How do I know if my boiler diverter valve is faulty?

Problems with a boiler diverter valve are common in older types of combi boilers. This is because over time this valve can experience wear and tear which can result in complete failure, causing mayhem on central heating systems. Fixing a diverter valve boiler can be simple, but potentially costly. In this guide, we’ll look at the main symptoms of diverter valve faults and give you an idea of what is needed to repair them.

Firstly, what is a diverter valve? 

The purpose of a diverter valve on a combi boiler is similar to that of a lock on a canal – it opens and closes to control domestic hot water (water from taps and showers) and the water that is used to warm up towel rails and radiators. The priority of the diverter valve should always be your domestic hot water over your heating system.

In other words, when you turn on a tap, the diverter valve will shut off the heating supply until you’ve turned the tap off. Given that the diverter valve is a mechanism and moving part of your boiler, a lot of the issues with them often come from the valve sticking. The diverter valve is essential to control the flow of hot water throughout a property and whether it is available on-demand.

Where is the diverter valve on a combi boiler? 

If you’re wondering where the diverter valve is on your boiler, it is part of the tub spout. The diverter handle pulls straight up to send all the water from the tub spout to the shower heads or radiators etc. The exact location of the diverter valve can differ between makes and models depending on their age.

What are the symptoms of a faulty diverter valve? 

Lukewarm hot water from taps and showers

Lukewarm water in your taps and showers is one of the most common signs of boiler diverter valve fault. Since most boilers are designed to prioritise hot water over heating radiators, a valve that’s even slightly stuck open on the heating side will enable some of the heat to escape. This causes the water to come out of the taps at a lower temperature than expected. Note that increasing the boiler temperature to compensate can cause it to suffer from over working.

You need to leave the heating on to get hot water 

If it’s a hotter time of year when you don’t normally have your heating on, try switching it on and letting it warm up. If the temperature of the water increases after you’ve turned on the heating, it is likely another common faulty diverter valve symptom. This is because the valve isn’t allowing hot water to flow freely to where it needs to be, creating a ‘lag’ in the hot water supply.

Water flow without heating

This is a common problem relating to diverter valves. If you’re experiencing this, it’s probably the case that your valve is stuck on the hot water side. Even though having hot water is the main priority, the valve is unable to open and let the radiators warm up at all, which is particularly problematic in the winter months. 

Boiler parts and spares for fixing diverter valves

Find any boiler parts you need for an affordable price at National Boiler Spares today. Our team are on hand to help make sure you get the right parts for your boiler, thereby saving you money and guaranteeing you’re getting high quality components that are built to last. We stock spares for all the leading brands including the Vaillant diverter valve, the Worcester boiler diverter valve, and more. Simply use our contact us form to check if we have the part you need in stock.