Loosing pressure very fast

NY_Hammer

My one-pipe steam system pressuretrol is set to 0.5 with 1. differential.

The story is once turned on by thermostat it takes about 7 minutes to get all radiators hot.  All this time pressure gauge next to pressuretrol  is raising slowly  from 0 to about 1 PSI. Once radiators are hot and vents are closed it goes very quickly to a little above 2PSI and boiler shuts off.

Then is the problem/question: it goes very fast within less than a minute to 0.5 and boiler starts again. In other words boiler short cycling until the thermostat shuts it off.



Is it a normal behavior or there is a problem, and if yes what should be done to fix it?





Thanks





Also worth mention is the fact that once the boiler starts for the first time, I can hear the water coming back in return lines. Is it normal?



And just to make sure there is no steam traps in one-pipe steam system?





Please excuse my questions< I am a beginner in steam systems, not a pro just a new owner of the old house with old steam heat system.







Thanks

 

 

Big-Al_2

Like Mine

Your heating system sounds just like mine.  My boiler was way too big for the amount of of radiation attached to it. I added a couple of radiators and downfired the boiler about 10% by installing smaller gas orifices in the burners.  It still cycles on pressure at the end of a long run coming off of a deep setback, but nothing like it used to.



No, that's not "normal" behavior for a properly sized boiler . . .  but it's typical for an oversized unit.  The boiler makes steam much faster than the radiators can condense it (once they are fully hot) so the boiler has to stop once in a while to let the radiators catch up. The only major downside is that it will use a little more fuel because it is cycling up to a higher pressure.  (After I downfired my boiler, the radiator vents got quieter, but I didn't notice a drastic drop in fuel usage.)



If the boiler were an ideal size, it might take a half an hour or more to build enough pressure to cycle off the pressure limit switch.  Some might tell you to install a lower pressure "Vaporstat" limit switch, but that doesn't address the root of the problem.  It would just start the short cycling sooner.  You need more radiation or a smaller boiler . . . or a little more cash in the checking account when the fuel bill arrives.

Jamie Hall

Well, Big Al

got the pressure and cycle thing right on the nose, so all that's left for me are the other questions... !



Yes, if you have decent hearing it's often possible to hear the water coming back in the return lines.



No, usually no traps on a one pipe steam system.  There are, of course, exceptions.  Just enough to keep one on one's toes.



And don't worry about asking questions -- there are no silly questions, just silly answers, which I try to avoid!  It's how we all learned this stuff.

NY_Hammer

need more details

Thanks for the quick answers.





So the reason for short cycling boiler is over fired boiler?

Does it also explains the quick drop in pressure that I described and which actually causes the boiler to start again?



I have those return line in the open in the basement so can hear the water.

My concern was it starts right after the boiler starts. I would understand if it happen after a while, but right away?





Thanks again

 

Big-Al_2

More

Not over-fired.  That term would imply that the burner was set to burn more fuel than the original rating . . . just over-sized . . . too big.  A steam boiler needs to be matched to the connected load.  If it's too big, the system cycles on pressure too much.  If it's too small, there isn't enough steam to fill all of the radiators, and the system will never cycle on pressure . . . and some radiators might stay cold all the time.



The quick pressure drop comes from the fact that there isn't much heat stored in the iron of the boiler.  After the burner shuts off, the amount of steam produced by the boiler drops off quickly, but the steam in the radiators keeps condensing at about the same rate.  Because the condensing is happening faster than the boiling, the pressure drops fast.



You hear a noise soon after the boiler starts up?  Is it a trickling noise or more of a whooshing noise . . . like somebody is running water upstairs and you can hear it in the pipes?  When my Burnham IN-6 boiler starts up from cold, I hear a kind of a whooshing/hissing noise after a minute or so, but it goes away by the time the boiler makes steam for real.  I'm not 100% sure what that is, but I'm speculating that there is some condensation in the upper part of the boiler that flashes off as steam long before the water at the bottom comes to a boil.  Is this what you are hearing?

Rod

Get the Book!

Hi- Since you're new to steam you might want to get some of the steambooks that are available on this website . Start with "We Got Steam Heat!"  It's a good introduction to residential steam heating.

http://www.heatinghelp.com/products/Books/5/61/We-Got-Steam-Heat-A-Homeowners-Guide-to-Peaceful-Coexistence

It's written for the homeowner new to steam. It's easy humorous reading, filled with diagrams and pictures. In an evening or two of reading you'll be light years ahead in your knowledge of residential steam systems. It is what most of the homeowners here started on and will save you a lot and make you more comfortable.

- Rod

Jamie Hall

Listen to a tea kettle!

Have you ever noticed that it is a good bit noisier just before it boils, than when it is boiling?  Maybe that's your whooshing noise, Al?  Can't hear it on mine -- that lovely efficient forced draught Carlin of mine quite overwhelms that sort of noise!

NY_Hammer

trickling

Now I started to understand the fast pressure drop and got the terminology right .

Over sized, not over fired LOL





My return lines sound, is exactly as if somebody is running water upstairs.

 

Big-Al_2

Not quite like a tea kettle.

Mine goes like this, but only when starting dead cold: At one minute, the noise starts.  I can hear it in the steam pipes all over the house.  It sounds kind of like a toilet tank is re-filling somewhere.  At three minutes, the noise stops.  At ten minutes, the boiler starts steaming. 



