Steam from top of Central Boiler

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escape2idaho

New Member
Nov 17, 2022
3
Boise, Idaho
I recently purchased a property outside Boise that has an older Central Boiler. The model is CL5648SB. I don't know what maintenance the former did or didn't perform on the boiler. Judging from the shape of the chimney stack, I'd say minimal.

I started using it last week. Things have gone well, especially with the reduction in my electricity use, but I was just outside in the middle of the night and noticed steam coming out of the water intake and I'm hearing kind of a rumbling sound. The temperature was 185 which was about as high as I've seen it. Typically, it's been in the 150s and 160s, occasionally getting up to the 170s. Prior to beginning to use it last week, I added water to bring it up to the right level.

So, it's the middle of the night in the high teens/low 20s and I'm in a bit of a panic. I know it's an open system so I'm not concerned about it blowing up. I've checked the vent on the door and it closed properly once it got up to temperature. I can't check door rope because it's too dark.

Where do I go from here? In the short term, should I turn off the power? Should I add water? If I need work done on it, who works on Central Boilers? Any assistance or advice would be appreciated.
 

sloeffle

Minister of Fire
Mar 1, 2012
1,140
Central Ohio
People have talked about this on Facebook before. The water in the old CB's didn't stratify very well and you'd get pockets of very hot and cold water "combining" and they cause it rumble. The worst thing that will happen is water comes out of the vent tube at the top. It can't "blow up" because it's an open system. Make sure your return temps are over 140F and that you are pulling from the bottom of the boiler and returning to the top. I would also check for air leaks too that might be causing the temp to overshoot. My boiler is set for 170 on and 180 off and I've seen temps around 182 so far. Good luck !

EDIT: Maybe up your pump speed. That might help with stratification.
 
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escape2idaho

New Member
Nov 17, 2022
3
Boise, Idaho
People have talked about this on Facebook before. The water in the old CB's didn't stratify very well and you'd get pockets of very hot and cold water "combining" and they cause it rumble. The worst thing that will happen is water comes out of the vent tube at the top. It can't "blow up" because it's an open system. Make sure your return temps are over 140F and that you are pulling from the bottom of the boiler and returning to the top. I would also check for air leaks too that might be causing the temp to overshoot. My boiler is set for 170 on and 180 off and I've seen temps around 182 so far. Good luck !

EDIT: Maybe up your pump speed. That might help with stratification.
It's running fine now. The only thing I can think is the door wasn't completely shut. I think I always make sure it's securely closed, but I've learned that user error happens in various aspects of my life from time to time.
 
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escape2idaho

New Member
Nov 17, 2022
3
Boise, Idaho
It started running hot again last night and I'm positive the door was closed tightly. I was just wondering if the temperature of the house via the thermostat affects the draw on the CB and pulls down the water temperature. When it was blowing steam last night, my wife asked if, since it has a radiator, would it act like an overheating car when you turn on the heater. I increased the thermostat in the house by 6 degrees and the steam flow diminished. I wasn't sure if that was a coincidence or her theory worked. I only had the thermostat at 62 and then increased it to 68. We like it a bit cooler when we sleep.
 

maple1

Minister of Fire
Sep 15, 2011
11,019
Nova Scotia
It started running hot again last night and I'm positive the door was closed tightly. I was just wondering if the temperature of the house via the thermostat affects the draw on the CB and pulls down the water temperature. When it was blowing steam last night, my wife asked if, since it has a radiator, would it act like an overheating car when you turn on the heater. I increased the thermostat in the house by 6 degrees and the steam flow diminished. I wasn't sure if that was a coincidence or her theory worked. I only had the thermostat at 62 and then increased it to 68. We like it a bit cooler when we sleep.
Well, yes, heat needs a place to go. If the house isn't using heat, there is potential to overshoot boiler temps. Maybe match wood loads to heat demand? (Smaller fires).
 

akgal

New Member
Jul 24, 2022
27
Alaska
Until this year we had a Central 5036. We had some pitting around the door that caused air to get into the firebox on a windy day. Steam and a mini geyser could result. The geyser happened may 6 times in 3 years, steam monthly. We would put new rope seals in regularly but they only helped a short time. Check the state if your door, you may be able to repair or replace. Either way don’t let the steam freak you out. Just occasionally check your water levels, and if you have a glycol mix get it tested once a year.
 
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ian_L

New Member
Jul 31, 2022
6
Yukon
I am not sure what model I just got rid of. It was a 25 year old Central.

It started as steaming, as said watch the water levels.
It took 2 winters and not realizing more than once it was about to boil dry. -40 is a bad time to figure out garden hoses.
Firebox was sealed, changes door gaskets multiple times, door was not warped.
Then it began to run away, regularly.
The solenoid opening the draft. The arm connecting it to draft door had become slightly loose. It occasionally stopped door from closing completely.
 
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coolidge

Member
Dec 16, 2008
216
Maine
I remember reading somewhere, a guy used to stand his wheelbarrow up in front of his door on his CB, especially when the wind was blowing.
 

salecker

Minister of Fire
Aug 22, 2010
1,969
Northern Canada
CB's have a bad reputation,and a lot of that was amped up by the dealers who pushed them.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
7,762
NE Ohio
CB's have a bad reputation,and a lot of that was amped up by the dealers who pushed them.
CB didn't help themselves any when they decided to quit honoring the lifetime warranty on their doors...you know, the ones that said lifetime warranty right on them! Tip of the iceberg though...
 
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