Rex Royal · bean to cup
Rex Royal S300 — PSSR examination & servicing
S300 machines are used in larger offices and hospitality sites running the machine hard nationwide. The engineer carries out the statutory PSSR examination, the front-end service and the water treatment on this model — a standalone examination is £265 + VAT, or £585 + VAT with the service included.
Quick answer
Does a Rex Royal S300 need a PSSR examination?
Yes, if it operates in a workplace. It carries a single steam boiler with its own protective devices, which is the pressure system in scope. Steam is a relevant fluid under PSSR 2000 and steam systems are covered at any pressure and any volume, so the boiler must have a Written Scheme of Examination and be examined periodically by a competent person.
- Examination only
- £265
- With service
- £585
The machine
Why the S300 matters to the Rex Royal owner
The larger Rex Royal, still on the same small sealed vessel as the S2 but with a bigger brew platform and more use per day.
In practice you will find it in larger offices and hospitality sites running the machine hard — which shapes what the examination looks like on site: how the machine is accessed, how long it can be offline, and how much scale it has accumulated.
On the day
- The steam boiler is located and examined. On a sealed stainless vessel the examination is external — wall thickness, corrosion at fittings, and the condition of every connection — with internal inspection by borescope only where the vessel design allows access.
- The safety valve, expansion valve, pressure sensor and thermal cut-outs are identified, checked and function tested.
- The pressure gauge is verified against our calibrated test gauge, not against itself.
- The vessel is small and sealed, so there is no drain-down and refill to wait for. The time goes on getting to it, which is why the brew unit and panels come off.
- The Written Scheme of Examination records the vessel as sealed and sets out the external examination and the protective devices it relies on.
Typical rates for this model
- Standalone PSSR examination
- £265
- Service + PSSR bundle
- £585
- Certified safety valve, if it fails
- £135 + VAT
- Water filter, fitted on a visit
- from £107
- Grinder calibration & deep clean
- £89
- If it does not pass
- Explained in writing
All prices exclude VAT. A single steam boiler with one set of protective devices to examine. We confirm the exact figure on the call.
Filters are fitted on site by an engineer and are not posted out. The filter price applies when ordered with a PSSR examination, service, call-out or water test; booked alone it is charged at the standard call-out.
What we see on this model
- 1.2 litre sealed steel boiler at a 2.3 bar rating — the vessel is the small part; the wear is in the brew unit and the grinders.
- Higher daily throughput on a small vessel means the safety valve is doing more work, so it is the first thing worth testing.
- The Rex Royal safety valve is a 2.3–2.4 bar part, not the 1.8 bar valve used on traditional machines, so a generic valve cannot be substituted. It retails at about £117 in UK trade and is quoted per machine.
- Rex Royal specify a Small Service every 30,000 brewing cycles or 12 months and a Main Service at 60,000 cycles or 2 years, with the boiler and steam safety valve replaced at the latest after four years.
- Steam boiler 0.8 L / coffee boiler 1.2 L (1.1 L CF boiler). Revision breakpoint: current 2024 boilers 033895/033897 (1.9/2.8 kW, 0.8 L) are shared with the S2, while earlier S300 certificates list S300-specific steam boilers 32984 (3 kW) and 32985 (2 kW) at 1.2 L - check the boiler plate before ordering. Cold-start fill timeout 360 s. Safety test each service; boiler and valve at 4 years.
- A standalone annual service on a bean-to-cup machine runs £250–£450 on site before any major parts. Dealers typically sell this as a contract instead — around £1,130 a year for an S2 or S300 including parts, labour, call-outs and the PSSR checks — so a one-off visit at our published rate is usually cheaper than a year of contract if the machine is healthy.
Verified boiler data
What is actually inside this machine
| Configuration | Steam boiler |
|---|---|
| steam boiler | 0.8 L |
| coffee boiler | 1.2 L |
Manufacturer's published boiler capacities. Where a maker publishes no figure we say so rather than estimate. Steam boiler 0.8 litres, coffee boiler 1.2 litres. Older S300-specific boiler types are certificated at 1.2 litres, so confirm the type number before quoting a vessel size.
