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Getting more comfortable with the boiler - but what on earth setup do I have?

First off, thank you so much for the generosity of this group in answering my questions. I know we are a long way off from heating season, but I am trying to get smart on how this thing works in anticipation of a cold and somewhat expensive winter.

Quick recap: ancient house (late 19th/early 20th century), single pipe steam heating system into cast iron boilers.

Two questions, one simple, and one complicated.

Simple question first: here's the Pressuretrol. Is that set right?


Complicated question: what the hell kind of setup do I have?! Let me explain. There are two thermostats throughout the house for heat. As I understood from the previous homeowner, one controls the heat for the radiators throughout the house except for the dining room. These are traditional "tube-style" radiators. The second only controls heat for the dining room. These are "fin style" radiators.

Below is a chart of my boiler setup. Note labels A, B, and C.


Label A is a 24V transformer that I've been able to trace via a tube going into the ceiling that points to my main (non-dining room) radiator control.



Label B is a Honeywell 8222K1000 boiler relay, wired pretty much how'd you'd expect.



Note the metal tube in the bottom of B. That goes from the Label A transformer, through the boiler, to the Label C transformer on the other side of the boiler. This, I've confirmed, goes to my secondary thermostat (in the dining room).



So... what is this setup? I've heard to get the same boiler to power different parts of your house, you need zone valves. But this appears to be 2 different 24V transformers powering 2 different thermostats.

I can confirm that I appear to have two of these things in the boiler room (I think they are called Aquastat controllers). One is hooked up very close and seemingly directly to the secondary thermostat 24V transformer. The other is hooked up in an obscure corner. So, do in fact have a two zone system, and just not realize it?




Finally, THANK YOU for taking the time to patiently explain this baffling (but fascinating) engineering set up to this new (and electro-mechanically illiterate) homeowner!

Comments

  • Snowmelt
    Snowmelt Member Posts: 1,334
    You have steam for the house except for the one room where you have a water radiator, most likely you also have a pump. Which is what my mom has for the addition of her house. Pressure trol looks a little high but I’m not the expert in that area. Should be set at just under 1 pound and 1/2 differential
  • 109A_5
    109A_5 Member Posts: 122
    Looks to me like you have a steam boiler (Presuretrol) with a Hot-Water zone loop utilizing the boiler water (Aquastat). One thermostat controls the Steam heating portion of the house and the other thermostat controls the Hot-Water zone.

    As for the Presuretrol settings I believe you want the minimum (reliable) settings. Since with most residential Steam boilers there is really no good reason to run the boiler to build pressure above the few ounces typically needed to mostly fill the radiators. Building Pressure just wastes fuel an may cause the air vent valves to malfunction. The Presuretrol is generally considered to be a safety device (limiting pressure), however, it seems to be also used to tame oversized boilers. Since with oversized boilers they can produce steam faster than the radiation can condense it.

    The Relay probably controls a pump or two and may give priority to one thermostat. The Aquastat probably shuts down the burner when the water temp gets to 180 degrees during a Hot-Water zone call. Not sure what the second Aquastat is for, except it may set up a differential for some reason. Or maybe one is for the burner and one is for a pump(s). A wiring diagram of the actual system would provide more clarity.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    Thank you and thank you. I'm sadly not enough to have figured out how to draw a wiring diagram, but the insight that I actually have two different radiators makes a LOT of sense. I didn't realize it.

    Looking around, I appear to have 3 pumps. Two are these green "Taco cartridge circulators":



    The second is connected to this red Grundfos pump. Btw, this red Grundfos pump also leads to the 24V transformer that controls the dining room water radiator system. So my guess is this is the thing that leads to dining room heat.



    So conceptually, how do I understand it? The same boiler powers both? It sends hot water to one radiator and steam to another? THANK YOU!
  • 109A_5
    109A_5 Member Posts: 122
    Pictures from farther back of the whole boiler system and surrounding pipes may help, giving a better view of the whole system. Seems like a lot of pumps for one Hot-Water zone. If there is a heat exchanger for the Hot-Water zone that may account for two pumps. Is your DHW also heated by the boiler ?
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    PC7060
  • 109A_5
    109A_5 Member Posts: 122


    So conceptually, how do I understand it? The same boiler powers both? It sends hot water to one radiator and steam to another?

