Pressure Sensor in water system

Discussion in 'Plumbers' Talk' started by Billericay-Boy, Aug 2, 2012.

  1. Billericay-Boy

    Billericay-Boy New Member

    I am looking for a suitable electronic pressure sensor to add into the solar hot water system in my house.

    The unit needds to be cheap, able to take water temperatures of up to 90 degrees and able to interface with a 15mm copper pipe (with or without a adapter).

    Any ideas on a suitable sensor - i believe some boilers have these but i have no knowledge of them.

  2. Onetap

    Onetap New Member

    Try Sontay.

    You'd connect the pressure sensor with a u-tube syphon, the air pocket would isolate the sensor from the water temperature.

    PS  When you say a 'sensor', do you mean a sensor alone, or a sensor with a digital display? Or a pressure switch?
  3. Spooner

    Spooner Administrator

    Awright Onetwat, I hope your sweat problem has improved??

    OP are looking for some kind of 'heat dump' system son?? Most quality Solar System controllers can do this with the NTC thermistors that control the panel & the cylinder, what kind of set-up do you have?
  4. Billericay-Boy

    Billericay-Boy New Member

    What i am lookig for is a way to monitor my system for leakage and subsequent pressure loss.
    The control station has an expansion flask and a saftety pressure relief valve but occasionally the system seems to drop pressure and stop working.
    Over night the pressure will drop to 0.5 bar and when stagnating (cylinder at temperature so pump stops and panels keep heating upto 190 degrees sometimes).
    the last couple of days i have had to refill the system, whether this is becouse the pressure relief vlave is dumping fluid then as the system cools and the pressure drops opens the Auto Air Expel Vent so next hot cycle the hot water steams off through the vent.

    If i can get an electronic sensor i can wire it in to the monitoring system that will chart the pressure along with temperatures etc and even set a warning email.
  5. Onetap

    Onetap New Member

    Sontay, as above, assuming industry standard sensors are compatible with the monitoring system. What make is the monitoring system?
    Wouldn't a pressure gauge provide adequate, but simpler,  indication of  what is going on?

    If the system is producing steam, the pressure relief valve should operate and steam would be discharged from the automatic air vent. Are ther not some safety devices to prevent that happening? I've never had any dealings with solar stystems, so don't know what should be expected.
  6. Billericay-Boy

    Billericay-Boy New Member

    HI, i think the Sontay sensors are in the £300 to £500 price range which is not really econimical.

    There is a visual pressure guage on the pump station but as it is located i the loft it means getting the ladder out to check the pressure and i cant interface with the Resol Pump Station or the Resol DL2 data recorder 

    The following is displayed via the internet to my iphone or ipad. there are additional data lines that could be programmed for 2 more temperature settings and i was thinking of using one of these, even if it needed a converter to change the input to the correct scale.
    Green trace = tank top temperature
    Blue trace   = tank bottom temperature
    REd trace   = panel temperature
    not bad considering the lousy weather the last few days.
  7. Spooner

    Spooner Administrator

    The Pumping Station is in the attic??  Bloody Hell!!  That's got to be a cowboy I think you've got either a leak in your system or your expansion vessel is knackered mate.  I'd get someone in(that knows what they're doing) to check it over, if you've been topping it up, then the glycol level will need to be checked also.

    If you need a heat dump then that's not difficult to do, but it's a big IF - on any domestic system.
  8. Onetap

    Onetap New Member

    £100 for a pressure sensor. I doubt that you'd be able to find one cheaper, unless you see a suitable one on E-bay.

    Although you say "it could be programmed", most of the cost would be in programming. Unless you have details of the sensor type required and the software required to reprogram the system, this is a non-starter. Many manufacturers intentionally make their control systems inaccessible to anyone other 'official' technicians and 'trading partners', so that you have to pay them whatever they want for parts and amendments. There are countless examples of this. Even if you have the software, the configuration (programming) manual for some systems is the size of a telephone directory and it usually requires  a lot of effort to understand it.
  9. Spooner

    Spooner Administrator

    But Onetap, he's got a leak in the system or a faulty expansion vessel, that's plain to see from what the OP has posted.  The system is flashing to steam due to the lack of circulating water or a glycol blockage.  Why monitor a leak, just get it fixed ***!!!????  Software & gagets will not fix these problems, only someone that knows their onions can help him...........................;)
  10. Onetap

    Onetap New Member

    You're probably right, Spooner, though I hate to admit it. ;)

    I've had no dealings with solar and was just answering the OP's question about  sensors.

    I wouldn't imagine the panels are meant to get up to 190 deg (C?) and I'd suspect the PRV &/or the AAV are discharging water or steam  when that happens.
  11. Spooner

    Spooner Administrator

    The glycol can solidify at these sorts of temperature & cause a blockage in the panel or panel header, very nasty!!   
  12. Onetap

    Onetap New Member

    The glycol reacts with oxygen when heated and turns acidic, causing rapid corrosion.Under normal conditions, it should last several yaers, but if there has been air getting in and the system has been overheating, I'd suggest the OP tests it with litmus paper.   I'd have thought the blockages would be caused by corrosion products.

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