New Gas Steam boiler short cycles

Gaz

There is no banging but one side (not sure which one) does heat up faster. 
Nde do you really think that pressure is locking up the system?

Gaz

EBEBRATT-Ed

@Gaz the pipe orientation for the old boiler does not matter the old boiler is gone. You will never be happy with this boiler the way it is piped. Modern boiler are a different animal especially on steam. Your installer did not follow the MFG minimum piping requirements.

This is one of the sole reasons this forum exists. We get boiler piping horror stories on here every day. And they is no reason for it. It's printed in the boiler manual. You can't skimp on the basics with steam. If you do it will not work.

Gaz

Could it be why this new boiler starts short cycling on pressure?

ChrisJ

It's behaving like it's piped wrong and it is piped extremely wrong.

That combined with dirty water is likely causing your problems.

You can try skimming it a lot and hope for some improvement but it'll never be right.  

nde

Yes, for sure it is pressure related b/c of improper piping, no skimming and possibly venting issues. Did they pipe the skim port for use? If the installer is now awol I would skim it yourself (take at least 4 one hour sessions) and then put as much venting on the main that is slower to try and balance it out. Likely one main and rads run is getting hotter faster but could be both need venting. If me I would put gorton #2 on each main and gorton 6 on the farthest rads on each main. These are the fastest best quality vents (generally) and are not cheap but your only hope if no repipe is to vent the air asap. Keep the thermostat at fixed temp as well (no swing temps). Finally it's tough to say it b/c I hate them but your install is why the cyclegard was invented. Looks like they used safgard (which I prefer on proper install) but cyclegard is designed for hack installs to reduce pressure cycling and water hammer.

fwiw I dont think the boiler is necessarily oversized as steam edr tends to run average 200+ per 1000 sf heating space under normal design where every rads is open and working..... so 3200 sf seems about right for 600+ edr. It def needs a skim and better venting but ideally a repipe as well.

ethicalpaul

but cyclegard is designed for hack installs to reduce pressure cycling and water hammer.

Well this is not true, but it can help with the issue as a side-effect of its operation.

The cyclegard was designed to get an accurate reading of the water level of the boiler which can only be done when the water isn't boiling. LWCO devices can be "tricked" into "thinking" there is a higher level than there is by this sloshing of the surface of the boiling water, so the cyclegard shuts off the burner for a few seconds a few times per hour (depending on model)

ChrisJ

ethicalpaul said:

but cyclegard is designed for hack installs to reduce pressure cycling and water hammer.

Well this is not true, but it can help with the issue as a side-effect of its operation.

The cyclegard was designed to get an accurate reading of the water level of the boiler which can only be done when the water isn't boiling. LWCO devices can be "tricked" into "thinking" there is a higher level than there is by this sloshing of the surface of the boiling water, so the cyclegard shuts off the burner for a few seconds a few times per hour (depending on model)

It's my understanding that commercial boilers have a cylinder on the inside to create a "deadzone" for the probe.

This would be a much better solution than shutting the burner down.

Gaz

I did the skim about 4 times each over 3 hours.  It didn't help. I added goron #2 vents on each main.  It did help a little.  I added Scout cleaner which helped alot with surging and even brought the initial start up run time from 30 min to 40 minutes.  But afterwards it still keeps short cycling on 3min off 1 min.

ethicalpaul

All those things can help and are good, but if your boiler is oversized, it will tend to cycle on pressure. You would rather the boiler turns off periodically rather than run for no good purpose, so cycling on pressure is a reasonable reality.

ChrisJ

Gaz said:

I did the skim about 4 times each over 3 hours.  It didn't help. I added goron #2 vents on each main.  It did help a little.  I added Scout cleaner which helped alot with surging and even brought the initial start up run time from 30 min to 40 minutes.  But afterwards it still keeps short cycling on 3min off 1 min.

Is the water staying in the boiler overall?

I.E. do you see the water in the gauge glass bouncing up and down a lot and getting lower fast? Or does it seem to stay fairly steady moving up and down an inch or so?

If it's bouncing a very small amount and not dropping fast your water is probably pretty decent.

ChrisJ

@Gaz
This is about what you want your water level to behave like while producing steam

https://youtu.be/dPIx0xnEVUo?si=q1DhfYbUmGgz6j3f

If it's a little worse that's not a problem, but a lot worse is a concern.

109A_5

Hello @Gaz,

If everything (system wide) is corrected as good as it is going to get, and the basic issue is a greatly oversized boiler building pressure due to the available EDR used, and the 4 minute / 1 minute cycle events have been proven to be a pressure issue, I would use a timer.

Boiler runs, all the radiators get hot, air valves close, pressure rises quickly, Pressuretrol or Vaporstat shuts down the boiler until the pressure drops, pressure drops quickly, boiler restarts scenario.

A timer can stretch the off time so you are not doing the rapid on-off-on-off-on-off-on-off until the thermostat is satisfied thing.

You can set the delay (maybe 5 to 10 minutes) to give the radiation time to warm the room(s), condense the steam they have, and thus greatly reducing the amount of needed boiler cycles for one thermostat cycle. The more the steam in the radiation is condensed the longer the next boiler cycle will be (if entirely needed).

