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Temperature Pressure Gauge Orientation Question

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PGB1
PGB1 Member Posts: 81
edited March 17 in Radiant Heating
Hello All!

I was out of town & a problem at home required calling an outside service tech. (Wire came off a zone valve. Poor timing, to be certain!)

My system has a bottom mount a temperature-pressure gauge (Dual-cator? Tridicator Minus Altitude) installed horizontally. The guy said it can't be like that. To be honest, I've encountered this many, many times in my work life. Mine is sideways so it can be read without a mirror. A drawing is attached.

Is this something I've always been wrong to ignore?

Also, he said the system pressure is too low. I keep the system at 6 psi-g cold and the expansion tank is kept at 12 psi-g cold. (Highest radiation unit is 12'- 4" above the discharge pipe on the boiler.) The system's been working fine for 30+ years as-set.

What am I missing about this reasoning? My assumption is that he knows a lot more about residential hydronics than I know because in my work life, I've only worked large, commercial & industrial systems.

I'm starting to question my skills.

Thanks for explaining.
Paul

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,323
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    Those gauges don't care which way up they are, or the orientation. If your system pressure is high enough cold that air can't creep in at the highest radiator, and if the expansion tank is on the inlet to the circulator... while it seems to me 6 psig is a bit low, if it works...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    PGB1
  • Big Ed_4
    Big Ed_4 Member Posts: 2,785
    edited March 17
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    12# setting ended up being the standard for hydronic system . The pressure is needed to raise the water column up to the highest radiator . 12# was enough for the old three story home with an open system . The open system had the expansion tank in the attic with a vent out to the roof . Systems were hands on back then stoking the fire and maintaining water pressure . The gauges were larger and easier to read too :) We were taught 12# was the right pressure setting from the mechanics before us and before them.... To figure out what pressure you need , figure 1# per 3' rise and add a few #'s for safety ...

    From the drawing the gauge seems to be located in the system piping . I would want to see the boiler temperature durning a service call ...

    There was an error rendering this rich post.

    PGB1
  • PGB1
    PGB1 Member Posts: 81
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    Thank You Jamie & Big Ed for taking time to reply and for explaining.

    Jamie mentioned expansion tank location with respect to the circulating pump. This system is built backwards. The circulator is "pumping toward". The expansion tank is on the supply, sharing a cross with a microbubble absorber. It's between the boiler discharge pipe and the zone valves.

    A quick sketch is attached that will hopefully explain better than my words.

    My guess is that this was once a gravity system (or maybe steam) and was converted. The guess is based on the large holes in the floor at radiator piping and the stacks of reducing bushings on each radiator.


    Big Ed mentioned the location of the gauge & seeing the temperature during a service call.
    The gauge is in the supply piping, immediately after the expansion tank. When operating, I usually set it to 170-F this time of year. In cold winter, I'll set it to 180 and in warmer, I'll go to 160-F.

    Thank You Big Ed for explaining about pressures and how the numbers came to be. That's interesting to know & will be useful.

    Your mention of stoking brought back a good memory. When I was young, I knew that may father was up and stoking the coal because the vents would emit steam. I'd hurry up and go to the basement to watch the amazing fire inside. Like my brothers did, I should have stayed in bed because my interest eventually lead to me being the coal shoveler. They got to stay under covers until the house got warm!

    I do wonder why the expansion tank is at 12 PSI-G and the system is at 6. Should they not be equal?

    Today brought a glitch. The relief valve is dripping with cold system (and operating). According to the Tridicator, pressure is good at 6 PSI-G. I'll put a test gauge on a boiler drain later today to try to rule out a bad pressure relief valve.

    I think tomorrow's project will be to verify that the Tridicator's pressure is accurate and to verify the expansion tank air pressure with it out of the system. Then I'll set the system pressure accordingly.


    Thank You Each Again!
    Paul

  • hot_rod
    hot_rod Member Posts: 22,158
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    Ideally pressure gauges should be mounted vertically. I think the same applies for P/T gauges.
    You can get rear mount gauges in pressure /temperature with rear connection.

    Also it is best to have the circulator just downstream of the circulator, pumping away from the tank.
    Here are two options for pumping away with cast, or low pressure drop boilers

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    PGB1
  • PGB1
    PGB1 Member Posts: 81
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    Thank You for the update & the drawings, Bob.

    I'll look at the system to find out what I'll have to do to mount the gauge upright, if it's possible.

    Ideally, in summer I will re-pipe for a Pumping Away system (and a few more changes). That has been a goal of mine for may years, yet I never get a chance.

    Thank You Again,
    Paul
  • PGB1
    PGB1 Member Posts: 81
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    Thank You again guys for helping.

    After reading what HotRod posted about calibrating for horizontal, I asked manufacturers & was surprised how many said "no" to horizontal. (Boshart said horizontal is OK & no recalibrating is needed with the TR-30 series)


    An interesting challenge arose from a friend yesterday:
    Find a true Tridicator with 3 separate pointers (Temperature, Pressure, Altitude).

    I explained how to use a temperature-pressure gauge to convert to feet of water & said I'd set the pointer. Not Acceptable.

    I showed Marsh's temperature-pressure with feet of water conversion already on it.
    Not Acceptable.

    The owner would like an old-timey 3-scale gauge to replace the existing bad one.
    This should be a challenge to locate!

    Thanks Again all for helping with my question.
    Paul
  • hot_rod
    hot_rod Member Posts: 22,158
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    Have them buy the gauge they want and you install it😉  Ive never found a top quality tridicator. Separate pressure and temperature gauges are an option, then you can get quality, accurate gauges and readings
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    PGB1
  • PGB1
    PGB1 Member Posts: 81
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    Thanks Bob for the good "let them buy it" idea.

    They are stuck on having Altitude- even though I've explained how the pressure scale can be used if the gauge is quality (as you mentioned).
    Paul

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,851
    edited March 22
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    To be more specific about altitude. 28 inches of water column = 1 PSIg. (not 36" as was previously noted) That means if the highest radiator in the home is at 24 feet above the gauge, there will be about 3 to 4 feet of water column or 1.7 PSIg left at the top of the system to vent air from the radiators. This is a Slide from the seminar I used to teach when I worked with EH-CC.org



    Since most American homes were 2 stories with a basement, the 12 PSI standard was adopted by the dead men that first installed these systems. It is overkill for your home, however, it is not detrimental or dangerous. One story with basement and slab on grade boilers would be installed the same way to keep systems the same for the installers that were able to work on them, but did not understand the reason. Those of us that just did it because it was how we were taught.

    The next slide is the “What If” the building was taller and what would you do? There are 2 answers.



    One answer is to increase the pressure at the boiler in order to get the air at the top out of the system.
    The other is to put the boiler room at the top of the building. The higher pressure at the bottom would still be within the maximum pressure ratings of the pipes, fittings and components.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • PGB1
    PGB1 Member Posts: 81
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    Thank You Ed for the drawings. They will be handy for explaining things to people.

    The people who want the Tridicator have a gravity system. They use the "one person fills while another watches the expansion tank level" method.
    EdTheHeaterMan