Baxi Potterton Condensing Combination Boiler manual Technical Data, Heatmax Combi 24, 28

4.0Technical Data

4.1Heatmax Combi 24, 28 & 33

Appliance Type					C13	C33	C53
Appliance Category						CAT I 2H
Heat Input CH (Net)						Max	Min
24 model				kW		20.5	7
28 model				kW		24.7	9
33 model				kW		28.9	9.7
Heat Input CH (Gross)						Max	Min
24 model			kW			22.7	7.8
28 model			kW			27.4	10
33 model			kW			32.1	10.8
Heat Output CH (Non-Condensing)
						Max	Min
24 model				kW		20	6.8
28 model				kW		24	8.7
33 model				kW		28	9.4
Heat Output CH (Condensing)
						Max	Min
24 model				kW		21	7.4
28 model				kW		25.9	9.5
33 model				kW		30.3	10.2
	Heat Input DHW (Net)					Max
	24 model			kW		24.7
	28 model			kW		28.9
	33 model			kW		34
Heat Input DHW (Gross)						Max
24 model				kW		27.4
28 model				kW		32.1
33 model				kW		37.7
	Heat Output DHW					Max
	24 model			kW		24
	28 model			kW		28
	33 model			kW		33
		Max Gas Rate (Natural Gas - G20)
				(After 10 mins)
		24 model		m3/h		2.6
		28 model		m3/h		3.1
		33 model		m3/h		3.6

Inlet Pressure (Natural Gas - G20)

mbar	20
Injector (Natural Gas - G20)
7.5mm (24&28 model)		12mm(33 model)
Electrical Supply		230V~ 50Hz
(Appliance must be connected to an
earthed supply)
Power Consumption
155W (24&28 model)		160W(33 model)
Electrical Protection
	IPX5D
External Fuse Rating		3A
Internal Fuse Rating		F2L

Condensate Drain

To accept 21.5mm (3/4 in) plastic waste pipe

Flue Terminal	Diameter		100mm
Dimensions	Projection		125mm
Connections		copper tails
Gas Supply		-	22mm
Central Heating Flow		-	22mm
Central Heating Return		-	22mm
Cold Water Mains Inlet		-	15mm
DHW Flow		-	15mm
Pressure Relief Discharge		-	15mm
Outercase Dimensions
Casing Height			- 780mm
Overall Height Inc Flue Elbow			- 965mm
Casing Width			- 450mm
Casing Depth			- 345mm
Clearances
Above Casing	200 mm Min
Below Casing	150 mm Min*
Front	450 mm Min (For Servicing)
Front	5 mm Min (In Operation)
L.H. Side	5 mm Min
R.H. Side	5 mm Min

*This is MINIMUM recommended dimension. Greater clearance will aid installation and maintenance.

Weights (kg)
	(24/28)	(33)
Packaged Boiler Carton	48.6	51
Installation Lift Weight	43.6	46

NOx Class		5
Central Heating Primary Circuit
Pressures
			bar
Safety Discharge			3
Max Operating			2.5
Min Operating			0.5
Recommended Operating Range			1-2
DHW Circuit		bar
Pressures
Max Operating		8
Min Operating		0.15
Flow Rates	(24)	(28)	(33)
	l/min	l/min	l/min
DHW Flow Rate
@ 30o C Rise	11.43	13.3	15.7
DHW Flow Rate
@ 35o C Rise	9.8	11.5	13.5
Min Working
DHW Flow Rate	2	2	2

IMPORTANT: Where Low Flow Taps or Fittings are intended to be used in the DHW system connected it is strongly recommended that the DHW flow rate DOES NOT fall below 2.5l/min. This will ensure reliable operation of the DHW function.

Pump
Available Head	See graph below
Expansion Vessel	- (For Central Heating
only. Integral with appliance)
		bar
Min Pre-charge Pressure		0.5
		(24,28)	(33)
Max Capacity of		litre	litre
CH System		125	155
Primary Water Content
of Boiler (unpressurised)		2.5	2.8

Temperatures

C.H. Flow Temp (adjustable)

25°C to 80°C max (± 5°C)

D.H.W. Flow Temp (adjustable)

35°C to 60°C max (± 5°C) dependent upon flow rate

SEDBUK Declaration

SAP 2005 Seasonal Efficiency for all

models is 91.1%

This value is used in the UK Government’s Standard Assessment Procedure (SAP) for energy rating of dwellings. The test data from which it has been calculated has been certified by 0087.

NOTE: All data in this section are nominal values and subject to normal production tolerances.

Pump - Available Head

	5.5
	5
	4.5
	4
	3.5
	3
(wg)	2.5
Metre	2
	1.5
	1

0.5

0

0 200 400 600 800 1000 1200

10© Baxi Heating UK Ltd 2012

Flow Rate (l/h)