Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Electric Boiler

Options
I work on a lot of electric boilers for commercial and residential steam rooms. There's a recent commercial one that's been temperamental and not producing steam. The water level probes were coated with mineral deposits which allowed the fill valve to completely fill the tank. Without room for steam, hardly any steam was being produced. Cleaning the probes solved that problem.

However, then another problem came to light. When the contactor pulled in on a call for steam, it would sometimes spark at one of the terminals on the load side.

This is a 240 volt, 38 amp, 9kw machine.

When I checked the amp draw, it came up as 48 amps, way over spec. I verified the voltage at 240 volts and also verified the heating element as 9kw. With a fixed resistive load and a fixed incoming voltage, how can the amp draw be so high? The only thing I didn't do when I was there was to ohm out the heating element.
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

Comments

  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    loose connection or broken connection will pull high current. Maybe where you see the spark?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    rick in Alaska
  • Alan (California Radiant) Forbes
    Options
    loose connection or broken connection will pull high current. Maybe where you see the spark?
    The connection screw was tight.
    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
  • Jamie Hall
    Jamie Hall Member Posts: 23,554
    Options
    Is this wired with a neutral? I'm presuming single phase? If there is a neutral, check and make sure that the neutral really is, and that the two lines are balanced. Check all the way back to the main disconnect.

    How did you verify the heating element? Did you ohm it out, pole to pole, each pole to neutral (if there is one) and each pole to ground?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Larry Weingarten
  • Derheatmeister
    Derheatmeister Member Posts: 1,558
    Options
    Not sure about your Electric Steam systems and the deposits..
    It seems like most but not all Steam guys like the "Drama" of maintaining a higher PH ,the deposits associated with that and the never ending usage of enviromental harming Chemicals..

    But because of the mineral buildup on Electric resistance coils some of the "Low temperature" Electric boiler manufacturers have reached out to us and our products at the Last AHR ...
    They reached out to us in order to be able achieve the new ANSI H 1001.1 Standard using high purity water in conjunction with Sacrificial Anodes which IMO is better and more cost affective in the long run..

    As per your high amp draw: Yes Just like a Waterheater you should Ohm out the coils and change them if they are out of Specs..In order to avoid additional issues i would probably change out the "Contactor/Relay" as well ,Especially if you encountered "Sparking" at the contacts due to a high amp draw..
    Hope you are doing well..Richard.
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    It sometimes takes a megger to find a fault like that, a bit more technology then an ohm meter.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Derheatmeister
    Derheatmeister Member Posts: 1,558
    edited February 2022
    Options
    hot_rod said:

    It sometimes takes a megger to find a fault like that, a bit more technology then an ohm meter.

    Depending on the Equipment and relays involved a regular Multimeter can work wonders and reveal simple issues on some of these E-boilers :)
    How have you been Mister Bob ?..Sorry that we did not seen each other at the AHR..I would have loved to seen you/some of your Students and possibly explain what we are doing and why..
    I guess our small booth was insignificantly located in the Back part of C hall. Small 10 x10 booth which easy to overlook..
    I did however Spark some interest in some larger boiler manufacturers that read between the lines and hopefully going to take on our full line..
    I also ran into a hand full of German Students that were somewhat versed on our VDI 2035 / ANSI H1001.1 subject and was able to pass some additional of the Knowledge on to them..
    As you know bringing new subjects to the Trades can take time and there are allways
    Naysayers.... Patience... time will tell.
    Hope you and your family are doing fine and again so sorry we missed each other.
    Richard.



  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    Just wondering if this is off a 240 Delta system that has a "crazy leg" or wild leg". The only way you would know this is buy checking each leg to ground. The crazy leg will be like 265v to ground

    And even if the heater uses the wild leg it shouldn't matter 240-240.

    Where did you get the KW rating on the boiler? Or on the heater itself?

    Just wondering if someone stuffed a 12kw in there to get more heat out of it?

    Is it just 1 heater? Or like (3) 3kw heaters?

    Are both legs pulling the same amps?
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options
    Check the voltage on the line side and the load side of the pulled in contactor. 