Service interval. Small Service at 30,000 brewing cycles or 1 year; Main Service at 60,000 cycles or 2 years; additional work at 120,000 cycles - whichever comes first. The machine raises 'Service required' when its own cycle or day interval is reached. Ever
What a service covers
- ›Brew group stripped and cleaned, with head seals and O-rings replaced
- ›Grinder checked for burr wear and recalibrated
- ›Water filter cartridge renewed where it is due — the filter itself is charged at our published rate, not folded into the labour
- ›Steam safety valves inspected, and boiler temperature and pressure checked
Fault finder
What actually goes wrong on a Rex Royal S300
Owners usually call us with a symptom, not a diagnosis. This is what that symptom most often turns out to be on this machine, and what putting it right involves.
| Symptom | Usual cause | What fixes it |
|---|---|---|
| Drink stops mid-pour or dose is short, E3 'flow error' | flowmeter not sending impulses: obstructed flowmeter nozzle, obstructed cream nozzle, failed flowmeter or its cable, tea/brewing/instant/inlet valve, check valve in hydraulic unit - or coffee boiler over-pressure valve not opening at 12 bar | restart (machine re-rinses until it sees an impulse), then flowmeter and cable, then valves. |
| No steam, coffee still works, E8 'steam boiler fill error' | on S2/S300 the machine allows 120 s to fill (180 s cold start), then flags it: water supply closed, filling line obstructed, inlet valve, filling valve not opening, level sensor, blocked filling nozzle, blocked check valve, or boiler earth conductance too low | supply and valve first, then filling nozzle and check valve, then level sensor and boiler earth. |
| Steam boiler overfills or over-pressurises, E9 or E13 | filling valve not seating properly, calcified level sensor, calcified boiler inlet, leaking steam/tea valve, or electrode-to-boiler earth short | strip and rebuild the fill valve, descale probe and inlet, verify the boiler earth. |
| No steam and no hot water, E10/E14/E15 | heating chain: calcified steam boiler filling line, pressure sensor or gauge, power board, triac, boiler element, E15 is cable/plug/not connected | resistance-test the element, check triac and contactor, then sensor and plug. |
| Coffee boiler over-temperature or won't heat, E11/E12 | temperature sensor calcified or defective, overtemperature fuse (Klixon) triggered, boiler element, triac, power board | descale or replace the NTC, reset or replace the Klixon, then element and board. |
| Brew piston or coffee piston position error, E5/E6/E20 | mechanical blockage of the piston, failed piston drive or motor, or missing Hall-sensor impulses | free and clean the brew unit, check Hall sensors and drive, restart to re-initialise. |
| Drink stops mid-pour or is short; E3 'flow error'. | No flowmeter pulses: defective flowmeter, clogged flowmeter or cream nozzle, valve fault, check valve in hydraulic block, unplugged flowmeter cable, or coffee boiler pressure above 12.5 bar. | Restart, then flowmeter (menu 20), cable and nozzles, then valves and boiler pressure. |
| No steam, coffee still works; E8 'steam boiler fill error'. | Fill timeout - level probe, filling tube/nozzle, filling valve, inlet valve or water supply. S300 allows 360 s on a cold start (120 s on older S2-class timing). | Supply and inlet valve first, then filling tube and valve, then level probe. |
| Steam boiler over-pressurises; E13 (above 2.0 bar for more than 10 s). | Scaled steam boiler inlet or level detector, filling valve not closing, triac short, ICE on controller, pressure sensor. | Descale, rebuild the filling valve, check triac and controller. |
| Coffee boiler over-temperature; E11 (above 120 C for more than 10 s). | Triac short circuit, heater output on control board, scaled/defective temperature sensor. | Test element, check triac/board, descale or replace NTC (140878). Clear the error history after repair. |
| Brew or coffee piston position error; E5 / E6. | Motor defective, rotation sensor defective, or piston mechanically blocked/running very slowly (maintenance due). | Free and clean the piston, check the rotation sensor and motor; a very stiff piston usually means the service is overdue. |
These are faults documented for this model, not a generic list.
Fault codes
Rex Royal error and message codes
The codes this range can display, transcribed from the manufacturer's error table. If the machine is showing one, the code names the system at fault before any strip-down.
