gledhill BOILERMATE OV PP, Instruction Manual

Page 14

Pipe Sizing / Materials / Push Fit

To achieve even distribution of the available supply of hot and cold water, it is 

important in any mains pressure system, that the piping in a dwelling should be sized

in accordance with BS EN 806:1-5: BS EN 8558:2011. This is particularly important in

a large property with more than one bathroom.

However, the following rule of thumb guide lines should be adequate for most smaller

property types as long as water pressures are within the recommended range.

1.  A 15mm copper or equivalent external service may be enough for a small 1 

bathroom dwelling (depending upon the flow rate available), but the minimum 

recommended size for new dwellings is 22mm (25mm MDPE).

2.   The internal cold feed from the main incoming stop tap to the BoilerMate SP 

should be run in 22mm pipe. The cold main and hot draw-off should also be run 

in 22mm as far as the branch to the bath tap.

3.   The final branches to the hand basins and sinks should be in 10mm and to the 

baths and showers in 15mm (1-meter minimum).

4.  

We would recommend that best results for a balanced system are achieved by 

fitting appropriate flow regulators to each hot and cold outlet. This is particularly 

relevant where the water pressures are above the recommended water pressure 

range. Details of suitable flow regulators are provided in Appendix A.

All the recommendations with regard to pipework systems in this manual are generally

based on the use of BS/EN Standard copper pipework and fittings.

However, we are happy that plastic pipework systems can be used in place of copper

internally as long as the chosen system is recommended for use on domestic hot 

and cold water systems by the manufacturer and is installed fully in accordance with

their recommendations. This is particularly important in relation to use of push fit 

connections when using the optional flexible hose kits - see installation section of 

this manual.

It is also essential that if an alternative pipework material/system is chosen the 

manufacturer confirms that the design criteria of the new system is at least equivalent

to the use of BS/EN Standard copper pipework and fittings.

Secondary circulation

If the length of the hot water draw off pipework is excessive and the delivery time 

will be more than 60 seconds before hot water is available at the tap, you may wish to

consider using trace heating to the hot water pipework such as the Raychem HWAT 

system. Also, a conventional pumped secondary circulation system (shown below) 

can be used with any model of the BoilerMate SP.

INSTALLATION

DOMESTIC HOT WATER

BoilerMate

Inline filter &

flow regulator

Single check

valve

Single

check

valve

Pump isolation

valves

Cold water inlet

Plate heat exchanger

Hot water outlets

Pipework length and

diameter to suit

property demands

Pipework length and

diameter to suit

recirculation flow rate

approx 1-2 l/min

Cold water sensor

Control

stat

Flow switch

Potable water

expansion vessel

Secondary

circulation

pump

A pipe thermostat is incorporated in the circuitry which cuts the supply to the pump 

when the water in the return pipe reaches the set temperature. Ensure the hot water 

temperature is set correctly to avoid excessively hot water at the outlets and long 

pump run times.

Secondary circulation pipework must be 

insulated to prevent energy loss in both heated

and unheated areas.

Bath Hot Water Temperature

Bath hot water supplies should be limited to a 

maximum of 48°C using an inline blending valve.

Pipe Separation

It is important that the cold-water pipework 

is adequately separated/protected from any 

heating/hot water pipework to ensure that the 

water remains cold and of drinking water quality.

Tap outlets

Aerated taps are recommended to prevent 

splashing.

Showers

Any type of shower mixing valve can be used 

as long as both the hot and cold supplies 

are mains fed. However, all mains pressure 

systems are subject to dynamic changes 

particularly when other hot and cold taps/

showers are opened and closed, which will 

cause changes in the water temperature at 

mixed water outlets such as showers. For 

this reason and because these are now no 

more expensive than a manual shower we 

strongly recommend the use of thermostatic 

showers with this appliance.

The shower 

head provided must also be suitable for 

mains pressure supplies.

However, if it is proposed to use a ‘whole body’ 

or similar shower with a number of high flow/

pressure outlets please discuss with the Gledhill 

technical department.

Shower Pipework

The hot water supply to a shower-mixing valve 

should be fed wherever practical directly from 

the BoilerMate SP or be the first draw off point 

on the hot circuit. The cold supply to a shower-

mixing valve should wherever practical be fed 

directly from the rising mains via an independent 

branch. The shower must incorporate or be fitted 

with the necessary check valves to provide back-

siphonage protection in accordance with the 

Water Regulations.

Bidet Supply

The supply of hot and cold mains water directly 

to a bidet is permitted provided that it is of the

over-rim flushing type and that a type ‘A’ air gap 

is incorporated.