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Thermal Store Hot Water Heater Faults

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Thermal Store Hot Water Heater Faults

Thermal Store Hot Water Heater Faults

While thermal store hot water heaters do not suffer from the same problems found with unvented hot water heaters, they are susceptible to a number of problems that might cause the need for professional repairs or service. In particular, they are prone to problems with the electrical supply, as well as faults in the thermostat and immersion heater. While some of these issues can be handled by the average homeowner, others will require the assistance of a professional EasyFlow technician. Below, we’ve detailed some of the more common thermal store faults that you might experience.

Burnt-out Immersion Heater
Corroded Immersion Heater
Fortic Immersion Heater Leaking
No Hot Water on a Thermal Store – Problems with the Blending Valve

In order to ensure a safe temperature at the taps, thermal store hot water heaters use a blending valve to mix hot water with cold water from the mains prior to sending it to the taps. Not only does this help prevent scalding (as required by G3 building regulations), but it also serves to enhance the capacity of the system, allowing a smaller hot water heater to provide a greater volume of hot water than what the cylinder could hold.

Of course, blending valves are subject to wear and tear, and will eventually fail. As they deteriorate, you will notice the water temperature at the taps steadily declining. Eventually, no hot water will be available. To check if the blending valve is the culprit, you can do a couple of things:

  • Check the Tank: Check the brass boss located where the immersion heater in the tank is installed to see if the water is actually hot. If it is not, your problem isn‘t with the blending valve. If it is, move to the next step.
  • Adjust the Valve: Turn the blending valve to the minimum setting. Check the temperature of the hot and cold inlet pipes and ensure that there is a large difference between the hot and cold pipes. Note that the water from the tap should feel similar to the cold inlet pipe.
  • Adjust the Valve Again: Now, turn the valve to its maximum. The outlet temperature should rise to about 55 degrees centigrade if the blending valve is working. If it does not, then the valve needs to be replaced.
Gledhill ElectraMate Changing Flow Boiler
Gledhill PulsaCoil-III Replacing Valve
Gledhill PulsaCoil-III Replacing Blending Valve
No Hot Water on a Thermal Store – Problems with a Plate Heat Exchanger

Thermal store systems can use one of two types of heat exchanger – some use a coil wound through the centre of the cylinder, while others use a plate heat exchanger. In plate type systems, the passageways within the exchanger can become clogged with debris (rust, dirt, sand/sediment, and lime scale). When this happens, water cannot move through the exchanger, which means heat from the hot water heater cannot be moved to the main water line, and it will run cold at the taps. The symptoms are similar to what happens if the blending valve begins to malfunction, but the underlying problem is very different. In this instance, you’ll need to service the plate heat exchanger, which is not something that you should attempt on your own. Call EasyFlow today.

No Hot Water on a Thermal Store – Problems with the Pump

In many thermal store systems, a pump has been added to force water through the heat exchanger. Water moves upward, out the top of the cylinder, and is then pumped back into the cylinder at the bottom, where it goes through a series of baffles to prevent it from coming in contact with cold water stores. Like all other components, pumps will eventually wear out and fail. The only recourse in this situation is to have a professional EasyFlow technician replace the failed pump.

Manco Powerstream Reservoir
Manco Riverstream Immersion Connections
Thermal Store Cylinder about to Burst
No Hot Water on a Thermal Store – Flow Switch

In a thermal store system that uses a pump, a flow switch will be needed to manage the pump’s speed. This actually determines the amount of heat exchanged by the hot water as it flows past. However, other systems use sensors rather than switches. If you’re experiencing a no hot water situation and the problem is not the blending valve, switches and sensors should be checked before inspecting the plate heat exchanger.

No Hot Water on a Thermal Store  – Immersion Heaters

Like most other hot water heaters on the market, thermal store hot water heaters use an immersion heater to warm the water within the cylinder. It’s located at the bottom of the cylinder, allowing hot water to rise toward the top. Immersion heaters have a specific lifespan and will not last forever. Often, failure will trip the breakers or the RCP, but that isn’t always the case. Sometimes a failed immersion heater’s only symptom is a lack of hot water from the taps. An EasyFlow technician can quickly replace a failed immersion heater in your system.

Faults on Discharge Pipe
Thermal Store Cylinder about to Burst
No Hot Water on a Thermal Store – Issues with the Thermostat

Many people might assume that because their unit’s immersion heater isn’t functioning, that it’s burned out. That may or may not be the case. There’s also the possibility that the thermostat has a fault. Most thermal store thermostats are set to 75 degrees centigrade, and it should not be changed. If the thermostat has failed, the immersion heater will not work, and there will be no hot water from the taps. An EasyFlow technician can diagnose the lack of hot water and replace your thermostat quickly.

No Hot Water on a Thermal Store  – Problems with the Control Unit

Thermal store hot water systems are highly dependent on electronics in order to function correctly. A control unit is used to ensure that all the different systems are working correctly in concert. However, if the control unit fails, or the controls are set incorrectly, it could create a situation in which no hot water is available. Before calling a plumber, check the controls. If they are normal, the control unit may need to be replaced.

Gledhill ElectraMate Changing a Flow Boiler
Gledhill Torrent Blending Valve
Water Discharge through Thermal Store Overflow Pipe

Thermal store hot water heaters are equipped with an overflow pipe that allows excess water to flow out of the cylinder without harming the system. It is tied to the cold water reservoir/expansion tank located at the top of the cylinder. Within the tank is a float valve (if the system is not controlled by a manual filling loop). If the float valve fails, it is possible for water to feed into the tank unhindered, overfilling it and sending cold water out the overflow pipe. An EasyFlow technician can replace the float valve for you.

No Hot Water on a Thermal Store  – Low Water Level

Evaporation within a thermal store system’s cylinder is possible. This can create a low water situation. In a manual filling loop or hand filling system, there is a low water sensor in the control unit that will detect this condition and turn off the electricity to the immersion heater. When this happens, you will not have hot water (because the heater is not warming the water). All that is needed to correct this is to fill the system with water to the correct level, and then normal function will resume.

Problems with Leaks

While thermal store systems don’t suffer the same issues as unvented systems, they are still tied to the electric lines. This means that any leaks, regardless of size or location, are serious concerns. It is absolutely essential that you call an EasyFlow engineer if you notice any leaks from the thermal store.

At EasyFlow, we offer repairs and service for thermal store systems. Call today at 0800 433 4043 or use the convenient form below to get in touch. EasyFlow is a Country and Town Limited Service and we provide services throughout Manchester, Liverpool and the surrounding areas.

If you need assistance with any hot water heater repairs, to schedule hot water heater maintenance, or to install a new hot water heater, call EasyFlow at 0800 433 4043

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