Yes.
@ January 7, 2014 7:14 PM in commercial boiler - burner on all day for this very cold day - is this healthy?I disagree. I don't think modulation is ever pointless. It's only pointless if the system is so undersized so as to require full fire under all conditions. The larger the boiler's headroom, the more useful it is.
Don't forget that both fuel and air are modulated, giving good flame to water temperature differentials and residency times before exiting through the stack. Combustion efficiency shouldn't suffer. Taken to its logical conclusion, this is why modulating condensing boilers work out. The boiler's output is matched to the heat demanded by and dissipated into the living space. The physical size and water content are mere intermediaries between the flame and the conditioned space. Is a grossly oversized boiler a bad idea? Yes, but mostly when the system shuts off and you have a large vessel of stationary heated water losing its energy into a boiler room or chimney. Under conditions of continuous operation? Not that big a deal, IMO. Boilers operated continuously tend to last forever.
@ January 7, 2014 7:00 PM in Good MorningIn 2009 we had about -12 or -13 here (NE Ohio). I got 4 emergency calls for frozen pipes that had nothing to do with me other than they were people I'd done steam heating for.
This time none of those people called. Why? They aren't my customers any more, because each one refused my diagnoses and advice. And each was extremely "high maintenance" --the people, not the equipment. Oh and they were all very late pay, like a week before they wanted seasonal startup. And "seasonal startup" always meant "the day before sub-freezing temps with snow flying." Never mind that the heating season started the month before.
Today? just a couple of calls wondering if some of the odd burps heard from the systems were normal when it's -12. "Yes." Or, should they turn the building heat way down due to prevent stress on the heating system. "No!" Don't need no stinkin' frozen pipes!
It's been a peaceful day. My current clientele has it's priorities pretty much straight in regard to heating and mechanical systems.
As to your other comments: yes. And it sure brings it back full circle to priorities.
@ January 7, 2014 6:37 PM in Whoa - one for the record booksbut on a below design day, would it MOD? Would it CON?