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Radiator (old C.Iron) - hot water shut valve questions

todd_14 Member Posts: 18
I have an older hot water, cast iron radiators system on 3 zones - 3 individual circ. Pumps. (New W/Mc- gv90-6 with taco 0015- 3 spd pumps). 

Zones re-plumbed circa 1950 with 1-1/4” copper loops connected to the original black iron pipes feeding each individual  radiator. Each radiator is fed off the zone loop with a pair of monoflo Tees.

not relevant to questions but  zone 3 feeds large copper finned convectors (each looks like like large radiator enclosures from mid 1950’s also fed with monoflo tees).  Zones 1 - 7 CI rads & zone 2 - 5 CI rads
Some of my cast iron (CI)radiators have shut off valves with a screwdriver slot to turn the stem.  The stem has a lock nut on it. 

My questions:
is this a 1/4 turn valve?

how do I know if the valves are fully open or closed?  

I don’t think these valves have been touched/exercised in a very very long time (like 35 or more years).

the T slot on mine are aligned/parallel to the radiator piping/flow. See pictures taken inside steel radiator enclosure. . 

I assume  there is packing on this stem like a typical radiator valve with a hand wheel. is this correct? 

Any advice if I try to loosen lock nut and turn stem? Likely hood of causing leaks?? 

can anybody post an old valve diagram of this style valve?

On radiator valves with hand wheels:

 are these typically 1/4 turn on/off? 

Do the hand wheel style of rad. Control valves require many full revolutions to open and close or are they typically 1/4 turn? 

Thank you in advance for your feed back.


  • Jamie Hall
    Jamie Hall Member Posts: 23,554
    Unless somebody has been playing games, the slot in the top and the hole in the valve should line up -- for if the slot is in line with the pipe the valve should be open.

    The other valves with hand wheels are very likely to be multiturn. Quarter turn valves are actually quite recent. Clockwise to close.

    Now. Unless you HAVE to turn the valve for some reason, don't. Older valves like that -- either kind -- like older people and older cats tend to get annoyed if you disturb them.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 11,093
    The screwdriver slot valves might be called balancing cocks and maybe used for

    isolation valves.

    I have these in a 1961 school and use them to control flow is certain parts.

    IF you want to move them, a dental pick to scrap off the crud and a shot of PB blaster.

    Clean out the screwdriver slot, I use a flare wrench that will exactly fit the packing nut or you could use a 6 point box wrench. I loosen about 1/2 turn, it might seep water a little.
    Then with the proper size screw driver you can turn the stem.
    Tighten the packing nut as you hold the stem where you want it.

    Some old wheel valves were 1/2 turn. When off there was a small port to continue some water flow to prevent freezing in an unheated room.

    Or if they are open....just leave them alone.
  • todd_14
    todd_14 Member Posts: 18
    Thank you both:

    so these valves are effectively 1/4 turn valves. 
    Correct ?? 

    Slot inline with pipe: fully open. 
    Slot 90 degrees to pipe: valve/flow turned off 
    JUGHNE Member Posts: 11,093
    Yes, for the slotted valves.

    The wheel/lever valves could be the 1/2 turn or multiple turns.
    EBEBRATT-Ed Member Posts: 15,764
    And with balancing valve they may not shut the water off 100%. They are to balance the flow between radiators
  • reggi
    reggi Member Posts: 522
    @todd_14 ..not quite.. 
    I found one I had laying around and turned nut which turned the screw head that closed the gate snug enough that I couldn't blow through it.. well less than a 1/4 turn of the screw head to close .. maybe a 1/8 ...on this particular valve..as you look at it the slot was straight and the wrench was pulled to the left side down... the gate went from straight to closed..as far as I can tell..I didn't really crank on it once it closed

    One way to get familiar something you know nothing about is to ask a really smart person a really stupid question
  • todd_14
    todd_14 Member Posts: 18
    Great.  Thank you for sharing this photo. 

    I suppose it Could be a partially blocked valve.  I was thinking it was more of a ball valve type bore as opposed to a wide rectangular like plug that spun to block opening.