    Also check for voltage drop from line to load on bothe sides of the contactor with ot under load. 

    Another thing you can do is put both hots in your clamp meter with the boiler running, you shouldn't read any current. If you do, the voltage is leaking somewhere. This is what a GFCI does.

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    Tinman
  • Derheatmeister
    Derheatmeister Member Posts: 1,558
    Options
    Which Make/Model of boiler are we talking about ?
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,076
    edited February 2022
    Options
    Is this wired with a neutral? I'm presuming single phase? If there is a neutral, check and make sure that the neutral really is, and that the two lines are balanced. Check all the way back to the main disconnect.
    I'm not sure on the neutral, but it's usually two legs of 110 volt plus a ground. Single phase.

    How did you verify the heating element? Did you ohm it out, pole to pole, each pole to neutral (if there is one) and each pole to ground?
    I haven't ohmed the heating element yet and should have.

    @EBEBRATT-Ed The mounting plate attached to the element says 9kw. Both legs are pulling the same 48 amps.


    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
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    @Alan (California Radiant) Forbes

    If it really is a 9kw heater something is amiss as it's drawing a 12kw load.

    Leaking to ground "should trip" the breaker. I would put an amprobe on the ground wire for ha ha's


    I was wondering if there is an additional name plate on the heater, thinking someone may have put an oversized heater in to get more BTUs

    To me it's unusual for a heater to draw over amps that much and not trip the breaker.

    9000 watts /240 volts should be 37.5 which matches the name plate rating


    9000 watts x 3.42 BTU/watt=30,780 btus/1000=30.78 lbs. of steam which also matches the name plate

    I would make sure its really grounded before I put my fingers on this thing with the power on
    Alan (California Radiant) Forbes
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    If it has indicator lights or relays with 120V coils it needs to have a neutral. Should be two hots, neutral, and bare or green colored ground wire?

    I sure wouldn't touch the brass steam head if it is not grounded properly, especially when wet or steamy :(
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Alan (California Radiant) Forbes
    Options
    If it has indicator lights or relays with 120V coils it needs to have a neutral. Should be two hots, neutral, and bare or green colored ground wire?
    There's nothing that's 120V on this machine. Even the control circuitry is 240V.

    To me it's unusual for a heater to draw over amps that much and not trip the breaker.
    I thought so too, but it's on a 50 amp breaker, so it won't trip when it's drawing 48 amps.
    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
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    @Alan (California Radiant) Forbes

    I don't think it can last much longer :)
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options
    Did you test the two hots in your clamp on meter and see if you get a reading? That is the best way to know if you have current going anywhere it shouldn't. 

    Ever electric boiler/on demand heater/furnace I've ever worked on or installed needed only 3 conductors. 2 hots and a ground, unless it was 3 phase. Never a neutral. The internal transformer usually makes 24volts just like any other heating system, just a 240 in 24 out transformer instead of 120 in 24 out. 

    It is very odd that it is overdrawn if it had thr correct elements. A poor connection etc would cause a lower than nameplate current draw. I'd also be suspicious that someone put larger elements in it. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    If you ohm out the element, convert that reading to KW to identify the element size. Most elements have the wattage stamped on them.

    What size wire on that 50A circuit?

    Regardless, the only spark on the job should be you :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,076
    edited February 2022
    Options
    Did you test the two hots in your clamp on meter and see if you get a reading? That is the best way to know if you have current going anywhere it shouldn't.
    Each leg was drawing 48 amps. I didn't do what @Solid_Fuel_Man suggested to put both hots in my clamp meter to see if there's any current, but that's a novel idea that I knew nothing about.

    If you ohm out the element, convert that reading to KW to identify the element size. Most elements have the wattage stamped on them.
    Healthy elements ohm out a between 5-20 ohms. I don't know how to convert that to kw. This element has "9kw" stamped on it. Not sure on the wire size.

