Rollout (or Spill Switch?) Tripping on Brand New Boiler?
New boiler installed a few days ago. Crown, 199,000 for a multi-family building. The boiler keeps dying, despite several tech visits to reset. At this point the installer says the rollout keeps tripping and he thinks its the flue, but he doesn't sound sure and it doesn't completely make sense.
The flue is about 15 years old, galvanized steel. It runs out the basement wall and up three stories of the exterior of the building, and it is very well capped. Of course, the bottom portion was taken apart and put back together during boiler installation. Here's how things have unfolded.
Day 1: Tech finishes install and runs new boiler for 15 minutes then leaves. I come home and run it for an hour with no issues.
Day 2: I run the boiler for an hour with no issues. Same night, boiler turns on for 15 minutes then dies. When the thermostat calls, it makes a very faint hum, like it's calling, but nothing else.
Day 3: Tech comes, starts boiler, and uses gadgets to "test everything" and runs it for 15 minutes. Same night, boiler won't start at all. It's making a faint hum, like it's calling, but nothing else.
Day 4: Tech comes, starts boiler, and uses gadgets to test everything. (I know that's vague, sorry.) Says "everything is OK, so we think it's the flue. We have to come back. Do you want me to turn it off or leave it on?
I say, "if you think it's OK, leave it on." Five hours later the boiler is still running fine. I touch the flue on the first floor and it's warm. Third floor, it's warm. I go to the roof and it's not quite as warm as below, but still warm. The cap is completely in tact and the holes are too small for most birds. (Definitely too small for any birds you see around here. Too small for squirrels. Maybe mice, but they'd be crazy to climb the slippery steel brackets hanging off the building and they have many more options for shelter below.)
I'm now waiting for the installer to plan an actual flue inspection, but I don't think the boiler would stay on if there really was a clog, and I suspect the CO2 alarms would go off in the basement at some point.
Could they be missing something else?
Comments
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There is a super simple test for a flue problem: what is the draught in the flue, measured at the boiler exhaust? The tech. and his gadgets should have measured that — and should have left you the results. Did he?
Which is not to say that you shouldn't get the flue inspected, too. Should have been done before the boiler install, but… oh well.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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If the venting is not clogged then the problem is most likely the boiler does not have adequate combustion supply air. Is the boiler installed in an open basement or in a small mechanical room? Is there any exhaust fans in the building? Was the installation of the boiler inspected by the local authority who has jurisdiction over these things? Pictures of the installation would greatly assist with being able to help you.
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I assume the "rollout" switch is on the boiler draft hood where the exhaust gases go.
Not the burner rollout limit? (which is a one-time fuse link).
The draft hood limit is often referred to as "blocked flue sensor"…….which should tell someone something.
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This is a concern to me
"The flue is about 15 years old, galvanized steel."
I would like to see a photograph of this FLUE. Is it B vent? Is it single wall? Is it enclosed on the interior of the home? Is it exposed to outdoor temperatures?
The old boiler may have had some high temperature flue gasses leaving the basement, This new Crown Boiler may have lower temperatures that will make a poorly constructed flue (that worked fine on the old heater) insufficient for proper draft to pull the flue gasses from the building. Then those gasses will spill or roll-out where they should not go, making the roll-out of spill switch trip.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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1st this company doesn’t have 24/7 service number?
2nd forget the store bought CO Detectors. There only good to let you know it’s too late! They will not alarm until 70PPM is reached and exceeded for up to 3-hours.
You need a non-UL listed Low Level CO Detector for below 70 PPM for 3-4 hoursCall the company and give them 2 options
a) Correct what’s wrong
b) remove it.
199,000btu/h
That’s huge!
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199,000btu/h, That’s huge!
Multi Family. I hope it is more than 3 families or that each unit is a mansion size apartment
LOL
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Ha! Five apartments and two stores. It's replacing a 299,000 boiler that only lasted 9 years. When it's on it's much smoother and quieter than the 299, which I assume was decided upon before the walls had insulation and when the windows were single pane. Original construction was somewhere between 1898 and 1900.
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Just curious, how was it determined that 199,000 was the right size?
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SWAG Method. LOL
And now it won't work in that chimney.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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A boiler that is 50% smaller is going to fall at a different place in the vent tables in the code…
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The old boiler may have had a hefty standing piolet light that kept the vent pipe warm enough to induce a good draft when the boiler fired.
