How to Drain Your Commercial Hot Water Storage Tank
There are many different types and styles of DHW Systems out there. This is a basic guide only. Whether you have a Horizontal hot water tank of a Vertical storage tank, most will be heated by direct feed boilers, or they have a tube bundle or plate and frame heat exchanger for tanks that are typically 250 Gal or larger. This does not include small gas-fired or electric hot water tanks. All tanks and systems should be shut down by experienced professional.
If there is only one tank or multiple tanks that cannot be isolated:
- Turn off and isolate all pumps connected to the water system. This includes the heating side (boilers or heat exchangers) and the hot water recirculation line(s). Also, if there are extra booster heaters or recirculation pumps on other floors they will need to be turned off and isolated as well.
- Turn off and isolate boilers / heat exchangers.
- Shut off valves at recirc lines, cold water feed to the tank(s), and hot water supply from the tank(s).
- Open the drain on the tank. The tank should be airlocked if the valves are holding and they are all shut.
- Open the bleeder on the hot out line to release the air so the tank can drain properly. If there is no bleeder on the hot out you can prop open the pressure relief valve on top of the tank to release the air.
- Another option if you feel comfortable, is you can slowly loosen the bolts on the man-way cover until you start to hear air sucking in via the man-way access door. Be careful you don’t open the bolts too much and never leave the area until tank is drained
- After the tank is drained, it is possible that one or more of the valves are passing so there could be a small amount of water still flowing out of the drain. Also, if the drain becomes plugged with media or the tank has become air locked it might appear drained when it’s not. Always be careful to remove the man-way access slowly to ensure the tank is empty.
If there are multiple tanks that are isolatable:
When there is more then one tank and they are plumbed in together you can simply shut down all the valves attached to one tank only and open the drain. There will be no need to turn off the pump(s) or heating system(s) as they will still feed the other tank(s) which should still be in operation. Again, you can open the bleeder or the relief valve on the specific tank you’re draining to release the air.
Hydrastone Inc. Hot Water Tank Services:
- Tank inventory and assessments
- Tank inspections and cleaning
- Sacrificial anode replacements
- Man-way cover replacements
- Weld repairs
- Tank relining
- Tube bundle cleaning and replacement
- Repair / replace tank insulation
- Complete tank replacement
If you would like an assessment completed for your Hot water Storage Tank feel free to visit call our head office toll free at 1-888-321-8265.