Can you recommend a good wireless thermostat?

Jeepers_Creepers

ritesh said:

Thank you for all the replies.
It is a new refurbished 1 bed flat with radiator in living room, hallway, bedroom and towel rad in bathroom. The new Vaillant ecotec combi boiler has a timer unit. All rads have TRV (except towel rad) and are set to 3. The mechanical dial thermostat had an issue so replaced with a digital honeywell DT90E. It measures the temperature as 21c, but the boiler sounds like it is always on and the flat is very warm. The electrician has checked the wiring and all seems fine. So really confused and therefore decided to replace with a wireless unit.

The flat is rented to an elderly lady so it needs to be the simplest of wireless thermostats to use and reliable as well, just to control the temperature of the flat as the boiler has a timer module on it anyway.

There is no wifi in the flat even though infrastructure is there as she does not want it, so needs to rely on wireless radio thermostat.

In that case I'd suggest you really want a simple 'dial' thermostat, something that takes care of the temp only, and that the occupant will already be familiar with.

I don't know why your boiler keeps on running and the flat appears warmer than 21oC (but there's a few things we can check), but I would definitely say the solution is not to go 'wireless'.

Wireless systems are used when you cannot run wires. Simple as that. Wires will always be more reliable than wireless, and also won't require batteries to be changed every year or so. 'Wireless' offers nothing over 'wired', except ease of installation if you cannot run wires in the first place! (Ok, I guess it also means the 'stat can be moved about, but few folk want or need that).

So, forget wireless, please :-)

The timings are taken care off by the boiler's timer, so I think you just want an analogue 'dial' thermostat with a large dial and clear temp markings. They all have that? Look again - some are the pits, I tell you... Perhaps one other addition - indicator lights to show when it's 'calling' for heat, and when desired temp has been achieved - the occupant might find that reassuring?

That SHOULD sort the issue - if your sparky knows what they are doing.

Ok, why is the boiler running all the time? A few possibilities:

1) The sparky is an idiot and hasn't wired the room stat properly - the boiler is 'on' all the time the timer says 'on', and the room stat has no effect. All that controls the temp are the rad's TRVs. How to check? Turn the room stat up and down, above and below the room temp - does it 'click'? Does it turn the boiler on and off (give the boiler a good 30 seconds to respond)?

2) The room stat is in the wrong place. Eg: the room with the room stat also has a rad with a TRV (set at '3'). It shouldn't have. The room with the 'stat should have a rad that's manually 'on', and doesn't have a TRV or anyone controlling it. That rad then heats the room with only the 'stat sensing the room temp, and controlling the boiler accordingly. If, instead, the room with the 'stat also has a rad with a TRV, then both the TRV and the 'stat will be monitoring the room's temp and acting independently, each one trying to tell the temp what to do, and ignoring the other. Ie: the 'stat calls for heat, the rad comes on, the room heats up, the TRV shuts off, and the room then stays just cool enough for the stat not to shut off - it keeps calling for heat, so the boiler keeps running.

So, where is the room stat located, and what rad is in there?

3) The new stat is faulty. Unlikely, tho'.

Another_Level

Tbh a straight forward wall mounted room thermostat could be the solution, maybe it needs moving to a better wall location or the heat source in the room containing the room thermostat checked out for comparability.

That dt90e is an ok thermostat, its  TPI (Time Proportional & Integral) control product, which once parameters are set up work wonderfully.

Maybe its a job for your regular service technician who maintains the heat/water system.  You know the type of person that has the tools and experience at hand.

Thermostats  

fenwick458

ritesh said:

It measures the temperature as 21c, but the boiler sounds like it is always on and the flat is very warm. The electrician has checked the wiring and all seems fine. So really confused and therefore decided to replace with a wireless unit.

you need to investigate more, as already said changing from a wired thermostat is not going to make a difference.
when the house is cold, you should be able to turn the thermostat up, physically see a flame symbol appear on the DT90E, then go to the boiler and look at the control panel the radiator symbol will appear on the "active operating status" of the display, along with the flame symbol, (page 5 of this PDF look at diagram 3.2.1 operator control panel) and the temperature should rise, boiler should make noise, radiators should get warm etc.
then after 5 minutes go to the DT90E and turn the temperature down and verify that the following happens:

1. the flame will disappear from the DT90E
2. the radiator symbol and the flame should disappear from the boiler display

if that happens, then the stat is working fine
some boilers continue to make noise after this, but only for a short while, to get rid of heat in the boiler

ritesh

Thank you again for all the comments..
Jeepers_Creepers - The wall stat (mechanical dial replaced with a DT90E) is in the hallway where there is one small single panel type 11 rad (700 x600) with a TRV. The temperature in the hallway measures 21oC, according to the stat. It is a small hallway. The stat temp has been set at 18oC, but the boiler is still on. I am going to go to the flat this week and place a thermometer on top of the stat to get a temperature reading.

Fenwick458 - I will check the symbols on the display when I am down there.

Jeepers_Creepers

Thanks Ritesh.

Really, the rad in the hallway shouldn't have a TRV, or at least it should be set to 'max' or '5', so that it is effectively always on. That then gives the room stat the correct role of setting the hallway temp, and the rest of the house is tweaked to match this.

If the temp in the hall is genuinely 21oC, and the room stat is definitely demanding only 18oC and the boiler is still running, then there's clearly a fault somewhere - but I suspect it isn't the 'stat.

Anyhoo, Fen's checks should get us closer to the cause.

(21oC is pretty warm for a hallway!)

southcoastrgi

Your room stat needs to be a boiler+ stat to go with your new combi to comply with regs so just swapping it for a normal rotary one shouldn't really be in your plans, as JC said the hall rad shouldn't have a trv on it & if this is turned down low this could be the issue  

ritesh

Hi All,

I just wanted to update you with the outcome of the non-responsive thermostat. The electrician explored in more detail and spoke to the Vaillant support team to get to the route cause of the issue. It transpires that a 24V terminal link also needed to be removed from the boiler, something not described in the manual. Hopefully this will make sense to most of you, but the existing thermostat is now working as it should. The hallway TRV has is now fully on and no longer needs to be fiddled with, but agree this should not have been installed in that location.

Thank you all again for your your advice and comments. 

Jeepers_Creepers

Blimey!

Pleased it's sorted, and many thanks for coming back.