Old Bryant steam boiler, and duty cycle

Precaud

First let me say thanks to the contributors on this website, which has come in very handy the last few days as I troubleshooted and repaired this old boiler. Many a google search landed me here. I have numerous questions but we'll start with these two.

1. Is there a way to find out the age of this wonderful old Bryant nat gas steam boiler? Here is a pic of the ID tag. The unit no. is 7S225 D296 3486. 157,500 btu input, 126,000 btu output. No deratings given for high altitude (the house is at 7,000 feet in north central New Mexico). The only date codes I can find are on the Honeywell Pressuretrol, which says 1974. (That may or may not be the same date as the boiler, though.)



2. This heater came with the house when I bought it in 1990, and was the sole heat source until 2006, when it starting acting up. A local heating specialist inspected it and said "it's old, replace it". I believed him, shut it down, and used that opportunity to build and install two large passive solar heaters, with woodstove backup. The solar/wood system has worked remarkably well, but it is not automated and has to be attended to every day. I'm getting on in years and decided the woodstoves are too much hassle now, and it's time to revive the steam boiler to cover the evenings and for backup duty. Two days of troubleshooting, repair, and adjustment and the Bryant is up and running great again.

So my question has to do with duty cycle. On a "cloudy day", the Bryant will cover 100% of the heating load (which it was desgned to do) and it does so comfortably. On "sunny days", it will start at 5-6am, and operate until 9am when the solar heaters take over, until 4pm or so. Then the boiler takes over again from 6-6:30pm until bedtime, when the tstat is turned down for sleeping.

So in the "sunny day" regime, the boiler has two 3-4 hour stints on with 8 hours off in between. I hunch that this is not an ideal way to operate this beast. Will there be predictable consequences for doing so?

ethicalpaul

I can’t think of any consequences. The mains will get cold between duty cycles, but that happens during the mild seasons anyway.

How much setback does it recover from in the morning out of curiosity?

Edit: also, how was it acting up when you retired it? Is it doing that behavior still?

Coincidentally, I was in Taos and Ft Garland yesterday, beautiful! Also visited the Earthship homes, speaking of solar! I may retire out there 😀

Jamie Hall

If it ain't broke... other than being remarkably inefficient, that old boiler is probably doing exactly what it's meant to do, and with continued maintenance will probably keep doing it for quite some time.

Precaud

Good point, Paul, I hadn't thought of that. I'm just getting started with this new setup, but last night I set the tstat back to 64. The system had already kicked on when I awoke at 5:30.

That's cool you were in Taos, yes its a beautiful area. And as you know, yes, we have real winters... it's -5ºF in Taos right now, +14ºF here in the capital. I'm "'sliding into retirement" myself... this heating change is part of the preparation.

Precaud

Jamie Hall said:

If it ain't broke...

Well it does need some TLC, but it is working just fine after sitting dormant for 13 years.

other than being remarkably inefficient, that old boiler is probably doing exactly what it's meant to do, and with continued maintenance will probably keep doing it for quite some time.

I like the sound of that! When I retired the beast in 2006, NG was averaging 90 cents/therm, with spikes to $1.75. With it now averaging around 25 cents (and futures indicating it will stay there for the next 10 years!), I will happily accept its inefficiency to get longevity.

ethicalpaul

I think you’ll enjoy not having to stoke the wood stove (unless you feel like it). As Jamie said, the old boilers just go and go. And I wouldn’t worry much about efficiency. My brand new Peerless is only going to get 82%

After your 64 nighttime setback, what do you put it up to during the day? I ask because if you have an oversized boiler vs your radiation (so many do), you may have pressure cycling after a setback which won’t hurt your boiler but wastes fuel.

Precaud

Only 82%? LOL. I guess something needs to keep the chimney warm for it to draft...

After nighttime setback, normal daytime setting (for cloudy days) would be 69F. And yes, the boiler is now significantly oversized (for the house, not the radiators) and is clearly loafing along - this place was built in 1930, and had zero insulation. Cycle times would be short if it weren't for the programmable tstat keeping them at 30 min.

By "pressure cycling" do you mean: A burn cycle cut short due to increase in pressure and consequent shutoff by the pressuretrol?

