UKC

Our gas combi central heating system has thermostatic valves on all radiators with the exception of the single radiator for the hall/stairs/landing which is permanently open. A "master" room thermostat linked to the boiler programmer is also in the hall (quite a common arrangement).
This seems illogical since if the hall becomes warm enough the radiators are switched off in the rooms where heat is usually needed; if these rooms are warm enough their rads switch off but the hall must continue to be heated even if not required.
    I'm thinking of putting a thermostatic valve on the hall rad  and replacing the wired "master" thermostat with a wireless programmable room thermostat so we could then move this new thermostat to whichever room was occupied and needed heat. However this would mean we had no permanently open radiator. Is this sensible and would it be sufficient to turn the radiator thermostatic valve to max temperature in any room containing the wireless thermostat? We'd presumably have to remember to do this every time we moved the thermostat.
Thanks in advance for any advice.

I'm planning on installing this type of system in my house after seeing it at my folks house.

The way I understand it is that you need to have at least one radiator without a thermostat valve, in the same room as the boiler thermostat, usually in a colder part of the house, e.g. the hallway. The (non-thermost) valve on this radiator is then set to a low number e.g. 2. The rest of the radiators are set to whatever temperature you want in each room. By having the radiator in the hallway at a low setting, it means that it's less likely to turn off the heating to all the house as it takes longer to heat up the hallway. Meanwhile, the valves on the other radiators will allow more flow through them, to heat up each room to the desired temperature.

At least that's my understanding.

Personally I would say this room should not be the hallway, because you largely don't care about the temperature of that, but rather your most frequently used room.  For most people this would be the lounge.  With a conventional system you should indeed not have radiator stats in the room with the main thermostat as they "fight" with each other.  For this to work properly your system needs to be reasonably balanced, though if it isn't (as mine wasn't until I had a radiator put in the kitchen) you can artificially balance it with the stats.

Alternatively if you want to be really clever (e.g. if working from home and thus not having one room that fits that description) look at a system that demands heat based on individual "smart" radiator thermostats and put one on every radiator.  I think Tado now offers this, don't know about the others.  This is the most efficient approach, as it will only heat the rooms you want heating at that time.

By wireless controls valves for every radiator you can set the room temperature for every room then.

Tado are really good.

I was told you need one radiator always open as a bypass in case all the other radiators reach temperature and close. I'm fairly certain however that most boilers have an internal bypass but it's probably not a bad idea.

If you want to select a different room to have as your always open bypass you can just remove the top off the thermostatic valve by unscrewing the knurled collar (some versions do vary and require removal of a small grub screw).

Thats the general idea. The issue is that if the feed shuts off to all the radiators the central heating pump is running against a closed head and it knackers it.

Our current boiler has an internal bypass loop fitted, but we added a very small radiator in the airing cupboard to act as an external bypass, just in case.

I may have this wrong, but I thought the whole idea was to use a room where you don't really care about the temperature as the one without the thermostat valve, you just have the regular valve in that room set low so that the thermostat doesn't turn off the boiler. You then use the thermostat valves in the rooms you do care about to set the desired temperature.

Thanks for the recommendation, I'll check out Tado.

Wouldn't that have the same effect as a thermostatic valve for every radiator? More cost to instal. I suppose it would have the advantage of being controlled from another room or from adifferent.  location 

That works, but it's not very efficient, as it results in the boiler being on when it doesn't need to be.

I have TRVs on all radiators except the heated towel rail in the bathroom which I use as the manual loop (even though the boiler has an internal bypass). With hindsight I would buy now buy a towel rail with an electric heater as well for the summer. The master stat is mounted in the hall, I have set the  TRV on this to low ( a couple of degrees colder than the master set point) so it doesn't override the master stat. 

It's more cost, yes, and you need a thermostatic valve anyway.

It's advantage is you have immediate control of all the radiators in the house.

I'm working from home today, only me in the house, I have the heating on but only my radiator is set to anything above 16C. So I'm only heating one room.

You can have zones set up so you can heat just the ground floor, upstairs, just the bathrooms, it's great but a bit pricey, though that's only a one off expense.

Tado do some refurbed units for half price too!

My thought was to move a wireless thermostat to different rooms as required and it would not be convenient to remove the top of the TRV each time. Hence I was wondering if I could just turn the rad TRV to max so that room's rad could act as a bypass (if the mobile wireless thermostat tripped at the lower room temperature required then the whole system would be switched off, so a bypass then wouldn't then be needed).

Though that means you continually have the bathroom rad on even if its not needed. Possibly more useful than my present bypass loop being the hall rad however.

My hope was that I could simply set the rad TRV to max in any room where I put a mobile wireless room thermostat (if the wireless one tripped at a lower temperature the bypass loop would be irrelevant anyway as the boiler CH circuit would be turned off).

Just set it to its highest setting which will result in it staying on all the time unless you have odd TRVs, no need to actually remove it.

Yes. That's what I hope to do but wondered if there were any disadvantages (apart from it being possible to forget to turn the rad TRV to max and then have no bypass).

This works so long as nobody else decides to turn it off. Removing it is a fail safe.

A disadvantage could be compromised safety.

