Bryant 4-94 conversion burner & Thermo Pilot 700 - short cycling

mynameisphunk

Hello all,

First time post - thank you in advance for any help.

House is a 1930 2 story brick colonial in south central PA. Single pipe steam. Original coal boiler, converted to gas with a Bryant 4-94, probably around 1939-1940 (gas line from the street was just replaced a month ago and dated to 1939). Though likely terribly inefficient and oversized, the system has actually been great for us since moving in 4 years ago. I add water every 2-4 weeks, leaks a little bit around the sight glass but otherwise has been quiet and reliable. Pressuretrol set to 0.5 with differential set to 1.

Two days ago, the system began short cycling. It will not keep the house up to temp when moderately cold out - may run for a few minutes, or kick off and on repeatedly in short succession, or just not fire at all when it feels like it.

Any suggestions on what I could look for/test?

I'd like to repair if possible. Our gas bills have been manageable, and the house reliably and consistently warm. We're potentially planning a remodel/addition in 2019, so if I could get another couple seasons out of this system without a huge investment, that would be amazing.

Thank you all - some pics below.

BobC

Is the pressure gauge reading higher than normal? Be warned a gauge that old might not be working right anymore.

Has the pigtail under the pressuretol been checked to make sure it's not blocked? If that were blocked the boiler might be running at higher pressure than it should. If the system were running at high pressure it can cause many problems.

Bob

mynameisphunk

The gauge does not work, and has not worked since I've owned the home. I haven't yet blown out the pigtail on the pressuretrol, though wouldn't high pressure typically make itself known at the radiators (hissing vents, etc)?

BobC

It does but it may not be enough to notice. The question here is what has changed to cause this behavior, if no piping work has been done that might have introduced oils into the system higher pressure is possible. Is the system shutting down do to a low water situation and has the water usage gone up recently?

Has the boiler been gone over since they replaced the gas line? The fact it doesn't seem to heat as well could indicate a combustion or control problem, get someone in to test the system. have them test the gas pressure and the combustion.

You may be burning more gas now because the pipe pressure might be higher now. You need some testing done to find out what is going on. If the gas pressure is higher that would let the boiler make more steam. Check the pigtail and get a working pressure gauge so you know whats going on - your flying blind now.

I would also drain and fill the boiler a few times to clean up the water, a good skimming wouldn't hurt either.

Bob

mynameisphunk

Thank you, Bob!

-Water usage has been consistent, and it's never been allowed to get lower than about 1/3 of the way up the sight glass while we have owned the home.
-The boiler hasn't been gone over more than just to seal up a couple tiiiiiiny gas leaks that gave a reading when the gas company checked. The main to the house was replaced 2/13, and the leaks addressed on 2/14. The pilot was relit, and the unit seemed to work normally after that point, though it's been quite unseasonably warm .
-When the burner is lit, the flame looks identical to what it looked like prior to the gas main change.

When it turns on and off, the electromagnetic switch/valve (sorry, don't know the terminology) that all of the wiring terminates to is clicking open and shut. The burner lights accordingly when it opens. It seems as if something is telling it to turn off when it shouldn't, but I'm not sure how to test that.

Without a doubt, the boiler should be drained. It likely never has been since at least 1988. The valves to do so are stuck shut.

BobC

Is this a millivolt system? If it is make sure the thermocouple is 1/4 to 1/2 in the pilot flame and that the tip of the thermocouple is glowing red.

Bob

mynameisphunk

I don't know what that means, unfortunately.

I had previously found this thread with a similar situation:
http://forum.heatinghelp.com/discussion/78525/bryant-conversion-burner-pilot-parts

It indicated that the pilot is a bimetal pilot. Would that be used instead of a thermocouple in this instance, serving the same purpose within the pilot mechanism itself?

mynameisphunk

From what I'm reading - the gas valve could possibly be replaced by a new combination valve, which would include new pilot, valve, thermocouple, etc...

1. Does that sound possible with this setup?
2. Is that something that would need to be purchased for a new boiler anyway, so spending money on that for this boiler wouldn't just be money down the drain as it could be reused when we replace this boiler?
3. What would a ballpark cost to perform this work by a professional be, typically?

Chris_L

mynameisphunk said:

From what I'm reading - the gas valve could possibly be replaced by a new combination valve, which would include new pilot, valve, thermocouple, etc...

1. Does that sound possible with this setup?
2. Is that something that would need to be purchased for a new boiler anyway, so spending money on that for this boiler wouldn't just be money down the drain as it could be reused when we replace this boiler?
3. What would a ballpark cost to perform this work by a professional be, typically?

I would not assume the problem is either of these things.

From what you describe, you have a bad electrical connection somewhere. It could be the thermostat, any of the control devices wired in series with it, or any of the wiring in between.