One of the things I need to attend to is pressure monitoring. The pressure gauge has never worked. The Pressuretrol was monkeyed with (adjustment screws removed) by the prior owner, and I have to wedge it so the mercury switch engages.

Jamie Hall

Try and keep that mercury pressuretrol. They are more reliable than the newer microswitch ones, although they do need to be mounted to be perfectly level and stay that way.

I'll be with a bit of thought you can figure out how to demonkey it...

PMJ

@Precaud , you have one of the finest boilers around. I have a Bryant and I know it was installed in 1956. If it is not leaking now you should just run it. It just might yet still run more years than a new boiler of today's quality. You have backup heat so if you were to get stuck at a bad time it really isn't so bad. If I had listened to the advice I got when I moved in and my boiler was already 36 years old I'd probably be doing at least my second replacement right about now.

As for efficiency....you do the math. How will even the theoretical fuel savings possibly pay for a replacement? All in annual cost efficiency is what matters. Why anyone talks about fuel efficiency alone is a mystery to me. These old Bryants win the all in annual cost contest walking away.

One thing though - does it have an automatic damper? With one that big boiler will stay warm for many hours which will mean a lot when you need it to get going again. I wouldn't worry a bit about running it as you are saying.

Precaud

Jamie Hall said:

Try and keep that mercury pressuretrol. They are more reliable than the newer microswitch ones, although they do need to be mounted to be perfectly level and stay that way.

I'll bet with a bit of thought you can figure out how to demonkey it...

Interesting, thanks. I should get a replacement, then. I see some NOS L604's on eBay for pretty reasonable $. This one is definitely trashed, the only thing that still works is the mercury switch. The indicators are missing and the adjustment screws do nothing. I'll post pics of it later, I have ?'s about how it is hooked into the system, too.

Precaud

@PMJ, thanks for your input, its great to hear from someone that owns one! That was my sense when the service guy told me to replace it, he didn't give any functional reasons, just that it was "old". Is there a way to find out when this one was built?

The 6" pipe has a manual damper, then connects into a large brick chimney. I put the damper in to be able to close it when using the woodstove, whose SS liner shares the chimney space. Are you wanting the damper to close whenever the boiler isn't burning?

I'll post some more pics later, gotta work now.

PMJ

I have the original manual though I don't think it has any dates on it. I just know based on previous owner records. Take a few more pictures when you can. Mine is considerably larger - 460K btu/hr input and a 10 inch flue.

Yes, you need an automatic damper that opens with the call for heat before the burner can run. It needs to be installed as far from the boiler as possible with the safety interlock done properly. It will make a huge difference in overall efficiency and response time to steam. Easily worth the cost.

Chris_L

If there is a serial number on the boiler, you might be able to get the manufacturing date from Bryant. Or if not, they may be able to tell when your particular model was manufactured.

As for your manual damper, I hope you have an interlock on it so the boiler can't fire it is closed. Otherwise, this sounds like a dangerous set-up. An automatic damper with one would take care of this.

JUGHNE

It should be pointed out that the pressure control is actually a safety control. It sounds like you have yours in effect jumpered out. Your tstat only must be doing the operating function.
If so then that is good match of boiler and radiation.

However without the pressure switch as high limit, the next safety is for the pressure relief valve to open at 15 PSI.

IIWM, I would get another pressure control and add a 0-5 PSI gauge above the pigtail with the control.

ethicalpaul

> @Precaud said:
> Only 82%? LOL. I guess something needs to keep the chimney warm for it to draft...

I’m not sure if you think that sounds high or low, but yes, basically all atmospheric gas boilers are 82 or 83% I think.

> After nighttime setback, normal daytime setting (for cloudy days) would be 69F. And yes, the boiler is now significantly oversized (for the house, not the radiators) and is clearly loafing along - this place was built in 1930, and had zero insulation. Cycle times would be short if it weren't for the programmable tstat keeping them at 30 min.

Your thermostat is forcing the boiler to run even after the setpoint is met? I wouldn’t use such a device.

> By "pressure cycling" do you mean: A burn cycle cut short due to increase in pressure and consequent shutoff by the pressuretrol?

