I've seen one of these in B&Q for £29.98 when I was looking at getting a
digital thermostat. From what I can find on Sunvic's website, the list
price is £40+

It appears to do 7 day programming (rather than 5/2), with 6
periods/programs for each day.

This seems to do everything I need it to, however it also mentions it can
replace a programmer (as well as doing a job of a thermostat). I take it
that you could use it as a very basic programmer if you wanted.

I just want to replace my normal analogue twiddly knob thermostat which goes
to an old Baxi wall mounted boiler with an oldish digital programmer (EP2001
I think).

I've seen some thermostats/programmers which talk about 'volt free'
contacts. Are these low voltage contacts as opposed to mains fed ones?

Basically, is the Sunvic TLX6501 going to do the job I want (7 days, 6
periods per day) with my programmer etc. It looks like it just takes a L/N
connection, and is suitable for up to 6A (which my current one has 6(2.5)A
stamped on it). I think its suitable.

Thanks

D

BTW - I've downloaded the manuals from the Sunvic website - and I'm looking
through them now.

David Hearn wrote:
I've seen one of these in B&Q for £29.98 when I was looking at
getting a digital thermostat. From what I can find on Sunvic's
website, the list price is £40+

It appears to do 7 day programming (rather than 5/2), with 6
periods/programs for each day.

This seems to do everything I need it to, however it also mentions it
can replace a programmer (as well as doing a job of a thermostat). I
take it that you could use it as a very basic programmer if you
wanted.

I just want to replace my normal analogue twiddly knob thermostat
which goes to an old Baxi wall mounted boiler with an oldish digital
programmer (EP2001 I think).

I've seen some thermostats/programmers which talk about 'volt free'
contacts. Are these low voltage contacts as opposed to mains fed
ones?

Basically, is the Sunvic TLX6501 going to do the job I want (7 days, 6
periods per day) with my programmer etc. It looks like it just takes
a L/N connection, and is suitable for up to 6A (which my current one
has 6(2.5)A stamped on it). I think its suitable.

Volt free just means the contacts are not connected to anything as in the
old bi-metal thermostats.
They will switch mains.
This kind of programmer is good with a combi boiler.
However, if your current programmer is also timing your hot water you will
need to retain that and jumper out the CH connections to it or merely switch
it so the CH is on constantly.

I bought a Sunvic one recently. Search www.google.com/groups for
+"programmable thermostat" +sunvic (on 6th October).

It seems similar, but the one you propose operates in a slightly more
sophisticated fashion. Yours allows ten minute intervals (instead of hourly)
and 3 temperature points instead of 2. It also has an extra hour boost.
Unfortunately, it isn't anywhere near as pretty or low profile, which was my
main feature requirement. I can't seem to find mine on the Sunvic website.

Basically, is the Sunvic TLX6501 going to do the job I want (7 days, 6
periods per day) with my programmer etc. It looks like it just takes a L/N
connection, and is suitable for up to 6A (which my current one has 6(2.5)A
stamped on it). I think its suitable.

Yes. It replaces the wall thermostat and has the correct contacts to do so.
It won't take L/N connection. It is a simple switch and in a typical control
system will be Live/Switched live at 230VAC. The "Live" will be connected to
the "CH On" output from your main programmer. The "Switched Live" will drive
your zone valve, which turns on the boiler.

You set your old wall programmer to run 24 hours a day. If you can't do this
without setting the water 24 hours a day, you'll either have to replace it,
rewire it (connect the "CH On" to permanent live instead of the programmer)
or heat your water 24 hours a day too.

Christian.

P.S.

When wiring it, you may find there are three wires to the thermostat. They
are live (at least when the wall programmer says CH on), neutral and
switched live. The neutral is used by old thermostats to run a little
heating element to provide hysterysis. It is no longer required. Almost all
modern thermostats are battery powered and don't require the neutral.

Typically flex is used and naughtily, the colours often found a

Blue - Neutral
Brown - CH on (i.e. permanent live)
Yellow/Green - switched live (not earth, bad boys!)

You should take care to note where the cable was connected and then
experiment with the old thermostat and a continuity testing to determine if
the contacts operate the way you expected. Consider rewiring by using brown
and blue (wrapped with brown tape) and rewiring at the wiring centre to
reflect the new colour uses. (The green/yellow should then be earthed at the
wiring centre and capped off at the thermostat).

Christian.