    Yes, If I understand it correctly from the pictures. The Hot-Water zone radiators may have an air bleed valve near the top to manually bleed the air out. The Steam radiators may have a air vent valve 1/3 up of the overall radiator height at the far end from the supply pipe to automatically vent the air out.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    Got it... and THANK YOU!

    I uploaded a quick video walkthru here: https://www.youtube.com/watch?v=GHehsP4lHxU

    Does that help clarify anything?
  • 109A_5
    109A_5 Member Posts: 122
    edited June 19
    Yes the video helped, although the panning was a bit rapid in places causing blurring when paused to study pipe paths. Definitely a steam boiler. Looks to me like (as near as I can tell) the two water heater tanks (DHW) are independent gas fired units.

    The vent damper motor is the black cylinder shaped item in the boilers flue pipe. The blower on the very left wall probably brings fresh combustion air into a fairly air tight boiler room.

    One pump (red) probably circulates boiler water through a heat exchanger. The green pump probably the dining room zone. I'm thinking there is an additional Hot-water zone (tan pump) you have not mentioned, basement or garage maybe ? That accounts for the third (tan, far right) pump. Following the pipes from the pumps that leave the room may give you a clue.

    The green tank is a diaphragm expansion tank needed for that type of Hot-Water zone system. The stuff on the left side of the boiler is the Low Water Cut Off (LWCO), the black cast iron spherical device and Blowdown valve below it. The Blowdown valve helps maintain the proper functionality of the LWCO. Also there is an automatic water feed valve and the sight glass to see boiler water level.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    BobC
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    THANK YOU! I really, really appreciated you taking the time to watch that video and write that up. I have a much better understanding of this thing I bought now.
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    By the way, this was the explanation given to us by the last owner:
    • The heat distribution in the house isn't good.
    • Therefore, in order to get the dining room to a decent temperature (say 70 degrees), you had to crank the main thermostat up to 90. Otherwise, the dining room (and most of the floor) was freezing. Even then, you often had to set up space heaters in the dining room.
    • But then it was too hot in the rest of the house, so you had to run the AC.
    Now: 1) this sounds absolutely insane, and 2) she never mentioned that the dining room had a separate thermostat. The thermostat itself is tucked away in a corner that is very easy to miss. I actually discovered it and traced it down to my boiler via multimeter.

    So my hypothesis is that she never turned on the dining room thermostat because she didn't know there was a separate hot water radiator on that floor, and was basically punishing the main steam radiator system to eke out whatever it could to the dining room (which it was never designed to reach). Hence why she 1) pushed it to 90, 2) ran AC concurrently in the winter, and 3) ran space heaters.

    Anyway, I am not going to test this now (obviously). But come this winter, I will give it a try. If that's the reason, then.. geez.. wow.. I would be speechless.

    If not, then I'll try to find the best NYC radiator techs and have them to a full top-to-bottom diagnosis of the piping, heat zones, etc.
  • 109A_5
    109A_5 Member Posts: 122
    If this is all new to you the LWCO should be exercised weekly to monthly (during the heating season) to verify proper operation of the LWCO. Put a bucket under the valve, while the boiler is running, open the valve the burner should shut off. Any time fresh water is added to the boiler the boiler should be run to reduce the oxygen in the system.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    Thank you! Let me make sure I understand what you mean. Here's the picture of what I believe is the LWCO. Once a week/once a month, I should put a bucker under that spigot (above the patch of gunk on the floor), and turn the yellow knob? If I do... the boiler should shut off? Where and how (and how often) am I supposed to "add fresh water"? This is my first boiler system.


  • 109A_5
    109A_5 Member Posts: 122
    edited June 19
    Steam heat should work very well and quietly. Sounds like the system has issues. You may have venting issues at the ends of the steam main pipes. Also the vents on the steam radiators may be bad or the vent holes could be plugged or painted over. There are plenty of resources to learn about these systems if you have the time and desire. If you are handy and can do much of your own work you could save money (labor and fuel / energy costs). Its amazing how messed up steam system can get when worked on by the wrong folks.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    edited June 19
    The vents were apparently diagnosed and replaced just last winter.