Yes. It’s wasteful because the boiler might as well shut off for awhile to let the radiators radiate their heat and cool off.

Your setback sounds OK but consider not going as low at night if the boiler gives you trouble in the morning.

Do you change the thermostat depending on if it’s cloudy?

> One of the things I need to attend to is pressure monitoring. The pressure gauge has never worked. The Pressuretrol was monkeyed with (adjustment screws removed) by the prior owner, and I have to wedge it so the mercury switch engages.

!!!! That isn’t good! As others have said, please get a new pressuretroll immediately.

Precaud

PMJ said:

I have the original manual though I don't think it has any dates on it. I just know based on previous owner records. Take a few more pictures when you can. Mine is considerably larger - 460K btu/hr input and a 10 inch flue.

That is a beast! So cool that you have the original manual.

Yes, you need an automatic damper that opens with the call for heat before the burner can run. It needs to be installed as far from the boiler as possible with the safety interlock done properly. It will make a huge difference in overall efficiency and response time to steam. Easily worth the cost.

I'll look into it. Methinks that can wait until the off-season.

Here's a pic of the beast. A little messy, not finished cleaniing up yet. The woodstove next to it heated the basement (when occupied) after the Bryant was retired. It's the perfect stove for that space (1200 sq ft basement) and a joy to use.

Precaud

JUGHNE said:

It should be pointed out that the pressure control is actually a safety control. It sounds like you have yours in effect jumpered out.

Understood. And yes, it's non-operational at present.

IIWM, I would get another pressure control and add a 0-5 PSI gauge above the pigtail with the control.

Pressure monitoring and limiting is definitely top priority. Here are pics of the front innards, and a closeup of the existing Pressuretrol L604A. As you can see, the L604A is pigtailed into the original LWCO unit (non-functional now). It defiinitely is responding to pressure increase, but the set screws spin freely. The nail allows the boiler to operate, for now.

Mark N

Precaud, order a new pressuretrol from supplyhouse.com or see if you can obtain one locally. You might want to consider picking up a copy of the Lost Art of Steam Heat available in the Store on Heatinghelp.com. Also, are you same Precaud on Cloudynights.com?

Steamhead

Even without looking at the manual, I can tell the steam piping coming off the top of the boiler is wrong. There is not enough height between the water line and the header- should be 24" at minimum, to help dry out the steam. So the boiler is not operating as efficiently as it could.

Get a copy of "The Lost Art of Steam Heating" which goes into a lot more detail on this:

https://heatinghelp.com/store/detail/the-lost-art-of-steam-heating-revisited

Precaud

ethicalpaul said:

> @Precaud said:<
> Only 82%? LOL. I guess something needs to keep the chimney warm for it to draft...

I’m not sure if you think that sounds high or low, but yes, basically all atmospheric gas boilers are 82 or 83% I think.

It was just a joke, highlighting the limitations on efficiency due to the need to keep the chimney warm enough for it to draft...

[Cycle times would be short if it weren't for the programmable tstat keeping them at 30 min.]
Your thermostat is forcing the boiler to run even after the setpoint is met? I wouldn’t use such a device.

Why not? Seems like its good for the whole system to come up to higher temp, otherwise the most distant radiator doesn't get as hot as the others. I can set minimum cycle time from 5 miin to 30 min. They recommend 30 for steam. Seemed reasonable to me.

Your setback sounds OK but consider not going as low at night if the boiler gives you trouble in the morning.

OK. What kind of trouble are you envisioniing?

Do you change the thermostat depending on if it’s cloudy?

I've only had the system up and running again for three days so probably too early to say. What I notice is that I set it to 72 for the evening kick-in vs the morning setting of 69. This is due to where the tstat is mounted, closer to the NW side of the house where the largest solar heater is. The LR is on the east side and is 2-3º cooler.

!!!! That isn’t good! As others have said, please get a new pressuretroll immediately.