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Here are some photos. It's in a big basement, though partially sectioned off with wood slat, semi-walls. There are no fans, but there are windows we sometimes crack open. It seems really hot where the boiler meets the exhaust pipe. And the inspector matter is complicated. I live in a place experiencing a ton of development and minimal staff in city hall. Installers are generally allowed to move forward with emergency replacements but final approvals are often delayed.
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He did not. So I can expect them to give me the readout data? Thanks, this is good to know. I assumed they did check the flue when it was apart in the basement. Guess not thoroughly.
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It looks like the vent may be reduced and unless that is something insulated for 0 clearance, not just type b pipe, it is too close to combustibles on the outside.
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If I understand you correctly, you mean the fact that the flue pipe is coming out near the gas line, the igniter, etc. and running across the boiler before it goes out to the wall? The old boiler was different. The exhaust and pipe were on one side and went out to the exterior wall without touching anything, everything else was on the other side.
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I should clarify, the new boiler is 241,000 btu. It has two sets of numbers on the back, input says 241 and output says 199. I read 199 the other day and it stuck in my head. My mistake.
We had paid one HVAC company to include an "EDR" assessment in the estimate. They never gave us an official report, or a written estimate (so we decided not to use them). But I kept the radiator measures and found a chart online to compute EDR. I came up with 250,000. Four other HVAC companies suggested between 240 and 260. So when this last estimate came in at 241 we just assumed the stars were in order and went with it.0 -
Its hard to tell from the picture but is the roof flat?
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Yes. The roof is flat with a slight pitch towards the center, where the drain is.
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But I kept the radiator measures and found a chart online to compute EDR. I came up with 250,000.
What was your EDR total? You already confused input and output BTU in this thread (no judgment, just stating the facts), that's why working with EDR and Sq Ft is better.
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el0 -
Your vent location may be the cause of your problem. Here is an excerpt from a typical B-Vent manufacturer’s installation instructions.
6. VENT LOCATION AND ENCLOSURES
Selkirk Type B Gas Vents are recommended to be installed within the heated portion of the structure wherever possible to reduce heat loss which may in turn lead to poor draft and/or condensation and/or ice problems.The building can cause reverseventing action when the appliance is off, or operating on its pilot.In multi-family residential, highrise and many other types of buildings, codes specify that vents must be located in fire rated shafts or chases. Building Code requirements in such cases must be carefully followed with respect to wall construction, access, clearance, support, initial penetration of breaching, and method of termination. If an exterior location is necessary, an exterior located Selkirk Type B GasVent (as per Figure 4) must be:- Enclosed by a chase spaced out 1” from the vent at least to the roof line.- The enclosure should be caulked to prevent entry of moisture.- It is also recommended that his chase be insulated to a minimum of R-12(RSI 2.1).- Rigid type insulation is recommended. If a non rigid type is use, it must be restrained in such a manner so that the 1” airspace clearance to combustibles respected.- The bottom of the enclosure must be closed off.- It is recommended to provide an access panel for future inspection and cleaning of the vent Appliances served by an exterior gas vent must have an air supply to the appliance room adequate to balance indoor and outdoor pressures. Otherwise,“stack action” of the heated building can cause reverseventing action when the appliance is off, or operating on its pilot. In multi-family residential, highrise and many other types of buildings, codes specify that vents must be located in fire rated shafts or chases. Building Code requirements in such cases must be carefully followed with respect to wall construction, access,clearance, support, initial penetration of breaching, and method of termination.
In order to reduce the “reverseventing action” of that B-Vent, commonly called a Down-Draft, you may need to enclose that venting system as indicated in this photo.
Be sure that you use the proper insulation on the interior of the enclosure so as to prevent the insulation from coming in contact with the galvanized vent. If you have questions about this, you can always contact the build permit folks and ask the fire code official what is the best practice to enclose the vent. You may need a variance if the enclosure encroaches on the property set back.
OR just do it on the weekend and hope no one calls the building inspector on you.
And why all of a sudden, do I need to do this now, since it has not been a problem for 15 years? you might ask
Your old boiler may have has the same problem and someone fixed it by eliminating the roll out switch. which would have been dangerous because that would make it possible for carbon monoxide to enter the building on a regular basis. And it was cheeper that following the B Vent manufacturer's instructions. I do not recommend bypassing the Spill switch limit device. I recommend fixing the problem the correct way. @Bob Harper is the Flue and Exhaust expert on HeatingHelp.com. Lets see if he agrees.
