Can someone explain flame rollout to me?

Sd134

This is part 2 in a series of me trying to figure stuff that's long overdue.

Anyway, hydrotherm steam boiler....I had an automatic rollout switch that broke apart many years ago, so the two wires have been hanging down by the side of the boiler, still attached to the terminals at the back of the switch, and never tripping because it's too far from the boiler. The other piece of it, the metal "plate" still remains attached to the boiler.

I know, I should have replaced years ago.  I mean, it's been at least 5 years like this and working fine, or so I thought.

So I buy a new switch, actually a manual reset that trips at 300f since the old switch had 300 printed on it.  I screw it to where it needs to be, and soon enough it trips, keeps tripping actually.

I unscrewed the new switch away from the boiler so it would run unimpeded and measured the temp at the spot where it was previously attached using a multimeter....312f, so it makes sense that it would trip.

So I'm trying to educate myself and looking for videos of what flame rollout actually is, because I don't actually see any flames coming out the front anywhere close to where the switch goes.  But when I crawl on my belly and turn the light out I can see five burners burning with strong high flames that doesn't appear to be out of control.....to me (admittedly not a pro).....but boy is it hot.

So I'm not sure if what I have qualifies as flame rollout.....I think it's safe to assume that everything needs cleaning, but will that reduce the temp of the flames coming from the burner.

Open to comments, questions, etc...if I can post pics/vid, I will. Thanks in advance.

Sd134

https://streamable.com/g5l458

That's a link to 3-4 seconds of video of the flame, if it helps

Jamie Hall

Perhaps it is a little misnamed. In many -- not all -- cases there is actually flame coming out where it sholdn't, but what one is actually concerned about is the hot combustion gas (which may not be still glowing) coming out. This you absolutely do not want. Not only may there be a fire hazard involved, but combustion gas may contain carbon monoxide, which is quite lethal.

The flame rollout switch is an essential safety circuit, and is required to be functional for the boiler to be safe.

The usual causes are poor overfire draught or overfiring the burners -- or both. The poor overfire draught may be from soot clogging the flame passages in the boiler; they do need to be cleaned now and then!, or it may be caused by something amiss with the chimney. The overfiring is usually too high a gas pressure (the regulator failing or simply misadjusted) or something amiss with the orifices.

Your video looks as though the unit is overfired, but you really should get a qualified technician in there to check everything, clean the boiler, and set the combustion properly.

You have been very very lucky. Go buy a lottery ticket.

pecmsg

Jamie Hall said:

Perhaps it is a little misnamed. In many -- not all -- cases there is actually flame coming out where it sholdn't, but what one is actually concerned about is the hot combustion gas (which may not be still glowing) coming out. This you absolutely do not want. Not only may there be a fire hazard involved, but combustion gas may contain carbon monoxide, which is quite lethal.

The flame rollout switch is an essential safety circuit, and is required to be functional for the boiler to be safe.

The usual causes are poor overfire draught or overfiring the burners -- or both. The poor overfire draught may be from soot clogging the flame passages in the boiler; they do need to be cleaned now and then!, or it may be caused by something amiss with the chimney. The overfiring is usually too high a gas pressure (the regulator failing or simply misadjusted) or something amiss with the orifices.

Your video looks as though the unit is overfired, but you really should get a qualified technician in there to check everything, clean the boiler, and set the combustion properly.

You have been very very lucky. Go buy a lottery ticket.

Ill agree with all the above except.............The The flame rollout switch is the Final Safety before bad things happen!

JakeCK

Let it be clear that switch you just replaced may have saved your and your families lives by letting you know something is a miss. 

You really should have someone come out and do a combustion test occasionally even if you are the diy type who can maintain the boiler yourself. If you have an older boiler that doesn't have any of those safety devices, it makes those tests even more important.

Sd134

@jakeck, agreed....I realize I probably need to bite the bullet and pay for professional help.

I do have a question about automatic vs manual switches though.

If the tripping of a switch is meant to indicate a problem, what purpose does it serve to have an automatic switch that resets itself? Hypothetically, I might never notice a problem if I didn't have to reset the switch myself.

JakeCK

There are automatically resetting rollout sensors?

Jamie Hall

A personal opinion -- I would prefer to see the flame rollout switch either be manual, or to have one with rather high sensitivity which was automatic, and a manual backup. This is normal on safety switches on bigger steam boilers.

Hap_Hazzard

I agree with @Jamie Hall about the video, but a picture of the outside of the firebox might be more telling. This is what chronic flame rollout does to a boiler:

EBEBRATT-Ed

@Sd134

You need to get this fixed it is not a small issue you could be putting carbon monoxide in your house without knowing it. Its oderless colourless and tasteless

Don't take any more chances and end up as a newspaper story

Think of flame roll out like pouring water into a funnel when the funnel can only take just so much water it overflows

That is what is happening with your boiler. It's not all going up the chimney so it's rolling out. either you boiler, burners flue pipe or chimney are plugged with soot

You need things cleaned and a combustion test

JUGHNE

I believe today's new boilers come out with one time fuse links for that function.
Apparently too many manual resets, without correcting the problem, posed many safety concerns.

Looks like you could have a little too much fire there.
And if dirty passageways there is no where else for it to go.

SteamingatMohawk

Your boiler probably has two SAFETY switches (capitalization for emphasis). The rollout switch in the lower front detects high temperature within the boiler heating section. This high temperature is a possible indication of restricted flow within the heat exchanger, which can be caused by buildup between the sections or some other problem. In addition to what was mentioned above, I had a situation where the insulation in my boiler came loose and exposed the switch to the hot gases and I believe it changed the flow of gases inside the boiler. None of these potentials are something to ignore.

The second switch is called a spill switch and is between the top of the heat exchanger and the exhaust duct (before the damper, if there is one). It detects a restriction in the ductwork and/or the chimney, causing the exhaust gases to "spill" out.

Why do I mention this? If the exhaust duct and/or chimney are restricted, it is more likely the spill switch will activate than the rollout switch.

After all that, I can't urge you enough to get competent help to fix all issues that exist. The other guys were too easy on you.

If there were a problem that resulted in damage to anything and your insurance company determined you had bypassed the rollout switch, they would not cover it.

What is the model number of your boiler? I may be able to find some technical information on the boiler if you don't have any.

This web site can help you find a competent boiler guy.

Sorry for sounding so pushy, but you may have been very lucky.

SteamingatMohawk

Slight correction. Some of the guys were too easy.