Sizing up STEAM

NickM

I manage a 37 unit, 5 story, unit brick building built in the '40's.  The present boiler is a Weil Mclain 88 series with 9 sections (installed in the late 80's) controlled by a Heat Timer. I took a survey of the radiators and came up with 3400 sq ft of radiation. I also noticed that the steam pressure was reading 5 lbs this morning (if that means anything)

The problem is the apartments are too hot (some measuring in the high 80's) and we burn way too much oil.  I have had Heat Timer look at the system on three occasions  in the last two years and they say that the equipment  is operating perfect.  I have had six professional boiler guys look at  and installed many new parts and pieces.  This year three sections failed (rotted at the top) and we replaced them.  Two Pro boiler men told me to replace the boiler because the increased efficiency will pay for itself in two years.   Pro # 1 says the boiler is too small and we need a larger  unit.  Pro # 2 says the boiler is too big.

Help. please

What size boiler is correct ?

Is the efficiency that much better ??

Is there anything I can do to control the boiler I have ???? 

Regards

Nick

Charlie from wmass

588 Weil if your size you stated is correct.

and the system can use the standard pick up factor for you piping. The near boiler piping is critical with boilers as modern as the one you have. Also water should be tested for chemical composition as chlorides are linked to some boiler failures. The 88 can also have a dual fuel burner that fires either gas or oil depending on which will give you more bang for your buck that month.

If height is an issue but length is not a 1080 Weil will also work.

Rod

System Type

Hi- What type of steam system is it- one or two pipe? Where are you located? As Charlie mentioned some areas have problems with chlorides in the water- notably south Boston for one.

- Rod

Dave in QCA

WM 588 Rating

The Weil-McLain 588 is rated for 3521 sq ft.  It is one of the most efficient Steam Boilers on the market.

Premature Rotting of the sections can be caused by high chloride levels.  Some local water is higher than others, but no matter where you live, the level will climb if you are loosing steam or condensate.

Also, it appears that in areas that are prone to high chloride problems, one approach is to get a larger than necessary boiler, but down fire it to the level that is matched to the radiation.  The high chloride problem manifests itself on boilers that have pins for aiding the heat exchange.  The pins just above the water line cause the iron to get excessively hot at that location, and the intense heat combined with the elevated chlorides in the water cause a reaction called graphitic corrosion.  It seems that when a boiler is fired at lower than design conditions, the pins at the water line to not get nearly as hot.



As for your temperature control, it appears that you need to continue to tune your heat timer control.

Charlie from wmass

You said you have a 9 section?

That is rated 7358 square feet of steam unless the R model which is still over 6000. The boiler must be very down fired if the building is not getting bounced around when it tries to force all that steam into the system.

nicholas bonham-carter

37 unit steam improvements

that pressure is much too high. for any pressure over a few ounces, the money spent on maintaining it at that pressure, goes straight to hugo chavez, and you know what he would like to do with the money!

as i have said before, these heat-timer/tekmar controllers cannot compensate for a system with "deferred maintenance". i recommend the following steps:

1.put on a good low pressure gauge [gaugestore.com 0-15 ounces]; with a pair of vaporstats [0-16 ounces]. the second vaporstat will control the hi-lo-hi on the burner.

2.increase the venting of the system. put on enough large main vents [plus one] to reduce the back-pressure during the initial air removal to 2 ounces. set the vaporstat to go to low fire at 6 ounces. your risers may have vents at the top, or they may loop back down to be vented in the basement. the gauge will show you what is still in need of more venting.

3.if replacing the boiler, you may want to read the excellent boilerpro article about undersizing the boiler, which only along with increased venting can reduce fuel consumption. i will try to find a link too it. get a meter on your makeup feed water so you know how much new water is being added.--nbc

here it is:

http://www.heatinghelp.com/article/11/Hot-Tech-Tips/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell

Dave in QCA

Don't know what I was thinkin!

Sorry, don't know why I thought you said 5 sections.  And, if it is an older model 88, it is not as efficient as the new ones, which have been completely redesigned, so my earlier post is pretty much worthless, except for comments on chlorides.

Your present 988 boiler is about twice the size as you need.  If it is not leaking at the moment, you might look into having it downfired to match the load + 34% for piping and pickup.

