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Why are there 2 circulators on this?

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HydroNiCK
HydroNiCK Member Posts: 182
There is one thermostat controlling this boiler.  The domestic hot water is hot and domestic but the house gets no heat.  I tested the aquastat and found bad circ relay.  The vent is leaking, the boiler is sitting in a puddle and notice the psi on the tridicator was at least 120.😳  I pulled the pressure relief valve and air w/ a little steam blew out then mud. The boiler heats a couple small radiators and like 40ft of baseboard.  Despite all that, why are there two circulators? Is the wire cut on the right hand one? I didn't notice until I was staring at the picture. 

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  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,176
    edited September 2023
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    Do you have 2 thermostats? if you do, then that is the reason for two circulators. One thermostat for each zone, one circulator for each zone. I have a suspicion that it is not wired up the best way though. without a second circulator relay like a R845A or RA889A, then the second circulator might rob hot water from the system if you still use the tankless coil in the boiler for your domestic hot water (DHW). A common mistake made by inexperienced plumbers. Do you experience water temperature drop when taking a shower sometimes in the heating months?

    Look for a line voltage thermostat in the area where the baseboard radiators are located.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,176
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    The tridicator does not go up to 120 PSI. 75 PSI max with a 170 FT H2O scale, and in the photo is is on 35 PSI.

    Is this a customer that you are working on? If so, that gauge is wrong or the relief valve is bad if it is not passing water. You mentioned a little air then water when you operated the relief valve. That is not good, I would have shut down the boiler until I could do more testing. Then wright on the service ticket "OPERATE AT OWN RISK" and have the customer sign it.

    If this is your boiler then shut it down, it may already be cracked since there is water under it. More info needed!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Jamie Hall
    Jamie Hall Member Posts: 23,675
    edited September 2023
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    I have a headache. Let's take the simplest one first: you have misread that tridicator. Your peak pressure was about 37 psi or 80 FEET. Too high, true -- but at least not 120 psi.

    I don't see a picture of a pressure relief valve; the valve which does have a picture is a pressure reducing and regulating valve. That said, if you did open the pressure relief valve with the lever, and steam (or air?) and a little water and mud came out followed by mud, you have a very serious safety hazard -- and the boiler should be turned off at the emergency switch (which is what you have and what it's for) and left off until you can find out why that valve is plugged and get the piping to it cleaned and the valve replaced (it's toast now).

    I repeat: turn the boiler off and leave it off until you are sure that the pressure relief valve is functioning freely.

    One of your two air release vents does appear to be leaking. The one which is leaking is probably shot. It may be surplus to requirements, but it should also be replaced.

    Now back to the pressure for a moment. As I say, it is too high. Further, if the boiler was off when you took the picture, the cold static pressure is too high. That strongly suggests that the pressure regulating valve is not functioning properly. You can check that with the boiler off (you do have it turned off now, don't you?) by closing the shutoff valve immediately before the regulator and finding a drain on the boiler and opening it and letting a little water out. The pressure should drop. Let it drop to about 10 psi on the gauge, close the drain you opened, and open that shutoff valve. The pressure should come back up to about 12 to 15 psi -- no more. If it gets over that, either the regulator is misadjusted -- or is shot.

    Now I think I do see a piece of Romex which is cut coming from the same place in the overhead as the power feed for the right hand circulator. If it is cut, it should either be removed completely, or the wires capped with wire nuts, individually wrapped, and the whole wrapped. I have no idea where the power for that circulator is supposed to come from -- or what is controlling it, nor are the photos enough to determine where the BX power feed to the left hand circulator is coming from.

    What I do see is a nightmare in what I think may be the wall box for thermostat? Are the two wiring pictures related, one of the wall box and one of the mounting plate for a thermostat?

    Whether they are or not... I have no deep seated objection to old steel BX. Nor do I have any deep seated objections to cloth and rubber insulated wire -- provided it is in good condition. The old wire shown in those two pictures is another shut it off now and don't turn it back on until it is replaced condition. Whatever those wires are connected to must be turned off and the wires replaced.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EdTheHeaterManbburd
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,176
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    What @Jamie Hall said!

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • HydroNiCK
    HydroNiCK Member Posts: 182
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    1 thermostat. 1 zone according to the home owner.  I Should have said 50psi. The relief valve is in the back. The coil was replaced a couple of years ago and a nice new oil tank installed.  The vent is leaking and the boiler is rotting because of the makeup water.  It may have cracked taking in cold make up.   So why two circulators?   Either there were two zones.or .one circ couldn't overcome the radiator head so someone thought they'd add a circulator?
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,255
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    Do you have an indirect water heater?  Some long shots please..can't see what you got there.  Mad Dog 🐕 
  • Jamie Hall
    Jamie Hall Member Posts: 23,675
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    To find out why there are two circulators you are going to have to do some pipe tracing. They definitely are not in series the way they are piped, so one is serving some of the piping and ther other is serving the rest of it (if there were an indirect, I'd say that one was doing that, but your reference to a coil suggests that there isn't).

