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Move Temperature-Pressure Gauge & Relief Valve: Which Is best?

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PGB1
PGB1 Member Posts: 77
Hello All!
I have to replace the tridicator (dublicator?) and relief valve on my hydronic system. (Both are bad.) The tridicator never was accurate, pressure or temperature. I don't know if it is the location that is poor or if the gauge has been bad since it was new.

Now is a chance to swap locations for them. This will put the gauge closer to the boiler and will let more of the stem in the water flow.

A drawing of As-Is and Proposed is attached.

Unfortunately, there are no other places to install these devices.

The boiler itself does not have a tapping for either except on the back which is against the block wall. (The original gauge is a Temp-Altitude Only attached by a 1/4" corrugated tube to a section. That gauge does not work.)

I wanted to ask your opinions if the proposed swap is better or worse for accuracy. Also, do you see any potential problems with my idea.

Thanks For Your Input!
Paul

PS: When time and money are available, or if the boiler needs to be replaced, I intend to change to Pumping Away and probably replace the zone valves with pumps.
The boiler is most similar to Model 26 Bryant from the late 1940's or early 1950's. It had no pilot safety device, such as a thermocouple, so I replaced the gas valve, pilot assembly and added other safeties years ago- including a flame roll-out switch, low water cutout, redundant high limit and a 30# relief valve.

Comments

  • Intplm.
    Intplm. Member Posts: 1,960
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    What does the boilers manufacturer say in the directions. I would not deviate from those directions.
    If you must change then the new gauge and the relief valve should be as close to the boiler as possible.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,526
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    The relief valve needs to be mounted on the boiler itself or in the main supply pipe as near to the boiler as possible. The pipe it is mounted on should be larger than the relief valve itself. The relief valve must be mounted in a vertical position with the stem up. If there is no tapping, then add a tee for this.
  • PGB1
    PGB1 Member Posts: 77
    edited March 24
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    Thanks Intplm & Ed for taking time to reply and help.

    Intplm asked what the manufacturer instructions say. The 1947 instruction book makes no mention of the relief valve and refers only to the (non functional) built in Temp-Altitude gauge that uses 1/4" tubing.

    I wish I could mount the relief valve on the boiler. There are no tappings anywhere except the back, down low. The block wall blocks access (and I'd be concerned about trying to remove a black plug in cast iron after about 70 years.) I tried to find a closer place, everything is so close coupled, there is none closer than where it is now (left drawing).

    The fitting it's in now is 1 x 3/4 x 1 (branch is 1", valve is in 3/4 end tapping)). The valve is 3/4", so it seems one thing is correct where it is now.

    I don't understand reason for relief valve vertical, stem up, Ed. Is it for safety or longevity?
    I've seen lots of relief valves mounted horizontally on the boilers (and domestic water heaters).

    From what you guys mentioned, it seems that the best placements are where the items are now. (Because I can't get the relief valve closer to or on the boiler.)

    Paul
  • hot_rod
    hot_rod Member Posts: 22,144
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    If you want to read the temperature of the water in the boiler itself, the probe needs to be into the vessel. The further away the temperature gauge the less accurate reading of the boiler temperature, especially when the pump is not running.


    The manufacturer of the relief valve valve will generally include the installation requirements. Here is a common Watts 174, this tag is attached to the valve when you open the box.

    A tee or cross fitting right at the boiler supply outlet would be ideal for the relief and T&P gauge.

    Most important with any safety valve is that it cannot be isolated from the boiler with a service valve for example.

    Other places you will see pressure only relief on hydronics is at the fill valve, or on and expansion tank mounting arm.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,526
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    @PGB1

    Don't know the exact reason for the relief valves to be mounted stem up. They used to be sideways for years but ASME calls for them to be up and most inspectors that know anything enforce it,

    Water heater are different. They use T & P valves and the probe has to enter the tank.
    kcopp
  • Intplm.
    Intplm. Member Posts: 1,960
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    @PGB1

    Don't know the exact reason for the relief valves to be mounted stem up. They used to be sideways for years but ASME calls for them to be up and most inspectors that know anything enforce it,

    Water heater are different. They use T & P valves and the probe has to enter the tank.

