Can I have a Smart TRV without a Smart thermostat controller?

gord115

We Have a combi boiler with a standard( ie not smart) wireless thermostat/timer programmer.
We only use the living room in the evenings and heating it seems a waste of money and the standard TRV is a bit awkward to get to.
I want to know if I can get a smart TRV that works with Alexa so I can turn the radiator on  and off as required using voice control.
Is this possible or do I have to completely upgrade all my system to Smart control?
Thanks in advance.

getmore4less

It will be possible but if you do it in isolation it may not achieve what you want.

you may have an issue if you are still heating the rest/part of the property on the timer/ thermostat as that will be controlling the boiler and if up to temp turning on te radiator in the living room will do nothing.

to get round  that you will nee to link into the call for heat but that will just over heat the rest of the house so back to individual controls(TVR) for those areas.

gord115

I will only want heating in the living room when the rest of the heating is on,not on it's own.
I will never want the living room warm and the rest of the house cool.
Is that what you mean?

getmore4less

Your house is warm because you have been using it and had the heating on.

In the evening you go to your living room

Your living room is cold because you have not been using it and had the radiator turned off.

"Alexa turn on radiator"

Nothing happens because the house thermostat is already happy the house is warm enough

You could take the house thermostat into the room as well and just use the TVR as an on/off

gord115

Thanks everyone.
I will get one ordered.

olbas_oil

I have the same query, but I don't think I've understood the responses. I have a Nest + Alexa, which does a good job in heating the whole house. But I have some rarely used rooms, which I don't want to heat that often. If there was a smart valve (doesn't need the Thermostat really) then I could set this to always turn off every night by timer (in case I've forgotten to switch it off) and come on only when I say 'Alexa, please heat up the rarely used room'. It wouldn't need to call for heat, because I'm assuming the system is already pumping heat round.
OP what have you ordered? 

bobfredbob

The problem with TRVs without a call for heat is that the room with the smart TRV may be cold and not heat up properly unless the main room's thermostat is on a while at the correct times when you want to heat the other rooms.

For example, today, my living room heating was last on at 5pm and the room kept the heat so didn't come on again.  Now, if we have a smart TRV in the bedroom and say "at 9pm I want it 20C", it won't actually get any heat at all since the living room heat isn't on and isn't circulating any heat.  Even if the living room heat does come on, it may not be on long enough to heat up the bedroom, since the living room would lose little heat so boiler may only be on for five minutes to top it up.

So, the bedroom is whatever temperature it happened to get to during the day through sunlight.

By contrast, some systems like Evohome have "call for heat", so the bedroom says "I want heat" and will fire up the boiler until it is at the correct temperature.

Given that many new Alexa devices have thermometers and Zigbee for talking to devices (a bit similar to Bluetooth), I'm hoping Amazon may bring out their own TRV/boiler controller...