    With regard to the coil again, and your comment that there is still hot water (please turn that boiler off until you get at least the pressure relief valve fixed) tells me that whatever is controlling the boiler for the domestic hot water is working -- probably the triple aquastat.

    Since you are working on this thing, I'd suggest stepping back and replacing --not repairing or reusing -- all of the wiring and miscellaneous controls and valves... as well as the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    GGrossMad Dog_2
  • HVACNUT
    HVACNUT Member Posts: 5,894
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    Moline heater in the garage?
    Have you followed the piping?
    Have you followed the wiring to the circulator?
    Rickoo
  • HomerJSmith
    HomerJSmith Member Posts: 2,511
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    You really need professional help. Get a hydronic expert in there.
    Mad Dog_2HydroNiCK
  • mattmia2
    mattmia2 Member Posts: 9,981
    edited September 2023
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    where does the bx and the romex to the circulators go? I'm betting the pressure issue is a compression tank that has seen no service in a decade and is waterlogged. Looks like the romex goes above the piece of drywall that was removed and replaced. where does it come back out and go from there?

    Oh, and if it does have a compression tank, that auto air vent will remove the air from the tank over time.
    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,255
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    Where'd he go??  Mad Dog 🐕 
    mattmia2
  • Jamie Hall
    Jamie Hall Member Posts: 23,675
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    Did we scare @HydroNiCK ?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Mad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,255
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    I don't know if those stats are tracked, but I see that alot.  They are probably used to other sites where questions can sit up there for days. Mad Dog 🐕 
  • HydroNiCK
    HydroNiCK Member Posts: 182
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    What. I'm here. I work and check the Wall when I get a chance.  Join date 2013 with 162 posts.   I got called there not because I'm the town photographer but for "a leak". They said it doesn't heat the house only provides dhw.  They used electric heaters over the past year. I told them to shut that thing off before I even got there.  I got there. No thermostat on wall. I put one on..had to start somewhere. I was going to fix leak and everything else to get it running but with all that's wrong it prob be cheaper if they get a whole new boiler. Im posting this mess here because the downfall of that thing can be explained. Except the two circulators they don't make sense.  
    CTOilHeat
  • Jamie Hall
    Jamie Hall Member Posts: 23,675
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    Ah. There you are, @HydroNiCK ! Good -- I was afraid I'd scared you off.

    No, as I said those two circulators really don't make much sense, unless they are piped to serve different parts of the heating -- which is the most likely. The only way you or anyone else is going to figure that out is to trace the plumbing, on the one hand, and figure out what, exactly, is supposed to make them run. Given the overall condition, I'm not totally convinced it's worth the effort -- better to start from the beginning.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 22,505
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    The right hand circ look different, is it a high head model? That may be a clue as to what it feeds
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    HydroNiCK
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 2,041
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    hot_rod said:
    The right hand circ look different, is it a high head model? That may be a clue as to what it feeds
    Assuming the installer had a clue
    Grallert
  • HydroNiCK
    HydroNiCK Member Posts: 182
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    hot_rod said:
    The right hand circ look different, is it a high head model? That may be a clue as to what it feeds
    The second floor of the house was updated.  Someone installed radiators in a bathroom and bedroom. There was a wall of baseboard in an existing bedroom. Whoever may have added the circ. for that. So they new enough that the first circ. wasn't cutting it. There is   a nice new roth oil tank in the basement near the boiler.  The young lady that owns the house said her oil guy replaced her coil not to long ago. She told me when I was asking her questions about the boiler that they gave her an on demand hot water heater. I told her about the psi..she said she remembers them draining boiler from the relief valve...   Where am I going with this?  I'm thinking at some recent point the boiler was cared for/at least looked at so what happened?  A chain of events / neglect lead to it's current state but that doesn't explain the circulator.  The girl said that when she turned up thermostat she heard it click but no heat however it does make dhw. I checked the aquastat with my meter and she's right.  That circulator on the right should have a separate relay the one with the romex is wired to the boiler.  The circulator on the right had to get piped in before the one on the left...Also the fact that the homeowner used space heater instead of the boiler for at least a year adds to the weirdness. So I was going to fix it but I may take all your advice and tell her she needs a new everything.
  • mattmia2
    mattmia2 Member Posts: 9,981
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    I think it is worth figuring it out. So far I haven't seen anything that wouldn't be dealt with with minor repairs and figuring out how it is supposed to work. That could change once you sort it out, but so far it looks minor.
    HydroNiCK
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,176
    edited September 2023
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    So this is my take:

    Since baseboard radiators installed in a series loop do not work well with cast iron radiators that are installed in a direct return, reverse return or monoflo tee system, the person who installed the baseboard also installed the separate circulator as it should be.

