Short cycling steam boiler

trisha

Hi,

I have a Weil-Mcclain steam boiler which provides heat to a 4 story, 8 family apartment building (approximately 8500 sqft in total).  It's model EGH105, with 450,000 BTU rating, installed in 1999.

Last winter, the boiler was short cycling a lot.  In trouble-shooting it, we (and by "we" I mean a licensed plumber) ended up replacing several parts, including the pressure gauge and pigtail, which was nearly occluded with gunk.  The short-cycling continued, so we also skimmed the boiler until the water was pretty clear.  That seemed to help, but by this time, it was near the end of the heating season so it was hard to get a good sense of whether the issue was fixed for good.

Fast forward to now.  I turned on the boiler to make sure it was ready to go for the winter and, again, short cycling.  The water, which had been clear, is now really rusty and won't really clear no matter how many buckets I empty. 

My real dilemma is that I have two plumbers that I really trust.  Plumber #1 says I have to put chemicals into the boiler to clean it (something to bind to the rust and then maybe a silicon after), while Plumber #2 says that you absolutely can't put chemicals into an old boiler.  I don't know which to listen to - any thoughts would be much appreciated.



While I'm at it, there are three 2 or maybe 3" risers coming off the boiler (which was installed by Plumber #2).  Plumber #1 says these should be at least 4" risers.  Any thoughts on this point of disagreement?

Thanks in advance for any help/advice!

Bio

Post some pictures

Take Boiler pictures and piping above it, not all chemicals are compatible with that type of boiler

BobC

Boiler piping

The manual states that a EGH-105 has 2ea 2-1/2" risers that should connect to a 3" header, the equalizer is 1.5".



http://www.weil-mclain.com/en/assets/pdf/eg_boiler_manual.pdf



What pressure is the boiler operating at and has it been recently skimmed to remove any oils that might be in the boiler water.



With some pictures somebody will probably spot what the problem might be.



Bob

The Steam Whisperer (Formerly Boilerpro)

Check the thermostat

If you have a digital thermostat and are in the US, they are set up for forced air from the factory.  The internal settings need to be adjusted for a steam system. Not all electronic thermostats can be used for steam, and there are some that try to lump hot water and steam together....also not a good idea.  If you have an older thermostat, the anticipator may need adjustment or is burnt out.

STEAM DOCTOR

Venting

Also check your main vents. Lack of adequate main vents can lead to short cycling due to pressure buildup.

Jamie Hall

Several thoughts...

First off, I'd avoid chemicals if at all possible.  They shouldn't be needed in a heating system (closed cycle) boiler, unless the water is really aggressive in some way.



You need to establish just what part of the control system is turning off the boiler -- cycling it.



Steam Whisperer's comment is very relevant -- particularly if you (or somebody!) have replaced a thermostat.  Worth checking.



Otherwise, it is more likely to be cycling on pressure -- but you need to establish that.  If it is cycling on pressure, the very first place to look is the pressuretrol.  Is it set right?  Is it behaving properly?  I have seen situations where (usually on vapour systems, at very low pressure) the normal pressure fluctuations in the boiler were enough to trip off the pressuretrol.  A snubber on the pigtail will solve that problem.  Also check the 'trols settings.  Then you need to check the venting.  While it is less likely to create a problem unless you have changed something, it is possible that the main vents have gotten stuck shut.



You might also spend a little time and think through what might have been changed in the building between when it ran OK and when it started short cycling...

trisha

Thanks for all the responses

I've attached pictures of the boiler and the color of the water drained into a 5 gallon bucket.  Not sure it translates in the picture well, but it's really rusty and, as I said in the original post, really doesn't clear no matter how much the water is changed.  Once the rust settles in the bucket, the water itself is relatively clear though, so it's not dirty, strictly speaking. 

Question:  Will rusty water cause short cycling and is it a reflection of a bigger problem with the inner workings of the boiler?

One poster said "no chemicals" but I can't see any other way to get rid of the rust if it is a problem.

Regarding the comment on the pressure, I don't think that's the problem - we replaced the pressure gauge and the pigtail at the end of last heating season and, since then, two plumbers have checked the boiler pressure and said it was ok. 

Neither plumber mentioned or checked the vents, so I will investigate in that regard.

There have been no real changes to the system or the building prior to the onset of the short cycling (the thermostat is digital with 4 time settings). 

STEAM DOCTOR

Near boiler piping is BAD

Anything short of repiping the boiler is like putting a bandaid on a surgical wound. The runs to the mains need to be after all the boiler risers. Also, I don't see an equalizer. Also hard to tell from pics but the header pipe size appears to be to small. Also the header is to low down.

Jamie Hall

Several comments

First, rusty water will not cause short cycling.  Your water doesn't look bad to me (it's certainly no worse than mine); live with it. 



Second, bn is being kind.  That near boiler piping isn't just bad, it's horrendous.  Find the boiler manual and find where it states how the boiler is to be piped, and then do it that way.  The boiler piping, as it is, suggests to me a third way in which the boiler may be short cycling.



To review: there are basically three controls for a modern boiler (there may be more, but these three are the main ones).  The thermostat, the pressure switch, and the low water cutoff.