Here is the link to the Selkirk B-Vent manual. You can also find the one for your particular brand online. it. will say something similar I'm sure.
https://www.selkirkcorp.com/literature/Model_RV_Cdn_Installation_Instructions.pdf
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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I may have missed it but,
Is the roll out switch getting tripped, or is the spill switch getting tripped?
There's a huge difference because the chimney / flue, to my understanding shouldn't effect the rollout switch when a drafthood is being used. The spill switch, absolutely. I'm not an expert, this is just my understanding.The spill switch is mounted up on the drafthood and the rollout switch should be down by the burners.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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@EdTheHeaterMan If that's a B vent, don't they require a minimum of 1" to combustibles? I.E. it shouldn't be strapped directly to the side of the house as shown in the picture? Wouldn't this need to be a class A vent?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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If you look close, there are special brackets that are strapped to the wall that have that 1" standoff you are speaking of.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Here are all the computations.
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So basically, when the system is off, the vent might be sending air back into the building and tripping the rollout?
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YES. When the vent is cold, there may be higher pressure outside and lower pressure inside causing a down draft. Then on a call for heat, that down draft will not let the exhaust gas up the outdoor vent stack, That will trip the spill switch. Now given enough time, that condition may reverse and the vent will start to work as designed, but if that time is too long, then you may be reading about CO poisoning at your building in the local news paper.
I like to read the instructions when there is something that is not working correctly. And you boiler is working as designed, so it won't be in there. The chimney is the problem and you will find that info in the venting system instructions.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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A simple way to see down draft conditions:
Shut boiler switch off
Locate blocked flue sensor under draft hood, remember where it is located
Set tstat to call for heat
Use a grill lighter with large flame to check for downdraft that might pass thru vent damper even when it is closed
Turn on boiler switch, while vent damper opens hold your flame in draft hood, under the Crown label, take caution to not heat up the flue sensor.
Observe the flame when the damper is open just before the burner lights
With burner running watch the flame…..it may down draft initially until a good draft is established up the flue pipe.
If the lighter flame comes out or down and stays that way after a couple of minutes, then there is down drafting from the top down.
You mentioned overheating where the flue pipe connects to the boiler, yes that would be hot but the exhaust should be traveling up the chimney.
You also may have to use "B" type vent from the boiler all the way to the outside pipe.
This $4 high tech gadget has been used by many for years.
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Your old boiler may have had the standing pilot and also not had a motorized vent damper.
Both of these factors may have kept the outside chimney warm enough to start the draft.
The pilot adding heat to the pipe and then with no vent damper, that would allow warm air from the basement to constantly rise up the vent pipe.
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Unless you did the radiator EDR incorrectly, you may have another problem on your hands this winter. According to the specifications of your boiler, you are 40% smaller than what might be suggested.
If you have 1026 Sq Ft EDR then your boiler is too small. Lets hope you counted wrong on the EDR
According the Crown Boiler specifications, the boiler you selected will handle 621 Sq Ft EDR. That is about 40% short of what you calculated on your spread sheet.
But stranger things have happened, The piping and pickup loss that is built into the boiler EDR is about 30%. so your boiler can handle 801 Sq Ft of radiation after all the mains risers and elbows are up to steam temperature. And maybe your radiators are actually oversized by another 30 % since the building has been made more efficient over the years with insulation, aluminum siding and window upgrades. All that may work to your favor. You should think about getting all the steam pipes you can get to (without opening up any walls or ceilings) in the building insulated so you have less piping and pickup loss.
I hope this all works out for you. If the contractor is the one that specified the boiler size, then you may need to get a good lawyer in February, after they can't make the boiler heat your building.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Thanks for doing all the sq ft lookups, Ed, and well-said on the ramifications. If I could snap my fingers and make one thing happen, it would be to make people never look at a BTU if they are working with steam, it's a constant source of mistakes and confusion. Since it's a multi-unit building, I am hopeful his boiler will be able to make it work…those are some big radiators.
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el1 -
It's interesting that this conversation started with folks worrying that the boiler was too big at my mistaken 199, and now that it might be too small at 241,000. The older 299,999 btu boiler was from another era - before double-pane windows, a remodel in 2006 with new insulation, new wood floors over the old wood floors that had no subflooring, and new exterior doors. The 299 heat was unbearable and most of us didn't use all our radiators. Before the 299 boiler went out, some of us purchased small radiators but didn't install them til now. They're the same size as the old bathroom radiators which often heated up my entire apartment, and so far the new ones get just as warm. Just can't get the damn boiler to stay on. :-/
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Right with you there, @ethicalpaul . Folks who make these things go to the trouble to determine what the steam EDR is — and then no one looks at it.