Until you have identified the source of the problem, I wouldn't go replacing the gas valve or the themocouple.

mynameisphunk

Sure, understood. The thermostat (Honeywell digital, battery powered) was put in place recently - a few months ago - and has worked reliably until now.

Is there any easy testing I can be doing with a multimeter to see what could triggering the valve to open and shut?

Tim McElwain

That is a real oldy. There are typically no parts for these anymore. You could do a complete changeover but be very careful with those vertical pieces coming up from the burner. You do not want to break those as they direct the flame for good heat transfer in the combustion chamber. There are several options for a changeover including Powerpile self generating. You are looking at parts plus labor so you have to consider the age of the boiler versus a new boiler.

Before you do all of that I would have a professional come and troubleshoot the system. Look for some old timer (over 60) as they usually have seen these before.

If you decide to do a change over contact me at gastc@cox.net and I will give you a parts list.

mynameisphunk

Thank you. FYI - just because I had a spare kicking around - I changed the thermostat back to the old round Honeywell style and the symptoms are the same. It will kick on for 10-15 seconds, then turn off. Just wanted to make sure it wasn't the thermostat, as it was a hand-me-down unit from a friend.

Do you have a ballpark of what a changeover would cost if we chose that route (for a pro to do it)? Are we talking thousands?

MilanD

Did you figure out what's happening?

What you are describing sounds like an electrical issue - could be the low water cutout switch being stuck and need cleaning. That's the black triangular housing attached to your sight glass. How often do you blow-down the boiler? There can be crud in there and could hinder with proper switch operation. With weekly blow-downs, I still have to open up and clean mine every fall.

Or, look for the flame sensor, roll-out sensor, temp sensor... not sure what's on there. Something is telling the burner to turn off.

The fact it starts up means it's getting the signal to do so. Check also the breaker box and the breaker for the boiler: those are known to also fail from time to time, esp. if pushmatics. Check for any other switch attached to the boiler (service switch, or any other switch that is/may be connected, 24v transformer...).

There was a similar post a few months ago about an erratic boiler operation just like yours - turned out they had an 'off' switch mounted at the top of the stairs, with a fuse inside, and a loose wire in there. Presented the same symptoms as what you describe.

mynameisphunk

I had thought it possible that one of the safety switches might have been telling it to cut off, but wasn't sure how to test. Is it possible/safe to bypass the LWCO STRICTLY for troubleshooting (I understand the safety concerns of doing this, and would not run the boiler unattended with this bypassed)? It looks like it's wired in series with the Pressuretrol. Alternatively, is there a good way for me to test the signal the LWCO is sending when the burner is cycling off with a multimeter? My electrical knowledge is limited - and my knowledge of how boiler wiring is configured - but I have time and a multimeter and would love to gather more info to troubleshoot further.

MilanD

The thing I would do would be to detach the wires coming to it an jump them by tying them together. I would not do this unless you are sitting there and observing the following first:

1. without jumping the lwc, what happens when the burners turn off, and how long it takes:
2. Observe #1 happen 2-3 times to look for consistencies (is the cutout the same pressure, same burn lenght, water bobbing in sight glass, is water disappearing, is the overall op. same each time the burners cut out??).
3. If you say it comes on erratically, how long does the burner run before cutting out? 1 minute, 10 minutes, enough for boiler to get hot and heat the house, or before it even starts heating the house?
4. Then short lwc and see what happens. Don't let the water from the boiler drop, meaning, if you get the boiler to come and stay on after shorting the lwc, therein is your problem. This switch may be easy to fix - it only needs cleaning. Do you blow-down that lwc? On the float models lwc, you should be blowing them down weekly.

I am not sure what voltage should be on all other switches, but assume you should be getting constant current between 2 sides of the switch unless the switch is tripped. Rollout switch, CO switch (if there), all should, if I am not mistaken, have manual pop-out switch. Thus, if boiler is coming on on its own without you resetting anything, I'd say lwc, pressure troll, or some other loose connection somewhere.

MilanD

Oh, definitely keep an eye on the pressure. Don't let it build past 1.5 psi. I'm assuming your pig tail is clear, and that you have low pressure gauge allowing you to observe what the pressure is doing as the water is cooking.

mynameisphunk

1. Without jumping the LWCO, with the firebox door closed, it's hit or miss (mostly miss) whether the burner will fire at all. If I jumper the top two terminals on the valve, it will engage for ~10 seconds or so each time then turn off.
2. No change in water depth in the sight glass. No bobbing, surging, nothing. It's always been that way, and no different now.
3. Boiler almost never cycles more than 15 seconds now from what I can tell. Never enough to get the boiler hot.

