Big old school needs two new boilers....

dan_64

i would strongly suggest a cyclotherm boiler www.cyclotherm.com they are a great simple durable boiler you will be very pleased with.

DrPepper

School Built in 1928, Coal fired Kewanee's

Here is the project:
One original boiler was disconnected and the other removed in 1965. It is either a #588 or a 589 Kewanee with an 8" steam supply opening. Rating would be 36,430 Sq.Ft. It looks like they were 100% redundant.

A new Johnston 150 HP was installed in 1965 to supply the whole building. 21,000 sq.ft. It would keep up with the building but, the main OAI (outside air intake) coils (massive walls 8'x10'+/-) would drag down the pressure when they come on. System has been running at 5 to 10 max psig.

Existing Nash-Jennings Vac. Pump rated at 40,000 EDR.

The building has a combination of steel pipe baseboard (when cast rad's broke) and cast iron wall radiators. Several AHU's with coils and the OAI coils. I know I should do a complete count of the building EDR, I'm resisting doing a count of radiation because: 1.I haven't found data on the OAI coils, 2.Based on the building history it looks like the 150 is just a bit to small but keeps up most of the time. (And the boss want's it done yesterday.;-)
All the radiators and coils have supply control valves on them to a building management system. (Pneumatic/electric)

We are going to a pair of Wet back, 4 pass Scotch Marine boilers with fully modulating burners. A nice dropped header to end the wet steam carry over. A plumber installed the 1965 system.
A new Nash Vacuum pump (34 cfm) slightly larger than the old one that worked fine.
New dedicated boiler feed pump (1 pump for each boiler) and elevated receiver to control water line in each boiler separate. The Nash will feed into the Boiler feed tank as will the makeup water.

Here is the question....
1. Can you go to a Smaller boiler(100 125 HP) and team them to provide enough output fot the design degree day and start up load for the OAI coils?
2. If you put (2) 125's with modulating burners on a common header, what would the sequence of operation be and where would you control from? If you control on steam pressure off the main header will it be to much of a change when boiler #2 steams and overshoot?
3. Does the boiler control have to be PID and watch pressure change over a time period. #2 Boiler comes on at <5# after more than 5 minutes of #1 boiler firing at 100%. Or, simply link to outdoor air temp and run both boilers when it goes below 30F.

DrPepper

School Built in 1928, Coal fired Kewanee's


Here is the project:
One original boiler was disconnected and the other removed in 1965. It is either a #588 or a 589 Kewanee with an 8" steam supply opening. Rating would be 36,430 Sq.Ft. It looks like they were 100% redundant.

A new Johnston 150 HP was installed in 1965 to supply the whole building. 21,000 sq.ft. It would keep up with the building but, the main OAI (outside air intake) coils (massive walls 8'x10'+/-) would drag down the pressure when they come on. System has been running at 5 to 10 max psig.

Existing Nash-Jennings Vac. Pump rated at 40,000 EDR.

The building has a combination of steel pipe baseboard (when cast rad's broke) and cast iron wall radiators. Several AHU's with coils and the OAI coils. I know I should do a complete count of the building EDR, I'm resisting doing a count of radiation because: 1.I haven't found data on the OAI coils, 2.Based on the building history it looks like the 150 is just a bit to small but keeps up most of the time. (And the boss want's it done yesterday.;-)
All the radiators and coils have supply control valves on them to a building management system. (Pneumatic/electric)

We are going to a pair of Wet back, 4 pass Scotch Marine boilers with fully modulating burners. A nice dropped header to end the wet steam carry over. A plumber installed the 1965 system.
A new Nash Vacuum pump (34 cfm) slightly larger than the old one that worked fine.
New dedicated boiler feed pump (1 pump for each boiler) and elevated receiver to control water line in each boiler separate. The Nash will feed into the Boiler feed tank as will the makeup water.

Here is the question....
1. Can you go to a Smaller boiler(100 125 HP) and team them to provide enough output fot the design degree day and start up load for the OAI coils?
2. If you put (2) 125's with modulating burners on a common header, what would the sequence of operation be and where would you control from? If you control on steam pressure off the main header will it be to much of a change when boiler #2 steams and overshoot?
3. Does the boiler control have to be PID and watch pressure change over a time period. #2 Boiler comes on at <5# after more than 5 minutes of #1 boiler firing at 100%. Or, simply link to outdoor air temp and run both boilers when it goes below 30F.

Thanks and enjoy.

DrPepper

Pictures ....

The piping main has a single 3/4" Illinois bucket with a 3/4" pipe welded to the bottom of the main, that is it. Yup it does have a bit of wet steam, wonder why??????

Note the "Portable " on the boiler door. Beautiful.

Enjoy

scrook_2

So...