    The owner is getting a new contactor and element in today and I've asked to be there when he turns it on.
    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
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    9000W, 240V= 37.5A, 6.4 ohm

    I cheat, and use the calculator at www.energyusecalculator.com
    Or do the math with Ohms law

    Good idea to replace the contactor if it has been arcing/overheated
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    Seems like there's and extra 10 amps going somewhere :)
    Solid_Fuel_Man
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options
    If it has 9Kw stamped on the element and is way over that rating.....I'd replace it too! The only thing I can think of is that the element has been replaced and is a 9Kw at a 208 volt rating and got installed your 240 volt boiler. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,076
    edited February 2022
    Options
    I think my meter is bad. It's reading 45 amps on a new 31 amp, 240 volt element on a residential steam machine.




    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
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    edited February 2022
    Options
    @Alan (California Radiant) Forbes

    I think your right. Do you have another back up meter you can check it against?
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    It is a 240V element 7.5 KW? It should be printed on the element.
    What is the actual measured voltage coming in?

    7500W/240= 31.5A

    If for some reason it is a 9000W/ 240 =37.5A

    Or as @Solid_Fuel_Man suggested a 9000W 208V element = 43A
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    @hot_rod

    Thinking he is on a different job now
  • Alan (California Radiant) Forbes
    Options
    Yes, this is a residential steam machine that is different from the beginning of the thread. I'll get another clamp ammeter to check mine.
    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
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options
    @Alan (California Radiant) Forbes fluke used to offer recalibration on their meter.....for a fee of course. You could reach out to them and see what it would cost instead of having a test instrument which is erroneous. 


    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    Do you suspect the ohm reading is off also? voltage?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Alan (California Radiant) Forbes
    Options
    Do you suspect the ohm reading is off also? voltage?
    They seem fine. I'm going to a different steam machine this morning and will take some readings.
    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
  • ratio
    ratio Member Posts: 3,676
    Options

    @Alan (California Radiant) Forbes fluke used to offer recalibration on their meter.....for a fee of course. You could reach out to them and see what it would cost instead of having a test instrument which is erroneous. 


    I had a tool in to Fluke Calibration a few years back. ZERO communications from them, not even a "you're in line after the million dollar customers." Took six months to get it back, I even gave up the weekly (& then daily) calls where I begged for any news at all, or even a STFU.

    Nah, not still torqued, why do you ask?

    Solid_Fuel_Man
  • Alan (California Radiant) Forbes
    Options
    @ratio You crack me up...........STFU was a new one on me...........Fluke is closed for the holiday...........maybe I'll just buy a new one.
    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
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    Always need a back up meter even though Fluke is very dependable. You don't have a meter you can trust is like not having your right arm. I always have 2 in my truck. Maybe more. I have a few used ones from e-bay
  • hot_rod
    hot_rod Member Posts: 22,382
    Options
    I have a 30 year old Fieldpiece stick meter that is ill. They told me to send it in and they would take a look and repair if it is possible.
    It's a nice compact meter and I have all the attachments.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    edited February 2022
    Options
    I was always kinda hard on my tools when I ran around like a nut doing service I lost a few meters (leaving them behind) that way or destroyed them by dropping them off a ladder. I got better as I got older. Back in the day if you dropped an older meter it was done or leaving it set on ohms while you checked some 480. POOF!

    So I got in the habit of leaving my good fluke stuff in the truck and used an "E-Bay" meter for my every day carry. Most of the calls you check voltage and amps or ohms.

    If I got into something that had to be accurate I would go back to the truck and get the Fluke. + that way I always had a back up

    Even now when I do some residential wiring I carry a "wiggy" solenoid operated tester.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Options


    FWIW, I've had this meter for several years and it has actually held up better than the Flukes I've had. I have several meters, so when I work on 3 phase stuff I can take simultaneous readings as that is sometimes helpful for troubleshooting. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,764
    Options
    I have a Fluke set up package. Comes with a #116 meter and a #323 amp meter. So the ammeter can do volts & ohms as well which gives you two meters for basic stuff.116 does Hz & capacetence as well
  • Jamie Hall
    Jamie Hall Member Posts: 23,554
    Options
    It's worth remembering that a clamp on meter is sensitive to magnetic fields around it -- not just the current in the wire. If it is possible, clamp it, zero it with the current off, and then read when the current is on without moving it. Not always possible...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Solid_Fuel_Man