    But I am also learning that the last owner was... impatient. And having read more, I now understand it can take a while (hours?) for steam to permeate throughout the house after initial calls are made to the radiator.
  • 109A_5
    109A_5 Member Posts: 122
    Yes, that chamber has a float in it. When all is well the water flow into the chamber is slower than when the drain / yellow handled Blowndown valve flow is when opened and the water drains from the chamber causing the float to drop down shutting off the burner. You don't want the burner running if the boiler looses water for any reason. When the Yellow handled valve is then closed the automatic water fill (to the right) should restore the water level if it is too low. If that valve leaks or if there is any other system leaks are found then get them repaired quickly. Fresh water constantly being introduced into the boiler (other than for maintenance purposes) greatly shortens the life of a boiler.

    The Blowndown interval I suppose is debatable, weekly, two weeks, monthly, depending on how clean the system is and the rate the rust is generated in the LWCO assembly. The Blowndown purges the junk and verify proper operation of the LWCO.

    If you follow the copper pipes there is a manual water fill valve, its handle is perpendicular to the copper pipe (or closed). That can be used if the automatic fill system fails.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    OK, so to confirm, the procedural step is as simple as: 1) place bucket underneath, 2) twist yellow valve, 3) catch gunk that drops out, 4) wait for the burner to stop, 5) return yellow valve to the right position?
  • 109A_5
    109A_5 Member Posts: 122

    But I am also learning that the last owner was... impatient. And having read more, I now understand it can take a while (hours?) for steam to permeate throughout the house after initial calls are made to the radiator.

    For example this house has 9 radiators of various sizes. When it is about 30 degrees outside the boiler runs for maybe about 8 Minutes (normal cycle, not a recovery from a setback), and all radiators are hot at least at one end to the middle. And I want to improve this (reduce this boiler run time) with better main pipe venting.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 122

    OK, so to confirm, the procedural step is as simple as: 1) place bucket underneath, 2) twist yellow valve, 3) catch gunk that drops out, 4) wait for the burner to stop, 5) return yellow valve to the right position?

    Yes, I just leave the bucket there. The yellow valve handle is more of an up-down movement. Step 6) verify the water level recovers to a reasonable level. If it does not you may have no heat and the auto fill may not work, in which case use the manual fill valve.

    Reasonable or normal water level for that system is at or just above that line on that LWCO chamber.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,483
    Btw, winter is not the time to test the heating season. Winter is the time to enjoy the heating system. You should really test everything now. If system has issues, address now and enjoy later. 
    109A_5
  • BobC
    BobC Member Posts: 5,306
    The advice above is all solid and should be followed. You seem willing to dig in and understand how the system works so maybe its time to get edumacated as my old sergeant used to say. Pick up a copy of this book if you really want to understand how steam heat works, this will give you a better understanding of how steam heat works than some heater techs have. It's very well written and could be the best $50 you ever spend.

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

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • 109A_5
    109A_5 Member Posts: 122
    @CaptainHoneywell, If you like books, I have the one @BobC mentioned and enjoy it. And was thinking about this one as a review or maybe it has some tidbits I missed along the way or I am unaware of. It also may be great for you (more focused on your situation), since you are new to the steam heating situation. It could be a new Hobby depending on how handy you are.

    https://heatinghelp.com/store/detail/we-got-steam-heat-a-homeowners-guide-to-peaceful-coexistence

    I would recommend you become an Expert on your system if you plan on living there for a while. Even it you don't do much work on it yourself, the knowledge will help screen potential contractors.

    Also a ton of YouTube videos, some of those folks post here too.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    STEAM DOCTOR
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,483
    Lot of qualified steam men in NYC area (lot of no so qualified as well). 
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    edited June 21
    Ordering the book when I get home. Thanks for the rec!

    One random question as I was laying awake last night trying to sleep (and thinking about steam heat), since I have 2 thermostats that control the same boiler, how does that work?

