Dimplex Unvented Water Heater SCx Performance, Connecting the Water Supply, Secondary Circulation

Dimp-15278-SCx_Instructions 31/3/06 9:32 am Page 5

STANDARD ENERGY LOSSES

The heat loss of each SCx Unvented Unit while maintaining the temperature of the stored water at 65 degrees Celsius. (See performance table below).

1)Tests carried out by BBA. Slight variations may occur with changes to water mains supply pressure

SCx Performance

Nominal	Heat up	Heat up	Reheat	Reheat	Heat loss in
Capacity	Model IDH	Model DH	Model IDH	Model DH	24 hrs
Litres	Mins	Mins	Mins	Mins	kw/hr
80	33	64	23	53	1.12
130	28	115	21	90	1.50
150	33	138	24	104	1.82
175	27	167	24	124	2.10
215	35	212	30	153	2.64
255	42	263	35	184	2.73
305	50	313	42	220	2.88

2)These figures relate to a 45 degree differential between the stored water and ambient temperature

WITH AN SCx UNVENTED CYLINDER THE FOLLOWING IS SUPPLIED AS STANDARD

●1 Element on IDH indirect models up to 305 litres and 80 litre DH direct model

●2 Elements on DH direct models from 130 up to 305 litres. Additional elements from 215 to 305 litres are available on request.

●Cold-water control valve comprising line strainer, check valve, pressure reducing valve set to 2.1 bar

●Expansion relief valve with non return valve set at 6 bar

●Tundish 15mm x 22mm F x F

●Temperature / Pressure relief valve set at 90 degrees Celsius and 7 bar pressure relief (factory fitted)

●Motorised valve (indirect units only)

●Cylinder thermostat-factory fitted to cylinder, maximum setting 85 degrees Celsius (indirect units only)

●Thermal cut out set to operate at 87 degrees Celsius plus or minus 3 degrees (indirect units only)

●Option – Expansion vessel with capacity as below: -

CONNECTING THE WATER SUPPLY

●Pipework is not supplied

●All pipework should be installed using good plumbing practice. We recommend 22mm mains cold water supply is used.

●Install a Stop Cock Valve before the cold water inlet assembly on the incoming mains water supply so the unit can be isolated if required.

COLD WATER VALVE

The combined cold water valve (supplied) can be connected anywhere on the cold water mains prior to the unit. It can even be located at a point near to where the mains supply enters the premises if this is more convenient. When installing the cold water valve, ensure that the arrow is pointing in the same direction as the mains water supply flow when connecting, see fig 2.

The cold water balancing port, on the valve, allows you to connect the cold water mains to the rest of the property thus giving balanced pressure throughout. If this facility is not required leave the cap on.

DRAIN TAP

A drain tap to drain the unit must be fitted to the cold-water inlet pipe somewhere between the SCx unit and the cold water valve assembly and at as low a level as possible, see fig. 1.

PIPEWORK TO TAPS

Ideally a 22mm pipe run should supply the outlets throughout the property with short lengths (max 1 metre) runs of 15mm going to baths, showers, and basin taps. Smaller bore pipe can be used to suit taps.

SECONDARY CIRCULATION

This is particularly easy to fit on the SCx units; a Swept Tee (not supplied) is needed for all indirect models if secondary circulation is required, see page 6 fig. 3 for fitting. A non-return valve (not supplied) must be fitted to prevent backflow. You will need a pump to circulate the hot water (not supplied). The return feed is in 15mm pipe and all work can be done on site.

Before commencing installation check that all the components of your SCx Unit are contained in the kit.

●3KW Incoloy 825 heating element-incorporating thermostat to 70 degrees Celsius and resetable safety cut out set at 80 degrees Celsius

Tank Size	Expansion Tank Required
80 to 130 Litres	12 Litres
150 to 215 Litres	18 Litres
255 to 305 Litres	25 Litres

Typical Indirect Tank installation using external expansion vessel option

	WATER FLOW
	HOT WATER OUTLET		Fig.1
		7 BAR / 90 DEGREES	EXPANSION VESSEL
			(WALL MOUNTED)
		PRESSURE &
		TEMPERATURE
		RELIEF VALVE.
WATER FLOW
TO COIL INLET	PRIMARY FLOW

SCx UNVENTED INSTALLATION INSTRUCTIONS

WARNING: Under no circumstances must the factory fitted temperature pressure relief valve be removed. This will totally invalidate any guarantee or claim. The cold-water inlet valve assembly must be fitted or the SCx unit will not perform satisfactorily.

DO NOT ATTEMPT TO VENT THE PRIMARY CIRCUIT THROUGH THE SCx UNIT.

All boilers should be installed to manufacturers instructions and the primary circuit through the SCx unit must be pumped.

		TUNDISH			WATER FLOW TO
	PRIMARY RETURN				MANIFOLD VIA
					FLEXIBLE HOSE
WATER FLOW	TWIN	SECONDARY	6 BAR	PRESSURE
FROM COIL INLET	THERMOSTAT
		RETURN FLOW		REDUCING VALVE
			EXPANSION
				SET AT 3 BAR
			RELIEF
		WATER FLOW	VALVE
	IMMERSION	TO OVERFLOW
	HEATER	WATER INLET				WATER FLOW
		SWEPT TEE
						INLET SIDE OF TANK
		DRAIN	WATER FLOW			BLANKED
		COCK	FROM EXPANSION
						PORT
			TANK TO 22MM
			FEMALE THREAD

SITING THE SCx UNIT

The unit can be placed anywhere convenient. Because it is connected directly to the mains water supply it is equally efficient on any floor – ground, first or second. Avoid areas that may be subject to frost. Try to keep pipe runs as short as possible for maximum economy, especially hot water discharge pipes running down from the SCx unit.

The unit can be fitted into a conventional airing cupboard and does not require any additional insulation.

ALL SCx UNITS MUST BE STORED VERTICALLY

CHECK WATER PRESSURE & FLOW RATES

We suggest 1.5 bar pressure & 15 litres / minute flow rate to be the minimum requirements for satisfactory operation. Less than this the unit will still operate but you will not be able to run two, or more, outlets at the same time. 85% of all U.K homes have more than 2-bar pressure.

The mains supply must not exceed 16 bar. If it does a special pressure-reducing valve will be required.

Important Note: - Stainless Steel Tectile push fit elbows are fitted as standard to all SCx Cylinders.

Cold water inlet valve assembly			BEHIND COVER
		BALANCED
		COLD WATER
		OUTLET
	6 BAR
	EXPANSION
	RELIEF
	VALVE
			PRESSURE REDUCING VALVE SET
			AT 3 BAR Fig.2

WATER FLOW INLET SIDE OF TANK

WATER FLOW FROM EXPANSION
TANK TO 22MM FEMALE THREAD BEHIND	BLANKED
COVER	PORT

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