Whatever is making the noise, like maybe water droplets at the top of the boiler, seems to be gone long before the rest of the water is all that hot.  That's why I'm speculating that there is some water clinging above the normal waterline.  Since the top part of the boiler isn't under water, it might heat up pretty fast.

Big-Al_2

Quiet

You must have a very quiet boiler . . . or maybe your ears haven't been exposed to as much industrial noise as mine have been.

NY_Hammer

not really

that particular return line is vertical pipe across the basement, around 8 feet from the boiler.

And of course I have to listen to hear it, it's not loud at all.

David Nadle

Not only oversized

My boiler's output is 1 ft^2 less than the attached EDR and it loses pressure in under a minute. I think this has more to do with the vents than the boiler. 

Big-Al_2

Universal

Any boiler will lose pressure quickly when the burner shuts off.  It's just the oversized ones that build pressure too quickly when it comes back on.  The vents shouldn't play a part at all.  If the system is under pressure, then the vents are typically all closed anyway.  They won't open again until they cool off, and by that time, the system is probably pulling vacuum.

Big-Al_2

Hmmmm.

All my pipes are insulated.  Maybe I would hear drainage if they weren't.

NY_Hammer

another related question

Should I insulate return lines as well?



it's so called wet return line.

Charlie from wmass

Check all vents

Start with the basics. You may have a few vents that are not closing quite fully. A cold piece of iron or other metal held to the vent port once your system shuts off on pressure and the radiators are heated all the way across.

Big-Al_2

Not as critical

Insulating a return line is not as critical to operation as insulating steam lines, but it isn't a bad idea.  I insulated ALL of my basement steam system pipes.  I figure that any heat that I can keep from escaping into areas where it isn't needed will result in less fuel being burned.

David Nadle

They shouldn't, but they do.

Ideally vents should hold until they cool off but in reality they don't always do so.

NY_Hammer

Trying to investigate on the boiler over sizing

Any idea what model this apparently Weil-McLain boiler could be?

At the same time if anybody can see anything wrong with around boiler piping?





Thanks

Dave in QCA

Probably a Model E

Sure looks like a Model E, probably about an E-8.

Take off the front access panel, you will find a rating plate inside.  It will have the model number.  Will also indicate the Steam EDR or sq ft. 

You can compare that to the radiation in your system to see if it is oversized.



As for your piping...  ugh... There is no equalizer and no hartford loop.  In otherwords, it's pretty much all wrong.

World Plumber

leaks, vents, condensation

If there are any piping leaks or leaking vents the pressure will drop off fast or not build at all. Also the cold cast of the radiators condenses the steam reducing the pressure. Does the boiler run considerably longer than the off cycle?

    I just repaired some piping leaks in a system that never went off on pressure. The concreted the floor and the leaks became noticeable. Now it is cycling off for a minute 37 seconds and firing for 3 minutes 49 seconds. Not sure if I should mess with the firing rate.

      By the looks of your piping your probably getting wet steam. It doesn't appear to have an equalizer coming down from the header. Any water will be pushed along with the steam. Can you notice a drop in the water level when the boiler starts to steam?

   Are you having other problems besides the sound of the water flowing? If not then it's cost vs operate as is. Other wise the near boiler piping is a starting point.

   Check out "it's a Steamy Deal" in the store section.

NY_Hammer

I will take and post more pictures

There is a pipe that drops down from the spot where header joins system riser.

May be it serves as an equalizer even though it's a small sized pipe.

This pipe marked red on following pictures.



The water level in the glass is right in the middle when boiler starts and goes down to about 1/3 if the glass as the lowest point.



I do not have other problems except for above mentioned short cycle and some minor water hammer in one of the risers in the wall or just under one radiator.

The main problem is .... gas bill



I changed most of the radiator vents and now all of them are working fine for sure.

Also the problem was the pressuretrol was set up to 5PSI with 1 psi differential.



I adjusted that of course  to 0.5 PSI and 1.5 differential.







The house consist of  finished basement with 3 radiators, and two floors with 13 radiators all together.



Also may be worth mentioning I don't have traditional iron radiators but heating convectors  recessed into the walls.

Bob Gagnon plumbing and heating

Steam Boiler

How often are you adding water, you might have a water leak vaporizing and going up the chimney.



Thanks, Bob Gagnon

NY_Hammer

not very often

In case I have that leak you mentioned where could that be?

In the boiler itself?





Thanks

NY_Hammer

Yes it is E-8 series 3

Rated 613 sqf for steam.



Any link to the docs on this boiler?



Thanks

Bob Gagnon plumbing and heating

Leaking Boiler

It's hard to read you post, my boiler picture runs over your wording. Does anyone know why this happens?? If your adding water every day or two your boiler could be leaking, if your adding it every week or two you should be OK.



Thanks, Bob Gagnon

NY_Hammer

I will repeat my post

I add water only once a week if necessary.

Sometimes it once in two weeks.

In case I have that leak you mentioned where could that be?



In the boiler itself?

I doubt it, it would show up on the floor under the boiler I guess.



 

Dave in QCA

Click Refresh

Bob, I have the same problem from time to time.  Usually, if you click refresh, it will clear it up.

Bob Gagnon plumbing and heating

Boiler Leaks

Steam boilers often leak at the water line, and as the water steams it turns to vapor and goes up the chimney, you never see it, but it doesn't sound like you have that problem.



Thanks, Bob Gagnon