Original was a redundant pair of 260 boiler HP boilers, replaced by a single (marginal?) 150 HP boiler (installed by a eunuch, since the urge to oversize is stronger than even the urge to have sex?)?

I'm no expert on boilers this size (other than to know you can't fit one into a cape or ranch (in case they do that addition) even with a crowbar, but: If the replacement's fully modulating (what's the turndown? Should be pretty good for a system that size). Why not install one 175-250 HP boiler (actual size depending on actual connected load), vs 2 100-125 HP units?

Steamhead (in transit)

For the OAI coils

which look like cast-iron "Vento" units, go here:

http://www.heatinghelp.com/pdfs/250.pdf

If that's not what you have, then just find the carrying capacity of the pipes feeding each of these units, and use that figure. The boiler should not be undersized- or oversized either, which far too many are. The full-mod setup will let it adjust its firing rate to whatever the building demands.

Yes, that Kewanee is a beauty!

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

ttekushan_3

I recall that

either cleveland controls or hayes cleveland has controls that will sequence and control firing of two or more boilers.

I had a chance to take a good look at a pair of 1999 Kewanees installed in a school that had such as setup (including vacuum pumps) only with two boilers. The system had pneumatic thermostats throughout. There was no outdoor thermostat or any automatic operation based on interior temp.

What they did was install two 100 HP boilers where a single 100 to 125 was typically necessary. The building went cold at night and weekends. Talk about temp setback!

Anyway, morning maintenance staff would simply push a button to start the boiler sequence. Starting would alternate between boilers. Boiler A would start @ 20% fire until warm. It would then ramp up to 40, 60, etc based on steam demand. If it spent a set time at 80% the Boiler B would initiate firing sequence. Boiler A would drop to 60% while Boiler B was ramping up to 60%. At this point, they now were operating in "tandem." If more steam was required they could ramp up together in steps up to 100% if necessary. Once pneumatic stats closed supply valves, or pressure otherwise began to rise, the pair would ramp down to 40%, and if no other changes occurred or steam demand further declined, Boiler A would shut down, leaving B Boiler to handle the rest of the day's load. B Boiler would hold at 20% and after a set period of time it would shut down for the day. And that was it. Someone would have to push the "GO" button again.

Don't forget, this was a THICK school building that could hold heat for a long period of time. Final shutdown was indirectly controlled by heat loss. On rare occasions it would get caught off guard when a severe cold front would blast through during the school day. Not a big deal.

Is this the kind of thing you were looking for?

-Terry

DrPepper

Thanks Steamhead...!

If they aren't Vento heaters in the school they must be great copies.

Thanks for the help, much appreciated.
Art

DrPepper

terryT thanks for the thoughts,

I'm working with Johnson controls on the sequence of operation and while Cleveland may be out of the picture, the ramping up part of your discription made a lot of sense to me. The OAI fan will come on as school is starting and the preheat coil will become the biggest load all of a sudden. The other 5 reheat coils will also come on to bring up the area temps. But, once up to temperature the building probably can be carried by one boiler until the outside air temperature gets below (40F ?) some temp. If we sequence the controls to tandum the boilers first thing in the morning when the outdoor temp is below (*F need some research) we will have the capacity for the cold air to the coils.

Thanks again for the thoughts...!

The Steam Whisperer (Formerly Boilerpro)

Question RE OAI coils

Whoops, reread post.
Boilerpro

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

DrPepper

Hi neighbor.....!

BoilerPro, glad to see your still lurking around the wall. Hope the year is keeping you busy.
Art

The Steam Whisperer (Formerly Boilerpro)

Dr. Pepper......

Are you working on one of those Rockford Schools? It looks like this may be my best year ever. I already have proposals out on a couple months worth of commercial work with some residential on the side. I am also working on some commercial steam stuff in Chicago area.

Also, give Ernie a call at R&D Electronics...I think he has a control that can do the job for you. He's in Morton Grove 1 847-421-7860. I had the opportunity to meet with him rather recently on a steam condo job on Chicago's north side...a great guy I hope to be doing business with. Tell him I sent you.

Boilerpro

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

DrPepper

Cyclotherm boiler

I've seen Cyclotherm ad's but never the boiler. We did have some literature but I can't find it now. Burnham and Johnston both build 4 pass, wet back Scotch boilers within 300 miles of northern Illinois, so now freight becomes a factor in the sale. I can include Cyclotherm in the spec's. that's about it.
Thanks...

nicholas bonham-carter

old school---new tricks?

wouldn't it be better to separate the outside air intake heating system from the baseboard steam? it seems to me their steam pressure requirements, as well as their sequencing needs are entirely different.

would anyone starting from scratch ever put on these complicated pneumatic controls today? especially when you consider the necessity of being married to the johnson control family? perhaps one boiler could handle the baseboard with a tekmar outdoor control, to maintain the indoor temp, at the times and days, needed.

the second boiler could supply steam for the outside air system, with a thermostat to keep the inside temperature of the intake constant, and would only run during school hours. look a freight train with several locomotives--#'s 3 and 4 only work when they cross the rockies with a load of coal!--nbc

Rich Kontny_3

Deja vu!