The thermostat responds to room temperature, and has either an anticipator or a timer in it as well.  You mention a digital thermostat.  Therefore, step one is to check the digital thermostat and make sure it is set either for steam or for one cycle per hour.



Second, the pressure switch.  It does not cause short cycling directly, but it will cause short cycling if the venting is poor.  Judging by the state of the near boiler piping, I would want to check the main venting; anyone who puts in near boiler piping like that may have not realised the importance of main venting.



Third, the low water cutout.  It would not, normally, cause short cycling -- but as bn noted, I don't see an equalizer on that boiler.  Therefore, when pressure builds as it should, water will back out of the boiler and into the returns -- and enough water may back out to trip the low water cutout.  Nothing to be done about that (it's only doing its job, after all) except to fix the near boiler piping.



Good luck

nicholas bonham-carter

Off&non boiler

I think with that boiler piping, that all the water is blown up into the mains by the bad piping, and then the LWCO will shut off the burner until the water returns, which it has trouble doing. In order to check this theory, set the thermostat high, and watch the water level in the glass, as it steams. Observation of the system is key in solving many steam problems.

Is this a new-to-you building, or have you owned it long enough to have a history of how it functions. The good news is that your fuel consumption should be reduced by at least 30%, when you get these problems solved.

Don't let anyone convince you that Steam is inherently noisy, inefficient,uneven, or too old to bother with. When your building's system was first installed, it would have been quiet, even, and economical. A steam fitter in those days who had piped the boiler badly would have been drummed out of the trade (we hope)!--NBC

trisha

yikes!

Seems that the universal opinion is that the piping/installation on this boiler was less than spectacularly done. When I bought the building 15 years ago, I put in this boiler with the same plumber (plumber #2) that I have been using all along. He generally is well-considered in the neighborhood so I'm a little dismayed by the feedback here. The heating has always been expensive for this building, but I attributed it to the challenge of heating a multiunit property to keep all happy, not to an ill-performing boiler. I don't recall that the boiler was short-cycling as much in earlier years, but I may not have been paying as much attention.

Thank you for all the points raised here - I don't think I'll be able to trouble shoot them all myself, but it's given me a format for conversation with the original plumber and for anyone I bring in to review the work for another opinion.

Dave in QCA

Not Weil-McLain

In your first post you indicated that the boiler is a Weil-McLain EGH model. But, the boiler in the photo you posted is NOT a Weil-McLain Boiler. It looks like a Peerless Series 64. I'm pretty darned sure that is what it is. I'm going to post a link to the Peerless Installation manual for that boiler.



Why don't you go get the make and model information off the boiler and post it here. If I haven't given you the correct manual, I'll go find the right one.



http://www.peerlessheater.com/DesktopModules/Bring2mind/DMX/Download.aspx?EntryId=83&PortalId=0&DownloadMethod=attachment

Rod

Boiler Piping Problems

Hi- You’re going at it the right way. Learn as much as you can about steam as that will allow you to decide whether the person you are talking to really understands steam. Unfortunately we see on here all too often that while all steampros are good plumbers, few plumbers are good steampros!  

   There are a lot of good resources available on this website. I would highly recommend that you get a book called “the Lost Art of Steam Heating” which is available from the Shop section at the top of this page. Here’s a link to it: http://www.heatinghelp.com/products/Steam-Heating-Books/25/68/Lost-Art-Of-Steam-Heating

It’s easy reading and  written so that someone new to steam,either a pro or a homeowner, can understand it.

Here’s a link to a good video explaining the need for properly configured boiler piping:

http://www.heatinghelp.com/article/107/Steam-Heating/118/Steam-boiler-near-boiler-piping

    Attached a page from a Peerless check list which shows what happens when  a riser to the steam main has its take off between to boiler risers.  

Tell us where you are located and perhaps we can recommend a good steampro to you. You might also check the Find a Contractor section above . Scroll down page the zip code to the States section as it is more accurate.

- Rod

trisha

doh!

First of all, DaveQC, thank you - you're absolutely right, the boiler is NOT  Weil-Mclain - it's a Peerless 62-14.  I said it was a WeilMclain because that's how the installing plumber registered it this past year when the city (I'm in Brooklyn) started enforcing the requirement to register boilers every 3 years.  He filled out the paperwork for the registration and I'm thinking now that he probably put the same boiler type for all of his customers to make the paperwork easier.

When Dave suggested I might not have the model right, I went to investigate and found there was no identifying tag.  I had to go back to the original contract from 1999 to see that it was actually a Peerless that was installed.

Between this bit of mis-information and all the comments on the lousy installation, I'm starting to feel not so good about my plumber!

Anyway, I'm planning to have a third plumbing company that isn't based in this neighborhood come check the thing out. 

sigh.

JStar

Boiler

I service Brooklyn. I'd be happy to offer a free assessment of the system and give a third-party opinion. Call or email any time:



908-337-3133

j.starosielec@ecuacool.com



The piping is a definite problem.

vaporvac

ACCEPT this Offer!

Hey Trish, I'm a fellow homeowner like yourself hit with the steam bug. Accept this offer from Jstar! Wish he serviced my neck of the woods. Consider yourself lucky. Colleen

P.S. Your piping is bad! I only repeat that because if I can see that it must be pretty obvious.