Inexpensive, and easy to try.
One timer example;

https://www.supplyhouse.com/ICM-Controls-ICM203FB-ICM203F-Delay-on-Break-Timer-6-Wire-Leads-03-10-Minute-Knob-Adjust-Delay

Dan_NJ

Jamie Hall earlier mentioned that even though the rated output of the old vs. replacement boilers may be comparable, the old one could have been downfired making it effectively much less output. It looks like your photo shows the old boiler still in the boiler room - how about a pic of the plate on that one for comparison? How many burner tubes does it have? I was considering taking burner tube out of my Peerless 63-04 to make it a 63-04L due to it being oversized but I got out of that place before getting around to fixing my botched install.

JUGHNE

For down firing, the burner tubes may still be in there, but the brass orifice may have been replaced by a plug.

A bent paper clip would let you poke into the orifice to see if they are blank plugs.

Gaz

Its got the same number of tube which is 10.
ChrisJ. Thats how much bouncing I get now after adding Scout boiler cleaner.

Gaz

This is the old boiler prior to the new Williamson.  

Gaz

JUGHNE

Yes, 10 burner tubes. But did you probe to see if all the orifices' have openings in them?
The orifice opening would point towards the back of the boiler.

109A_5

Manifold


Orifice


Plug (no hole)

Gaz

I'll check but I know that all 10 fire.

109A_5

Hello @Gaz,

Gaz said:

I'll check but I know that all 10 fire.

I think the point was, do you still have the old boiler, and can you check the orifices on the old boiler's manifold to see if the old boiler was down fired (orifice(s) removed and plugs installed) to better match the old boiler's output to the building's actual Equivalent Direct Radiation (EDR).

The old boiler's output may have been intentionally significantly reduced. So now the new boiler is effectively behaving as a much bigger boiler even though the BTU ratings of each boiler are similar.

Gaz

Can anyone say for sure its oversized?
I roughly measured them up to 610 sq ft steam.
I have a GSA 238.

Gaz

ChrisJ

Gaz said:

Can anyone say for sure its oversized?
I roughly measured them up to 610 sq ft steam.
I have a GSA 238.

Without being there and actually listening to vents etc no I can't say for sure that it's oversized.

But 238k input, 198k output and it's piped like that?

I can say it's piped terrible and it's hurting it's performance.

109A_5

Gaz said:

Can anyone say for sure its oversized?
I roughly measured them up to 610 sq ft steam.
I have a GSA 238.

Seems good, very close Boiler Sq. Steam to your EDR, you should not be building enough pressure to short cycle, are you sure it is actually a pressure issue ?

109A_5

Hello @Gaz,

Are the pipes the correct size ? If the steam can't get out of the boiler correctly it will build pressure.

nde

Other than recipe one more thing is could be almost plugged at return low spot. This would explain why it limits after long run.  Do you see a clean out valve before the Hartford loop? Flush any clean outs with boiler off.

Otherwise the main with the "straight pipe" must be screaming hot and other side cooler to build pressure on correct sizing at set temp. Thermostat in cool main side? You need that 90 turn on exit pipe before feeding mains equally.

Gaz

I hear the pressutrol cutting out every time. I also see the pressure rising on the gauge(around 2.5 psi, which is what its set for on the pressutrol) every time just before it cuts out..  Not sure how test it though.  

Gaz

I just want to see if the boiler was oversized.  It was concerning me.
I agree the piping is not to specification.

Gaz

The thermostat is on the side which the boiler is connected to the straight pipe.
My returns take an hour to even warm up.  They stay cold for that long.
The valve at the bottom of the return by the hartford loop has clear water coming out of it.

Gaz

The pipes coming out of the boiler are 2.5 inches diameter vs 3 inch requirement. 

ChrisJ

When it starts doing this are all of the radiators heated all the way across and down?

reggi

From a cold start ..30 minutes then 3:1 

Are you using setbacks on your thermostat? 

In those 30 minutes how many of those 18 radiators are hot and is it possible the thermostat is satisfied.... even briefly before calling for more heat again ?

I'll tell you why I'm asking about the setbacks... If I turn my boiler off and the house cools down before I'm done doing what I'm doing and I start it up and have to bring the house temp. back to 68 from low 60's I'll start it and hang out and keep a eye on the pressure, once it trips I'll turn it off for a bit because the steam from the boiler has no where to go because the radiators aren't needing more steam right then and it's backing up in the pipes and the boiler pressure is increasing trying to push it out... so I shut it off for a bit..give everything a chance to catch-up..then refire and maybe once more... Only because of trying to make up 4+ degrees..along those lines 

Gaz

Its not,
I watched it.  Once the temp has been reached it just shuts down till the temp goes down hours later.

Gaz

Btw The orifices on the old one were all open.

Gaz

Also noticed as the boiler approaches the 40 min mark of non stop heating the water in the glass also starts going down about 1/2 inch with pressure increasing and then boiler shuts off.

Gaz

Then the 3 on 1 off till thermostat satisfies.

EBEBRATT-Ed

@gaz You might want to measure the pipes again. 2" pipe is 2 3/8" OD, 2 1/2" pipe is a little shy of 3"OD and 3" pipe is 3 1/2" OD

Gaz

Its says 2 1/2 on the fittings the pipes are attached to.