SuperStor Indirect Water Heater Problems
On this page (6 sections)
The Short Answer: A SuperStor is an HTP indirect water heater: a storage tank heated by boiler water flowing through an internal coil. With no burner or element of its own, no hot water usually means the boiler is not being told to heat the tank, the circulator or zone valve is not moving boiler water through the coil, or air is trapped in the coil. A leak from the tank shell means replacement.
How an indirect tank gets hot
A sensor or aquastat on the SuperStor tells the boiler (or a zone controller) that the tank needs heat. The boiler then fires and a circulator pump or zone valve sends hot boiler water through the coil inside the tank. When the tank is satisfied, the call stops. Many systems give the tank priority over the house heating for a short time. Any break in that chain leaves the tank cold even though the boiler itself works.
What the symptoms point to
| What you notice | Likely cause | Urgency |
|---|---|---|
| No hot water, radiators or baseboard still heat | Tank sensor or aquastat, circulator or zone valve, priority setting, air in the coil | Service soon |
| No hot water and no heat | Boiler is off or locked out | Check boiler display; service |
| Hot water runs out faster than it used to | Boiler supply temperature lowered, scale on the coil, mixing valve issue | Service |
| Scalding at one fixture, lukewarm at another | Mixing valve set wrong or failing | Plumber |
| Boiler runs constantly in summer | Tank sensor reading cold, recirculation loop pulling heat | Service |
| Water at the relief valve | Thermal expansion or high supply pressure | Do not cap; call |
| Water from the tank jacket or base, fittings dry | Tank leak | Replace tank |
What you can check safely
- Boiler status. Is the boiler display showing an error or lockout? Your boiler manual says what the owner may reset.
- Tank thermostat setting if your SuperStor has an aquastat dial on the outside. Make sure nobody turned it down.
- Zone controls. Some zone controllers have a light for the domestic hot water zone; note whether it comes on when the tank should be calling.
- Recirculation. If the home has a recirculation pump on a timer or set to run constantly, it can pull a lot of heat out of the tank.
- Where water is coming from if there is a leak: relief valve pipe, a union on the boiler piping, the drain valve, or the tank itself.
Leave the boiler, circulators, wiring, and the boiler-side piping to a heating technician.
What the heating technician will check
A hydronic (boiler) technician will confirm the tank sensor or aquastat is sending a call, check that the circulator or zone valve opens and that the boiler responds, and compare boiler supply and return temperatures at the coil. Hot supply with little heat transfer can point to air in the coil (common after boiler work), a closed isolation valve, or a coil coated with scale. Purging air from the boiler loop is done from the boiler side with the system’s purge valves, not by opening household faucets.
Sensors, aquastats, circulators, and zone valves are part repairs. A leaking internal coil or tank shell means replacing the SuperStor.
Anodes, odor, and lifespan
SuperStor Ultra tanks are 316L stainless steel, and HTP markets them as needing no anode rod. If your hot water smells of sulfur, the cause is more likely bacteria or the water supply than anode corrosion; a heating or water-treatment professional can test it. Other indirect lines from different makers use glass-lined tanks with anodes, so check the model on your tank’s label before buying an anode. For other indirect brands, see Amtrol indirect problems and Buderus indirect problems.
Frequently Asked Questions
Q: The boiler heats the house but the tank is cold. Is the tank broken? A: Rarely. The tank has no heating parts of its own. The problem is almost always in the call for heat, the circulator or zone valve, or air in the coil.
Q: Can a leaking SuperStor be repaired? A: Leaks at unions, the drain valve, or the relief valve are repairable. A leak from the stainless shell or the coil inside the tank is not; the tank is replaced.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- A. O. Smith technical bulletin 51: puddles around a heater (opens in a new tab)Common water-leak sources and the distinction between fittings and a failed tank.
- A. O. Smith technical bulletin 45: thermal expansion (opens in a new tab)Background on pressure rise in a closed water system. Pressure testing and repairs are professional work.
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