Fault Finding & Servicing; Spare Parts - Ecodan 150 Standard Installation And Servicing Instructions

FAULT FINDING & SERVICING
IMPORTANT
• After servicing, complete the relevant Service Interval Record for the installation.
• Servicing should only be carried out by competent persons in the installation and maintenance of unvented water heating
systems.
• Any spare parts used MUST be authorised Mitsubishi Electric parts.
• Disconnect the electrical supply before removing any electrical equipment covers.
• NEVER bypass any thermal controls or operate system without the necessary safety valves.
• Water contained in the Air Source Heat Pump pre-plumbed cylinder may be very hot, especially following a thermal control
failure. Caution must be taken when drawing water from the unit.
Table 7 - Fault Finding Table
FAULT
No hot water flow
Water from hot taps
is cold
Water discharges from
Expansion Valve
Water discharges from
T&P Relief Valve
Milky water

SPARE PARTS

A full range of spare parts are available for the Mitsubishi Air Source Heat Pump pre-plumbed cylinder range (see Table 8,
page 37). Refer to the technical data label on the unit to identify the model installed and ensure the correct part is ordered.
You will need to quote the serial number which is printed on the data label.
FAULT FINDING
The fault finding chart (above) will enable operational faults to be identified and their possible causes rectified. Any work carried
out on this unvented water heater and its associated controls MUST be carried out by a competent installer for unvented
water heating systems. In case of doubt contact Service Support (see contact details on back page).
WARNING
DO NOT TAMPER WITH ANY OF THE SAFETY VALVES OR CONTROLS SUPPLIED WITH THE PRE-PLUMBED CYLINDER
AS THIS WILL INVALIDATE ANY GUARANTEE.
36
POSSIBLE CAUSE
1. Mains supply off.
2. Strainer blocked.
3. Cold water combination valve incorrectly fitted.
1. BACK UP immersion heater not switched on.
2. BACK UP immersion heater thermal cut-out
has operated.
3. Programmer set to Central Heating only.
4. Air Source Heat Pump not working.
5. Thermal cut-out has operated.
6. DHW circulating pump not connected
correctly.
1. INTERMITTENTLY
Expansion vessel charge pressure has reduced
below 3.5bar.
2. CONTINUALLY
a. Cold water combination valve pressure
reducer not working correctly.
b. Expansion valve seat damaged.
1. Thermal control failure. NOTE water will be
very hot.
1. Oxygenated water.
REMEDY
2. Check and open stock cock.
2. Turn off water supply. Remove strainer and clean (see
maintanance section).
3. Check and refit as required.
1. Check and switch on.
2. Check. Reset by pushing button.
3. Check. Set to Domestic Hot Water programme.
4. Check heat pump operation. If fault is suspected, consult
heat pump instructions.
5. Check. Reset by pushing button on cut-out. Check
operation of DHW thermal sensor
6. Check wiring and/or plumbing connections to DHW
circulating pump. Check isolating valves are open
1. See Maintance section for re-charging procedure.
2a. Check pressure from cold water combination valve. If
greater than 3.6 bar, replace pressure reducer cartridge.
2b. Remove expansion valve cartridge. Check condition of
seat. If necessary, fit new expansion valve cartridge.
1. Switch off power to immersion heater(s) and /or shut down
Heat Pump. DO NOT turn off water supply. When discharge
stops check all thermal controls, replace if faulty.
1. Water from a pressurised system releases oxygen
bubbles when flowing. The milkiness will disappear after
a short while.