Installation Guidance

Installation Guidance

Professional advice from ThermaQ.

All our stainless steel range is manufactured from the very latest high specification grade of Duplex stainless steel to resist all form of corrosion – including crevice and stress – whilst its high mechanical strength gives it fantastic durability.


Internal cylinder: Duplex Stainless Steel.
HE Coil: 22mm Stainless Steel.
Bosses: Stainless Steel.
Totally insulated with 100% CFC-Free (ODP zero) polyurethane to minimise heat loss. White pre-coated, corrosion resistant, Zintec case work.

Expansion Vessel Sizing Guide

Control Settings

Inlet control valve (3 bar). Expansion pressure relief (6 bar). Temperature (900C) and pressure relief valve (7 bar). Dual thermostat high limit (850C). Immersion heater high limit (850C).

Immersion Heater

13/4” BSP, long life incoloy sheathed low noise element. Long life thermostat pocket. Element rating 3kW at 240 A/C.

Guarantee Terms Overview

The ThermaQ stainless steel inner vessel on the Evocyl range of products carries a fully transferable 25 year guarantee applicable from the date of purchase. The guarantee covers material defect or manufacturing faults in domestic use only, of products up to the capacity of 300 litres. Please refer to installation guide for guarantee terms for calorifiers and nondomestic installations.

All components supplied with the Evocyl cylinder are guaranteed against material defects or manufacturing defects faults for 2 years from date of purchase.

Full details of guarantee terms, conditions and exclusions can be found in the installation guide provided with the cylinder.

Evocyl Approvals

(Subject to product specification).

Tested by NSF-Wrc to BS EN 12897:2006
The Building Regulations 2000 (England & Wales) Approved Document G (2010).
The Building Regulations (Scotland) 2004.
The Building Regulations (Northern Ireland) 2000.
Compliant with Building Regulation Part L WRAS Approved Product.
The UK Water Supply (Water Fittings) Regulations.
The Scottish Water Byelaws.
Components CE marked to EN Standards as applicable.

water cylinder installation


ThermaQ Evocyl is covered by Section G3 of the Building Regulations (England and Wales), Technical Standard P3 (Scotland) and Building Regulations P5 Northern Ireland). All Unvented units with a capacity over 15 litres must be installed by a competent installer in accordance with these regulations.

Mains Supply

The Evocyl unvented cylinder needs a minimum of 1.5 bar (max 10 bar) mains pressure and 20 litres per minute flow rate to ensure that the cylinder meets its minimum capabilities. Higher mains pressure and flow rates will result in a higher performance from the cylinder.

Cylinder Siting

With no header tanks to consider, ThermaQ Evocyl units can be sited almost anywhere in the house. Evocyl can supply outlets both above and below its location and must be fitted on a flat surface capable of holding its full weight. (Refer to installation instructions supplied with cylinder).

Boiler Compatibility

Evocyls are compatible with any appliance that is fitted with an integral control thermostat and Its own energy cut-out (these include natural gas, lpg, electric and oil boilers). Solid fuel appliances such as Aga, Rayburn, etc., without full thermostatic control cannot usually be installed with an unvented unit. Please consult the Evocyl installation guide for further information.

Secondary Return Connection

As standard 210, 250 and 300 litre models are fitted with a secondary hot water tapping. Other sizes can be fitted with a secondary return if required.


All electrical wiring should be carried out by a competent electrician and be in accordance with the control scheme being used and the latest IEE regulations. The controls provided with the Evocyl will ensure the safe operation of the unit within a central heating system. The Evocyl is compatible with Y and S plan plus layouts.

External wiring to the immersion heaters must comply with the relevant IEE wiring regulations and the circuit must be protected by a suitable fuse and a double pole isolating switch.

Connection Sizes

Cold Inlet

Hot Outlet

Coil Connections

Safety Valves

Inlet Control Set


22mm Compression

22mm Compression

22mm Compression

15mm Compression Outlet

22mm Compression Inlet and Outlet

15mm Compression Inlet /
22mm Compression Outlet