I wish to replace my simple thermostat with a single channel central heating controller. First, look on toolstation as always: This seems to have the main features I would need, but programming looks a bit of a fiddle (its a Sunvic SunPro 1000):
What it obviously does not have is different thermostat temperatures for the different ON periods - do any of them ?
Any recommendations ?
Thanks, Simon.
For that you need a programmable thermostat, rather than a programmer and a separate thermostat, e.g.
One review (for the 2 channel version) seemed to suggest that the first ON time could not be set before 6.30am - surely that cannot be possible?
Simon.
Do you want to go the whole hog for something fancy and remote controllable - eg NEST, HeatGenius etc? The latter certainly allows as many temperature/time profiles as you like. I think the NEST does too.
Both are a straight swap for a roomstat as long as you have a neutral present.
(thats the Sunvic SunStat Room Thermostat Wired). That looks fine, has the right level of functionality, Even has adaptive control (TPI) which I might switch off. Only thing is it appears to only take batteries. I wonder how long the batteries last. I suppose a battery box adapter (for an external power supply) may be available, or I can make one !.
Simon.
I don't think so, just a wired one with 3 or 4 on periods per day would be fine.
Simon.
Must admit I hadn't noticed the batteries, my old programmer took 4xAA and lasted ages, you could keep an eye for the LCD 'fading' before they went totally flat.
for the different ON periods - do any of them ?
control (TPI) which I might switch off. Only thing is it appears to only ta ke batteries. I wonder how long the batteries last.
ilable, or I can make one !.
Oh, the manuals are poor in this aspect, but there appears to be mains conn ectivity, since it says that if batteries need to be replaced, the mains po wer must be isolated before the unit is removed from the back plate. I supp ose the battery is advised to retain the settings if you remove it from the back plate in order to change the battery ... er, hold on ...
Simon.
Its got a battery level indicator. Simon.
There could be mains since it is switching supply to the boiler
There may be that mode of operation. I need the simple thermostat mode, which they seem to refer to as "volt free" switching. Simon.
Following this thread I am not really clear on what the existing boiler control set up is. If it is a simple hall thermostat, then this frequently will only control the pump, with a separate controller for boiler on/off cycles and/or another separate controller for boiler temperature. If you wish to simply replace the hall thermostat, then the Horstmann HRT 4A From Amazon) is about the only unit which runs without batteries and which has optional TPI(guesswork?)control. My experience of this unit is excellent, using TPI temperature control has never been so good. If you are looking for a programmable thermostat, then IME you can have anything you like provided it is battery powered. I'm sure there are some mains powered units out there, but many have batteries for display back up and it is not easy to spot them from the data. Battery powered electronic thermostats using latching relays have IMO a poor reputation, with many users reporting poor battery life. YMMV. The question is, will a programmable thermostat suit your boiler control system without rewiring?
An important feature to consider is how the wiring will work.
So I would ask:
replaced, the
That'll be it, boiler pumps valve etc generally operate with mains voltages. If you don't isolate the heating system there will almost certainly be one terminal with mains on it.
"volt free" switching just means that the switches used for boiler/pump/why control are isolated from the rest of the unit.
i.e. provide your own volts, which will generally be mains for C/H
I used a wired programmable stat for many years. The batteries tended to last about 2 years. If battery life is a concern, then can you afford heating? I would suggest buying good batteries as cheap ones tend to self discharge more.
ating controller. First, look on toolstation as always:
s a bit of a fiddle (its a Sunvic SunPro 1000):
r the different ON periods - do any of them ?
Sorry, I did not describe the heating system. It is just a Vaillant Turboma x combi boiler, and a single zone - no extra valves, etc. Hall electromecha nical unpowered thermostat - just a switch. Two connected wires from boiler - whatever voltage is on there comes from tbe boiler.
If the battery life is short, a couple of AAA to AA battery adapter shells will get the terminals out to an external power supply. However, battery is supposed to last 2 years.
Simon.
Well its not the cost obviously, just the inconvenience. I've now got a Sunstat unit, and it has a battery life indicator so should be OK. Simon.
There are many battery operated thermostats, presumably because they are easier to install. I am not a fan of such devices myself as there is always the problem of the battery going flat, maybe in the winter when you have gone away, and you need the CH to work at a low setting to stop pipes freezing. I replaced my original mechanical thermostat and programmer with a Danfoss TP9 which uses a remote sensor where the mechanical thermostat was. Possibly the best improvement I made to my CH system. The first one I got was replaced after a couple of months under warranty. Its successor is now more than 10 years old.
When I installed a programmable thermostat, I put a programmable thermostat that uses a remote sensor next to the boiler and then put the sensor where the existing thermostat is. The programmable thermostat is mains powered.
Two wires to the existing thermostat were used to connect the sensor.
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