Pub Glasswasher Not Heating Up: What to Check Before Calling an Engineer
A cold rinse cycle is one of those problems that brings everything to a halt fast. Glasses come out smeared, cloudy, and technically unfit for service. I’ve been through this at Teal Farm more than once, and the first thing I learned is that a call-out fee lands whether the engineer fixes something major or just resets a tripped breaker you could have found yourself.
Here’s what to work through before you pick up the phone.
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1. Check the Power Supply First
Before anything else, go to your consumer unit. A glasswasher drawing full load on a heating cycle will trip a circuit breaker if there’s any underlying fault or surge. Reset it, run a short cycle, and watch whether it trips again immediately. If it holds, you may have had a one-off spike. If it trips again within minutes, stop there — that’s an engineer job.
Also check the machine’s own isolator switch and the plug connection if it’s a plug-in undercounter unit. Sounds obvious, but after a busy Saturday service things get knocked.
2. Test the Thermostat
Most commercial glasswashers have a wash thermostat and a separate rinse thermostat. The wash tank should hit around 55–60°C and the final rinse should reach 82–85°C to achieve proper sanitisation. If you have a temperature display on the machine, watch what it actually gets to during a cycle.
A faulty thermostat will either cut the heating element too early or fail to signal it at all. Some machines have a manual reset button on the thermostat itself — usually a small rubber-tipped button behind a panel or on the element housing. Press it. Genuinely, this fixes the problem a reasonable percentage of the time after a thermal trip, and it costs you nothing.
3. Inspect the Element for Limescale
Washington sits in a moderately hard water area, and limescale on the heating element is the single most common reason a glasswasher stops heating properly over time. Heavy scale build-up acts as an insulator and forces the element to work harder until it either trips or burns out entirely.
Pull the wash tank basket out and look at the element at the base of the tank. A healthy element is largely clean metal. A failing one will have thick white or grey crust around it.
If it’s moderate scale, a proper descale cycle with a quality commercial descaler can recover it. I run a full descale on our Winterhalter every two weeks without fail.
If the crust is extreme or the element looks visibly cracked or corroded, it needs replacing. A replacement heating element for most undercounter glasswashers costs between £30–£80 if you source it yourself — [search for your machine’s element on Amazon here](https://amzn.to/4ukKRuU — though fitting it means working with live electrical components inside the machine, which most operators will rightly leave to an engineer.
4. The Drain Pump Rule
I mention this in every glasswasher article because it catches people out: if your drain pump is partially blocked or failing, the machine may not complete cycles correctly, which can mask itself as a heating fault. Before you conclude it’s the element or thermostat, check the drain is clearing properly between cycles. A slow drain backs up dirty water into the wash cycle and the temperature readings go wrong.
5. When to Call the Engineer
Call immediately if the circuit breaker keeps tripping, if you can see burn marks near the element housing, or if the machine is making new noises alongside the heating fault. DIY descaling and thermostat resets are reasonable. Anything involving internal wiring is not.
A glasswasher not hitting sanitisation temperature is also a food hygiene issue, not just an operational inconvenience. At Teal Farm we hold 5-star EHO status and an NSF audit pass — cold glass cycles are a risk we simply don’t carry.
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