SuperStor Indirect Heater Problems Fix

The Short Answer: A SuperStor is a storage tank with a boiler-heated coil. No hot water means the boiler is not sending heat, the aquastat/sensor is dead, the coil is air-bound, or the tank leaked out. A wet jacket is a replacement. Do not treat it like a gas water heater with a pilot.

Search Intent & The Real Problem

The radiators are hot. The SuperStor is not. Or the opposite: the boiler never shuts up because the tank sensor thinks the water is always cold. HTP SuperStor Ultra tanks are workhorses until the anode is ignored, the coil gums up, or someone piped the mixing valve backwards.

What other guides get wrong

Generic troubleshooting pages often jump to a part or a reset before identifying the unit, fuel, and failure sequence. Start with the model label and the safest outside checks. If the fault involves gas, combustion, pressure, or 240 volts, stop at that boundary and call a licensed professional.

Step-by-Step Troubleshooting

Step 1: Prove the tank still has water

• What to look for: T&P weeping, a wet foam jacket, rust at the base, or a tank that feels light after a leak. A SuperStor that emptied itself will not recover. Running a boiler coil in an empty tank is how you warp the coil.
• Required tools: Flashlight, dry paper towel, your hand on the tank shell (careful — it may be hot).

Any leak from the vessel or from inside the insulation is replacement. Tighten fittings first; do not confuse a dripping T&P or a coil union with a dead tank.

Step 2: Confirm the boiler is being asked to heat DHW

• What to look for: Aquastat or tank sensor calling, DHW pump or zone valve energized, boiler in DHW priority. Many “dead SuperStors” are a failed tank sensor, a pulled Molex at the boiler control, or priority disabled after a thermostat swap.
• Required tools: Multimeter if you are qualified, otherwise eyes on pump LEDs and boiler display.

If the DHW pump runs and the boiler fires, the control chain is fine. Move to the coil.

Step 3: Coil temperature in vs out

• What to look for: Supply from the boiler hot, return almost as hot (no heat left in the tank — either the tank is already satisfied or the coil is not transferring). Supply hot, return cold, tank still cold = air in the coil or a closed isolation valve.
• Required tools: Contact thermometer on both coil pipes.

Air-bound coils are common after a boiler drain. A licensed tech will purge the hydronic loop at the coil, not by opening domestic faucets.

Step 4: Mixing valve and recirc

• What to look for: Scald at one bath, lukewarm at another; recirc pump running 24/7 and cooling the tank; a mixing valve installed on the cold inlet. Recirc without a properly placed return will strip the tank and make the boiler short-cycle.
• Required tools: Thermometer at the mixed outlet vs tank-top.

Step 5: Anode, sediment, and popping

• What to look for: Rotten-egg hot water, popping on recovery, a never-changed anode on a 8–12 year tank. SuperStor Ultra is stainless; it still wants an anode on many models. Ignore it and you buy a tank.
• Required tools: Correct anode socket, breaker/boiler off, a way to relieve pressure.

If the anode is a stump or the tank is past its warranty and leaking at the weld, stop shopping parts.

When DIY Ends: Calling a Licensed Pro

Stop for vessel leaks, hydronic purging you cannot do at a dedicated coil vent, boiler-control programming, and any mixing-valve replacement that requires sweating near a foam-insulated tank. A SuperStor is only as good as the boiler that feeds it. I fail more of these on zone-control mistakes than on the tank itself. A licensed plumber or boiler tech will test the sensor, prove pump flow, combustion-check the boiler, and tell you honestly whether the tank has another winter in it.

Frequently Asked Questions

Q: Why is my SuperStor not making hot water but the house is warm? A: DHW priority, the tank sensor, the DHW pump/zone valve, or an air-bound coil. The boiler can heat radiation while the tank circuit is dead.

Q: Can I repair a leaking SuperStor tank? A: Unions, valves, and T&P yes. A wet jacket or a leaking coil inside the tank is replacement. Do not inject stop-leak into an indirect.

Q: How long should a SuperStor Ultra last? A: With an anode and annual boiler service, 15+ years is common. Without an anode in aggressive water, I have cut out tanks at year 8.