Now from the immediate preceding comment it looks like @NewGuy (or their contractor) may have happily jumped into the other steam booby trap. Steam is sized by the connected EDR of the radiation, not by the heat loss of the building. All that remodeling and insulation and doors and whatnot is all very fine, and will reduce the fuel used to heat the building. Wonderful. But it won't change the required size of the steam boiler to power the radiation.
No way.
I think our OP is in a world of hurt here. The installed boiler is too small, even supposing that somehow magically he can run at a 0% "pickup" factor. Just to clarify. He needs about 240,000 BTUh to power the radiataion. The chosen boiler has 199,000 BTUh output. Or he needs and EDR rating of about 1000 square feet, and he picked a boiler with a rating of 621 square feet.
Nope. Aint' going to work.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
I am not that quick to render judgment on how well the boiler will work (once he figures out how to keep it running!). After all, if the radiators are massively too large, they will never fill up all the way anyway during a normal call for heat and the boiler won't even know there is too much EDR connected. I know some people disagree with this idea, but it is obvious in my mind, think about it with me without judgment and see if you might agree.
@NewGuy as for us guessing the boiler might be oversized, you'll have to forgive us, but our experience around here has shown that at least 95% of all boilers brought to our attention here are indeed oversized by a great deal, sometimes over 100%. Of course once we saw your spreadsheet (assuming we trust it haha) we saw what EDR you were working with compared to the Sq Ft of steam of your boiler (which is the same as total system EDR it can handle)
NJ Steam Homeowner.
Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
See my sight glass boiler videos: https://bit.ly/3sZW1el
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Oh some of the radiation will heat, at least eventually. Unpredictably. And uncontrollably. And there are ways to make it work better — for two pipe systems. But getting all the radiators to heat to capacity if needed on a cold day? Nope. Predicting which radiators will heat and how much at other times? Good luck.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Guys install orifices for just this purpose, no?
If the capacity flat out isn't needed, why would it matter if you can't get them to heat to it as long as the system is properly balanced?
This is @The Steam Whisperer 's speciality.
One step at a time. Get the flue working correctly and go from there. For all we know it'll work perfectly as is.
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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We are all kinda' funny that way. one small bit if info changes the entire conversation to flip in a different direction. I have a feeling that your EDR calculation may be flawed. I would not worry about that right now. Although you are supposed to size your Steam Boiler to the EDR, those new windows and other energy efficient upgrades may be all you need to make that boiler heat your building.
Top get the boiler to operate with the existing vent you may need so the enclosure thing. I know that is not an overnight repair. But the only way to get it to operate to test the theory is to manually open the flue damper and make sure it does not close, place a temporary fan in front of the draft hood and force the draft out the vent to get it warmed up with basement air moving in the correct direction. Then start the burner and remove the fan within seconds of each other. If the vent starts drafting right away, the spill switch will not get overheated. And you will get the boiler to operate properly.
If I were your contractor, I would do this test for you in order to prove that the enclosing the vent is necessary. I would want to prove it to myself before asking you to hire a contractor to build this covering only to find out I was wrong. The covering must have the ability to keep the vent system warmer enough on the coldest day of the year from down-drafting. So pay particular attention to how you design and build it. A minimum of 1" clearance from the metal of the vent system to the interior of the enclosure so heat can rise from the basement to the top of the enclosure. warm air is lighter so it should rise, however if there is not enough insulation in the walls, that warm air can cool off pretty fast in the cold cold winter nights.
Finally while drawing this illustration it occurred to me that your new boiler has an automatic vent damper. Your old boiler probably did not. Your old boiler allowed heated basement air to leave through the vent system. That probably kept the vent warm enough to prevent down-drafting. If your vent damper has a switch to disable it, try keeping the damper open all the time to see if that helps.
EDIT:
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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It had a motorized damper and electric pilot. It wasn't that old which is another conversation... As for draft hood limit vs burner rollout limit, I think it's thr draft hood. Here's a photo under the draft exit:
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Spill, I believe. This one.
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Yessir,
That's the spill switch.
What was the temperature outside when you ran the boiler and it had an issue? Roughly?
And was the old boiler operated under similar conditions?
Single pipe 392sqft system with an EG-40 rated for 325sqft and it's silent and balanced at all times.
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