rockerarm
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Post by rockerarm on Apr 18, 2016 22:32:55 GMT -8
I'm upgrading the fresh water system in my 68 Concord. Thinking around a 20 gal plastic tank with a 110/115 pump. I'll probably use metal barbed fittings and reinforced plastic water lines. Should there be a vent in the system ....? My only water needs are a hot water heater, sink and toilet. I'm replacing a galvanized iron water tank and all the copper tubing, non pump, pressure system that has been repaired and spliced throughout the years.
Any advise is welcome, including types and sources of tanks. I'll be using a city water type fill.
Thanks Will.
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cowcharge
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Post by cowcharge on Apr 19, 2016 7:15:45 GMT -8
I'm curious, why 110v instead of 12v? Seems like a lot more weight and expense.
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trotwood56
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Post by trotwood56 on Apr 19, 2016 7:38:26 GMT -8
I'm about to plumb my camper, the water pump is the only 12v item besides a single small light. Everything else is on a independent 110v system. Other than a 12v battery what do you think wouls be a good way of powering my water pump? It is mainly just for the sink, no toilet or shower.
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edbrown
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Post by edbrown on Apr 19, 2016 7:43:41 GMT -8
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cowcharge
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Post by cowcharge on Apr 19, 2016 7:52:36 GMT -8
If it's no longer a pressurized system, a vent should no longer be necessary, no? Assuming you're using just a regular "loose" filler opening and not one that the hose screws onto?
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edbrown
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Post by edbrown on Apr 19, 2016 11:26:43 GMT -8
If it's no longer a pressurized system, a vent should no longer be necessary, no? Assuming you're using just a regular "loose" filler opening and not one that the hose screws onto? The tank is not normally pressurized. Think about what happens when you want to fill the tank. The "empty" tank is full of air. Water comes in, and air must go out. That's the vent's job. Expecting the air to come out through the same tube you're pouring water into might work. Whether it works and how much splashing there is will depend on how large the tubing is. With the normal fill tube diameters I would expect that to be a problem.
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rockerarm
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Post by rockerarm on Apr 19, 2016 11:41:39 GMT -8
My theory about 115 as opposed to 12V is that I can run my pump off a hook up, or my generator, in the event my battery goes dead. Seems the xtra weight would be miminal.
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rockerarm
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Post by rockerarm on Apr 19, 2016 11:50:14 GMT -8
If it's no longer a pressurized system, a vent should no longer be necessary, no? Assuming you're using just a regular "loose" filler opening and not one that the hose screws onto? The tank is not normally pressurized. Think about what happens when you want to fill the tank. The "empty" tank is full of air. Water comes in, and air must go out. That's the vent's job. Expecting the air to come out through the same tube you're pouring water into might work. Whether it works and how much splashing there is will depend on how large the tubing is. With the normal fill tube diameters I would expect that to be a problem. The system will be pressurized through the parks "hook up", I use a 55 Lbs pressure reducer. I have just opened the sinks cold water tap to act as a vent in the past. Like a tap, wouldn,t water start to exit through a vent....? I'm leaning towards "no vent" at this time.
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cowcharge
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Post by cowcharge on Apr 19, 2016 11:51:56 GMT -8
If it's no longer a pressurized system, a vent should no longer be necessary, no? Assuming you're using just a regular "loose" filler opening and not one that the hose screws onto? The tank is not normally pressurized. Think about what happens when you want to fill the tank. The "empty" tank is full of air. Water comes in, and air must go out. That's the vent's job. Expecting the air to come out through the same tube you're pouring water into might work. Whether it works and how much splashing there is will depend on how large the tubing is. With the normal fill tube diameters I would expect that to be a problem. Mine's got about a 2-inch filler neck on it.
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cowcharge
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Post by cowcharge on Apr 19, 2016 12:55:26 GMT -8
The tank is not normally pressurized. Think about what happens when you want to fill the tank. The "empty" tank is full of air. Water comes in, and air must go out. That's the vent's job. Expecting the air to come out through the same tube you're pouring water into might work. Whether it works and how much splashing there is will depend on how large the tubing is. With the normal fill tube diameters I would expect that to be a problem. The system will be pressurized through the parks "hook up", I use a 55 Lbs pressure reducer. I have just opened the sinks cold water tap to act as a vent in the past. Like a tap, wouldn,t water start to exit through a vent....? I'm leaning towards "no vent" at this time. Wait, I'm getting confused. If you're always going to be on a city water hookup, why bother with a tank and pump at all? Just run lines from the city water inlet to the water heater and the cold supply lines, with low-point drains for winterizing. If you're going to boondock as well, then yeah, you need a tank and pump. The way my '76 was laid out at the factory to handle both city water and a tank/pump is in the pic below. The red lines are hot water output from the heater to both the bathroom and the kitchen, the blue lines are the cold supply lines used by both pump and city water. I didn't draw in the sink and tub drains that go into the grey water tank. The line from the city water hookup (street side) just joins the cold water supply line from the tank/pump near the water heater, upstream of a branch to the heater, so either shore water or pump water could supply both hot and cold. The city water hookup also has a check valve so that if I use the tank and pump, water doesn't come backwards out of the hookup (I think that's standard), just as the pump has a check valve in it to keep city water from entering and overfilling the tank. The tank, the tank filler, and pump are all on the curb side, and don't need a vent while filling because the filler tube is about 2" in diameter, with plenty of room for air to come out. I can't fill the tank from the shore water hookup because of the pump's check valve. If I wanted to add that capability, I'd need to add a bypass line around the pump with a valve, which I'd open when I wanted to allow city water to go around the pump into the tank. And I would need to open the tank filler to vent the air in that case, but no dedicated vents are/would be needed. The only reason I can think of for needing a vent would be if you're filling the tank from a hose, and your tank filler was a screw-on type like a city water filler. Of course your hot water heater should have its own pressure relief valve already installed. Hope this helps...