    If I turn one thermostat on in the steam zone, but turn it off in the water radiator zone - will that shut down the boiler, or just shut down the heat to one specific zone?

    If I turn off the thermostat in both zones, will that shut off the boiler?

    Do I need to turn on the "steam" thermostat before I turn on the "water radiator" thermostat?

    Basically, which thermostat "governs" the boiler if there's a conflict in instructions? Or does it behave in the one thermostat is enough to get it to turn on, but both thermostats must be instructed for it to turn off?

    Hopefully, I am making sense. This is bringing me back to first year engineering classes when I was trying to learn about logic gates.
  • bburd
    bburd Member Posts: 331
    edited June 21
    Your system should be set up so that each zone can work independently, or both at the same time. Just set the temperature you want in each zone.

    One of those aquastats should limit the boiler temperature to prevent it from steaming when the hot water zone is calling but the steam zone is not. The hot water zone thermostat should be wired through a relay to turn on the burner and circulator when that zone calls. The steam thermostat should just fire the burner, until either the thermostat is satisfied or the pressuretrol turns the burner off.

    Bburd
  • 109A_5
    109A_5 Member Posts: 122
    edited June 21

    This is bringing me back to first year engineering classes when I was trying to learn about logic gates.

    Excellent, you realize it is a logic problem. Without drawing a wiring diagram I can only guess. Often there is a controller box to handle the logic and any needed priority. The relay looks like a Single Pole Single Throw type (SPST). In your case, I am guessing (and I still think there may be a third thermostat). The third pump makes me feel there is a second Hot-Water zone that could be independent (if desired). Two pumps for radiators in only one room seems a bit much. That during a Hot-Water call the pump(s) are turned on and the boiler is fired. When the Aquastat for a given zone is below its set point it will keep the boiler running the two Aquastats may be in Parallel. I truly think there is not enough logic to make the system function as it truly should. For a Hot-Water zone only call the water does not need to be over 180 degrees.

    One random question as I was laying awake last night trying to sleep (and thinking about steam heat), since I have 2 thermostats that control the same boiler, how does that work?

    If I turn one thermostat on in the steam zone, but turn it off in the water radiator zone - will that shut down the boiler, or just shut down the heat to one specific zone?

    The boiler should come on and stay on until the steam call for heat is satisfied (except for any Presuretrol interruptions, if any). The Hot-Water zone pumps should stay off (assuming only actually one Hot-Water zone thermostat ).

    If I turn off the thermostat in both zones, will that shut off the boiler?

    It should, as long as there is not a third thermostat calling.

    Do I need to turn on the "steam" thermostat before I turn on the "water radiator" thermostat?

    You should not, but if the proper logic does not exist, Maybe. All the zones should act independently producing the most even heating of the environment.

    Basically, which thermostat "governs" the boiler if there's a conflict in instructions? Or does it behave in the one thermostat is enough to get it to turn off, but both thermostats must be instructed for it to turn off?

    They both should govern the boiler in along with the Aquastats. An OR situation with AND as a valid state (but see the comment below) either thermostat should be able to call for heat and get it.

    Ideally the boiler firing should be controlled by the thermostat and the aquastats during a Hot-Water only zone call, you don't need Steam. Also Steam verses Hot-Water zone calls maybe better if they were mutually exclusive to minimize pump cavitation due to the water being over 180 degrees. More logic... Which may be absent.



    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    This is a terrific answer. Thanks for making it so clear. Just to clarify, why do you think I have a third thermostat? Btw, I say "dining room" but's in reality most of an entire floor.
  • mattmia2
    mattmia2 Member Posts: 5,506
    edited June 21
    This quick and rough sketch is my best guess of what is happening. The 3rd circulator is a bit of a mystery unless there is another hot water zone you don't know about or some abandoned DHW scheme.

    EDIT: I had the circualtor control from the HW t-stat wrong:







  • 109A_5
    109A_5 Member Posts: 122
    109A_5 said:

    One pump (red) probably circulates boiler water through a heat exchanger. The green pump probably the dining room zone. I'm thinking there is an additional Hot-water zone (tan pump) you have not mentioned, basement or garage maybe ? That accounts for the third (tan, far right) pump. Following the pipes from the pumps that leave the room may give you a clue.

