4300 Gallon Plywood Build (3600+ Take 2)

  • We are currently upgrading MFK. thanks! -neo
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subscribed, I cant wait to see this completed
 
I am new here but not at all new to fish keeping. Pete, this is an impressive build and I cant wait to see the fininshed product but I don't envy you at all when the fill date comes. Sitting by the tank looking for that single stream/drop of water indicating a leak. I remember those days when I built a 360G about 20ys ago. Anyway, the reason I post is you had mentioned using a THWH to heat your tank and had heard of issues of them super heating the water. I have had a THWH in my last 2 homes covering the last 8 years and can assure you it will superheat the water to the point where it will melt pex water pipes. It is recommended that you use copper pipe coming out the the heater the first 3' because of this. We had a small piece of pex bubble up and almost melt away because of this. We have found that the superheated water is usually cause by the flow going throught the heater not being constant due to pressure variations or just dialing back the handle on a faucet and not giving the unit time to adjust to the flow change. Good luck on you build and like many others I will be tagging along.
 
BadOleRoss;3749151; said:
I am new here but not at all new to fish keeping. Pete, this is an impressive build and I cant wait to see the fininshed product but I don't envy you at all when the fill date comes. Sitting by the tank looking for that single stream/drop of water indicating a leak. I remember those days when I built a 360G about 20ys ago. Anyway, the reason I post is you had mentioned using a THWH to heat your tank and had heard of issues of them super heating the water. I have had a THWH in my last 2 homes covering the last 8 years and can assure you it will superheat the water to the point where it will melt pex water pipes. It is recommended that you use copper pipe coming out the the heater the first 3' because of this. We had a small piece of pex bubble up and almost melt away because of this. We have found that the superheated water is usually cause by the flow going throught the heater not being constant due to pressure variations or just dialing back the handle on a faucet and not giving the unit time to adjust to the flow change. Good luck on you build and like many others I will be tagging along.
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That's huge. Very good point. I always wondered about the reaction time with heating water in a pressurized tank (hot water heaters). Your adding the ice cold water into that tank I figured the heater would over shoot its set point a little, more so with a smaller tank. I figured the tankless would have an even harder time with controlling temps when the water flow changes or every time it stops. I would run copper pipe as far as possible and then change to PEX for the heat exchange at the last moment.
 
um......I believe pics were promised after the holidays..............LOL You know how we are about pictures ;)
 
Thanks BadOleRoss for the info, but I did away with using the THWH a while back in the thread. I'll be feeding the PEX from my existing hot water heater by putting a Y on the faucet that supplies my washing machine in the laundry room right next to the fish room.

Egon, I did post pics after. Check around post 616. The PEX will be wrapped in pipe insulation from the faucet to where it enters the tank. I shouldn't have much heat loss in the 15' run from the faucet to the tank. BTW, the hot water travels through the PEX and never enters the tank.

The PEX is in the tank, a thermostat turns on the second thermostat that checks the temperature at the end of the PEX run and opens a solenoid valve that allows hot water to flow through the PEX until it's hot enough. A pump that is always on pumps water through the pvc frame the PEX is mounted on to circulate the heat throughout the tank.

Just imagine the heater coil inside a regular aquarium heater. The only difference is that instead of electricity flowing through the coil and it being made of wires, mine is made of PEX and hot water flows through it.
 
PEX is made of polyethylene so its a natural insulator. You will have better results with your heat coil if you made the coil itself out of Copper.

You'll actually need less copper then PEX as the heat transfer through the copper is quicker so you need less length.

You can still use PEX between the solenoid and the water source. But for the element portion I highly encourage copper.
 
Bighurt;3749840; said:
PEX is made of polyethylene so its a natural insulator. You will have better results with your heat coil if you made the coil itself out of Copper.

You'll actually need less copper then PEX as the heat transfer through the copper is quicker so you need less length.

You can still use PEX between the solenoid and the water source. But for the element portion I highly encourage copper.
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My water is hard and the pH is high, so I don't think copper is a good idea for contact with tank water with any kind of biological activity. PEX is used in radiant floor heating, so I'm sure it's heat distribution will be more than adequate for my application.
 
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