Over the last year, almost half of our private enquiries concern underfloor heating.

We have designed systems to run in conjunction with most commonly available underfloor systems, as well as some rather unique custom systems. A sample of those is listed below.

Technical Editorial on Underfloor Heating

GX Underfloor Buffer Stores
Vented Primary System

The following table links to specifications which provide both underfloor heating, as well as radiator.  Such systems are typically more common than UFH alone, with the upstairs floor typically being on radiators.

Link to Specification	DHW Plate Size	DHW Blender	GX Valve (Boiler)	Pumped Radiator Circuit	Pumped UFH Circuit	Solar Coil	Solid Fuel Boiler Connections	Twin Cylinder Thermostats	Controls
4522-2	14	22mm	22mm		22mm				RF Programmable Rom Stats x2
5375-2	28	28mm	28mm		22mm
5395-1	28	28mm	28mm		28mm				Store Timer with Overheat Controls
5477-1	28	22mm	22mm		22mm

Operation of the GX Heat Bank Thermal Store

Underfloor Buffer Store
Sealed Primary System

Specification 4914-1

	Mains pressure hot water supplies, without the need for an overflow or discharge from the cylinder cupboard.
	Fully sealed underfloor heating, with optional radiator circuit.  All pumps, controls, and wiring factory fitted.
	Buffer operation, whereby the heating can pull heat back out of the store to overcome boiler cycling.
	Underfloor heating can make use of all heat sources - boiler, immersion heater, and even solar panels if called for.
	Connects to basic manifolds, without the need for separate pumps or thermostatic controls.
	No motorised valves - simpler, lower pressure losses, and more reliable.
	Suitable for all types of boiler (even oversized ones).

To make the store act as a buffer between the boiler and the underfloor system, we use the primary heating coil (in the store) to both heat the store, and transfer heat back out of the store to the heating.  The boiler is controlled entirely by the store, only firing when there is a sufficient amount of water in the store that needs heating.  This overcomes cycling of the boiler at low heating loads.  The underfloor pulls its heat out of the bottom half of the store via the coil, until the store drops in temperature enough for the boiler to fire again.

We have also managed to do away with all motorised valves, instead using two primary pumps - one for the boiler and one for the heating circuit.  This makes for a simpler and more reliable system, that is also easier to service.  Temperature control of the underfloor flow is provided by a very reliable thermostatic mixing valve. 

Underfloor Buffer Store
Vented GX Primary System

Specification 870-9

This system is a 'true' thermal store, in the sense that the water in the store is the same water that flows through the boiler and the underfloor heating. Because of this, it is not possible an option to have a sealed primary system - there must be a feed and expansion tank higher than the store and all primary pipework.  If the store is to be located on the top floor then the F&E tank can go in the cupboard directly above the store. 

Indirect Store with Underfloor
Sealed S-Plan Primary System

Specification 3892-1

This system is a as near to a standard S-Plan system that underfloor gets.  The controls provide for both a radiator circuit, and a temperature controlled under-floor circuit.  The primary system is sealed, with all the necessary controls.

Underfloor Buffer Store
Vented GX Primary System including Radiators
with Sealed Underfloor

Specification 4668-2

This system combines the rapid response GX system with the ability to drive a sealed underfloor system via a coil in the store - no underfloor controls are provided. Radiators are fed directly from the store, and will respond extremely quickly when turned on.

Underfloor Buffer Store
Vented GX Primary System
with High-Output Underfloor

Specification 2001-1

This system combines the rapid response GX system with a direct fed high output underfloor system.  It also includes a secondary return system to ensure hot water is available immediately at taps - no cold water to run off first.