hot water return with no pump
how to circulate hot water without a pump:eek:
on larger homes, apartments, condos, there is a need to keep the hot water circulating so that you don't have to wait for or waste hot water.
the typical system use a circulating pump and a return line from the remote fixture or fixtures back to the heater. one of the biggest problems with this system is the water is circulating too fast and the copper tubing is wearing out too fast. i have found that pumps are not sized properly and the velocity of the hot water going through the tubing is moving too fast. this is typically happening 24-7. tubing that is not properly reamed or sized will wear out faster than properly sized and reamed tubing. type "m" copper faster than type "l" tubing. "l" faster than "k".
one practical way to slow the process down is to downsize the pump and put the pump on a timer or aquastat. the problem is that once the tubing has developed its first pinhole leak, the others are just a month away.
i have found another system that has worked for years without pumps or electricity:confused: this is called a "passive hot water loop". it basically works on the principal of specific gravity. hot water being lighter than cold water.
this system is typically not a retrofit to a typical hot water return, but a design that needs to be built into the original piping installation.
a hot water return line is run from the remote fixture up to the highest location in the system (attic). then back down to the heater at the bottom of the tank. a check valve, ball valve and hose bibb is installed at this connection too. the system is flushed of all air throught the hose bibb and the water is run until hot. as the water cools down, a natural flow will occur as the water cools it will settle from high loop and travel back to the heater at the lower level.
the water will move slow enough to cut out the wear from velocity. as long as the system is not shut and drained it will work forever. if you do shut off the system, just bleed the air and run the water till hot.
this is a brief summary and was condensed so it didn't get too technical:eek:
for all that have a circulating pump, try unplugging it and see if the return line back to the heater stays warm. you might already have a high water passive loop. if so, keep the pump off and you'll save all the wear and tear along with the cost of electricity and replacement pumps.
if not, try putting the pump on a timer and shut off every 15 minutes and then on every 15 minutes.
hope this helps.