Will do. It's worth noting, in the 16 years I operated this (1990-2006), I only saw evidence of overboiling /overpressure once. In 2003 the water supply return at the bottom rear of the stove, where city water meets boiler water, closed from lime/calcium buildup. That's the most serious service failure It has had. Except for the Pressuretrol, the ones I just repaired were all water-supply-related too; clogged pressure reducer, clogged LWCO filter, and clogged blowoff valve. They all ckeaned up fine and are back in service. Had my troubleshooting been more systematic and methodical in 2006, I probably would not have taken the unit out of service...

Speaking of LWCO, here's a pic of the M&M 47-2. The sight tube is so clean you can hardly see it.

Precaud

Mark N said:

Precaud, order a new pressuretrol from supplyhouse.com or see if you can obtain one locally. You might want to consider picking up a copy of the Lost Art of Steam Heat available in the Store on Heatinghelp.com. Also, are you same Precaud on Cloudynights.com?

I think I already checked supplyhouse and they don't have the mercury switch version, but I'll doublecheck. There are no good local sources. There are a few NOS on eBay.

Yes, same Precaud. This is what I've been doing instead of observing Are you visual or imager?

Precaud

Steamhead said:

Even without looking at the manual, I can tell the steam piping coming off the top of the boiler is wrong. There is not enough height between the water line and the header- should be 24" at minimum, to help dry out the steam. So the boiler is not operating as efficiently as it could.

That may be true, but I'll live with it; there is almost no chance that I will redo the near-boiler piping just to gain a couple %...

Here's the last pic, the three main distribution pipes. Once I see where daytime basement temps settle out, I'll consider insulating some of the bare ones.

This house originally had a wood-fired boiler (the builder owned the town's lumber yard). That big prod hanging on the upper left is what he used to poke the fire in that boiler - it must have been huge!

ethicalpaul

That last picture reveals very weird near boiler piping. It’s like there are two headers. Sort of a fake low one that steamhead mentioned, but then another one much higher that might actually work. I’ll look forward to see what others say.

The reason I wouldn’t want a thermostat to call for heat after my setpoint was reached is because then I’d be too hot 😅. Better to balance the radiators with venting at an appropriate rate for each radiator (vent the hot ones slower).

Mostly the morning trouble I was thinking about was cycling due to pressure but it sounds like you aren’t experiencing that (especially with your current pressuretrol!)

I’m nervous about your float-style LWCO, did you say you tested it and it works? It is supposed to be replaced after 10 years I think and blown down weekly.

Finally I see you have a main vent (just before your return) but I wonder if it works and if it’s sized correctly and if the others main is vented. You said 3, but I think there are two. But only one return? Is there another off-camera?

Precaud

ethicalpaul said:

That last picture reveals very weird near boiler piping. It’s like there are two headers. Sort of a fake low one that steamhead mentioned, but then another one much higher that might actually work. I’ll look forward to see what others say.

It looks odd to me, compared to the diagrams I've seen of good installs... I'll take another pic of the piping behind the boiler and woodstove after I clear that area up.

The reason I wouldn’t want a thermostat to call for heat after my setpoint was reached is because then I’d be too hot 😅.

I guess I'm accustomed to wide daily temperature swings, and an extra degree is nuthin'. The solar heaters drive indoor temps to 75F minimum even on the coldest days, and I'd wake up to 62F on the coldest nights. I do sleep better in cool temps...
Also, our RH% is lower here, it's a drier heat and not as oppressive.

I’m nervous about your float-style LWCO, did you say you tested it and it works? It is supposed to be replaced after 10 years I think and blown down weekly.

Yes, it works. Which is amazing, because it was there in 1990 and my maintenance habits were not great. I'd do regular (weekly) blowdowns with the unit running to also check the LWCO, but only flushed the system once - in 2003. Maintenance will be more thorough now that I understand the components better. This is the 1st house I've owned that has a central heater... the previous one was solar + wood, a well-designed one.

Finally I see you have a main vent (just before your return) but I wonder if it works and if it’s sized correctly and if the others main is vented. You said 3, but I think there are two. But only one return? Is there another off-camera?

If you're referring to the vent on the top of the pipe that goes through the wall, that pipe feeds the heaters on the west side of the house. I should check that vent, thanks for the reminder. I don't see vents on the other mains pipes. The radiator vents are all clear.