    The reason for the no heat from the boiler may be from having too much air in the system so the water will not circulate, OR the circulator relay not working as mentioned by @HydroNiCK Either way you need to check to see if the circulator is getting power, then if it is getting power, that the pump is actually rotating, and if it is rotating, that there is water in the radiators. So there is more diagnostic work needed there.

    It appears that the boiler is holding pressure, enough to get water in the radiators to do the above test.

    Also, I wouldn’t mistake you for the town photographer by the photos posted herein. You might want to step back about 8 feet to get an overall boiler shot from several angles. That will help us in diagnosing your issues.

    Click on spoiler
    That last paragraph was an attempt at humor

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Alan (California Radiant) Forbes
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,255
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    Pictures of all piping equipment and boiler room would help...Mad Dog 🐕 
  • HVACNUT
    HVACNUT Member Posts: 5,894
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    I don't understand why this is so hard. There's 3 trails. Supply, return, and wiring with a thermostat and maybe a relay somewhere. 
    Do you not have access to snoop around?
    bburdMad Dog_2
  • HydroNiCK
    HydroNiCK Member Posts: 182
    edited September 2023
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    HVACNUT said:
    I don't understand why this is so hard. There's 3 trails. Supply, return, and wiring with a thermostat and maybe a relay somewhere. 
    Do you not have access to snoop around?
    I didn't post this because it's so hard. I posted this because I think it's so odd.  I wouldn't have done it like that. Would you? If you answer Maybe then tell me why since Im interested in learning. In the above situation I became more interested with "why" rather than "how". If I was the homeowner I wouldn't spend money on a new tank, coil, and radiators then when my circulator stops working say F it and use an electric space heater for a year. Odd.  But what do I know? I'm just a lowly plumber. So I posted this to get everyone's take on it.  Ed's photography tips alone are worth their weight in gold.
    Alan (California Radiant) ForbesEdTheHeaterMan
  • mattmia2
    mattmia2 Member Posts: 9,981
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    Different parts added at different times in the easiest way possible at the time. Separate zoning of the 1st and 2nd floor because they will never have identical changes to heat load as conditions change.

    There could be a whole control for the 2nd circulator complete with thermostat wiring above that piece of drywall.
  • HVACNUT
    HVACNUT Member Posts: 5,894
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    HydroNiCK said:
    HVACNUT said:
    I don't understand why this is so hard. There's 3 trails. Supply, return, and wiring with a thermostat and maybe a relay somewhere. 
    Do you not have access to snoop around?
    I didn't post this because it's so hard. I posted this because I think it's so odd.  I wouldn't have done it like that. Would you? If you answer Maybe then tell me why since Im interested in learning. In the above situation I became more interested with "why" rather than "how". If I was the homeowner I wouldn't spend money on a new tank, coil, and radiators then when my circulator stops working say F it and use an electric space heater for a year. Odd.  But what do I know? I'm just a lowly plumber. So I posted this to get everyone's take on it.  Ed's photography tips alone are worth their weight in gold.
    Apologies. I was under the impression there was a mystery zone. Sometimes I read too fast.
  • Alan (California Radiant) Forbes
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    I haven't read through the entire thread, but it could be that there was once two zones with a pump on each zone.

    Failing that, installers have different levels of experience as well as different thoughts on the right way to fit pipes and pumps together.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,176
    edited September 2023
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    HydroNiCK said:

    I didn't post this because it's so hard. I posted this because I think it's so odd.  I wouldn't have done it like that. Would you? If you answer Maybe then tell me why since Im interested in learning. In the above situation I became more interested with "why" rather than "how". If I was the homeowner I wouldn't spend money on a new tank, coil, and radiators then when my circulator stops working say F it and use an electric space heater for a year. Odd.  But what do I know? I'm just a lowly plumber. So I posted this to get everyone's take on it.  Ed's photography tips alone are worth their weight in gold.


    THAT IS EXACTLY THE WAY I WOULD HAVE DONE IT!

    Modifying a home with an existing radiator design heating system, with a different design heating system, rarely has a good outcome. Baseboard radiators in a series loop connected to the branch tee of a former radiator is a common mistake made by inexperienced heating professionals. The radiators may have a flow rate of as little as 1/4 of a gallon per minute flow. The baseboard series loop works better with a 4 gallon per minute flow rate.

