Do new central heating installations require a wireless thermostat?

I have found that when the thermostat hits the target temperature it tends to continue calling for heat before eventually going off, so I always have it set a bit low. I agree with Harry that its main advantage is choice of location to heat up the area where most people congregate (but don't do what I did and accidentally leave it in the airing cupboard next to the water cylinder!).

Vicario said:

I have found that when the thermostat hits the target temperature it tends to continue calling for heat before eventually going off

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You mention you've got a TR3, in which case might you be being misled by its TPI control and the flame symbol in particular? To elaborate further, the TPI control function of the TR3 emulates a proportional demand by varying the duty cycle of a call for heat. So, for example, from a cold start it'll signal a continuous call for heat to the boiler but once the measured temperature is within a degree or so of the target set point then it'll enter a proportional demand mode to minimise/eliminate overshoot. It can't do this by asking for a lower heat output (like it might with something like Opentherm) but can only do so by varying the on and off periods of demand. For example, if it determines that, say, required 20% of max heat output is required then it'll tell the receiver to call for heat for 2 minutes then remain off for 8 minutes and do this every 10 minute cycle (or whatever the cycle time has been set to). It is extremely effective in practice and results in a very smooth measurable control of temperature with minimal overshoot of the target and ripple once met - if you indpenedlty log the room temperature you can see how incredibly well it does it. What can cause confusion on Honeywell's TPI stats, thougn, is that the flame symbol on the transmitter remains lit whenever there is a non-zero demand signal set even if a demand for heat isn't being made for the majority of the cycle. So, even if the demand is 1 min on 19 mins off (5% demand signal) you'll get a flame appearing throughout. Similarly, even though the stat is showing the target temperature is met it'll still require occasional boiler firing to maintain it (due to the constant heat loss from the house) - it doesn't wait until the temperature drops below the target like a non-TPI stat would.

Do you have underfloor heating? If so *that* might be way you're getting an overshoot (assuming you are, or was it just unexpected boiler firing or flame symbol that you've witnessed?) as the thermal momentum is relatively high such that even when the demand is gone the heat continues to be emitted. The thermostat should learn the response rate and adjust it's control strategy to accommodate that though (that's the Integral portion of a TPI control strategy).

Thanks MJN, that explains what's happening quite well. One disadvantage of these stats is that they encourage fiddling with the settings instead of leaving things alone. I'll follow your advice and not get too stressed when it calls for heat after reaching the set temperature.