Precaud

We'll try this again, the system ate my previous reply.

ethicalpaul said:

That last picture reveals very weird near boiler piping. It’s like there are two headers. Sort of a fake low one that steamhead mentioned, but then another one much higher that might actually work. I’ll look forward to see what others say.

Yeah, it's different than any diagrams I've seen of a well-designed system. But it has been problem-free... I'll take a better pic of the piping behind the boiler and woodstove after I clean that area up.

The reason I wouldn’t want a thermostat to call for heat after my setpoint was reached is because then I’d be too hot 😅.

I guess I'm accustomed to wide daily temp swings, so an extra degree is nuthin'. The solar heaters drive indoor temps to 75F minimum even on the coldest days, and I wake up to 62F on the coldest nights. I don't mind that - I sleep better in the cold.

I’m nervous about your float-style LWCO, did you say you tested it and it works? It is supposed to be replaced after 10 years I think and blown down weekly.

Yes, it works, which is amazing, since my maintenance was less than stellar. I'd do weekly blowdowns when the unit was operating to also check the LWCO. But it has only had one system flush siince 1990. Now that I understand the system better, my maintenance will be more rigorous, I assure you...

Finally I see you have a main vent (just before your return) but I wonder if it works and if it’s sized correctly and if the others main is vented. You said 3, but I think there are two. But only one return? Is there another off-camera?

If you refer to the vent on top of the main pipe that goes through the wall, that's the only vent on a main. That pipe feeds the heaters on the west side of the house. The radiator vents are all original and all still work fine. Like I said, this has overalll been an amazingly reliable system, especially considering its age.

ethicalpaul

Hmm that seems to me that it must be the end of a main due to that vent location (the vent would basically do nothing if that was the start of a main) and due to its lower height.

But I’ll see what others say. One or more of them might be counterflow with which I’m not as familiar.

Jamie Hall

On the header... the piping is eccentric, but that insulated line up higher is going to function as an excellent header, eccentric or no, and I dare say the steam will be quite acceptably dry. The arrangement makes me wonder, though... was there, originally, a taller boiler there? And this one piped in somewhat later?

Mark N

Precaud, I just do visual. Good luck getting your issues resolved.

Steamhead

ethicalpaul said:

That last picture reveals very weird near boiler piping. It’s like there are two headers. Sort of a fake low one that steamhead mentioned, but then another one much higher that might actually work. I’ll look forward to see what others say.

The drip from the higher of the the two headers ties into the drip from that steam main well above the boiler's waterline. I'm positive steam is going up that drip and shutting the main vent. It was probably piped like that for the original boiler, whose waterline would have been above the tee where the drip ties in.

That's reason enough to repipe. The system will heat much faster if the steam doesn't flow backwards into the main. If done right, the piping will also be right when the boiler is replaced, so it wouldn't need to be redone.

Precaud

Jamie Hall said:

The arrangement makes me wonder, though... was there, originally, a taller boiler there? And this one piped in somewhat later?

Yes, there was originally a wood-fired boiler there, much larger than the Bryant and whose waterline was certainly higher.

Precaud

Mark N said:

Precaud, I just do visual. Good luck getting your issues resolved.

Thanks. What's your handle on CN?

mattmia2

Am i right at looking at this right where you would just have to put a high loop in the return to make a false water line above that tee to make the near boiler piping function properly?

Jamie Hall

That would probably do it, @mattmia2

ethicalpaul

Steamhead said:

ethicalpaul said:

That last picture reveals very weird near boiler piping. It’s like there are two headers. Sort of a fake low one that steamhead mentioned, but then another one much higher that might actually work. I’ll look forward to see what others say.

The drip from the higher of the the two headers ties into the drip from that steam main well above the boiler's waterline. I'm positive steam is going up that drip and shutting the main vent. It was probably piped like that for the original boiler, whose waterline would have been above the tee where the drip ties in.

That's reason enough to repipe. The system will heat much faster if the steam doesn't flow backwards into the main. If done right, the piping will also be right when the boiler is replaced, so it wouldn't need to be redone.

