ESI - Energy Saving Innovation ControlsESRTE2 Electronic Room Thermostat

Last year I had a new Vaillant boiler fitted. A propriety programmable wireless room-stat was fitted which gave nothing but trouble as it kept losing connectivity and also the internal relay stopped switching properly. I tried a variety of other room-stats, none of which operated properly. So I installed a simple 2 wire mechanical room-stat, but it proved unreliable and needed a temperature variation of +/- 4 degrees before the contacts closed/opened - despite being a well known make, and it wasn't cheap.This ESI room-stat at £12 is a gem. It is a three wire device and internal electronics sense the temperature accurately and operate a relay that switches the control line to the boiler. A big bonus is the neon light that fires when the boiler is on. No more fumbling in the dark to figure out where the dial is set or listening for faint clicks to determine if it's on or off. Wiring is simple - mains power is connected to the Live and Neutral terminals and the 3rd terminal gives a switched 230v output to the boiler controller. You need to site the room-stat where mains power can be picked up but it's a small downside to having an accurate room-stat that will save power by not having a large temperature overshoot before turning the boiler off. Two wire room-stats (volt-less) are never going to be as good as an electronic unit because they depend on bi-metal strips to sense the temperature and an arrangement of spring strips to flip the contacts to open or closed.

Really good thermostat, easy as pie to install and works well.It’s a bit thicker than the Honeywell it replaced but unlike the branded one it works and was half the price.Currently connected to a boiler that I believe was taken from Noah’s Ark and doing well.I have a 3 wire set up (live, neutral, return), this product will not work with a 2 wire configuration.

This is a drop-in replacement for older, far less accurate electro-mechanical thermostats. The hardest part of the install was removing the old one. The ESI is a similar size, even has the mounting holes in the same place on the back and very easy to hook up with screw connectors. Works perfectly -- my old thermostat was way off in terms of temperature sensing and wouldn't kick off the heat until it was well above the target temperature. This one is far more accurate.

Cant add a comment as i had 2 send back wrong one ordered. But it looked like it was ok.

Good product, good price.

Terrible product, needs batteries 2 AA’s went to install the batteries and there are no battery terminals

Hysteresis is the same as thermostats that are decades old ... 1.5C or more. In this day and age, 0.5C should be taken as a standard. Indeed, making hysteresis an adjustable parameter would hardly be innovative as a fully programmable thermostat costing under £50 from a local supplier, has that feature and can be set to have different temperatures through the day and night. can be set to auto or manual and has a boost function at the touch of a button. So, this one is NOT value for money and is NOT even close to being of value in century 21 !!

Good