NickM

Dazed and confused

OK from what I have read, the boiler is too big and this is resulting in the excessive burning of fuel oil.... correct ?

Here is today's million dollar question,  can I remove sections from the 9 and get a more efficient boiler ?

And what is down firing ? what do I tell my boiler Pros to do ?

I have attached a photo of my monster.

Thanks for the help -- all of you guys are great, 

GOD BLESS AMERICA

NickM

Is this what I tell my PRO

I read you responce, thanks for taking the time to help,  but is that exactly what I should tell my boiler Pro to do and he will understand , or is it above his head also ?

I put a water meter on it several years ago and monitor it all the time We add very little water, ( after I fixed all the condensate lines)

Thanks

NickM

DOWN FIRED

What and how do I Downfire the boiler ?

Thanks for the help

Gordo

A Good Oil Burner Man

Should be able to change the nozzles (there are 3 in that burner) to down-fire that boiler.  That should be done with the proper nozzles and with combustion test equipment and not "by eye". 



That burner also looks capable firing low-high-low.



Set it up to run at high fire until 4-8 oz/in2 or so with a vaporstat, then have it drop to low fire for the rest of the burn/heat cycle.  One psi should be too much.



The above assumes that the system is properly vented, and by that I mean a mess of Gorton #2s and not just a lonely Hoffman 4a "quick-vent" somewhere at the end.



Don't cheap out on the venting.



I'd hire a good steam man to go over your system.  It don't sound like you've found one yet. 



I'd insulate that header and any bare steam pipe.



Good Luck!

BobC

Reduce nozzle size

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



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



good luck,



Bob

Rod

Boiler Problems

Hi Nick-  One of the first things that would concern me when I read your post is the comments by your "pros". One says too big and the other one says too small. I'm just a homeowner and not a pro but I'm quite confident I can figure out the proper size of a boiler to match a existing steam system. Since one or more obviously don't know what they are talking about I'd go very slow on making any big changes like removing sections or down firing at least until I understood the whole problem. Earlier I asked where you are located as someone here maybe able to recommend a good steam pro to you. You might also look at the top of this page in the "Find a Contractor" section. Scroll down past the zip code section to your State and see if a pro is located near you. There are some very good steam pros listed there and since your "pros" are giving you conflicting advice, I'd seek a third opinion. You might also call Weil McLain and contact the factory rep. for your area as he might be able to put you on to someone with more steam experience especially in your size boiler.



You haven't told us much more about your system. Is it a one pipe or two pipe system?

Are just a few units overheating or are there a lot?   Your steam system should be running at 2 PSI or under. The Empire State building  http://en.wikipedia.org/wiki/Empire_State_Building (scroll down to the Architecture section for steam specs)

 runs at 2 PSI or under, so your system running at 5 PSI is too much. This can cause over heating and can also wreck your vents.

I would also think that a boiler that size would be able to be configured with a multi stage burner so I would investigate that. Weil McLain should be able to give you advice on burners and what configurations are feasible.

- Rod

Charlie from wmass

Nick I hate to say this but

If you need to be here your boiler guy is not a pro. On the top of the page is a find a pro function. There must be a steam guy who does not need his hand held near you.

jpf321

NBC .. typo?

0-15oz??? do you mean lbs? and perhaps even 0-5lbs?

NickM

Finding the Pro

The building is located in Mount Vernon NY (not exactly a nesting spot for the rich and famous)

The system is two pipe and the water is treated every year

Typical radiator is a single tube  -- pictured below  and all of them get very hot

I have wasted lots of time and money trying to find a "Pro".  I am almost positive that if I use the words "downfire" to 3 out of 5 that they will start babbling and spew nonsense.    I will call  those listed on  FIND A CONTRACTOR  (3)  - but the descriptions indicate that they are geared to residential..... 

If anyone has a contact  or company with experience in this I would surely give them a call.

AGAIN - Thank you all for extending me your time and knowledge 

NickM

Insulating

How do I insulate the Header --

Is there a method or product you can recommend ?

Thanks again

Charlie from wmass

I spent last January in White plains

just north of you. It was a bit smaller of a building as it only had a 680 weil installed when it called for a 480. Did they only use one riser off that boiler?