(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 8 of 8

Thread: Check valve doesn't work with Solar Drainback system.

Threaded View

  1. #1
    DIY Junior Member politics123's Avatar
    Join Date
    Jun 2010

    Default Check valve doesn't work with Solar Drainback system.

    Hi --

    Looking all over the place for a solution to my problem. Even though I've installed a check-valve, my system "flows" the wrong way at night, sucking hot water out of the tank.

    I have a Radco DBX type drainback system connected with AET panels on the roof. The Radco is a drainback tank with integrated heat exchanger, mounted on the floor next to the water heater, 2 pump setup -- one on the collector loop, one circulating water from the HW heater to the heat exchanger.

    During the day, the system works perfectly. Sun heats the collectors, collector-loop pump works like it should, drainback tank gets hot, circulatory pumps circulate domestic water through the heat exchanger and it heats up. At night, however, the flow reverses... how water leaves the HW heater, circulates the reverse way through the circulatory loop (out the top of the HW heater, through the heat exchanger, into the bottom of the HW heater).

    In other words, at night, I lose some of the BTUs I gathered during the day. I've installed various swing/spring checks, but they don't always shut-off the reverse flow (and, eventually, they go bad and get stuck in the open-position... i guess oxygenated hot-water is a bit corrosive)

    Anyone have an idea how to stop the reverse flow? Do I need to mount the drainback tank above the HW heater?


    PS -- just to be clear -- no flow at night through the collectors. Thermo-syphoning is only occuring on the HW --> heat exchanger loop.Name:  Solar Hot Water Drawing v2.jpg
Views: 1191
Size:  42.9 KBName:  solar_bug.jpg
Views: 806
Size:  74.1 KB
    Last edited by politics123; 06-27-2010 at 11:44 AM.

Similar Threads

  1. Solar Drainback Water Heating System
    By Alphacarina in forum Solar and Geothermal Water Heating Forum
    Replies: 9
    Last Post: 09-03-2011, 05:46 PM
  2. Swing Check vs. dual check vs. double check valve
    By colbymom in forum Plumbing Forum, Professional & DIY Advice, Tips & Tricks
    Replies: 25
    Last Post: 05-10-2011, 01:19 PM
  3. Check Valves in Recirc System and Mixing Valve Cause Hammer
    By dwheels in forum Pumps and Tanks Well Forum & Blog
    Replies: 11
    Last Post: 05-15-2010, 09:32 AM
  4. Check valve on a closed loop hydronic system?
    By CHRISUPNORTH in forum HVAC Heating & Cooling
    Replies: 3
    Last Post: 11-24-2008, 06:12 AM
  5. Drainback system?
    By gerhard in forum Pumps and Tanks Well Forum & Blog
    Replies: 24
    Last Post: 09-28-2006, 10:03 AM


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts