Vented Cylinders
(Open-Vented Systems)
Vented cylinders are gravity-fed systems that rely on a cold water tank (usually in the loft) to supply the cylinder. They are simple, proven and can be easier to maintain.
- Uses a header tank in the loft as the feed and expansion point
- Operates at low pressure (gravity-fed) unless boosted by a pump
- Generally simple to install and repair
- Often cheaper initially, but can be less space-efficient and may deliver lower water pressure
Unvented Cylinders
(Pressurised Systems)
Unvented cylinders connect directly to the mains water supply and provide high-pressure hot water throughout the property. They require additional safety devices and, therefore, must be installed by a trained professional.
- Direct mains supply gives strong, consistent pressure at taps and showers
- Requires an expansion vessel, pressure relief valves, and safety controls
- No loft tank required; frees up space and reduces risk of freezing/contamination
- Installation must comply with Building Regulations; periodic servicing is recommended
Which Should You Choose?
If you need improved water pressure and want to remove a loft tank, an unvented system is often the best choice. However, vented systems remain a good, cost-effective option for some properties. For the most informed decision, our engineers will advise based on your building, water supply, and hot water demand.
Hot Water Cylinders
We work with a wide range of hot water cylinders, including direct and indirect cylinders, unvented pressurised cylinders, stainless steel and copper cylinders, and insulated models designed for efficiency. We size cylinders to match property demand and heating systems to avoid under or over-sizing.
Cold Water Tanks & Cisterns
Cold water tanks (header tanks and cisterns) are commonly sited in lofts or roof spaces and feed vented systems. We offer new installations, replacements and repairs, including anti-legionella measures.
Materials & Insulation
We fit robust tanks and cylinders made from high-quality materials (e.g. stainless steel, copper, pressed steel) and install water tank insulation jackets where appropriate to reduce heat loss and running costs.
Ruth Lewis
Fantastic work carried out on a tired shower room that was long over due a refit. Dan and the team were professional, friendly with excellent attention to detail nothing was too much trouble. We are thrilled with the final results!!!
Luke Taylor
We had our boiler serviced by gaswise for the last couple of years and the service has always been great. We had Jake come over this time and he went above and beyond by sorting out a loose tap that he noticed while servicing. It may seem like a small thing but goes to show how he goes above and beyond for his customers. Thanks for your help.
John Robinson
Very diligent company. Installation of two commercial boilers into a large church. Thorough site surveys carried out over three visits including specialist flue manufacturer and the boiler manufacturers. Well managed installation with excellent post installation hand over and follow up.
Alison Taylor
Jack initially came to service our boiler, he was friendly, professional and did a great job. We wanted our heating system flushed, so asked for a quote. This was sent the same day and our system was flushed through on the day we wanted, all ready for the winter months by Jack & Harry. Again a friendly professional manner, and our home left clean & tidy.
David Stemp
We just moved in to our new property on Friday, we reported the taps not working in the kitchen on Thursday, Ryan came around, identified the problem, and changed the taps. Great, professional service, Ryan was very friendly and professional. Thank you.
Jess Slater
Ryan completed a boiler replacement and a Landlords certificate for us on our rental property. He was friendly and efficient, and we really appreciate the effort he went to, to ensure we were happy with the installation and that we understood how to use it before he left. Thanks
