Fitting a wireless room thermostat

[Rogeranerley]

I want to change to a wireless stat as the present hard wired one has failed as well as proving not to be in the best location.

The one I'm homing in on is Horstmann's HRFS1. This is not badly priced at £60 and allows daily settings as well as working in 0.5 degrees.

Where I'm uncertain is the mention in the installation sheet of either '230V APPLICATION' or 'VOLT FREE APPLICATION'

As my present circuitry runs from the mains I assume terminal connection to the unit should be based on the '230V APPLICATION' one. The installation sheet is at http://www.horstmann.co.uk/download...ermoStats/RF Programmable Room Thermostat.pdf

If '230V APPLICATION' is correct , am I right in concluding that the 'SL ON' terminal is the switch wire to the valve?

I'd also be grateful for any comments on the CH wiring as I originally set my S plan system up using Sunvac valves which had a switch wire to turn off on 'satisfaction' and had a neataheat boiler. Since then, a local fitter has installed Honeywell V4043H, 'non-sat' requiring valves when a megaflo was installed, followed by a Baxi Solo HE boiler a few years later.

I also have the original 25 year old Drayton Tempus seven programmer which is still in good running order. As a result, if I install the Horstmann stat, I envisage the CH wiring as follows:

The mains Live on the Tempus Seven L terminal feeds to terminal 4 when time called.

This switches through to the HRFS1 mains feed L terminal, which switches through to the SL ON terminal when temp called.

This then feeds to the 4043H's Brown flex, which then opens the live feed from the programmer through to the Grey flex which switches the live feed to the Boiler's L terminal via the valve’s Orange flex.

Meanwhile, the programmer's mains Neutral connects to HRFS1 N terminal, 4043H Blue flex & Baxi N terminal…… with Earth (G/Y) from all 3 units running back to mains. The old Tempus is double insulated, requiring no earth.

From what I can see, this circuitry mimics the hot water configuration.

Grateful for any guidance on where I'm right...and where I might be going wrong.

Thanks

 

[D_Hailsham]

Where I'm uncertain is the mention in the installation sheet of either '230V APPLICATION' or 'VOLT FREE APPLICATION'

Yes, you use the 230V wiring; but the way you suggest is not quite right.

The receiver needs a permanent supply to the L terminal, not a timed one. However, this is easily done.

Connect the CH output of the Drayton Tempus (terminal 4) to the L terminal of the receiver (as you say) but set the Tempus 7 to CH permanently on. The Horstmann will then control CH time and temperature.

The Horstmann SL terminal connects to the Valve brown wire.

Neutral and earth connect as you say.

 

[Rogeranerley]

Many thanks for your swift guidance, D_Hailsham.

If I've understood correctly, based on my intended circuitry, I now only need to leave the Tempus CH side on constant to achieve a perminant live feed to the Honeywell valve. Ironically, this was the manner in which I deployed the now defunct Smiths electronic stat which also controlled time as well as temp.

Thanks again

 

[D_Hailsham]

If I've understood correctly, based on my intended circuitry, I now only need to leave the Tempus CH side on constant to achieve a permanent live feed to the Honeywell valve.

That's correct. However, if you want to make sure nothing will happen if someone 'accidentally' changes the Tempus to timed heating, move the wire in Tempus T4 to the Tempus Live terminal.

 

[Rogeranerley]

Thanks again, D_Hailsham, switching Tempus 4 line to L.

All now functioning well; however, had a problem initiating RF despite using all channels. Eventially fired up . Not sure of the reason. I made several replicated changes to the DIP settings, ensuring to press the reset each time. The only difference on final success appeared to be having the receiver already switched on before undertaking any DIP or 1st stage clock/day settings.