New froststat clicking/lighting up but no response from boiler

[Ron S]

are you referring to the Honeywell or the Greenbrook? Can I just clarify. I am using the Greenbrook now.

 

[Ron S]

Presme the NTC will be bypassed if 4 is not wired. What will the consequence of this be?

 

[Taylortwocities]

Presme the NTC will be bypassed if 4 is not wired. What will the consequence of this be?

The NTC is an....

accelerator to limit hysteresis, so not hugely important.

It means that the stat will not be quite so inaccurate as it would otherwise be. But its not a big concern for what you are trying to do.

 

[Ron S]

I tested the blue with electrician scredriver...it's the switchable live. So I will move this from 4 to 3 in the GREENBROOK. Pls let me know if this is not right, or even right??!! Thank you.

 

[Ron S]

it will not be quite so "inaccurate"? So if it is more accurate now (term 3) does this mean froststat will stay activated for longer? (One of the things I was trying to avoid...)

 

[Ron S]

is it feasible to add a neutral to term 4? In that case do I cap off the switchable live?? Where would the neutral be wired to...presumably into the boiler switch?

 

[RandomGrinch]

is it feasible to add a neutral to term 4?

Given this thread is getting on for four pages, for what is basically a simple two wire switch replacement - I would stick to what we have already suggested many times

Instead of using terminals one and four, you need to use one and three.

 

[Ron S]

Thanks I am learning. If poss I would like the light and hysteresis accelerator so will look into fitting a neutral. You didn't say where the switchanble live would go in that case, so I assume it is capped off. Thank you.

 

[Taylortwocities]

You didn't say where the switchanble live would go in that case, so I assume it is capped off.

Yawn.....
For the thermostat to work it needs a permanent live and a switched live (call for heat). If you bring a neutral in for your light then you still need both of the existing connections. The neutral is an ADDITION, not an alternative.
IF you connect an neutral to the thermostat, it MUST come from the same power source as the rest of the boiler/heating system voltage supply.

I really suggest that, at least for now, that you stop worrying about the light and the NTC. Get the thermostat at least working basically - does not need a neutral for its basic function - you can add the cosmetic light function at a later date.

 

[Ron S]

Sorry this is a yawn for you - it is far from it for those like me with less expertise. And I very much appreciate the expertise you are imparting. I have basic skills but keen to learn, hence asking these questions. My old froststat has been on the blink for ages so I am really keen to sort this properly. I will leave off the neutral idea for now though like the idea of the hysteresis system I will be losing.

(Greenbrook instructions do not mention the switchable live hence the query of where that would go. I'll assume for now it would remain in t3).

Thank you for your very kind attention this afternoon. It's much appreciated!

 

[Deleted member 267285]

Thanks I am learning.

Then learn this...

I tested the blue with electrician scredriver...

Only use suitable test equipment such as a multimeter or 2 pole voltage indicator.

 

[Ron S]

Thank you, again I am learning and have seen that it is said best to use other equipment. My circuit test screwdriver is certified for use up to 250 volts and I am trying to understand what the potential dangers of using this on a live would be...I am v wary. May I ask for your expertise as to what the danger is of using this 250 V electrician screwdriver on a live wire actually is? Assuming all standard precautions are met. Thank you very much.

 

[Taylortwocities]

Opinions on this vary - especially on this forum -
There is one very informed bloke @flameport who has made an excellent video about these neon screwdrivers. It’s here, judge for yourself.

Neon Screwdriver Mains Testing Device

A poor quality screwdriver item with a neon lamp in the handle, intended to check whether an item is live or not

flameport.com

 

[Ron S]

Thank you, I am v careful with mine but take all this on board!!

 

[Taylortwocities]

The main issue with those type of voltage testers is that you can only test for the presence (or lack) of a live conductor.
For an electric device to work you also need a neutral and those (and the no contact wands) screwdrivers wont tell you that.

They are ok as a quick voltage on or off indication, given their limitations as Flameport has outlined, but they dont help in fault finding. Thats when a two-probe test device is necessary.