Horne Engineering Ltd

FAULT FINDING CHART

REFER TO

SYMPTOM

POSSIBLE CAUSE

ACTION

SECTION

Temperature setting too

high.

Re- adjust temperature setting

4

Temperature has been set

when hot water

temperature is too low

Mixed water

Inspect Check Valve at cold

temperature too

Hot water has migrated into

3.6.1 to 3.6.6

inlet . If the check valve leaks

high

cold water supply

replace the strainer body and

See Drg.6397

check valve subassembly

Thermostat Element has

failed this can be checked

Replace element (8)

6

by carrying out a hot or cold

water failure test.

Temperature Setting too

Re- adjust temperature setting

4

low

Hot water supply

Check hot water supply

3.2

temperature has fallen

system

Mixed water

Inspect Check Valve at hot

temperature too

Cold water has migrated

inlet . If the check valve leaks

3.6.1 to 3.6.6

low

into hot supply

See Drg 6397

replace the strainer body and

check valve subassembly.

Cold valve face requires

Remove valve Cover (5) and

6.4.7

cleaning

service valve face

Partly blocked strainers

Clean strainers

6.2

Check all valves are full open.

Unusually high pressure

Check Pressurisation unit.

Mixed water flow

drop in supply pipework

Check mains supply

rate too low.

Extra Demand added to

Check pipe sizing

system

Valve requires de-scaling

Slide-Valve (9) is seized

6.4.5

Mixed water temp

Remove HORNE 15 TMV

does not respond

from pipes and reverse

to adjusting screw

Hot and cold inlets reversed

connections. Connect inlet

with red dot to hot pipe

Valve requires De-Scaling

Slide-Valve (9) is seized

6.4.5

Mixed water temp

Thermostat element has

changes and is not

failed (This can be checked

steady

Replace elements (8)

6

by carrying out a hot or cold

water failure test)

Hot inlet is marked with Red

Water at outlet

Hot and cold inlets are

dot.

runs full hot or full

reversed

Cold inlet is marked with Blue

cold

dot.

Valve continues to

Cold valve face requires

Remove valve cover (5) and

pass cold water

6.4.7

when hot supply is

cleaning

service cold valve face

isolated

Valve continues to

Fouling at hot valve seat

Clean hot valve face

6.4.7

pass hot water

Slide-Valve seal is

Replace Slide -Valve Seal

6.3.4 & 6.3.5

when cold supply

damaged

(13)

is isolated

Element has failed

Replace Element (8)

6

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Issue 2 19/09/05