Solar collector t&p valve excessive tripping

Discussion in 'Solar and Geothermal Water Heating Forum' started by joe smith 100, May 12, 2009.

  1. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England

    Legionellae can still develop, it's a bacteria and given the right conditions could rapidly develop. The Regs here will not allow any contamination or possible contamination to backflow into the cold water supply. so that could depend on the materials the water is sitting in ie the solar panel piping material, the storage tank
    The Regs here will not allow any contamination or possible contamination to backflow into the cold water supply. so that could depend on the materials the water is sitting in ie the solar panel piping material, the storage tank. A hotwater circulation loop (called a secondary return here) would form what is called the distribution circuit and the regs state the water should be stored at not less than 60c and distributed at not less than 55c. The recommendation on scalding grounds is that it should be 50c but that thermostatic mixing valves be used at every outlet to prevent harm to persons particularly the young/old, vulnerable, infirm and sensory challenged. So that shouldn't pose a problem here.


    Ahh but I quoted the price an installer or shrewd diy-er could buy it for also, and the installation cost would depend on local circumstances. Most hoses here are at least 2 story which is more risky to install on so it would cost more here. So the cost of $3592 +$1000 for installing it isn't far off your price of $4000 and this is for a premium branded product (not that i'm saying yours isn't). For a non branded system it would be up to $1000-$1200 less. I'm often under cut by £1000 - £1500 but their the people that phone up a year later when the company that installed it have done a runner or folded and reset up under a similar name without the liablities, with a system that was shodily installed and on the cheap, non solar rated components, such as central heating pump, pressure vessel soft soldered pipe work, heating pipe insulation, pressure relief into the house,... I'm sure you see your own horrors there.

    Plus I also pointed out that you could install a simple indirect system for $1500
  2. Alphacarina

    Alphacarina New Member

    Messages:
    26
    Location:
    Biloxi, MS
    What I don't understand is . . . . how could a closed loop system prevent this from happening?

    Your tank(s) could backflow just as easily as mine . . . . and since you're closed loop, the water in your tanks isn't as hot as mine. I'll bet virtually none of your neighbors have 140 degree water in their tanks either

    I have a well, so it would have to back up a long ways to contaminate anyone else . . . . but then I don't understand how you could get enough backflow to get back past your water meter in a public system anyway???

    I would hope your public officials have bigger/better things to worry about

    Don
  3. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England
    Well a closed loop is not then directly connected to the water suppliers water main.

    Yes the tank is, but as I have mentioned prior it is normal to keep tanks (cylinders here) at 60c here minimum but with the indirect systems the cylinder can be set to store at up to 90c before upper limits kick in.

    Indirect systems here can easily reach 140F that you mention and in any case say in the winter months low solar days the cylinders have twin coils for after heater from a boiler or an electrical immersion heater element, to ensure the cylinder heats up to 60c.
    Some of the controllers will even allow the whole store to be heated to 60c to ensure the cylinder is sterilised on a pre settable time period.

    you can view a live feed from this http://www.seconsolar.com/DL2/Live data.html but you'll have to check the weather to see how the output is affected.

    The water regs here are allowing for say a drop in supply pressure from the water main which would then allow the system to back flow into the water main. You could argue that a check valve would prevent that but they have 5 categories for water and the risk attached to them and the backflow prevention that each category of risk must be provided with.

    the complete regulations are available here for those interested.

    http://www.opsi.gov.uk/si/si1999/19991148.htm

    and this guidance might be more helpful in explaining them

    http://www.defra.gov.uk/environment/water/industry/wsregs99/waterregs99-guidance.pdf
  4. protech

    protech Master plumber

    Messages:
    53
    Location:
    Central Fl
    Your regulations (known as "codes" state side) make no sense.

    You’re saying they don't want hot water (fluid category 2) from the open collector loop to be siphoned back into the municipal supply, so you should replace it with a more hazardous fluid (category 3)? That is the most backward logic I have heard in some time. You want to replace a fluid that MAY under very rare and ideal circumstances contain a pathogen with one that is ALWAYS hazardous and has a good chance of getting into the water supply at some point in its service life (closed solar loop leaks into potable hot water tank).

