Imagine the big, tall water tank in your house (that’s your unvented cylinder) is like a giant bottle of fizzy drink – except the drink is actually boiling water.
Unlike a traditional vented system (which has a plastic tank in the loft to let off steam), an unvented cylinder is a sealed unit connected directly to your mains water.
Because the water inside is under a lot of pressure, that tank has a very important job: it has to stay strong and not pop! A regular service of the cylinder is essential to prevent a potential safety hazard in your home.
Here’s what’s involved and why servicing your cylinder can also save you money…
1. Checking the “Safety Whistles”
The tank has special buttons and valves that act like safety whistles. If the water gets too hot or the pressure gets too high, these whistles let a little bit of steam out so the tank stays calm. If a spider builds a web in one, or they get rusty, they might not work. Our service engineers make sure they are clear and ready to “whistle.”
2. The Expansion Relief (The “Bubble”)
Inside the tank, there is usually a hidden bubble of air at the top. When water is heated, it expands, and, since the cylinder is a sealed steel “box”, that extra volume has nowhere to go. The bubble gives the water room to grow.
Over a year, that air bubble can dissolve into the water. Without it, the pressure inside the tank spikes every time the heater kicks in, putting immense stress on the welded seams of the cylinder. Our engineers can recharge the bubble, reducing the stress on the cylinder.
Some cylinders have an external expansion vessel (a small separate tank) to act as a shock absorber, and this will also require regular servicing.
3. Cleaning the Inside
Many cylinders have a “sacrificial anode” (a metal rod that attracts corrosion so the tank doesn’t have to). During a service, our engineers check if this rod has been eaten away. If it has, and it isn’t replaced, the tank itself will start to corrode from the inside out.
We will also check for limescale buildup on the internal heating coils, which acts as an insulator and delays the heating process. A serviced, descaled cylinder heats water faster and costs significantly less to run.
4. Consider Your Home Insurance
If your cylinder leaks and causes floorboard damage, many insurance companies will refuse the claim if you cannot produce a service record for the last 12 months. Is it worth the risk to delay your servicing?
Contact our team if you’d like to check when your next unvented cylinder service is due, or if you have any other queries. Call 01227 263473.