What are the common problems with Heat Pump Hot Water Heaters?

What are the common problems with Heat Pump Hot Water Heaters? Heat pump hot water heaters have several common issues – the main ones are slow hot water recovery, a reduction in efficiency when it’s cold, not enough airflow, problems with condensate drainage, noise from the fan and compressor, a cylinder that’s the wrong size, and an excessive use of the backup electric immersion heater. Just like any other fridge-based appliance, trouble can also show up with the temperature sensors, controls, compressor or refrigerant system. But it’s surprising how many reported problems are actually to do with getting the system wrong, installing it incorrectly or having the wrong settings, rather than the heat pump itself having a fault.

1. Slow hot water recovery

The number one complaint about heat pump water heaters is that they take longer to reheat the water in the cylinder than a conventional boiler or a high-powered electric immersion heater.

This is because the heat pump isn’t designed to heat water quickly – it takes heat out of the air and puts it into the domestic hot water. This is not the same as a conventional boiler, which quickly heats water using several kilowatts of electric resistance heating.

If you’ve had a few consecutive hot showers or taken a big bath, recovery time becomes a real issue. To get around this you need to make sure the cylinder is the right size. If the cylinder is too small, the heat pump will struggle to keep up with demand and you’ll end up with cold showers.

2. Reduced performance when it’s cold

An air source heat pump water heater works by pulling heat from the air passing over its evaporator. The temperature of the air can have a big impact on how well it works and how efficient it is.

As the air gets colder, the heat pump has to work harder to get the water to the right temperature. This can make the system less efficient and take longer to heat the water.

When you’re looking at the performance of a heat pump, you need to pay attention to the C.O.P rating and what conditions it was tested at. This is because the performance of the heat pump will be different in different temperatures – and you want to make sure it will perform well in your local climate.

3. Poor airflow around the heat pump

If the airflow around the heat pump isn’t good enough, it can cause problems.

The fan needs to be able to move enough air over the evaporator to get the best out of the heat pump. If you put a small heat pump in a tiny cupboard or enclosed space without any ventilation, it can quickly get cold and perform poorly. This can be a real problem if you try to install heat pumps in very small spaces, because the ducting needs to be designed to make sure it gets enough air.

4. Condensate drainage problems

When warm, moist air passes over the cold evaporator in a heat pump water heater, condensate forms. This needs to be drained away.

If the condensate pipe is blocked, put in the wrong place or routed incorrectly, water can collect around the appliance or trigger a fault on some systems.

When you’re installing your heat pump water heater, you need to think about condensate drainage – including making sure the pipe will work at low temperatures.

5. Noise from the fan and compressor

A conventional hot water cylinder is virtually silent, but a heat pump water heater has a fan and compressor that can make a bit of noise.

This noise does not necessarily mean there’s something wrong with the heat pump – but if the noise changes or gets louder, it’s worth taking a look. When you’re choosing where to put your heat pump, location is key – especially if it’s by a bedroom or some other quiet space.

6. Excessive immersion heater use

Some heat pump water heaters have an electric immersion heater which kicks in when the heat pump can’t get the water to the right temperature quickly enough.

The problem is if this immersion heater is used too much. Because electric resistance heating is not as efficient as the heat pump cycle, excessive use of the immersion heater can increase your electricity bills.

There are a few reasons this might happen – it might be because the cylinder is the wrong size, you’ve set the temperature too high, or you’re just using a lot of hot water. Either way, it’s worth checking.

7. Sensor, control and refrigerant circuit faults

Because a heat pump water heater is more complex than a simple electric cylinder, there are more bits that can go wrong.

This might be with the temperature sensors, electronic controls, fans, compressors, expansion devices or even the refrigerant circuit. If you’re using a heat pump that uses R290 refrigerant, you need to be careful when working with the refrigerant circuit because R290 is propane and classified as a flammable refrigerant. Any repairs need to be done by a competent person following the manufacturer’s instructions and relevant safety guidelines.

Our air source heat pump water heaters are available for different applications and hot water requirements. Explore the ranges below:

Wall mounted air source water heaters
Air source water heaters for homes
Commercial air source water heaters

Are heat pump water heaters reliable?

Heat pump water heaters can be a reliable source of hot water for years, if you get the right size of cylinder, make sure there’s enough airflow, get the condensate drain right, use the right temperature settings and position the appliance in the right place. If your heat pump water heater suddenly starts guzzling electricity like never before, seems to be stuck in neutral when it comes to recovering heat, starts making some weird noises, or constantly has to rely on its immersion heater to get the job done – it’s definitely worth digging into why. These symptoms can be the result of anything from simply getting the settings or airflow right to something a bit more serious like a faulty component.