I don't know what's different - and this is what got me thinking thermocouple/thermopile/whatever this super old pilot has -

When I open the firebox door, the burner will almost always fire within 10 seconds of my opening the door. It will then fire for roughly 15 seconds on, 10 seconds off, repeat (have watched through 4 cycles before closing the door). As soon as I close the door, it won't come on again. I though perhaps my opening the door caused enough of a draft, etc... to alter things enough for it to kick on temporarily.

Also - no change when LWCO is bypassed.

mynameisphunk

Also - pigtail not verified to be clear. Definitely on the list. Actually I'll go down and see if I can knock that out now.

MilanD

Huh... This doesn't sound like ptrol issue or pigtail. If your pilot is on all the time, thermocouple is fine. Could be your flame sensor... Or the gas valve itself if the burner fails to light as the heat is calling. Try tapping on the gas valve.

So, it comes on, just doesn't like staying on can mean that after fire is lit some safety engages and shuts the burner off, like flame sensor... Or, it not coming on at all when heat is called means gas valve is not opening. Valve not functioning could also manifest as the first symptom... Bad gas valve would be my guess at this point.

Just for fun, check that the chimney didn't get obstructed.

Someone else better chime in as I'm out of ideas. At this point I'd call a pro and see what they find.

MilanD

And all other electrical connections are fine? Breaker, kill switch, 24v transformer? No loose wires anywhere?

Tim McElwain

Get a pro as based on what folks have been posting to try and fix this tells me they are not aware of how this system operates.

As to a changeover we do not discuss prices here but if you call me at 401-437-0557 for a fee of several thousand dollars I will tell you all my secrets to doing a changeover on this.

EBEBRATT-Ed

This system is pretty outdated and the old Watts low water cutoff with a mercury switch can be troublesome.

My fear is if you start changing parts you will find it not cost effective to keep this running.

If it was mine I would try and make it 2 months until summer (if it operates safely), bite the bullet and get some quotes from people that know what they are doing and say good buy to that boiler. It's done it's job and you need to keep your family safe

mynameisphunk

I'm headed to Lowe's now to buy a 220v 4000w electric heater to heat the first floor - we have a 220v circuit for a huge window AC unit, and I'll feel a little better about having a dedicated circuit and a more heavy duty heater vs. multiple cheap 1500w space heaters on our old house wiring. We'll get through until spring/summer when it will be less intrusive to have this work done (replacement). I wish our kids (2 and 4) would allow us to put blankets on them at night!

EBEBRATT-Ed

K. Be careful with the space heaters

Harvey Ramer

You say South Central PA? Where at. I'm in that general area as well. If you are close enough, I may be able to help.

mynameisphunk

I'm in Hanover.

Just bought this, which is currently kicking out decent heat downstairs.

https://m.lowes.com/pd/Fahrenheat-13-652-BTU-Utility-Cabinet-Electric-Space-Heater-with-Thermostat/1082601

Steamhead

Harvey Ramer said:

You say South Central PA? Where at. I'm in that general area as well. If you are close enough, I may be able to help.

Hanover. That's just outside the green circle on your website. I've looked at this job and can tell you he won't need new main vents

I'd love to take this on but the permit/license authorities would probably take a dim view of it, since there's no reciprocity between Maryland and Pennsylvania that I know of. So if that's not too far for you...................

Tim McElwain

I used to take those valves apart and replace the diaphragm in the valve. When they go it does just what yours is doing. The only thing to do is replace the valve, pilot etc or install a new boiler. If I was going to do a recontrol I would do Powerpile. I would also clean the LWCO and replace the pressuretrol.

mynameisphunk

The diaphragm definitely has a slight leak - gas company detected it when they replaced the main (2/13), and a local HVAC company came in to check it out and used some sort of sealant on the edge of the diaphragm to try to stop the leak (seemed to work, but might have had other adverse affects). That makes sense.

Everything worked fine before 2/13, except for the slight leaks in the valve we weren't aware of.

Harvey Ramer

@Steamhead
Go for it. Hanover is a bit far and you are a much better steam guy than myself.
I highly doubt you will have any problems with local codes. PA doesn't get excited about anything until we are talking commercial projects. I recently did a large boiler in a church. I called the borough for permits and they said, just go ahead and do it. The permits and inspections work off of the municipal authority, not state. It's not until you get into larger cities that permits are required for things like boiler changeouts. This is contrary to the Commonwealth code, but municipal authority overrules. If you tried to pull a permit for a residential boiler changeout in a rural area, they will look at you funny and tell you to quit wasting their time.

That is how it is in my area. Could well be more or less as you traverse the state. Licensing, if it even exists, is also done on a municipal level. And not all municipalities reciprocate.