hot water by solar

Mike Umholtz

I have a customer who wants to preheat his potable water with his solar panels. He wants to use a heat exchanger (flat plate, etc) and a storage tank to accomplish this task. Basic route of potable water would be to go through a heat exchanger,into a storage tank,out of the storage tank and into a indirect water heater(for boiler back up, to make up for any temp. difference) before being consummed. How do I go about sizing a heat exchanger for this task? How big of a storage tank is necessary for solar storage?

joel_19

????

Why a storage tank with a flat plate ? why not just get an indirect tank with the coil already in it? That's how we do it. With solar more storage is better an 80gal. indirect would be minimum . We like to use a 120 . Viessmann also has thier tanks in 92 gallon with a double coil 1 for solar 1 for boiler . Less storage than two tanks but is a space saver and works great , IMHO

hr

I too would

use a tank with the HX inside. If he wants to use an existing tank, with external HX, you would need to circulate the tank through the FP HX. A single pass on the way to the storage would not exchange enough BTUs. An external HX will cost you an addition bronze or stainless circ pump.

Usually size about 2 gallons of storage per square foot of panel. Varies a bit depending on location.

A 4X8 panel (32 sq. ft.) would use a 65 gallon tank. Smaller tank capacity= hotter water, larger tank cooler water. Make sense?

Most of the online solar companies have piping examples. www.thermomax.com has some good examples.

hot rod

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