Short cycling on new steam boiler

DamnYouSandy

Hello and many thanks for any help you can offer.



Our Burnham gas fired steam boiler (Independence Series, Model # SIN6LNC / LE2) was destroyed by Hurricane Sandy, and we just got an identical replacement. My question is about proper settings for the Honeywell Pressuretrol given that the boiler has been short cycling and taking much longer to produce full heat.



When the thermostat calls for heat, the boiler has been running for 25-35 minutes. Then, it shuts off and starts a pattern of running for 3 minutes, cutting off for one minute, then restarting for another 3 minutes, and on and on. Although the radiators start to get warm in those first 30 minutes, they're not delivering the same full heat as before. (FYI, I've isolated the thermostat wires, and the same results occur, so I know it isn't a thermostat problem.)



The settings currently are 2 PSI on the main, and 1.5 PSI on the differential. With the current settings, the boiler runs until 2.75psi on the gauge, cuts off, then restarts at 2.25psi. This is a large scale gauge (0 to 20 or so psi), which I know are not the most accurate, but that seems to me like the pressuretrol settings are not being followed--is that device faulty?



The installer has told me to adjust to several settings, including having the differential set to 2psi and the main a 1psi (which doesn't make sense to me, but I'm no expert). Nothing else has worked, and the results (3 mins on, 1 min off) have been the same. I know modern boilers shut off to save on fuel, but cycling on and off within one minute doesn't seem right to me.



Any help is greatly appreciated! Many thanks.

Paul48

?

Did the installer leave a copy of the digital combustion analysis with the documents for the boiler?

DamnYouSandy

?

No, unfortunately, no digital combustion analysis docs were left with the boiler, only the basic installation guide from Burnham.

Paul48

Normally

I'd say ...call the installer, but that would be a waste of time. It is time to bring in a steam pro. Your installer is just that....an installer. He will not get your system functioning properly, and you're wasting fuel dollars. If you're interested, give your location, and I'm pretty sure there's someone close to you.

DamnYouSandy

Info

Paul--thank you very much for your posting. The installer has said it is just a matter of finding the right main and differential settings for our house, and that settings will vary for every installation with one-pipe steam systems.



I'd be happy to get a recommendation, we're in New York City, in the Rockaways, Queens.



In the meantime, does this seem like a problem with the equipment, or just the settings? We had the exact same boiler previously, and never had a problem, so I don't think there are any issues with the steam system in the house overall.



Many thanks.

Jamie Hall

Somethings fishy...

If the boiler is shutting off on pressure -- pretty much regardless of the pressure -- before the radiators get hot, there is something very much amiss.



First thing to do is to get the pressure under control.  While it is true that various systems run sweetest at various pressures, it is very rare indeed to find a system which runs over 2 psi.  Therefore, since what I read in your post suggests that your pressuretrol is additive, the main should be set as low as you can -- say 0.5 psi -- and the differential to 1.5.  If you have to go higher on the main, say to 1, go lower on the differential, say to 2.



And give that a try.  It is possible -- though not likely -- that the vents on your radiators are closing and are not able to reopen due to the pressure.



I would be inclined to wonder, too, if the boiler is firing at the same rate as the old one.  If, in fact, the installation is exactly the same and piped exactly the same and fired exactly the same, it should work the same!  Therefore, something is different -- and the question is what.



Do you have main vents?  And if so, did they get flooded?  And if they got flooded, do they still work?



There are a number of really good steam guys in your area; try looking in Find a Contractor, but look by state, not zip code.  It works better that way.

Paul48

If

the boiler was not skimmed properly,  or set up with a digital analyzer,it's possible you're not getting the proper btus out of the boiler. If the smallest amount of oil is left in the boiler from the install, it will spit water up into the mains and further reduce the steam output. Observe the water in the sightglass when the boiler is making steam. Is the water level fairly steady, or is fluctuating wildy?

JStar

Steam

How was the boiler sized? Did they measure the radiators or just match the old boiler? If the pressuretrol is working correctly, I would look at your main venting, and suspect that they are not working or not big enough.

Paul48

What

does it say on the cover of the pressuretrol? Cut In? Main Scale Cut Out?