HTP Water Heater Troubleshooting: Phoenix and SuperStor

The Short Answer: Start by identifying which HTP product you have, because they fail in different ways. A Phoenix is a gas-fired condensing tank with its own burner. A SuperStor is an indirect tank that gets its heat from a boiler. HTP has also sold boilers and tankless heaters. Read the rating plate, then work through the checks for that design. Gas, electrical and boiler control work belong to a technician.

Identify the HTP product first

The rating plate on the side of the jacket gives the model number. These are the main types you are likely to find:

If you are not sure, identifying your water heater walks through rating plates and venting.

Phoenix: how it differs from an ordinary gas tank

A standard gas water heater has a burner under the tank and a flue up the middle. The Phoenix works more like a boiler built into a stainless steel tank: a fan pushes combustion air through a sealed burner, the hot gases pass through a coiled heat exchanger inside the tank, and the exhaust cools enough that water condenses out of it. That adds parts a basic tank does not have:

• A condensate drain. The heater produces acidic water every time it fires. If the drain, trap or condensate pump backs up, the control shuts the burner down to protect it.
• Sealed venting. Plastic intake and exhaust pipes run outdoors. Snow, ice, leaves, insects or a crushed pipe can stop the fan from proving airflow.
• Electronic ignition and flame sensing. There is no standing pilot to relight. The control runs an ignition sequence and locks out if it cannot prove a flame.
• Temperature sensors and a display. Fault messages and lockout codes are specific to the Phoenix generation and model. Use the manual for the model on your rating plate, not a code list from another HTP product.

Phoenix: what the symptom points to

Phoenix: what you can check safely

1. Photograph the display and note what was happening: time of day, weather, whether someone had just run a long shower. Write the code down before any reset.
2. Look at the vent terminals outside. Clear loose snow, leaves or debris that is plainly sitting on or in front of the openings, from the ground or a safe surface. Do not take the terminals apart or push anything into the pipes.
3. Follow the condensate line from the heater to where it drains. Look for a kink, a section that runs uphill, a frozen outdoor run, or a condensate pump that is unplugged or full. Plugging a pump back in is fine. Do not open the trap inside the heater.
4. Confirm power and gas. The heater needs its electrical supply on, and the gas shutoff on the supply pipe should be open. Check that another gas appliance works.
5. Check the setting and any mixing valve. Many Phoenix installations have a thermostatic mixing valve on the hot outlet. If the tank is hot but taps are cool, that valve or its setting is the first suspect.
6. Reset once using the procedure in the owner’s manual, after you’ve cleared an obvious cause. If the same lockout returns, stop and call. Repeated resets can mask a venting or combustion fault.

A steady drip from the condensate line into the drain while the burner runs is normal. Water on the floor around the heater, or condensate that is hot, is not.

Phoenix: what the technician checks, and repair or replace

A qualified gas technician will read the control’s fault history, which often says more than the current code. They check that the fan proves airflow and that the vent and intake length and terminals match HTP’s installation requirements. They inspect the condensate trap and neutralizer, test inlet and manifold gas pressure against the rating plate, inspect the igniter and flame sensor, and use a combustion analyzer to check the burner. If scale is suspected, they check the tank and heat exchanger and descale according to HTP’s procedure for that model, rather than pumping vinegar through the tank or relief valve. Sensor faults are confirmed by comparing readings with actual water temperature before any part is replaced.

Condensate parts, igniters, flame sensors, temperature sensors and fans are replaceable parts. A control board is a bigger repair but still a repair. Water coming from the stainless tank itself, or from the heat exchanger coil inside it, usually means replacing the heater. Check the warranty before deciding; HTP uses the serial number to confirm what is still covered. For how age factors in, see how to tell a water heater’s age.

SuperStor and other indirect tanks: the usual faults

An indirect tank has no burner, elements or gas valve. When there is no hot water, the tank is usually fine and the problem is that the boiler isn’t sending heat to it. Common causes:

• The boiler is off, locked out, or in summer mode with domestic hot water disabled.
• The tank’s aquastat or sensor isn’t calling for heat, or it is set too low.
• The zone pump or zone valve that feeds the tank coil has failed or isn’t being switched on.
• Air in the coil after recent boiler work stops circulation.
• Priority settings. If the boiler doesn’t give hot water priority, the tank can recover slowly while the house heat is running.

What you can check: whether the boiler display shows a fault, whether the boiler is set to make domestic hot water, and the temperature setting on the tank’s control. If the boiler is heating the house normally but the tank stays cold, tell the technician that, because it points to the tank’s controls, zone pump or valve rather than the boiler burner.

Leaks: a drip at a pipe fitting, the drain valve or the relief valve is usually a repairable part. Water coming through the jacket or insulation means the tank or its internal coil has failed. That is a replacement. SuperStor indirect water heater problems covers indirect tanks in more depth.

HTP tankless and combi units

These behave like other condensing tankless heaters. No hot water usually comes down to flow, an error code, gas supply or venting. Combi units also share their burner between space heating and hot water. Use the manual for the exact model to look up any code. Tankless water heater no water flow covers the flow side.

Information to have ready for the service call

• The model and serial number from the rating plate
• A photo of any display or code, taken before resetting
• Whether the problem started after a storm, freeze, power outage, or recent service
• For indirect tanks: whether house heating still works
• Where any water is coming from, as precisely as you can tell

Frequently Asked Questions

Q: My SuperStor has no hot water but the house heat works. Is the tank bad? A: Probably not. If the boiler is firing for heat, it can make heat. The usual suspects are the tank’s aquastat or sensor, the zone pump or zone valve that feeds the tank coil, or the boiler’s hot water settings. A failed tank usually shows up as a leak, not as a cold tank.

Q: Why does my Phoenix only lock out in winter? A: Cold weather is when vent terminals ice over and outdoor condensate lines freeze. Both stop the heater safely. Clear any snow or ice from the outside of the terminals and check the drain line for a frozen section. If lockouts continue in mild weather, the vent may be too long, poorly sloped, or the fan may be weak, and a technician needs to look at it.

Q: Are HTP parts still available? A: Parts are ordered by the model and serial number on the rating plate. Give those to your technician or supplier rather than buying a generic part that looks similar, especially for sensors, igniters and controls.