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Spill switch

in Gas Heating
Hello All,
I have a customer how had a Burnham Independence steam boiler installed three years ago. Last year the spill switch tripped and shut the boiler off. Homeowner reset it and worked fine. Tripped again toward the end of the heating season. I went by to reset it and checked the chimney for blockage and draft, all seemed good at the time. Well it tripped again this year and was reset. The room seems to have ample air for combustion, but left a boiler room window open to see if that was the problem, it tripped again a few weeks later. I does not trip all the time just once in a while.
Anything to look for? Should I change the spill switch? It's located in the back of (close to boiler) the built in draft hood.
Thanks in advance.
I have a customer how had a Burnham Independence steam boiler installed three years ago. Last year the spill switch tripped and shut the boiler off. Homeowner reset it and worked fine. Tripped again toward the end of the heating season. I went by to reset it and checked the chimney for blockage and draft, all seemed good at the time. Well it tripped again this year and was reset. The room seems to have ample air for combustion, but left a boiler room window open to see if that was the problem, it tripped again a few weeks later. I does not trip all the time just once in a while.
Anything to look for? Should I change the spill switch? It's located in the back of (close to boiler) the built in draft hood.
Thanks in advance.
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Comments
Is the pressure set pretty high on the control that it may never cycle and get a chance to cool down?
Or the limit button could be wimpy and popping early, can't be much money to change that.
I would check the firing rate maybe you can reduce it slightly less input needs less draft
Danny, thanks for that tid bit, I was wondering how long before the spill switch trips.
Thanks again everyone. I'll keep you posted.
Inspect the chimney, make sure it's sized properly and lined.
Any huge kitchen exhaust hoods without a proper makeup air damper that could be causing a down draft? What about fire places? Whole house fan someone had running with the heat?
Something is starving the mechanical room (basement?) of air, or the chimney isn't drafting, randomly. Sounds like a switched fan somewhere to me.
The good news is because of how a drafthood works, if the appliance is spilling in theory it shouldn't be spilling any more CO than when connected to a proper flue. This is typically very low, 0-50ppm? Many do not realize a draft hood appliance doesn't require any outside draft to burn properly. But you're still venting a huge fuel burning appliance into a home. The real dangerous side comes when the appliance runs out of O2 and starts spewing CO because of it.
The bad news is I still wouldn't want it in my house very little CO or not.
Went to the job today and met with chimney person. Flue is 6" and about 25' tall (Outside) and all clear. Hooked up a draft gauge and the draft was 0.01(above the built in draft hood and vent damper) and would not rise. Turned on the water heater that is connected to the same flue and still no rise. Chimney guy and the roof felt a very good draft while I got nothing at the base of the vent. When the burner turned off (water heater is already off) the draft gauge did not move up or down. While the burner was off and the damper closed the chimney guy disconnected the W/H flue and put his hand over the 4" and the draft gauge went up almost 0.05". I have clue why that would happen.
I also clocked the gas meter and found it over firing about 15,000 BTU's (boiler is 140,000 input). I adjusted the gas valve and got it down to the firing rate.
I hooked up my combustion meter and the numbers were way out of wack.I pulled the burner cover off and found part of the flame retardant material missing behind the burners (left side only) and what looked like soot on a couple of burner tubes. I pulled two burners out and they were a covered a little and had some soot in them.
I will go back and remove the draft hood and check out the sections and will clean if necessary.
Any suggestions would be appreciated.
Best solution is to install barometric vent dampers on both appliances. Alternative would be to install a restrictive orifice on the draft hood of the water heater to restrict the amount of relief it can provide to the main stack. Tricky proposition when the vent connector is only 3" to begin with.
In any case, if you do install barometric dampers, you will need to install a roll out spill switch that is interfaced with the thermocouple of the water heater to avoid long term spillage from the barometric damper.
ME
A roll out switch and spill switch are two different devices. A double swing barometric needs a spill switch installed as per the manufacturer's instructions. Two spill switches, one mounted on top and one mounted at the bottom of the barometric is even better but most consider one good enough.
I don't get what your saying about a relief vent at the water heater. The water heater flue is 4" and about 18" long before it hit the 6" wye coming out of the chimney.
The boiler has a built in draft hood so I don't think I can install a barometric damper on it.
I'm just trying to get to the bottom of the problem that just started in the last 18 months. Everything seemed to be fine the 4 previous years.
Nothing has changed in the house.
However, barometrics reduce draft, they can never increase draft which is why I'm a bit baffled by the recommendation.
Perhaps @captainco or @Tim McElwain have a recommendation.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
You couldn't look straight down mine though as there was an offset in the attic.
When the flue come up from the draft hood how far does it rise up before it turns toward the chimney??
A word of caution, and I am sure that Jim and Tim will concur. If you choose to do ANY of these recommendations, you are modifying the appliance outside of its approved application, and you therefore are responsible for and assume all liability for any dangerous situations that might occur.
Quite honestly, if you are not certified and qualified to do this work, then don't. Find a person who IS properly trained to handle it for you. Qualified people can be found at https://www.nationalcomfortinstitute.com/pro/index.cfm?pid=1072
Sorry to be so blunt, and I have been through the certification process, but I can't tell whether you are a licensed professional who is qualified to do this type of work, or not.
ME
Thanks
Safe travels and never stop learning. If you get a chance to attend one of Jim Davis (Cap'n CO) classes, or Tim McElwains classes, by all means do so. Money well spent in either case.
ME
Drafthoods are designed to prevent appliances from venting and totally eliminate the control of combustion air to the burners.
Barometric connect the flue to the equipment and control venting and combustion air under all variable conditions. Barometrics when set up correctly do not allow dilution air into the flue until all the flue gases go out first. A drafthood does just the opposite which is stupid. Barometrics minimize dilution air whereas drafthoods maximize it.
Spill switches needed to be added to the barometrics which will shut the equipment off if the flue gets restricted or there is severe negative pressure.
As Mark said, it really requires someone who has the training and knowledge to do this or at least consults with us that do. I personally started eliminated drafthoods from appliances back in 1979, not necessarily for this type problem initially but this ugly problem showed its face very soon.
Flue restrictors are only recommended when used with barometrics and then only if draft is always in excess of -.05" or higher 12 months a year.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
Would it be possible to have some pictures of the chimney and the connected appliances along with their flue piping?
Hatt, did not think of the knock out plug. Will look into that when I go back.
Chris, I will take pictures when I go back just don't how to upload them onto the site.
Boiler room really never gets hot. The roon is roughly 13' x 28' with a open doorway and 4'x4' opening into the other side of the basement (same size).
Thx again to all
Not sure how to do it on a phone.
Here is an update.
When back to the job and took some combustion reading while on the phone with David from NCI (thanks for the recommendation ME) and all the numbers were in normal range. The draft for the boiler were -0.02 while running and jumped a little when shut-off. Spoke to Burnham about the spill switch and got a little lesson the inner workings of it along with the temperature its designed to shut off at. Used my meter to check the ambient temperature near the spill switch and it started at 98 while the boiler was running and went up to 168 when the damper shut-off, which is all below the 200 or so its designed to shut-off at. All seemed fine until I heard the auto feed come on and did some investigation. Was a little surprised to find the boiler has a hole in it.
Not sure if that could have something to do with spill switch but who knows it might.
Need to replace the 7 year old boiler.
I'll keep you posted.
cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating