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Always Wondering-Where should we put a LWCO?

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STEVEusaPA
STEVEusaPA Member Posts: 6,505
I, like probably most of you, have lots of 'things', 'ideas', etc always rattling around my brain.

The one problem I have come across most on hydronic systems where I think 'there has to be some better ways' is keeping the right amount of water in the system.
I get many calls (we see them on the wall) about 'my upstairs radiators aren't getting hot', or I bleed them and nothing comes out. Usually it's not enough water in the system.
Many times I found the water feed either won't open, or when it does, it won't close. Also, many pressure gauges are just not accurate, so I always bring my own to verify (I also wonder why I can't get a large gauge on my boiler that reads 0-40 psi). Maybe a better question is why do these gauges fail, and does anyone make the 'best' gauge?
In the beginning, I go to a boiler, pressure on zero, start filling, and the relief valve pops at '10' psi (not really 10, but the gauge was bad). Now the relief won't seat, and the feeder won't stop-and of course either no ball valve or bad gate valve. So replace those, take care of the steel expansion tank, or check the bladder tank, bleed/purge, clean up the water, and everything is fine.
So I wonder, why is the LWCO installed at the boiler? I understand as the last fail safe (if it works) before the boiler either gets dry fired, or thermally shocked. Shouldn't there be 2, or a remote probe at the top, or near top of the system? Maybe the higher probe could shut down, send a signal and/or give you 1 24 hour override until you can resolve the problem. Another alternative would be an actual pressure gauge that would work, probably digital, that would tell you when the pressure drops below a predetermined amount-obviously accounting for temperature/pressure fluctuations.
So I guess the real question is: Why do I want to know about a low water condition when practically the entire system is out of water? I'd rather know when it the highest radiation starts to lose water. The homeowner saves money, because their system isn't constantly running to try to satisfy a thermostat in a zone that's not getting the right amount of heat. And the tech can schedule the call when it's more convenient, making it less of an emergency (unless of course there is an actual water leak).
I'm sure there are controls for this, or people have made their own. I just think there has to be a better way.
Just a mini rant.
Thanks for reading.
Steve

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Comments

  • Fred
    Fred Member Posts: 8,542
    edited January 2017
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    Seems like something like the Safegard 711, or the 724 could be installed in a way that would allow it to do that, if you can put a remote probe on it, up high and mount the unit with the second probe, down lower, or visa versa. (since you don't need the steam vent, maybe the remote probe tapping could be moved from the back of the unit to that vent tapping and the back tapping plugged?) It's made for steam systems and has a blowdown capability but you probably don't need or want to use that feature on a hot water system. Of course this assumes the boiler has tappings at appropriate places. You might want to talk to Hydrolevel ???
    http://hydrolevel.com/wp-content/uploads/2015/12/Safgard-711-LWCO-Feeder-Inst.-061515-final.pdf
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    Thanks for your input @Fred . Ideally I wouldn't want to have to run 'something' to the highest radiations. I would think doing something by checking pressure in the basement would be easier.

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  • hot_rod
    hot_rod Member Posts: 22,497
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    These Grundfos sensor are used for solar and server cooling, critical applications. One model reads pressure and temperature, the other reads flow and temperature.

    On large solar arrays they alarm to indicate pressure drop or loss of fluid.

    All of our solar differential controls have a connection for them.

    They are built into some of the Grundfos pumps also, like the Magna. They position one in the Magna that reads the inlet and outlet from one sensor location, clever.


    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    Sure is, thanks HR!

    There was an error rendering this rich post.

  • Paul48
    Paul48 Member Posts: 4,469
    edited January 2017
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    I'm cheap, I'd contact SquareD and find out if they have a Pumptrol that's diaphragm would be appropriate for hot water. You can buy Pumptrols for $20.
  • hot_rod
    hot_rod Member Posts: 22,497
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    Sure is, thanks HR!

    Some mod con boilers has small pressure switches right on the header inside. They serve as a low water (pressure) cutout. I have not seen an adjustable version.

    It seem a probe type cutout device as an alarm would only alarm when a certain amount of fluid has left the system. A pressure switch would alarm before you got to that condition.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    edited January 2017
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    In theory a low pressure switch would be the best protection. However, given that it would still there for many years with the possibility of crud building up on diaphragm, or in the small orifice leading up to a pressure transducer. It could be rendered ineffective. A probe-type LWCO should in theory be the best fail safe.

    That said I'd love to see Safeguard, OEM, Hydrolevel, etc. make a probe&pressure LWCO. With adjustable pressure, or maybe a set 8psi would cover most applications. Now there is an idea!

    Who gets royalties?

    Taylor
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • hot_rod
    hot_rod Member Posts: 22,497
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    If your goal is to know of a low pressure condition, before a low water condition that would be needed to trip a probe type, seems a pressure switch is the correct solution.
    Probe type controls need attention, harsh water can coat them or aggressive water can destroy the probes, nothings perfect.

    A dual function is a great idea, make it a wifi to ring you up, or send a text when it alarms :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hvacfreak2
    hvacfreak2 Member Posts: 500
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    Paul48 said:

    I'm cheap, I'd contact SquareD and find out if they have a Pumptrol that's diaphragm would be appropriate for hot water. You can buy Pumptrols for $20.

    This reminded me that Amtrol has a digital pressure switch with an integral alarm. I am not sure of the maximum water temperature rating but the pressure adjustment is from 1-99 psi.

    hvacfreak

    Mechanical Enthusiast

    Burnham MST 396 , 60 oz gauge , Tigerloop , Firomatic Check Valve , Mcdonnell Miller 67 lwco , Danfoss RA2k TRV's

    Easyio FG20 Controller