I remember back in the early seventies when we converted many of those Kewanees from coal to combination gas/oil. One in particular was so large two of us stood inside it to build the new fire box. The old Kewanees were built like tanks. If your bid requires removal of that old Kewanee make sure you allow enough labor.

Rich K

ttekushan_3

Ooh. This may be the first time

that I disagree with nbc. I recommend keeping the pneumatics. No one need fear pneumatics any more than they should fear steam heat. I think school rooms must be controlled individually since there's so much variation in heat demand based on occupancy, time of day, solar gain, wind load heat loss.

Another thing I like about pneumatics is that they're proportional. The thermostats can release small amounts of air so that radiator valves can creep open to maintain temperature. You can even use dual pressure stats that can perform day/night temperatures if you like.

I've worked with pneumatics and never understood the aversion to them.

-Terry

The Steam Whisperer (Formerly Boilerpro)

Agreeed.....

I was at the show in Chicago where all the boiler manufacturers were showing off the cutaways of their boilers....none of them has nearly the tie as the little Kewanee I had cut up last year. It was sad, but high water content steam boilers with on/off burners just don't belong on single zone steam systems which use setbacks.

Boilerpro

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

DrPepper

Boilers only sez the school board...

If they had the money they would have gutted the school and gone hydronic. We did that to (3) 1930's schools about 4-5 years ago, the fuel bills were cut in half.

Todays project is: install (2) reliable boilers and leave the controls and systems as they are. The Pocket$ are low on ca$h.

As to pneumatic controls, they have the same problem as steam systems. Technicians aren't taught how to servicce them and engineers are mandated to install building management systems. Companies like JCI, HWell and TAC (Barber-Coleman) have started to eliminate the slow moving products. So, the "old reliable device" that you used for years has been or is about to be eliminated like the right and left hand thermostatic radiator trap.

Sorry, I may never get to ride in a DC-3 either. Life goes on.

tim smith

Hey, maybe get ahold of Cleaver Brooks and see when the

condensing super boiler may be available. Or better yet maybe they would do a beta test on this site. I guess they have a couple out there running now and I think there getting something like 92% efficiency, Wow! Tim

ttekushan_3

funny enough,

I predict that if the rest of the system is in decent shape, you'll see significant fuel savings with new boilers and controls. I've done a number of projects at small private schools and churches where 50% reductions in fuel use were had by putting the steam system right. Those organizations should be sending me more fuel usage numbers soon as this heating season winds down. So far, the results have ranged from 25% savings on the low side to 60% on the high side.

It'll be interesting to see how your project affects fuel usage.

-Terry

Rich Kontny_3

Kewanee

Has folded now I believe. I went to burner school there in 1974. There burners were a lot like Gordon-Piat

Rich Kontny_3

Kewanee

Has folded now I believe. I went to burner school there in 1974. There burners were a lot like Gordon-Piat

Rich Kontny_3

Kewanee

Has folded now I believe. I went to burner school there in 1974. There burners were a lot like Gordon-Piat

DrPepper

Agreed Terry....

The system now is a bad cobble job with the Nash vacuum pump used as a boiler feed, via feeder control on the boiler, "the boiler only floods in the spring and fall....". Good grief Charlie Brown..!

When it gets installed I will try to get some pix and hopefully show off a nice 10" drop header.

You and BoilerPro would get along great, he is working in the same type of market. Big old churches that can't afford the fuel bills and have been screwed by the low bid and fast sales pitch. He puts them right and is a hero.

DrPepper

Unfortunatly....

saw it at ASHRAE Chicago, the C/B new design steam boiler is not close to 90%. Their marketing department has overstepped itself, read the fine, fine print. The fire tubes have an aluminum insert that makes a brush cleaning impossible, they say use a pressure washer...! The burner is a glow box made of some kind of metal, ?, and "will probably need to be replaced in 3 to 5 years". I asked how much the burner cost, they never got back to me. It's steam, you can't do condensing, so where is the advantage?

Don't get me wrong, I like C/B, but I don't like to be
bs'd. Oh, and the output isn't near the 125 HP I need.