    109A_5 said:

    In your case, I am guessing (and I still think there may be a third thermostat). The third pump makes me feel there is a second Hot-Water zone that could be independent (if desired). Two pumps for radiators in only one room seems a bit much. Also two Aquastats ?

    You only need one Aquastat to control the boiler water temp so it does not exceed 180 degrees. The second Aquastat for a second HW loop, I wonder why ?

    To me the only Aquastat needed would be on the primary loop to control the boiler water temp.

    If it were me I would draw a wiring diagram (since I can) to understand the existing functionality and logic flawed or not. In your case I am betting it could be improved by an off the shelf zone controller or if you are an EE you could do your own control. Although custom control usually confuses Plumbers and the like.

    It just seems like you have some extra parts without the needed logic controller.

    Just as a guess unless that house is huge and / or very drafty that boiler should have no problem heating it.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 122
    edited June 21
    One Aquastat was set at 180 degrees (probably the Boiler's primary loop the way it looks). What is the setting on the other Aquastat ? As @mattmia2 stated maybe the other is for an abandoned DHW. Although your hot water tanks are in the same room and the pipes connected to the pumps appear to go elsewhere. Pool heater ? Another Hot-Water radiator you are not aware of ? Garage ? Radiant heating slab ? Neighbors house ?
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 5,506
    I think one aquastat is to fire the boiler to 180 for the hot water call and the other is to run the circuator on the closed side of the HX when the open side gets hot. I thought I saw mention of a heat exchanger somewhere.
  • 109A_5
    109A_5 Member Posts: 122
    edited June 21
    I like @mattmia2's drawing, but the extra pump is missing and the relay in the system appears to be only be a SPST. and the second Aquastat is way over near the third (Tan) pump.

    Is that another relay under the right side transformer ?
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 5,506
    I'm pretty sure those "fan center" relays are available with a set of aux contacts on them so it could be spdt. That beige/tan/brown circulator is probably brass/bronze(usually that is what the beige instead of green or red paint means) so it might be DHW recirculaion or some scheme to heat DHW from the boiler.

    I see the HX in the video on the back wall mounted to the piece of 2x. Looks like there is a tridicator on it too.
  • 109A_5
    109A_5 Member Posts: 122
    mattmia2 said:

    I think one aquastat is to fire the boiler to 180 for the hot water call and the other is to run the circuator on the closed side of the HX when the open side gets hot. I thought I saw mention of a heat exchanger somewhere.

    It appears the HX is behind the boiler.
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 5,506
    But I am just guessing about the aquastat controlling the circulator directly. The second aquastat is a bit of a mystery. The part that I am pretty sure of is the thermostats and the pressuretrol and the auqastat for the boiler. That setup is a pretty common way to control both simultaneously without extra controls. That boiler relay and the LWCO are in there somewhere too but it just partially isolates the thermostat from the boiler controls.
  • CaptainHoneywell
    CaptainHoneywell Member Posts: 16
    I poked around some more and think I have an answer as to why there are three pumps. On the floor of my house with the dining room, there is a hot water radiator "set" (with fins and stuff) in the dining room itself. However, outside of the dining room, tucked into a window alcove, there's a smaller water radiator set of fins, hidden underneath a windowsill. I think it's being fed separately from the system that powers the dining room. Could that be it?
  • 109A_5
    109A_5 Member Posts: 122
    Only you can tell, follow the pipes if you can. A reasonable sized house with Hot-Water heat can work with only one pump and zone valves. Another way is to have a pump for each zone and not have the zone valves.

    You could fire up the Hot-Water thermostat and see what gets warm, and what pumps run. Maybe a 10 minute test.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • mattmia2
    mattmia2 Member Posts: 5,506
    It is possible that some of it is broken too and that is why it isn't heating well. That wet rotor circulator on the boiler side doesn't like all that iron sludge from the steam system. The sludge could plug that brazed plate heat exchanger too.