HOT TOPICS
hot topics
The Altecnic 311 Series and 313 Series (pictured) are high-quality examples of SRVs approved by the UK’s Water Regulations Advisory Scheme (WRAS).
ALTECNIC EXPLAINS THE APPLICATIONS AND COMMON ISSUES OF SRVS, AND HOW TO INSTALL THE SO-CALLED “LAST LINE OF DEFENCE” ACCORDING TO REGULATIONS… Overpressure protection: safety relief valves
A safety relief valve (SRV),
or a failed expansion tank – so there is nowhere for the expansion to go. Occasionally, the system pressure may be correct, but the valve has activated and has not correctly re-seated. This can be due to a few factors which include: 1 System debris is sitting under the seat, not allowing it to re-seat correctly. 2 System pressure has not reduced significantly for the seat to drop and is being held open via pressure. 3 System pressure is very close to the set point of the valve and the water can create a valley to pass through. INSTALLATION GUIDELINES AND REGULATIONS In a sealed heating circuit building, regulations state, where possible, to install an SRV close to the heat source on the flow circuit. It should be installed in the cold-water supply before the water heater, ensuring that there are no other fittings or narrowing of pipework between the water heater and the valve.
To comply with Water Regulations, valves should not be connected directly to a drain – the discharge should pass through a visible tundish with an AUK3 air gap and be located adjacent to the SRV, to allow vented water to escape. The discharge pipe must be the same size as the valve discharge outlet, cannot be longer than 2 metres, and must have no more than 2 elbows. The SRV should be located at a maximum distance of 1 metre from the boiler. Due to the high temperature of the discharge, the terminal point of the discharge pipe should be located where sudden discharge cannot cause scalding or injury. “In a sealed heating circuit building, regulations state, where possible, to install an SRV close to the heat source on the flow circuit.”
sometimes known as a pressure relief valve, is primarily a safety
device and in many cases the last line of defence. An SRV is not a process valve or pressure regulator and should not be misused as such. It should have to operate for one purpose only: overpressure protection. SRVs are normally installed in sealed heating systems that include a closed expansion vessel or a hot water cylinder. These valves are used for relieving excess pressure on boilers in heating systems and on stored hot water cylinders in domestic hot water systems. SRVs are also used in solar heating systems and water distribution systems generally. COMMON SRV ISSUES If the valve is passing water, the system has reached the pressure set point of the SRV and the valve has activated. The most common reasons for activation are an incorrectly sized expansion vessel, incorrect pre-charge setting in the vessel
For more information, contact Chris Reilly, Country Manager for Ireland, on +353 (0)85 215 2288 or e-mail chris.reilly@altecnic.co.uk or Gary Swann, Northern Ireland Sales Manager on +44 (0)7760 596727 or e-mail gary.swann@altecnic.co.uk or visit the website at www.altecnic.co.uk
FOLLOW US ON:
www.plumbingmag.com
PLUMBING & HEATING MAGAZINE | 31
Made with FlippingBook - professional solution for displaying marketing and sales documents online