    Hey there @EBEBRATT-Ed
    The reason for the "stem up" is because [some] relief valves were thought to have the internal stem and prob lean downward over time. This was/is thought to make the relief valve perform inadequately.
    I believe this vertical installation requirement was started some thirty years ago for some relief valves. Im not sure if its for all relief valves
  • hot_rod
    hot_rod Member Posts: 22,144
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    I think vertical, spindle up is to help prevent dirt and debris from accumulating inside the valve.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Intplm.
  • PGB1
    PGB1 Member Posts: 77
    edited March 25
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    Thank You guys for your helpful information.

    I asked the manufacturer of the new relief valve (Cash Acme) and was told "any position except inverted".
    After reading what each of you wrote, I'll put it vertically.

    As far as getting the relief valve and gauge actually into a boiler section, that will be impossible due to lack of ports to use. The only ports are a supply and a return and the 1/4" for the original, factory gauge.

    I probably could replace the supply outlet tee with a cross and, from the bottom branch, pipe a U-Turn and install the relief valve upright. The probe on the low water cut out is long, so it has to stay in the branch leading into the boiler section.

    But, I'd rather have a high limit in the outlet. (Existing are strap-on-the-pipe kind. I have two in series.)
    A little higher on the supply pipe, I can cut in a tee and street ell. The relief valve can go in there. It'll be a little closer to the boiler than it is.

    When time, temperature and money permit, I'll get a more efficient boiler.
    This one has one seemingly unfixable problem- No one can get a very good flame. Very, very tall and lots of yellow.
    I've asked combustion analysis guys here 3 times & they each gave up, suggesting "worn out" burners.
    My guess is either the cast iron burner ports are rusted open like the combustion people said or the Thermizer is preventing good exhaust of combustion gasses.

    Thanks Again For Helping Guys! I'll keep the relief upright and get both as close to the boiler as I can.

    Paul

    PS: This system was the poster child for Don't Do This...
    No pilot safety. If the pilot went out and heat called, burner gas would flow forever.
    No pilot burner. It was a copper tube with the end soldered closed and a hole drilled in it. 8" flame!
    Missing plate & asbestos pad on top of boiler sections (Dry a wet sock in 10 seconds on top of boiler)
    Missing flame baffles between sections & resultant holes burned through the boiler lid.
    No high limit
    No flame roll out switch
    No relief valve
    No pressure gauge
    No low water cut-out
    Expansion tank turned off
    No pump control. It was wired to run 24/7
    No air venting near boiler
    No way to purge air at radiation
    Pipes in outside walls which froze in winter. (So much for 24/7 pumping.)
    And more!


  • Intplm.
    Intplm. Member Posts: 1,960
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    @PGB1

    Ports not available? Ok try this.
    Here's a thought.
    In both of your pictured drawings, at the first elbow coming out at the feed, you can replace that elbow with a tee. Replacing the elbow with a tee will give you another port.
    If it isn't too much trouble you can have the gauge and relief valve installed at the new port created by using a tee there.
    PGB1
  • PGB1
    PGB1 Member Posts: 77
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    Thank You Intplm for your idea above. I, however, goofed on my drawing. The shown elbow is a tee (branch facing up). The low water cutout probe is in the end of the tee, reaching beyond the boiler jacket.

    But your idea has me thinking about adding a 1" npt cross above the existing tee. The cross will have a short nipple and cap with a bleed port. The low water probe can go in the cross. The bleed port is to get the air out on initial fill.

    This will free up the existing tee for the temperature-pressure gauge or the relief valve. (I'll probably put a street ell and the relief valve here. The tridicator can go where the relief valve is now. It'll be about 36" above where the supply pipe exist the boiler.)