How do I find out what type of thermostat I have

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Lisa85

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I currently have underflooring heating, however the individual room thermostats are very old and have the bimetal side dial feature. I am wanting to see if it's possible to upgrade the thermostats to a more mordern, digital one. Although, I'm not sure the model of the exisiting thermostats. All I know is they are Sunvic.
Can anyone help at all?
 

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Cannot tell from the picture but if it only has 2 wires then any 2 wire stat will do the job, however most with displays will require a Neutral wire which you may not have,
A black wire is not always a N wire, if you only have 2 wires.
 
JohnW2 said:
In fact, in the context of a thermostat, "A black wire (or any other colour wire) is never a N wire, if you only have 2 wires".

Kind Regards, John
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Thats a bold statement , what about some of these new fangled stats that only need a L and N supply and the switching done by RF
 
333rocky333 said:
Thats a bold statement , what about some of these new fangled stats that only need a L and N supply and the switching done by RF
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:)

I thought it would be obvious, but perhaps, instead of writing "... in the context of a thermostat ...", I should have anticipated comments like yours and written something like "... in the context of the wiring of a thermostat as old as that one ..." :)

I was merely trying to clarify things for the OP - i.e. given the age of that thermostat (and hence its wiring), IF there are only two wires, there's no way that either of them could/would be a neutral.

[ in passing, as for "new fangled stats that only need a L and N supply and the switching done by RF", do such things actually exist? Battery-powered with wireless switching I could understand, as could I understand mains-powered with wired switching, but you are talking about a mixture. I suppose it would make sense for situations in which people wanted a 'clever' (with electronics and/or display) mains-powered thermostat (hence needing L+N), but wanting to use existing 2-core wiring - but I can't say I've seen one (yet) ! ]

Kind Regards, John
 
If it’s 2 wire and you want digital then a battery operated one would work. If you wanted a smart thermostat such as nest, hive, etc then these need permanent live and permanent neutral plus switching, and if you wanted like for like, you would need one in each room.
 
Nest E (the cheaper white one) uses a battery powered module designed to replace the "traditional" 2 wire room stat, then the actual display/sensor is wireless with USB power.

The standard Nest however uses a "heat link" module which requires L/N as well as whatever switching signals are required.
 
Just so you’re not confused Lisa, the Nest e does use batteries, it also uses 2 wires (switch).
 
Nest e is about the only wifi enabled thermostat that is not direct mains powered, I say direct as the base is battery powered but the thermostat is USB powered and the USB power likely comes from the mains.

This
2923G_P
Flowmasta 24701SX is battery powered straight thermostat at £23.14 and this
6259G_P
Flowmasta 22199SX is the programmable version at £27.56 I have used the latter, not as easy to alter temperature as the one it replaced, but does a reasonable job, seem to remember 6 temperature chances per day possible.

Personally I prefer the analogue dial of the Nest
9382X_P
easy to work, just turn outer dial, however you say under floor heating and not if water or electric and if electric which type, many electric under floor heating systems need a sensor in the floor so it can't over heat.

I am not sure how exactly they work, I know general idea is hot water is added to the circulating water to maintain it at 27°C until the room is warm enough, but controlling without hysteresis needs cleaver algorithms, I know Nest Gen 3 has the ability to be set for underfloor heating, however not a clue about the others.

I have looked at the opposite to under floor heating with fan assisted radiators, i.e. very fast warm up and cool down times. I know many early systems the under floor heating was back ground only and a radiator did the fine tuning of temperature.
 
Thank you Eric. I was actually looking at the Nest analogue dial.
I have electric underfloor heating. I'm not entirely sure which type though. I'm new to the property, I've just recently moved.
 
Lisa85 said:
I have electric underfloor heating.
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Most thermostats available will NOT be suitable for that.

Those old Satchwell and Sunvic things typically switched 16 amps, which is the full load of the eectric heating for that particular zone.
Most modern thermostats can only deal with 2 or 3 amps at most.
 
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