    Those categories were taken right from your own code book http://www.defra.gov.uk/environment/water/industry/wsregs99/waterregs99-guidance.pdf
  5. protech

    protech Master plumber

    Messages:
    53
    Location:
    Central Fl
    I'm sorry flamefix, but I still fail to see how the solar loop can contain any more pathogens than the tank it self. Please explain a set of conditions that would allow this could occur.
  6. protech

    protech Master plumber

    Messages:
    53
    Location:
    Central Fl
    Look, let’s cut the crap here. Are you saying that YOU regularly install an active-indirect system sized for 2-4 people for the equivalent price of $4000 on a daily basis or not. Because I, and most of my legitimate competitors do. That's out the door. Materials, Labor, Building Permit, Delivery.........everything.

    Yes, or no. If no, what's your average price for the above.


  7. protech

    protech Master plumber

    Messages:
    53
    Location:
    Central Fl
    No, it can't. Well not in Florida anyway. The collector loop will not be in the ideal growth range for enough time for that to occur. We get just a few days out of the year that the loop isn't sterilized.

  8. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England
    I think you're misrepresenting or interpreting what I am saying. and to clarify some of your points I have posed the question to the regs here so some things i'll get back to you on, and if i'm right or wrong I'll freely admit it publicly however; I am talking about my opinion and the regs here in the UK and I am not saying you are wrong to do what you are doing in any way, I have only said It wouldn't be allowed here (which I am confirming) and I 'personally' don't see the need.

    your point above doesn't make sense either because the collector and the cylinder are as one the fluid in the two freely circulate they could gravitate if the pump wasn't on and if there are check valves then these could fail.

    Now an indirect system is less risk because there is a physical barrier between the two fluids, be it the coil a cylinder within a cylinder or a plate heat exchanger.
    That said I have clearly stated the cylinder holding the hot water must be heated to 60c. or be capable of heating to 60c to kill any legionellae.

    here is an article relating to preheated water that is heated by solar and either flows to a hot tap if at the required temperature or is then passed through a combi boiler on the cold inlet side to be heated by the boiler. Another system I am not a fan of however,
    http://www.wras.co.uk/Preheated-Water.htm
  9. flamefix

    flamefix New Member

    Messages:
    71
    Location:
    Exeter, England
    no I am not saying that nor have I . I don't know what you purchase your system for and or your mark up for profit and labour content. All I have told you is the cost of the items as they are here, I am not saying what you can install them for and make the level of profit you require because I don't know your cost base. I have stated that you can buy an indirect system a lot cheaper than I believed you thought.
    The systems here are integrated differently to the ones you have described in that they are connected to the central heating system, they are installed at height requiring safety platforms access towers and insurances and other factors are likely different here to there, so a true comparison on installed costs is difficult to compare equally, whereas the material cost isn't. I also don't know how local factors influence things for example It's cheaper for me to buy a Mac from the US than in the UK its the same bloody machine though. It might be you buying solar equipment is more or less expensive than buying it here.

    However for your information a premium system with evacuated tubes 80 gallon cylinder (tank) as I described installed and warranted is $8600 a flat plate version is $7500 but equally a perfectly good quality system could be installed for $5750

    That's based on my input costs but without your rebates, as I have no idea what they would be.

    Why are you not also comparing your system to the integrated tank and collector system that you can get for far cheape,r than the system you fit that I have also given information on?

    I'm not going to argue it's your professional opinion and I respect that, I am not fully convinced there is no risk, so personally I'd rather not take the risk given there is an alternative option.
  10. mkiernan

    mkiernan New Member

    Messages:
    4
    Location:
    Oklahoma
    protech is very right, do not use a t&p valve any where near the collector.
    t&p valves are set to go at 210f as per ipc.
    you only need a pressure relief valve.
Similar Threads: Solar collector
Forum Title Date
Solar and Geothermal Water Heating Forum O-I Sunpak Solar Collector Parts Aug 17, 2012
Solar and Geothermal Water Heating Forum ABS for solar collectors May 10, 2012
Solar and Geothermal Water Heating Forum Fabricating A Header For Solar Collector WIthout Reducing T's May 14, 2009
Solar and Geothermal Water Heating Forum How to plumb a movable solar collector May 29, 2007
Solar and Geothermal Water Heating Forum Summer Winter mode for Solar heat and Water. Aug 24, 2014

Share This Page