| Code | Meaning |
|---|---|
| E1 | NTC Coffee Boiler — Interruption of the coffee boiler temperature sensor. Coffee products blocked. |
| E2 | NTC Steam Boiler — Sensor 2 error, only old models. Interruption of the steam boiler temperature sensor. Products with steam blocked. |
| E3 | Flow Error — Flowmeter does not send any pulses. Products still available. |
| E4 | Product Timeout — Coffee or tea preparation takes longer than 120 s. Products still available. |
| E5 | Brew Piston Error — Error of the brewing water piston. Products still available. |
| E6 | Coffee Piston Error — Error of the coffee piston. Products still available. |
| E8* | Steam Boiler Fill Error — Steam boiler could not be filled in the designated time. Coffee is still available. |
| E9* | Steam Boiler Level Sensor — If the filling valve does not open after a defined period of product consumption with steam (hot milk, choco etc.). Coffee |
| E10* | Steam Boiler Pressure Sensor — If the steam boiler heater is active within a defined time, but no pressure change occurs. Coffee is still available. |
| E11* | Coffee Boiler Temp Error — Please unplug the power cord immediately !!! Coffee boiler temperature is above 120 °C for more than 10 s. No products avai |
| E12* | Coffee Boiler Heat Error — Please unplug the power cord immediately !!! Coffee boiler heater switches off after a defined timeout regardless of the bo |
| E13* | Steam Boiler Temp Error — Please unplug the power cord immediately !!! Steam boiler pressure is above 2.0 bar for more than 10 s. No products availabl |
| E14* | Steam Boiler Heat Error — Please unplug the power cord immediately !!! Steam boiler heater switches off after a defined timeout regardless of the boil |
| E15 | Manometer disconnected — If the manometer is not connected. Coffee is still available, product dispensing with steam is blocked. |
| E16 | Fridge milk temperature too high — Temperature limit in refrigerator (parameter 6.41) exceeded and delay time (parameter 6.42) passed. Milk products b |
| E17* | NTC CF Boiler — Discontinuity of the CF boiler temperature sensor. |
| E18* | CF Boiler Heat Error — CF boiler heating switches off after a defined timeout. |
Transcribed from the Rex Royal error table supplied with the engineer documentation. Codes vary by software version.
Common parts
Common parts for the Rex Royal S300
The components most often replaced on this machine, listed by reference number, as a reference for engineers and owners identifying a part.
| Part no. | Description |
|---|---|
| #044731 | Rex S300 Sieve |
| #058417 | S200/S300 Pressure Gauge 0-4 Bar |
| #2102 | Parker 3 Way Grp Solenoid Valve 24v (Plus 3 housings in) |
| #2841 | Element Protection Thermostat - Original |
| #0398 | Lucifer 3 Way Grp Solenoid Valve 230v (Ruby) |
| #18281 | Parker 3 Way Solenoid Valve 24v |
| #0450 | PARKER 3 WAY GRP SOLENOID VALVE 230V (RUBY) |
| #23371 | PARKER 2 WAY INLET SOLENOID VALVE 230V |
| #29950 | PARKER 3 WAY SOLENOID VALVE 24V |
| #040170 | Rex Seal |
| #044987 | Tempreture Sensor |
| #047686 | Seal 46.2 X 38.6 X 4/4.1 |
Parts most often needed on this model
| Part | Number | What it fixes |
|---|---|---|
| Flowmeter armature cpl. S300 (2024) | 142023 | E3 flow error |
| Level sensor steam boiler STE | 140905 | E8/E9 fill and level faults |
| Safety valve 2.4 bar (Romer) | 058629 | Opens at 2.3 bar; 4-year replacement |
| Triac 25 A 200-800 V | 055812 | E13/E14 heating faults |
| Temperature sensor (coffee boiler STE) | 140878 | E1/E11/E12 temperature faults |
| Filling tube coffee/steam boiler STE | 142377 | E8 blocked filling line |
Questions
S300 questions, answered
How a boiler of this size is examined, how often, and who carries the duty — see the complete PSSR guide.
0208 037 9340
How much does a PSSR examination cost on a Rex Royal S300?
A standalone examination is £265 + VAT, because a single steam boiler with one set of protective devices to examine. Combined with a front-end service it is £585 + VAT, which is what most larger offices and hospitality sites running the machine hard choose, since the boiler has to be drained for the examination either way. The bundle on this range is higher than our standard ladder because its service parts are proprietary: a manufacturer service kit and an OEM safety valve cost several times the generic equivalents, and on some models there is no generic equivalent at all. We confirm the exact figure on the call.
How often does a Rex Royal S300 need examining?
The Written Scheme of Examination sets the interval, and for a commercial machine used in larger offices and hospitality sites running the machine hard it is typically 12 to 14 months. A single boiler on this duty normally sits at the middle of that range unless the water is hard, which we test on the day and report with the certificate.
How long does a Rex Royal S300 examination take, and what happens on the day?
The vessel is small and sealed, so there is no drain-down and refill to wait for. The time goes on getting to it, which is why the brew unit and panels come off. The visit runs: the steam boiler is located and examined. on a sealed stainless vessel the examination is external — wall thickness, corrosion at fittings, and the condition of every connection — with internal inspection by borescope only where the vessel design allows access. the safety valve, expansion valve, pressure sensor and thermal cut-outs are identified, checked and function tested. The gauge is then verified against our calibrated test gauge, the system is pressure tested and held, and the machine is re-assembled, refilled, heated and function tested. The Written Scheme of Examination, signed report and asset record follow within 48 hours.
Other Rex Royal machines covered
Call and we'll price your S300 on the spot.
Same-week appointments nationwide, the Written Scheme of Examination issued within 48 hours of the visit, and a fixed price agreed before we travel.