Simple idea = simple plan?

GilliganGilligan Registered Users Posts: 4
Not sure if this is the right section but I'll give it a go either way.

I have an open tank (30 gallons) of plain water that I dip a photo sensitive emulsion coated screen in (Screen Printing). This water works to soften the emulsion that was not exposed and then it rinses off really easily.

It works really well right now, but I read of people agitating the water with air and some talk about using water heaters (like for live stock watering tanks).

I have always played around with solar thermal water heating and thought... why not put a tank on the roof, paint it black and have a pump circulate the water on a timer(thermo siphon would be ideal, but just logistically won't work here).

Of course the first thing to think/worry about is siphoning and having the water over flow the tank inside. So I first thought of a vacuum breaker, then I thought... what about all that air in the line? So then I started looking at evacuators (sp), but now we are getting more and more complicated and costly.

Then I thought of an idea that I'd like to get you guys opinion on.

Couldn't I just have a pipe that T's off and goes well above the outlet in the tank and that would serve as both vacuum breaker and air release? Or would I need a vacuum breaker for good measure and would a cheapy one work? It wouldn't be a huge mess as there is probably a gallon of extra space at the top of the dip tank as well as it's a shop and not that big of a deal if it over flowed, but I'd rather it not.

I did a quick little doodle in paint to demonstrate my point better... maybe I need a reverse pee trap as well? For some reason, I just can't wrap my head around this concept and what will happen when the pump is turned off in the different scenarios.

Attachment not found.


Thanks,
Gilligan

Comments

  • BB.BB. Super Moderators, Administrators Posts: 30,175 admin
    Re: Simple idea = simple plan?

    At the very least, you would need a check valve in the pump line (to prevent water flow back into the pump--And/or put the cold water up over the top of the tank and then down to the bottom with a vacuum break at top (to prevent siphoning/backflow into the dip tank).

    On the hot water side, you would want another vacuum break too, so you don't draw water from the thank (you can collapse the tank if there is no air inlet).

    One thing I would worry about--Elevated temperatures and material in the dip tank "gunking up" the heating tank... May be a mess up there after a few months/years unless you can clean it.

    Perhaps a closed loop water circulation system back into the dip tank (distilled water/antifreeze in heating loop)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • tmarchtmarch Solar Expert Posts: 143 ✭✭
    Re: Simple idea = simple plan?
    Gilligan wrote: »
    Not sure if this is the right section but I'll give it a go either way.

    I have an open tank (30 gallons) of plain water that I dip a photo sensitive emulsion coated screen in (Screen Printing). This water works to soften the emulsion that was not exposed and then it rinses off really easily.

    It works really well right now, but I read of people agitating the water with air and some talk about using water heaters (like for live stock watering tanks).

    I have always played around with solar thermal water heating and thought... why not put a tank on the roof, paint it black and have a pump circulate the water on a timer(thermo siphon would be ideal, but just logistically won't work here).

    Of course the first thing to think/worry about is siphoning and having the water over flow the tank inside. So I first thought of a vacuum breaker, then I thought... what about all that air in the line? So then I started looking at evacuators (sp), but now we are getting more and more complicated and costly.

    Then I thought of an idea that I'd like to get you guys opinion on.

    Couldn't I just have a pipe that T's off and goes well above the outlet in the tank and that would serve as both vacuum breaker and air release? Or would I need a vacuum breaker for good measure and would a cheapy one work? It wouldn't be a huge mess as there is probably a gallon of extra space at the top of the dip tank as well as it's a shop and not that big of a deal if it over flowed, but I'd rather it not.

    I did a quick little doodle in paint to demonstrate my point better... maybe I need a reverse pee trap as well? For some reason, I just can't wrap my head around this concept and what will happen when the pump is turned off in the different scenarios.

    Attachment not found.


    Thanks,
    Gilligan

    Actually this would work well, all you would need is a shutoff at the lower tank so you can shut the water off when it's full, use the water then pump it back to the top tank to rewarm etc. That's assuming there is nothing in the water from the lower tank that will hurt the pump. You could just put a air vent in the top of the top tank and do the same without the extra pipe for venting. IMHO
  • GilliganGilligan Registered Users Posts: 4
    Re: Simple idea = simple plan?
    BB. wrote: »
    At the very least, you would need a check valve in the pump line (to prevent water flow back into the pump--And/or put the cold water up over the top of the tank and then down to the bottom with a vacuum break at top (to prevent siphoning/backflow into the dip tank).