Thanks for the thought.

nicholas bonham-carter

too hasty in my condemnation?

maybe i was too hasty in my condemnation of "extreme control complexity", but the installer is very reliant on the johnson control "expert", but who will take the heat when the kiddies are cold?

in such a system, is the vacuum pump providing control operation, or is it getting the air out to assist with steam arrival?

i do think that the outside air intake/heater would benefit from being separate from the baseboard heating system, with a different boiler. the schedule of heating for both systems is entirely different [OAI on only during classtimes]. i am sure much money could be saved, if anyone were interested!--nbc

DrPepper

It's always a dillema...

We have 95 in summer and -15 in winter here, and all that's in between. The school takes in fresh air at what the weather man delivers. Since there is no return (face & bypass) 100% of the OAI passes the coils. Load on a day when it's 50F is very little and one boiler can handle both radiation and OAI (temp rise 20F ie?), but on the design degree day the rise is 80F and a whole lot more BTU's are required. Both systems work nicely on 5 psi steam, they just need the volume when it is required and shut back when not. Separation of the systems is simply not in the scope of our project or their budget, and I don't feel it is necessary. It's worked OK since 1928...!

The vacuum pump is (should be) used to provide air and noncondensible evacuation of the radiation and coils allowing the steam to reach the far end quickly and condense / heat the space. The new boilers will be fed by a new dedicated boiler feed unit so no waiting for condensate to return.

The JCI guys we have here are pretty good and seem to be able to provide control to meet our sequence of operation.

Hope this answers your question.
Thanks

Rich Kontny_3

Heavy finger

Post did not seem to post so of course I hit it again (several times)Lost my head

nicholas bonham-carter

thank you!

one more thing, how is it that this system can operate so well at 5 psi, when all 1 and 2-pipe systems seem to work better at much lower pressures? is it because the system has some sort of pressure reducing valves on it? i recall a thread here which also said that the heat content of higher pressure steam was less than lower pressure steam although the temperature was higher. thanks for the info!--nbc

DrPepper

I'd run it at 2 psi...

but the school district's personnel are not very technical so the head of the fitters (he actually does know steam) gave up and said, "On at 5 psi and Off at 10 psi". On the average when you have almost 200 buildings and lots of steam, that policy works for them.
Generally as long as you don't get above 10 psi on a low pressure system it will work. These are not vapor systems and are pretty straight forward, boiler, traps, vacuum return, boiler feed....back to boiler.
Is it a good answer...no, but it's what I have to work with.

There is good literature available from Spirax-Sarco, ITT Hoffman, and others that explain in much greater detail. There are also courses available in some cities for a price.

tim smith

Dr Pepper, heres a link, it goes to 300hp. Maybe different than

you saw. Tim


https://www.gastechnology.org/webroot/app/xn/xd.aspx?it=enweb&amp;xd=4reportspubs\4_8focus\superboilerfocus.xml

DrPepper

Same set up, the Devil is in the details.....

There is a significant difference in application between a school and a paper mill. The paper industry (and many others) consume steam rather than recycling it. A typical mill may only return 20% of the condensate, which means they have 80% to heat up to steaming temp. This is where C/B gets the 90% figure. As always it's the application that drives the opportunity. Also, the pressure in an industrial setting is a huge factor. If your factory needs 300# steam to run, you can install medium and low pressure systems and cascade the flash from traps and process to do other tasks like preheating and space heating. A typical industrial boiler plant will ring high pressure steam down to less than 10 psi by heating or reheating everything they can. Then they heat it up and pump it back into the boilers. If you ever have the opportunity to visit a paper mill like in Kentucky or Montana, it is an awsome site to see the size and economy in these facilities. Many paper mill boilers run on a high % of "black liqure" which is the sap from the wood pulp. As the the butcher said," we use everything but the squeal".
However my little school will return 99% of its condensate and it will be at 160 - 180F. Do the math and you quickly see that the opportunity is just not there.

Thanks for the thought.

The Steam Whisperer (Formerly Boilerpro)

There's also the Super Boiler at 94%

which is/has been developed in Chicago and is undergoing testing at a number of locations, I understand. There was just a thread on this in the last few weeks and this sounds like a for real efficiency number, not just process. Also, of interest, is that Weisphaut's new US headquarters is also in Chicago (Elgin), if you are looking for good burners. I've been speaking to Christoph Petri, office 1 847 531-5800,cell 1 847-917-7579, cpetri@weishaupt-america.com. Maybe a superboiler as the fixed lead and a standard, less efficient boiler as secondary. You could keep costs down by specifying a less expensive, basic boiler for the secondary boiler (ie. two stage burner, two pass 80% or cast iron) that doesn't run much, and put the savings into purchasing a much more efficient fixed lead model. Maybe just rebuld and keep one of the old Kewanees going as the secondary boiler, I've seen a number running at 80% or higher combustion efficiencies with just atmospheric burners in them.

Boilerpro

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"