Thanks @Steamhead I see now what's up with that. Does that make sense, @Precaud? The line behind the boiler with the vent on it, is the end of a main, not the start (or supply). In the original boiler, the waterline was high enough that steam would never flow from the boiler in that direction. Even if you don't fix it now (or ever), this is valuable information. One (or both?) of the two high mains must run around and become that return.

> That may be true, but I'll live with it; there is almost no chance that I will redo the near-boiler piping just to gain a couple %...

If not for the fuel savings (and you must care about fuel savings even on a philosophical level considering what you’ve done with the solar heat--which I am a huge fan of), consider it for the balancing. Getting steam fast and evenly to the all the mains is the foundation of being able to tune this system for actual comfort

Precaud

Edited to correct my earlier misunderstanding...

ethicalpaul said:

Thanks @Steamhead I see now what's up with that. Does that make sense, @Precaud? The line behind the boiler with the vent on it, is the end of a main, not the start (or supply). In the original boiler, the waterline was high enough that steam would never flow from the boiler in that direction. Even if you don't fix it now (or ever), this is valuable information. One (or both?) of the two high mains must run around and become that return.

Yes, I see what you're suggesting. If so, then that vent shouldn't even be there, correct? We don't want outgoing steam going up that pipe, yes? So should I remove the vent and plug the hole?

Edit: You guys are correct. That pipe with the vent is indeed the END of the main loop, which starts as the pipe going vertical off the upper "header". The pipe that comes off the header at 45º feeds two radiators and terminates at the second one.

I'll try to post a better pic of the rest of the piping a little later.

If not for the fuel savings (and you must care about fuel savings even on a philosophical level considering what you’ve done with the solar heat--which I am a huge fan of), consider it for the balancing. Getting steam fast and evenly to the all the mains is the foundation of being able to tune this system for actual comfort

Well played... appealing to my conscience!
As an engineer (electronics and acoustics), of course I value efficiency and functional elegance. And I enjoy tweaking things toward those ends. I'm just not prepared to take on a project of this magnitude. Reviving the ol' Bryant was done to make my life easier...

Jamie Hall

To which end, remember that the bottom line on a heating system is does it work? Does it keep you comfortable? If something about it (noise, poor heat, whatever) bugs you, fix it. Otherwise...

If it ain't broke, don't fix it.

ethicalpaul

> Yes, I see what you're suggesting. If so, then that vent shouldn't even be there, correct? We don't want outgoing steam going up that pipe, yes? So should I remove the vent and plug the hole?

Steam is currently going up that pipe regardless of whether we want it to the only way to stop it would be to set up a false waterline nearer where it was on the older larger boiler, as described a few messages up.

If you don't want to modify your near boiler piping to make it optimal again, you don't have to worry about that vent...it's irrelevant with the steam going backwards through that pipe (unless it's stuck open leaking steam--you don't want that)

>The pipe that comes off the header at 45º feeds two radiators and terminates at the second one.

OK, so this is a short "counterflow" main. I had one of those once. I disconnected it and fed that radiator from a runout on the "real" main to help with my balancing and overall good performance (the additional condensate running down into my header caused me hammer problems). Details here: https://forum.heatinghelp.com/discussion/168172/diy-false-main-repipe-diary

We're all learning so much about your steam system

Precaud

ethicalpaul said:

Steam is currently going up that pipe regardless of whether we want it to the only way to stop it would be to set up a false waterline nearer where it was on the older larger boiler, as described a few messages up.

OK, got it. Thanks for the explanation. If it makes any difference, the radiator at the extreme end of the loop is shut down (valve closed), at least for now.

We're all learning so much about your steam system

Whether you wanted to or not...

Here's a pic of the piping behind the boiler.

Precaud

Pls tell me if I am understanding this correctly. See pic below with points labelled A and B in red. Are you saying that the pipe labeled "A" should be connected to the return pipe lower, at, say, point "B", which is below the header and preferably even below the boiler waterline, so that it won't feed steam up into the return? Is this right?

Jamie Hall

Got it. Connect it in below the waterline. Do that and you'll actually have a very good -- if odd -- installation

ChicagoCooperator

The question I have is: does his altitude necessitate any design changes in the system based on temperature and pressures functioning slightly differently?