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rockerarm
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Post by rockerarm on Apr 20, 2016 15:39:44 GMT -8
I started confused, now your getting confused. What a team. LOL. Perhaps I am misstating what I think is city water. Rarely do we "boondock". Just once a year for 5-6 days. We normally pull into RV parks that offer full hookups. Never had any issues getting the water system up and operating with no pump and no vent. (My system consists of a sink with hot and cold, a toilet and a water heater. That's it). I added a outside water spigot as a drain/exterior water source. The pump is for the 5-6 days we don't have a water hook up available. I am now convinced I don't need a vent.
Any reliable water tank brand names....... ? I've settled on a 20 gal plastic tank and need one that will with stand at least 100LBS pressure. (Just a little overkill).
Thanks for all your responses.
Will.
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cowcharge
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Post by cowcharge on Apr 21, 2016 12:47:43 GMT -8
"Normal" tanks that use pumps aren't pressurized at all, other than by the weight of the water inside. They have their own filler tube separate from the city water hookup, and are never subjected to pressure because the 12v pump is gravity fed from the tank, and is between the tank outlet and where it connects to the plumbing, and the pump has a built-in one-way check valve to keep city water from going backwards through the pump into the tank (as in my diagram). On mine the tank filler is on the opposite side of the camper from the city water hookup. And the city water hookup also has a check valve, so that when the pump's running no tank water goes backwards out the hookup. The two water sources are physically unable to affect each other, as you're using either one or the other, not both at the same time. The way Shasta built mine, any plastic tank would work fine.
However upon reflection, there is a tiny vent tube built-in to the tank filler, which serves to squirt a bit of water at you to show when you've filled the tank, and to let air into the tank as the water level drops, to prevent a vacuum that would make it harder on the pump the lower the water level dropped. It's just a thin piece of clear vinyl tubing that connects to the filler tube a few inches down from the filler opening, and comes out below the opening so that water comes out of the vent before it gushes out the filler all over your shoes. But there's no separate vent in the system other than that.
Now if you built it so that the city water hookup also served as the tank filler, then yes, the tank would become pressurized once it was on city water and filled. But doing it that way seems unnecessarily complicated, as well as more expensive, in that you'd have to then find a tank suitable for pressurizing, and either a pump with a bypass to allow pressurized city water through, or some bypass plumbing.
And I can't imagine that a 110v pump would be of much use in a camper, because if you're boondocking you'd need to run a generator or an inverter off the batteries to get 110v, and when you're using city water and have the 100v hookup you don't need a pump. A regular Shurflow 12v pump could run off the battery, saving you from running a generator every time you wanted to get a drink.
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rockerarm
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Post by rockerarm on Apr 23, 2016 22:01:08 GMT -8
Thanks for all your help, now I have things to think about. I can see the advantage to a tank vent in order to be able to fill the tank with the sink faucet closedI'm not sure I understand why you need two separate water fills. The system I am replacing was pressureized by the water source, (faucet or spigot). It worked quite well. The only addition I am considering is a pump. Which I can go either way, 110 or 12V, as I would be running a generator when I needed it anyways. I am going to call the plastic tank manufacturer Monday and get the pressure limit specs. and see what their thoughts are. My only real need for the pump is so the wife can use the toilet at night. Perhaps a 5 gal jug of water is all I need.
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cowcharge
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Post by cowcharge on Apr 24, 2016 15:03:57 GMT -8
Did the old system have a tank, that you filled from the city water connection?
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rockerarm
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Post by rockerarm on Apr 28, 2016 19:20:34 GMT -8
Did the old system have a tank, that you filled from the city water connection? Yes. The system I'm replacing had a iron tank, about 30 gal. from the looks of it. I don't think it was original to the trailer.
I talked to a tank supplier and found that the plastic tanks shouldn't be pressurized. After studying your diagram and a couple others I have ordered a 25 gal plastic tank, a 12V pump and strainer, a combo city water and gravity fill, and will be using 3/8" reinforced plastic hose throughout the system. The city water hookup does not require a tank. The tank will store water when boon-docking and the pump will pressurize the system. It will be turned on with a switch and only runs when demand, (spigot or toilet), lowers pressure. The tank requires a vent, which is included in the dual unit I ordered. I'll let y'all know how it works out.
Will.
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