    On the hot water side, you would want another vacuum break too, so you don't draw water from the thank (you can collapse the tank if there is no air inlet).

    One thing I would worry about--Elevated temperatures and material in the dip tank "gunking up" the heating tank... May be a mess up there after a few months/years unless you can clean it.

    Perhaps a closed loop water circulation system back into the dip tank (distilled water/antifreeze in heating loop)?

    -Bill

    Bill, do you think a check valve (cheap one) would seal well enough? Or should I do both, a check valve and an anti-siphon trick?

    I'd likely add a filter somewhere in line, might as well filter it (put an oil filter relocation kit on my parts washer and it's working beautifully!)
  • GilliganGilligan Registered Users Posts: 4
    Re: Simple idea = simple plan?
    tmarch wrote: »
    Actually this would work well, all you would need is a shutoff at the lower tank so you can shut the water off when it's full, use the water then pump it back to the top tank to rewarm etc. That's assuming there is nothing in the water from the lower tank that will hurt the pump. You could just put a air vent in the top of the top tank and do the same without the extra pipe for venting. IMHO


    Not sure I'm following or I didn't explain something well to you.

    The bottom tank will ALWAYS have water in it. I would just periodically cycle the pump to circulate the water and get some nice warm water in there. I'd probably also have a manual override to run the pump on command while I have screens in there.

    I do like the idea of venting the tank for the sake of expelling the air, because even in my situation it's possible to ingest air into the tank. Would I develop a problem with air in the tank? Needing too much pressure to push it DOWN the outlet pipe? Basically it would constantly burp and cause issues with pressure, I think.
  • BB.BB. Super Moderators, Administrators Posts: 30,175 admin
    Re: Simple idea = simple plan?

    It depends on what happens if something "fails"... Do you have an overflow for your tank that will direct water safely away--Or will you ruin your workspace (flood floor, get into your stock, etc.).

    After working years in engineering design--Just about anything that can fail, will fail. Preventing syphoning from the roof tank back into your work tank (and flooding the tank).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • GilliganGilligan Registered Users Posts: 4
    Re: Simple idea = simple plan?
    BB. wrote: »
    It depends on what happens if something "fails"... Do you have an overflow for your tank that will direct water safely away--Or will you ruin your workspace (flood floor, get into your stock, etc.).

    After working years in engineering design--Just about anything that can fail, will fail. Preventing syphoning from the roof tank back into your work tank (and flooding the tank).

    -Bill

    It's a shop, so not TOO much of an issue if it floods a bit.

    Just went and measured, right now the tank is over 13 gallons from the top... granted it could use a bit of a topping off and would need a bit more when we move to a larger screen size... but I don't see much of an issue with a few extra gallons.

    I know this goes against everything in the engineer in you, LOL, but this isn't for production so to speak... just kind of a seat of the pants project for a means to an end.
  • SlappySlappy Solar Expert Posts: 251 ✭✭✭✭✭✭
    Re: Simple idea = simple plan?

    If the roof tank does not have vacuum leaks and both lines are below water level in the dip tank that should keep the water from siphon back?pump should fill the top tank and purge air out of the exit line???
  • BB.BB. Super Moderators, Administrators Posts: 30,175 admin
    Re: Simple idea = simple plan?

    This website has a lot of good projects--Look for batch heaters:

    www.builditsolar.com
    http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm

    Basically an insulated box, metal tank of some sort, glass cover.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • tmarchtmarch Solar Expert Posts: 143 ✭✭
    Re: Simple idea = simple plan?
    Gilligan wrote: »
    Not sure I'm following or I didn't explain something well to you.

    The bottom tank will ALWAYS have water in it. I would just periodically cycle the pump to circulate the water and get some nice warm water in there. I'd probably also have a manual override to run the pump on command while I have screens in there.

    I do like the idea of venting the tank for the sake of expelling the air, because even in my situation it's possible to ingest air into the tank. Would I develop a problem with air in the tank? Needing too much pressure to push it DOWN the outlet pipe? Basically it would constantly burp and cause issues with pressure, I think.

    I wonder if a flat collector with tubing would be better than the tank. With that as you pumped the water in it would naturally force the warm water out. The warming tank looks like the outflow for warm water could be lower so you could get more warm water out without worrying about valves etc. or pumping against pressure. If the tank is vented at the top it will allow the warm water to just "fall" into the tank until it reaches the outlet, which means you would need to manage the shutoff so it was off before the drop pipe sucked air. I can't see much of a problem with air as it will expel itself at either tank unless they are sealed tanks.
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