Unvented Water Cylinder Engineers
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Safety valve replacement

Most manufacturers recommend that unvented water heaters are serviced each year is to ensure that safety valves are tested for faults. The role of the safety valve is to guard against systems overheating, becoming over pressured and causing floods. Whether you have noticed that a safety valve has malfunctioned or whether it was identified as faulty in a service, it should only be changed by a competent person.

What Is a Safety Valve?

Unvented hot water cylinders are under a good deal of pressure. This allows them to supply hot water to the tap at a rate that matches or exceeds mains pressure, which is the maximum a vented hot water heater can supply.

However, there are potential dangers with unvented cylinders. One of those is the potential to become over-pressurised. If this occurs, there must be a way to eliminate the excess pressure to avoid catastrophic failure of the cylinder wall or other components. The safety valve is responsible for releasing this pressure in these instances.

There is also the potential for water within an unvented cylinder to become overheated. In normal operation, a thermostat controls the heat of the water, allowing the immersion heater to achieve the right temperature and then stopping the increase before it becomes too hot. However, if the thermostat were to fail, then there is the potential for the water to become overheated. In this instance, a similar situation to over-pressure could occur, creating a dangerous condition. The safety valve is designed to release water if it exceeds a specific temperature.

As you can see, the safety valve within an unvented cylinder is a critical component. It ties in directly to the safe usage of the system. Under normal conditions, it should work correctly for years, but there are potential issues that could render your safety valve unable to function properly.

Why Would a Safety Valve Fail?

A safety valve can fail for a number of reasons, but the most common is deterioration of the washers, gaskets, and other rubber components. This is often due to prolonged exposure to high temperatures as well as a lack of adequate maintenance during annual inspections. The point of the mandatory annual inspection for unvented hot water cylinders is to ensure safe operation of this critical component and timely replacement in the case of deterioration.

The first set of photographs show a temperature and pressure relief valve being changed. The valve on an Albion Stainless HE unvented water heater began allowing water to be discharged from the cylinder at 50°C instead of the 90 – 95°C. As a result water was discharged under normal conditions causing a waste of water and electricity.

Albion Stainless HE

Albion Stainless HE

Snapping the Olive

EasyFlow is a Country and Town Limited Service and providing an unvented water heater and a thermal store water heater repair and maintenance service in Manchester and Liverpool.

Step by step photos TPR valve

These photos show the steps an EasyFlow heating engineer would take to replace the valve. As is the case with immersion heater replacement the electrical supply should be isolated and the cylinder drained down.

We cannot stress enough that replacement of any components on an unvented hot water heater be handled by trained, certified, and experienced professionals. At EasyFlow, our service representatives have years of experience with repairs, part replacement, and new installation on vented and unvented thermal stores, and they can provide you with an expedient, professional solution to your needs, whether the TPR valve has failed, the combination valve is at fault, the immersion heater has stopped working, or something else has gone wrong with your water heater.

Isolating the Electrical Supply

Isolation the Water Supp

Draing Down the Cylinder

Combination Valve replacement

The combination valve is a combination of a line strainer, single check valve and a pressure reduction valve. Often and in the case of the combination valve on the MegaFlo water heater shown in the photos it is also connected to an expansion valve.

Temperature and Pressure Relief Valve

Unvented Water Heater Without TPR Valve

The Replacment TPR Valve

The valve in these photos had failed and needed to be replaced. Because of changes to the manufacture of valves since the installation, Heatrae Sadia advised that an exact copy of the old valve was not available and recommended a suitable replacement. This is quite a common occurrence as the manufacturers of the cylinders are not the manufacturers of the valve and the valves get redesigned quite often.

Installation fault

When the valve was inspected the EasyFlow engineer noticed that the original installation was incorrect. If you look at the photo titled ‘Faulty and Incorrectly Installed Valve’. The single check valve installed (and partially hidden by the cylinder) should not have been installed after the expansion valve.

Replacing the PRV

New Valve Inplace

Incorrect Set Up

By placing this check valve between the expansion valve and the cylinder the function of the expansion valve has been removed. In effect the cylinder has been operating since its installation without this safety valve. This check valve should have been used if the residence was to have balanced hot and cold water and then it should have been installed before the expansion valve.

Gauage Showing no Pressure in Cylinder

New Temperature and Pressure Relief Valve

Removing Faulty TPR Valve

Please note: EasyFlow will guarantee the work we undertake for you but we will not guarantee manufacturers’ parts. Manufacturers often offer a 12 month warranty on parts; this will be passed on to you

Why You Should Invest in an EasyFlow Maintenance Plan

As mentioned, insurance companies require that any unvented hot water heater be inspected every year. This is a vital consideration for continued safe operation. At EasyFlow, we offer a professional Maintenance Plan that includes an annual inspection of your unvented thermal store. We are also happy to provide professional service and much more as part of our maintenance plan, and we invite you to call us today to learn more about it.

Our Maintenance Plans deliver the ability to ensure continued safe operation, and also provide you with replacement parts and professional service for your hot water heater. However, if your unvented thermal store cannot be safely repaired, we cannot service it. We also cannot provide repairs or service for hot water heaters if spare parts are no longer available.

In most instances, the designer and manufacturer of the hot water heater is not the same company as the one that designs components, such as safety valves. If comparable spare parts are not available, we will be unable to service your hot water heater, and our service professionals will recommend a full replacement instead.

EasyFlow is a Country and Town Limited Service and providing an unvented and a thermal store water cylinder repair and maintenance service in Manchester and Liverpool

Faulty and Incorrectly Installed Valve

Fitting a New TPR Valve

Removing Olives

If you need an EasyFlow hot water specialist call now on 0797 153 7227

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