Another room thermostat wiring query

[StuB78]

Hi all

Firstly my apologies for asking a question which has roba my been answered a million times, however when trying to find an answer that relates to yours, all the different wire colours start to blend together lol.

I am replacing the old dial room thermostat for a digital wireless jobbie so I can move stat downstairs to regulate the heating system better.

Could someone please confirm which wires go into the new positions, and also which wiring diagram to follow, the 230v application, or wiring to the external thermostat loop of a boiler.....

Thanks in advance all

 

[StuB78]

Is this right? Trying to get my head around this

 

[ianmcd]

nope you are miles off, start by saying what your existing Set up is and what you want to replace it with and @stem will tell you what to do

 

[ericmark]

Leave link in place L to L, N to N and 3 to SL normally open or heat on.
Looks like a Horstmann HRFS1 which I fitted in this house, I found over time the RF lost sensitivity and when it failed it did not fail safe but continued to heat, and if it missed when the thermostat sent message to switch, it did not seem to repeat so I found mother both sitting in a room at 16°C and 26°C when thermostat failed.

Not being willing to through good money after bad, I moved to using an electronic TRV head instead, in hind sight realised did not need wifi and the Terrier i30 would have likely done the same job but cheaper, but the Energenie MiHome have worked well keeping the rooms at the set temperatures.

I had originally a Honeywell Y6630D and thought at £126 these were over priced, however when the Horstmann HRFS1 failed I realised it was worth the money to have a thermostat which fails safe and has built in anti-hysteresis software. If possible I would use non wireless types, I used a Flomasta 22199SX in the other house and at £35 worked A1, but if your going wireless learn from my error and use a good quality one.

 

[StuB78]

Sorry, yes it's as Eric says the Horstmann HRFS1, to replace an old Honeywell dial stat.
I read it had great reviews, but to be fair only needs to last a couple of years when we'll replace the system with a combi and new ancillaries etc

So my sketch is right with the exception of adding the neutral into the neutral then?

I read that neutral wasn't needed....but seems strange if there's a slot there for it

Thanks again in advance

 

[Madrab]

You need the Neutral connected. Use the 230V diagram. It needs the N + L to power the stat. It then uses the link wire to send the Live down to the stat's Live to power the stat, without the Neutral the stat won't power up. When calling for heat it switches the L (switched live) on the top over to the black wire sending the power to the boiler.

 

[stem]

nope you are miles off, start by saying what your existing Set up is and what you want to replace it with and @stem will tell you what to do

I can't tell what colour the existing wire in terminal 3 is, so I've shown it black.

 

[StuB78]

Perfect, thank you both for your comprehensive replies. I will fit this tonight now thank you.

 

[StuB78]

And terminal 3 is black with a yellow stripe running through it

 

[stem]

OK thanks. I should have gone to spec savers

 

[StuB78]

Haha no worries...appreciate your help hugely

 

[Madrab]

@StuB78 - the live from the wall wiring goes to (L in) - not into the L terminal at the bottom - This is to stop the link wire from being overloaded in case the live draw to the boiler exceeds the link wire capacity..- It specifically mentions that in the 230V instructions!!

The brown live from the wall wiring goes to the L in at the top - the link wire then sends current to the bottom L terminal to power the stat
The blue goes to the N terminal at the bottom for the stat
The black wire will go into SL (on) to go to the boiler

 

[stem]

In the UK, the boiler's fused spur will have a 3A fuse fitted, so there's no chance of overloading the link. It's probably thicker than the black supply wire that will be going to it anyway. @StuB78, if you want to wire the black wire to 'Lin' instead of 'L' as Madrab says, then that's fine. From an electrical circuit point of view, as both terminals are connected together anyway it's the same thing.

 

[Madrab]

Wasn't a ping at the advice @stem, should have pointed that out ... apologies ... certainly agree that the link should easily take the current across it, it's more a point of if there's any issues and/or there isn't a 3A fuse in there ..... as long as the MI has been followed ..... then it sits with them.

 

[telnet]

It needs the N + L to power the stat.

I replaced a 50 year old Honeywell with a new Honeywell and the internal mechanism is identical. If it 'aint broke don't fix it.

I was surprised that the stat needed to be powered until I saw that it had a little resistor that generates heat to keep air flowing through the casing so that the stat can quickly respond to a change in air temperature. Interesting that the build everything from domestic stats to nuclear power stations.