My understanding is you don’t want a system without a by pass for safety reasons. I think my current boiler does have an internal one (it does on the HW side anyway as I hear the pump continuing after the hot taps go off), however my piping circuit has it’s own bypass  anyway that’s been since it was installed some 25 years ago.

My system doesn’t need any radiator on permanently as the heating circuit is an open circuit (reducer involved to effectively force water through any open roads) under the floor and unaffected by how many or few radiators are on and if all go off it just returns water to the boiler which uses it’s own thermostat to switch off. Without some form of by pass somewhere in the system my understanding is that one radiator has to be unrestricted.

I also have a master thermostat - one of the portable one - and can be used in any room. It is normally on a wall bracket in my lounge by my choice, but can be removed and used in any room.

Depending on your circuit/system is it may be possible to fit a by pass near the boiler as a safety? Alternatively is there a small radiator in your house that still would serve a heating purpose as well as the bypass if it was set permanently on?

You absolutely, shouldn't switch to all TRVs, there needs to be a bypass in the system at some point,(usually the furthers point away from the boiler) if you don't want it to be a radiator, you could join the flow and return pipes at the end of the run.

A bathroom is always a good one, if it's far enough away, but a hall isn't that much of an issue since the hall radiator gives a general heat source for the whole house usually.

If you need the heating on, it is usually cold, at least it is here in our house.

Change the hall radiator for a really small one, if it's that much of an issue.

How do you know the temperature the TRVs are set at?

I have been looking at these recently, has anyone worked out what the return on investment is? How much will it decrease your heating bills by?

I've not costed it, but if you are working from home, or spending a significant amount of time in one room, then I can't think the pay-back time would be too long, esp. now!!

6 rooms and 2 bathrooms in this house, I heat the kitchen and both bathrooms on a morning, if no one is going to be home. Add one room if I working from home.

After everyone has left, one room only if I'm here all day. If not a warm up before people get home, boost about 9pm before bed, so the rooms aren't freezing. Rinse and repeat.

The beauty of it, is I can open and close radiators from any room, so if I'm suddenly home, office heating only, If I'm called out, shut everything down. All from my phone. My son's sometimes here sometimes at his girlfriends, close his heating off as if he's on holiday, till he comes back.

I "zoned" our last house upstairs/downstairs, but that was before technology allowed us max control.

I have no idea about bills, Mrs. Cobra deals with those.

Thanks this is really helpful, so do you have the Tado smart radiator valves and also some sort of hub "Tado Starter kit"? 

I've seen that TCP also have some smart valves that seem a bit cheaper, and their hub also looks cheaper. I wonder if does the same thing?

I've been wanted to get smart light switches and smart blinds, but I can see this meaning I'm going to end up with three different hubs (one for lights, blinds and radiators) + a wifi router + god knows how many alexas dotted around the house to make it all work. Feels like it might be quite a fragile system!!

The thing to watch out for (I don't know TCP) is that smaller firms or firms where smart thermostats aren't their core business (such as the "traditional" manufacturers) is that to use these products you're relying on their online service remaining available and the hardware supported.  Tado is unlikely to go away quickly, though it's not improbable that they might end up being purchased by one of the bigger players, e.g. British Gas and Hive*.  Whereas the smaller firms or ones where it's not a core product might either fold or close the service down if they move onto something else.  It's not a big job to swap a smart thermostat at all, but it is a fairly big cost if you need to swap a thermostat and say 5-10 TRVs.

* Hive, despite the publicity, is hugely inferior to Tado because it doesn't really properly do geofencing, though you can sort of hack it to work using If This Then That.  But it's probably the most secure in terms of the service remaining available, as it's in tens if not hundreds of thousands of UK homes.

I use the master thermostat, which is a Salus wireless unit. It shows actual temperature as well as the set point. For the other rooms I use the comfort test! I have one "smart" TRV in the bedroom which has its own program cycle. Gives me an hour of warm to get up then the rest of the day sits at 14°C. At £30 to £60 a pop, until now, I couldn't justify more smart TRVs. However will probably fit more before next winter, particularly the living room as I spend most daytime in the upstairs "office". Another layer of loft insulation and raised flooring is the top project first.

As I understand it the settings are somewhat arbitrary and anyway give just an estimate of room temperature (which varies with the valve's environment) rather than water temperature. Starting at a low setting and trying gradually raising that is probably best. One site said it was approx 0 = Off, * = 7°C, 1 = 10°C, 2 = 15°C, 3 = 20°C, 4 = 25°C, 5 = 30°C.

Unfortunately we've a mix of old and new rads, The smallest is in the bathroom but is still a double with fins. I suppose I could the close the outflow valve on the hall rad even more but that might restrict the flow too much and still strain the pump.

Yes, you need a spare Ethernet port on your router, I've got a separate switch so not an issue.

I've used a couple of types, but settled on Tado, it's seems to do everything I need / want (not tried TCP, sorry).

We don't have any Alexas, the only issue we've had was with a replacement bulb my son bought which wiped out our wireless for the whole house, by interfering with e signal. It was a cheapo Chinese thing.

We have kept the original thermostat as it's fixed wired one. We use this as an "override" if you like, it's in our hall, so generally a bit cooler than the rest of the house, set to about 18C.