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PRVs

Unknown
Unknown Member
in THE MAIN WALL
http://fhaspapp.ittind.com/literature/files/610.pdf

I think this instruction sheet addresses it pretty well.

The others I looked at, so far, either don't mention it, or they insist on leaving it on.

Noel

http://www.taco-hvac.com/uploads/FileLibrary/%20Pressure%20Reducing%20Valves%20-%20(102-006.pdf

http://www.wattsreg.com/pdf/1910265.pdf

http://www.zurn.com/pages/catalog.asp?ProductGroupID=86&OperationID=11

Comments

  • TT
    TT Member Posts: 2
    Pressure Reducing Feed Valves

    Hey Dan,
    Afew years back I come across a posting on the wall stateing that the isolation valve before the pressure reducing valve on a residential hot water boiler should be left off unless filling the boiler . Do you remember this topic or where this may be documented. I looked in the installation instuctions for an FB-38,3350 and a 329-T3 without any luck.
  • TT
    TT Member Posts: 2
    Pressure Reducing Feed Valves

    Hey Dan,
    A few years back I come across a posting on the wall stateing that the isolation valve before the pressure reducing valve on a residential hot water boiler should be left off unless filling the boiler . Do you remember this topic or where this may be documented. I looked in the installation instuctions for an FB-38,3350 and a 329-T3 without any luck.
    Thanks in advance,
    TT
  • thp_8
    thp_8 Member Posts: 122
    You're going to

    get alot of different views on this one. Pros and cons of both. 1. Is the system leak free? 2. Is the system monitored? 3. Is the system treated?
  • Edward A. (Ed) Carery
    Edward A. (Ed) Carery Member Posts: 138
    Also,

    The PRV manufacturers also differ in their requirements. B&G requires you to fill the boiler then turn off the feed valve to the PRV, however Watts wants the feed valve to the PRV left on.

    See the links below regarding the I&O manuals for both.


    http://www.wattsreg.com/pdf/1910265.pdf

    http://fhaspapp.ittind.com/literature/files/610.pdf#search='Bell & Gossett boiler feed valve'


    Ed
  • Joe Mattiello
    Joe Mattiello Member Posts: 735
    PRV pressure regulating valve

    This may be a rhetorical question, but if you shut off a flow control valve prior to the PRV, why have a prv at all? Couldn’t you use the flow control valve to fill the system, and use the boiler pressure gauge to set the pressure? My position on this issue is to leave the flow valve open. This will assure a constant pressure based on the setting of the valve. I understand that there could be a catastrophic system failure and the potential for a flood would be immanent, but how often does that happen. Does anyone shut the mixing valve off at their washing machine? Same issue

    Taco, Inc.
    Joe Mattiello
    Technical Service Technician
    joemat@taco-hvac.com
    401-942-8000 X 484
    www.taco-hvac.com
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
  • Paul Rohrs_4
    Paul Rohrs_4 Member Posts: 466
    System Fill

    For all of those "Wall-flowers" lurking, let this not be confused with power-purging on the inital fill to get the majority of air out. Trying to fill a system with the PRV fill valve could cause you some major air-lock problems.

    Fill and purge the system with as high a water pressure as is available, then as the system is brought on-line, the PRV will replace the volume of the system as entrained-air is removed.

    Regards,

    PR

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Unknown
    Unknown
    I think it's used in that situation

    more for safety if you accidentally leave the hand valve open . Instead of continually filling the boiler to street pressure , it'll stop at the PRV setting .

    We exclusively use Taco and leave the PRV open . Very , very rarely do we hear of water damage from this practice . I guess once the systems start aging the occurances will multiply though .
  • Larry (from OSHA)
    Larry (from OSHA) Member Posts: 733
    I would suspect

    that this only applys to systems with expansion tanks as opposed to compression tanks. Yes? And if so, is there a need or local code that mandates one. As stated above, if it is filled, leak free and closed, why have a prv in the first place? I don't see it as a replacement for a low water cut off switch. If well purged, does entrained air removal reduce volume that greatly?

    Larry (from OSHA)
  • Edward A. (Ed) Carery
    Edward A. (Ed) Carery Member Posts: 138
    Problem solved

    The answer to this is actually quite simple.

    If you want to properly install any heating equipment, you must follow the manufacturer's I&O instructions for that equipment. If you do not follow the manufacturer's I&O instructions, and something goes wrong, you are responsible.

    Therefore, if you wish to install a PRV, and you wish to leave the feed valve on while the system is in operation, you must install a PRV that is designed by the manufacturer to be operated in that manner.

    However, if you wish to leave the PRV off during the boiler operation, after the original fill & purge, you must install a PRV that is designed by the manufacturer to operate in that manner.

    There are valid arguments for both sides of this discussion. However, there is no reason for you to use a PRV in a manner that the manufacturer specifically states it should not be used.

    So, you should do what you feel the job requires, and simply purchase and install the PRV equipment that is designed for use in that application.

    Ed
This discussion has been closed.

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