Beckett SolarHot - Manual (Page 22)

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© SOLARHOT 2006-2009
Appendix A: Destratification
One of the real concerns that people should consder when nstallng a solar hot water system s what to
do about destratification. Your hot water heater (or any body of water) naturally has the hot water rise
to the top. Ths s useful n a hot water heater snce t allows the homeowner to enjoy the hottest water
the tank has to offer snce the hot out to the house comes from the top of the tank. In a solar hot water
system where you use a sngle tank wth a back-up element or where you have a pump crculatng the
water n the storage tank you have a chance to str up the tank by over-pumpng. Ths strred up water
can cause two problems; 1) by movng the colder bottom water around n the tank t can cause your
element to fire (using energy) when you don’t really need it, 2) by moving the colder water to the top the
owner who thnks they are takng a hot shower gets water that s colder than they would lke.
Three ways to handle destratification:
1. Use a specal solar dp tube on the return of any heated water back nto the tank. Ths
dp tube has a closed end and multple perforatons down the length. Ths allows the return
water to seep out rather than gush.
2. Use a storage tank pror to feedng the pre-heated water nto a tank wth the back-up
elements. This is a great solution for a retrofit since it allows you to hook up the solar system
without taking out the existing hot water tank. (If you do this, be sure to turn off the lower
element of the existing tank and turn back the upper element to maximize your solar gain.)
3.
Pump the water really slowly on the tank sde of any two-pump system. I thnk ths
idea stinks!!! Remember the rules of how a heat exchanger works, speed is good. If you slow
down to a crawl on the storage tank side of the equation, you are destroying the exchange rate
through your heat exchanger.
The Beckett SolarHot Advantage: The SolVelox package comes with a special dip
tube to prevent destratification. The system is also designed to pull the coldest water
from the bottom of the tank or (f water s comng nto the tank) the cold ncomng water,
thus improving the overall efficiency of the system.