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Wrong boiler pressure relief valve?

kaliber50
kaliber50 Member Posts: 17
As I embarked on a mission to rehabilitate my heating system piece by piece from the previous owner, I am at the part where I want to replace the boiler pressure relief valve since it looks old and oxidized. Problem is that I can’t find a replacement for it. For one, the previous owner put in one rated at 535K BTU 30 PSI but boiler max gross output is 120K. Am I missing something here? 

Also, since this is an Energy Kinetics System, I can’t simply call them up and order the one that it calls for even though they list the part number in their manual (see pic). I would have to go through my oil provider. Can you guys maybe suggest an equivalent? I thought it would be as simple as going to the big box store but given what the previous owner put in and EK lack of transparency in what exact product they call for my particular system, it would great if I can get a suggestion. Thx guys. 



Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 5,730
    edited May 1
    It’s fine. The 535,000 btu is a max rating, not a sizing indicator.
    The plastic pipe is worrisome. Also the drain pipe shouldn’t run horizontally like that.
    Any 30 psi male thread 3/4” relief valve will work. Just not a P&T valve like you would use for a water heater.
    steve
    kaliber50
  • mattmia2
    mattmia2 Member Posts: 5,742
    Looks like it just got leaked on by the failed automatic air vent. CPVC is usually legal for the relief valve discharge pipe as long as the normal operating temp of the system is below the rating of the pipe, that is what the model residential code requires. i can't tell if that is cpvc or just ordinary pvc.
    kaliber50
  • kaliber50
    kaliber50 Member Posts: 17
    It’s fine. The 535,000 btu is a max rating, not a sizing indicator. The plastic pipe is worrisome. Also the drain pipe shouldn’t run horizontally like that. Any 30 psi male thread 3/4” relief valve will work. Just not a P&T valve like you would use for a water heater.
    Thx for the feedback and reassurance. In that case i will just get a relief valve. I just wasn’t sure. I did buy one but as u said, it can’t be T&P valve but i didn’t know at the time. The pipe is just temporary until I get the room painted and it’s actually going vertically. It’s just not showing in the pic. 
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,153
    @kaliber50

    You can't just put on any relief valve. It needs to be rater 30psi & for more BTUs than the boiler will output (almost any 3/4 relief valve should work.............just check the tag)

    Also, I would use metal pipe either copper or black pipe for the relief valve outlet.

    The pipe needs to come out of the relief valve and elbow down. You cannot elbow it up it must drain down and terminate about 12" off the floor
    kaliber50
  • szwedj
    szwedj Member Posts: 45
    I thought I would post this in addition our PM. For reference, a Conbraco/Apollo 10-0407-05 30 PSI / 535,000 BTU Capacity relief valve is typically provided on that model. Based on the appearance of the system in addition to some of the comments already posted by the professionals contributing on HeatingHelp, we would also recommend a thorough review by a qualified heating professional to ensure the system is restored to safe working order. Please contact us if we can be of assistance.
    Joe Szwed
    Energy Kinetics
  • SteamingatMohawk
    SteamingatMohawk Member Posts: 743
    As a point of reference, the relief capacity can be stated two ways, BTU/HR and LB/HR. The actual approximate BTU/LB is 970, but for simplicity, the rating is based on 1000. Thus, a boiler "rated" at 150,000 BTU/HR requires a relief valve with that BTU/HR capacity or 150 LB/HR.

    In other discussions there has been a debate of sorts about whether the capacity is input or some other number. Bottom line, my 20+ year old HB Smith boiler relief valve capacity (134 LB/HR) is based on heating capacity (134,000 BTU/HR), not the input (165,000 BTU/HR). Other boiler capacities may be described in a variety of different terms.

    The nameplate on your boiler states 240 LB s/HR ( located just above the serial number, so that is your minimum number.

    The nameplate also states 120,000 BTU/HR for the largest fuel rate. This makes figuring out the different ratings even more confusing, unless the input capacity is twice the output for that boiler and the manufacturer used that instead of output (perhaps, including pickup and efficiency in what is required relief valve capacity). I'm not sure if oil fired boilers are rated differently. Several others can correctly answer that question.



  • SteamingatMohawk
    SteamingatMohawk Member Posts: 743
    It would be interesting to understand why the manufacturer uses that size valve for your model boiler.

  • Jersey2
    Jersey2 Member Posts: 106
    As long as it is rated to relieve the pressure at 30psi it is good. To me, if the current one doesn't drip you may as well not change it. Just shine it up with steel wool.
    I'm not a plumber or hvac man and my thoughts in comments are purely for conversation.
  • HomerJSmith
    HomerJSmith Member Posts: 1,625
    It seems to me that the PRV piping is wrong. As I recall the PRV must be within 6" of the vessel it is protecting. I would have installed it differently.
  • GGross
    GGross Member Posts: 191

    It would be interesting to understand why the manufacturer uses that size valve for your model boiler.

    It's because that is a standard 3/4" relief valve available at every supply house in the country. They could spend extra time and money to design proprietary relief valves for each size of equipment, but there would be no benefit to that and the result would be a more expensive, less readily available safety device.
    EdTheHeaterMan
  • bburd
    bburd Member Posts: 339
    edited May 4
    A couple of comments on the discharge piping from the PRV: it must be run full size, with no valve at all and no screw threads on the discharge end, which must be within 6 inches of the floor.

    As others have pointed out, the pipe material must be rated for the maximum discharge temperature. Theoretically that is 274°F for water at 30 psig, although I might be overthinking this.

    Bburd
    EdTheHeaterMan
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,153
    I would not use PVC or any plastic for a boiler relief. The relief valve sizing is based on the boiler output (but may be and usually is larger)
  • ChrisJ
    ChrisJ Member Posts: 13,077

    I would not use PVC or any plastic for a boiler relief. The relief valve sizing is based on the boiler output (but may be and usually is larger)

    I've been told many inspectors at least in my area will not allow black iron or galvanized either as it can clog with minerals over time from leaking valves.

    So basically, the only material you can use seems to be stainless steel, copper or brass?
    I guess Monel will work too, if you can find such a pipe.

    On my own stuff I do copper with a union if there's a 90 so I can easily remove it for inspection and replacement if need be.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • SteamingatMohawk
    SteamingatMohawk Member Posts: 743
    @GGross Interesting statement about relief valve capacity. My boiler has a 134LB/HR capacity, but is more than 20 years old. I agree completely that bigger is OK.

    That being said, out of curiosity, I searched several sites, including manufacturers and suppliers and did not find any valves smaller than about 300LB/HR. Perhaps, manufacturers buying in bulk is the driving force.

    From what I can see of the design of the valves, the technical difference for a given inlet/outlet size is the spring. I don't think it's all that expensive to have different springs, so there isn't much proprietary effort to have smaller ones available. The issue may be how many of the smaller capacities are bought each year and whether it is worthwhile to produce them.

    I believe the larger capacities are done that way.