    By taking the supply branch of a disconnected radiator and running 1/4 GPM thru the 40 ft of baseboard back to the return of the disconnected radiator equals NO HEAT in the baseboard loop. To solve that, you operate the baseboard on its own separate loop with its own separate circulator operated by its own separate thermostat. It is basic Hydronics 101 (if there was a Hydronics University)
    After new circulator and some remodeling you might find this mistake.

    You would fix it this way

    I believe you might find this booklet very helpful. I used it to teach a one day seminar. Most of the technicians that attended found lots of good information in there https://s3.amazonaws.com/s3.supplyhouse.com/product_files/108119-Reference Guide.pdf



    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Alan (California Radiant) ForbesHydroNiCKMad Dog_2
  • realliveplumber
    realliveplumber Member Posts: 354
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    We see it in our area. 2 separate zones, controlled by a single thermostat.

    Dont ask me why, but its done that way sometimes.

    I would trace out the wiring and piping, , and try to think outside the box, as to why someone would do what they did.

    Was there an addition added over the years? If it was a quality contractor, it will be difficult, if not nearly impossible, to determine.


    If you think about it long enough, it'll come to you, probably in the middle of the night.
    EdTheHeaterManMad Dog_2
  • HydroNiCK
    HydroNiCK Member Posts: 182
    edited September 2023
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    I didn't post this because it's so hard. I posted this because I think it's so odd.  I wouldn't have done it like that. Would you? If you answer Maybe then tell me why since Im interested in learning. In the above situation I became more interested with "why" rather than "how". If I was the homeowner I wouldn't spend money on a new tank, coil, and radiators then when my circulator stops working say F it and use an electric space heater for a year. Odd.  But what do I know? I'm just a lowly plumber. So I posted this to get everyone's take on it.  Ed's photography tips alone are worth their weight in gold.
    THAT IS EXACTLY THE WAY I WOULD HAVE DONE IT! Modifying a home with an existing radiator design heating system, with a different design heating system, rarely has a good outcome. Baseboard radiators in a series loop connected to the branch tee of a former radiator is a common mistake made by inexperienced heating professionals. The radiators may have a flow rate of as little as 1/4 of a gallon per minute flow. The baseboard series loop works better with a 4 gallon per minute flow rate. By taking the supply branch of a disconnected radiator and running 1/4 GPM thru the 40 ft of baseboard back to the return of the disconnected radiator equals NO HEAT in the baseboard loop. To solve that, you operate the baseboard on its own separate loop with its own separate circulator operated by its own separate thermostat. It is basic Hydronics 101 (if there was a Hydronics University)  After new circulator and some remodeling you might find this mistake.  You would fix it this way I believe you might find this booklet very helpful. I used it to teach a one day seminar. Most of the technicians that attended found lots of good information in there https://s3.amazonaws.com/s3.supplyhouse.com/product_files/108119-Reference Guide.pdf
    That's exactly what it looks like.  Adding Monoflo tees could also fix it right?  They may already be somewhere in the system.  The radiators are new but the house was built 1952. 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,176
    edited September 2023
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    Adding a Monoflo tee instead of a circulator will probably not work. You need the have the pressure drop of the monoflo tee designed to the original system for them to work properly.

    Homes built in the late 1940s and 1950s often were heated with a "ONE PIPE" design heating system. by using a diverter tee system or Mono-Flo® tee system and convector radiators. There must be a diverter tee on each return for every radiator. There was a cost savings on the amount of pipe used to heat a home. In the late 1950s until today, there was a new design that was more common. The series loop baseboard system cost less to install than the One Pipe Mono-Flo. Series loop became the industry standard.

    So if you found this in the 1970s someone didn't do their homework and the homeowner never got heat from the baseboard system.

    The way to fix this problem was to use a separate circulator like this.

    Now you need to determine if the original system is a One Pipe Mono-flo design, or is it a direct return as in the original illustration. In either case, the older system will operate fine with the original circulator. The original circulator will not make enough water flow into the 40 ft of baseboard in the way you believe it should. The only way to get the water to flow thru the baseboard is to be on its own zone with its own circulator pump as illustrated in the last slide of each system.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    HydroNiCK
  • HydroNiCK
    HydroNiCK Member Posts: 182
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    Update: I went back to the house and fixed the auto vent leak, replaced the fill valve, expansion tank (which was empty), pressure relief, tridicator, purged then turned it on. I opened the flow checks which are clogged up   ....the radiators started heating up but not great since they probably need to be purged and also clogged up.  The boiler supplies domestic hot water fine BUT the aquastat wasn't shutting off the burner.  The gauge went to 220F.I told the owner not to turn the heat on. The aquastat and coil are running fine with DHW.  I'm going back to replace the aquastat and making sure it's not shutting off when it's supposed to and that thing isn't over heating do to scale build up and circulator(s) dying and not getting the heat out.  
    j