Author Topic: diy hot water storage tank with geyser heat pump water heater  (Read 3663 times)

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sunpower

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Hi

i have a geyser heat pump water heater which does a great job but my 19 year old water heat ( that was only used for hot water storage ) has rusted up and leaking so i am thinking of making a wooden water storage tank kinda like this tank but hold about 30 gallons of water(http://www.builditsolar.com/Projects/WaterHeating/KnickSystem/Tank.htm)
the tap water will run thru the copper/pex tubing heat exchanger  then the box will have water in it that will run thru the heat pump water heater so when i turn on the hot valve in a sink i should have hot water 
what i need help with is what size box would i need for about 30 gallons of water and about what size heat heat exchanger  and all the other stuff i may have forgot about LOL
the box will be insulated
thoughts ?

thanks

TDC

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #1 on: May 31, 2015, 10:31:09 AM »
  http://www.answers.com/Q/What_is_the_volume_of_one_gallon_of_water

A square box has the best ratio of volume to surface area. The pex won't transfer heat as well as metal tube, but it's cheap cheap so you can use more. What size exchanger? How much hot water do you want?  A Bosch intercooler pump is an efficient 12v pump.

sunpower

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #2 on: June 01, 2015, 07:35:48 AM »
thanks for the reply
so if  One US gallon is 0.133681 cubic feet my box would need to be about 5.34724 cubic feet....  no wait i need to fit in the heat exchangers too........... anyone know about how many feet of exchanger tubing i would need ?
my old water heater the tank was 40 gallons so thinking about going with a 40 gallon this time
i have room for a box size of 4 feet by 2 feet

may go with copper tubing for the exchanger not sure what size exchanger i will need  might fill the box mostly full or half way full with the heat exchanger

the geyser heat pump water heater has a water pump in it  to pump the water from the box to the geyser unit and back to the box then the tap water will flow thru the exchanger and pick up heat on the way to my shower

joestue

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #3 on: June 01, 2015, 08:04:34 AM »
you can buy 3/8th stainless steel tubing on ebay for twice the price as pex when comparing surface area.. however, its .035 thin stainless so much better heat transfer.

OperaHouse

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #4 on: June 01, 2015, 10:30:22 AM »
I have a NYLE and don't quite understand this.   Is the box pressurized?  Why does the NYLE  need a heat exchanger in the box?  What is the need to isolate the two water systems?

sunpower

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #5 on: June 01, 2015, 10:53:41 AM »
Hi OperaHouse

my old water heater the tank has rusted out and is leaking  so i do not want to buy a new water heater just for the tank....
the box will not be pressurized that's why i need to 2 water systems

the Nyle will heat the water in the box that is not pressurized and the tap water will flow thru the home made heat exchange then to my shower

joestue thanks for your reply i think metal tubing will work best for me

Mary B

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #6 on: June 01, 2015, 02:15:12 PM »
You made need a circulation pump for the water in the box or it will stratify with no heat input stirring it.. still not quite sure what you have planned...

sunpower

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Re: diy hot water storage tank with geyser heat pump water heater
« Reply #7 on: June 01, 2015, 04:00:57 PM »
Hi Mary
the Nyle  heat pump water heater has a temp prob that will go in the box and when the temp drops down to what ever temp the Nyle  heat pump water heater will kick on and the water pump in the Nyle  will circulate the water and heat it up and store it in the box/homemade tank

when i get it done i will post pix