Your stove element now seems to have two settings: full heat or nothing. Turning the knob down makes no difference, or one zone of your ceramic cooktop has stopped heating while the rest work normally.
These are classic signs of a faulty cooktop simmerstat. Replacing one sounds simple, but many simmerstats look almost identical while being built for different elements, wiring layouts and appliances. Single and dual versions are not interchangeable, and choosing by appearance alone is one of the most common ordering mistakes.
This guide explains what a simmerstat does, the main types, the symptoms of a failed control and the details to check before you order from our range of oven switches and regulators.
What Does a Simmerstat Do on a Stove or Cooktop?
A simmerstat, also known as an energy regulator or infinite switch, controls how much heat a cooktop element produces. It sits directly behind the control knob for that element.
Instead of reducing the power, it switches the element on and off in cycles. On a low setting the element spends more time off than on. On high it stays on continuously. A faint clicking from the control panel during cooking is normal.
Simmerstats are often called oven simmerstats because on a freestanding stove the cooktop and oven are one appliance. In practice, they control the cooktop elements, whether on a freestanding stove or a separate built-in cooktop.
The oven temperature is managed by a separate oven thermostat. Note which knob the faulty control sits behind before you look for a part.
Single vs Dual Simmerstats: Which One Do You Need?
This is the most important thing to get right. The type of element decides which simmerstat you need.
Single Simmerstats
A single simmerstat controls one heating circuit. It is used with standard coil elements and single zone ceramic elements.
One of the most common single simmerstats on New Zealand stoves is the MP101 simmerstat. The version we sell is an original Robertshaw part used in many Fisher & Paykel, Westinghouse, Simpson and Electrolux freestanding stoves.
It replaces part numbers 532008P (Fisher & Paykel), 0534001654 and SM215K. It is rated at 15 amps, has a 6mm D-shaped shaft and includes a switch for the pilot lamp.
Dual Simmerstats
A dual simmerstat controls a dual zone element, which has a smaller inner zone and a larger outer ring. It lets you heat just the centre for small pans or bring in the outer ring for larger ones.
The MDP110 dual simmerstat is widely used on dual zone ceramic elements in Fisher & Paykel, Simpson, Westinghouse and Haier freestanding stoves and cooktops. It replaces part numbers including 532009P (Fisher & Paykel) and 0534001720.
The MDP110 is not suitable for single elements or solid hotplates. In the same way, an MP101 cannot run both zones of a dual element. If your cooktop has a mix of single and dual zone elements, it may use both types, so check the control behind the specific element that has failed.
Other Simmerstat Types
Not every appliance uses an MP101 or MDP110. Brands such as Smeg, Bosch, Ilve, Parmco and Omega often use E.G.O or other regulators, which can differ in shaft length, terminal layout, mounting and switching pattern.
Some Fisher & Paykel cooktops use a different single regulator (part number 544513P), and Bosch, Smeg and Siemens have their own dual regulators for dual elements and grills. These are less common, so the original part number on the old control matters even more.
What Are the Signs of a Faulty Simmerstat?
The most common symptoms include:
- The element stays on high regardless of the knob position
- The element does not heat at all
- One zone of a dual element no longer works
- The element will not hold a low or simmer setting
- The indicator light no longer behaves as it should
Scorch marks, melted terminals or a burning smell from behind the control panel should always be checked by a technician before the appliance is used again.
Check the Element First
A failed element can cause the same symptoms as a failed simmerstat, particularly when the element does not heat at all. Before replacing the control, have the element's resistance tested. The wiring and connector block can also be at fault.
If the element runs on full heat no matter where the knob is set, the simmerstat is a more likely cause.
How Do You Find the Right Replacement Simmerstat?
Start with the appliance rather than the part. The model label on a freestanding stove or cooktop is usually found under the cooktop or behind the oven. Our guide to finding your appliance model number covers other common locations.
Record the model number exactly as printed, including every letter, number and suffix. A clear photo of the rating label avoids transcription errors and is useful if you need to contact us.
Before ordering, gather:
- Appliance brand and full model number
- The part number printed on the old simmerstat, such as MP101, MDP110, 532008P or 532009P
- Whether the element is single or dual zone
- The shaft shape and length
- The number and position of terminals
- How the control is mounted, for example with screws or a nut behind the knob
Why Looking Similar Doesn't Mean It Will Fit
Many simmerstats share a similar body, so it is easy to assume they are interchangeable. Small differences in terminals, shaft, pilot switch and internal cycling mean a lookalike part may not fit, may not wire in correctly, or may not control the element properly.
The safest approach is to match the original part number or confirm your model number is listed as compatible. Our MP101 and MDP110 product pages list interchangeable part numbers and compatible models, and include a search box where you can type your model number to check the description.
This matters for another reason too. Home Appliances Online does not accept returns on electrical products, so confirming compatibility before you order saves time and cost.
Can You Replace a Simmerstat Yourself?
A simmerstat connects directly to mains-voltage wiring behind the control panel, and wiring can vary between models or where a different control has been fitted previously. We recommend having it installed by a qualified appliance technician or electrician.
If you are arranging a repair, ordering the correct part first can save a second call-out. Always make sure the appliance is isolated from the power before any panel is removed.
What If the Part Number Is Missing or Worn Off?
Older simmerstats often have faded or heat-damaged labels. In that case, rely on the appliance model number instead, and note whether the failed element is single or dual zone.
If you are still unsure, email us your model number with photos of the rating label and the old control, including the terminals. We can help confirm the correct replacement.
Where to Buy a Replacement Stove or Cooktop Simmerstat
Home Appliances Online stocks the MP101 single simmerstat and the MDP110 dual simmerstat, along with a wider range of energy regulators and switches for brands including Fisher & Paykel, Westinghouse, Simpson, Electrolux, Haier, Smeg, Bosch, Parmco and Delonghi.
You can search our site by appliance model number or original part number to narrow down the right part, and orders can be shipped nationwide or collected from our Albany, Auckland warehouse.
Browse our oven switches and regulators to find the right simmerstat for your stove or cooktop.