Home heating automation

ted1

deezell wrote: »

Thats an obscure one alright. Made I think by a Tipperary company who went bust in 2016, not a trace of a user/installer manual on the net, but it would not be difficult to determine where the firing switched live from the timer is connected, this would likely just go straight to the burner. Tap this and you can fire the boiler on and off. Look for a terminal block with a loop in and out, this is where a wall stat would have been optionally connected. Any handy sparks would figure it out, there may even be a wiring label inside on the panel. Theres a few phone nunbers on this old brochure if you wanted to do a bit of ringing around, you might get to talk to someone who could dig up a diagram, but like I said, its just the switched live from the back of the timer, so follow this to the terminal block and connect there.

https://drive.google.com/file/d/1r43v6KOcD8Vq0s-gU9WzsJ0KXNwpMJdD/view?usp=drivesdk

You might get away with setting it always on and then using the nest on the mains supply. Depends on how the pump works

maxamillius

ted1 wrote: »

You might get away with setting it always on and then using the nest on the mains supply. Depends on how the pump works

Pump is controlled via the wall stat, switched live from boiler to stat and then live back to pump

deezell

Originally Posted by ted1
You might get away with setting it always on and then using the nest on the mains supply. Depends on how the pump works

Depends on the burner used, it it has post purge (fan on for a whille after firing is off), then just whacking off the power might give rise to fumes and smells.

wandererz

Here's how the Heatmiser Neo Stat is connected as a timeclock for my immersion.

https://drive.google.com/file/d/1YmEZqLYLXAhTmKWL3HC1v1UYnpzXK6ZP/view?usp=drivesdk


And here's a screenshot of the app on my phone.

https://drive.google.com/file/d/15akvkc2OckD7d-LSfNivOU60gvRsPVMy/view?usp=drivesdk

deezell

wandererz wrote: »

Here's how the Heatmiser Neo Stat is connected as a timeclock for my immersion.

https://drive.google.com/file/d/1YmEZqLYLXAhTmKWL3HC1v1UYnpzXK6ZP/view?usp=drivesdk


And here's a screenshot of the app on my phone.

https://drive.google.com/file/d/15akvkc2OckD7d-LSfNivOU60gvRsPVMy/view?usp=drivesdk

This would be the most acceptable relay setup to install for an immersion element. A standard gk202no 20a normally open contactor relay in a 2unit enclosure will cost about €25-30. The SonOff is a bit tight at only 16amp rating for say a 3kw immersion element, which would pull just 13a when on. A switch controlling any device does not in itself have to rated to the MCB supplying it. You can plug in a wall lamp to a mains outlet on a 20a - 25a radial or ring MCB circuit, the inline switch on the cord would not be rated at this. It would of course be fused at the plug. The sonoff is rated at 16, there are 18a sonoff devices out there, especially the US where mains voltage is half so current is double for a given power rated device.
If the sonoff is hardwired in, it's argued earlier it should match the capacity of the MCB. Great colourful row here in that regard.
https://www.google.com/amp/s/amp.reddit.com/r/homeautomation/comments/8h0hr7/boltr_sonoff_wifi_switch_cheap_aint_so_cheap/#ampf=undefined
There are sonoff rated at 20a, these are walk outlet devices, which are designed for plugs, so they really only expect 13a max. from a UK plug, though the round pin European sockets are rated 16a.
Make what you will of the above, but the contacter relay is probably the best and safest setup. The hot press where the immersion is located is very dry, warm and packed with flammable material, so locate any relays well away.

2011

deezell wrote: »

A switch controlling any device does not in itself have to rated to the MCB supplying it.

Correct, but in my opinion this is misleading. Cleary you know far more about boilers than me but believe me when I say this: For safety reasons every device be it a switch, a relay or a Sonoff should be protected by a suitably rated protective device. The is a fundamental of electrical design. This protective device could be a fuse or an MCB or other. When something draws more current that it is designed to it may overheat and become a fire hazard.

You can plug in a wall lamp to a mains outlet on a 20a - 25a radial or ring MCB circuit, the inline switch on the cord would not be rated at this.

Correct, this is why we install a fuse in the plug (as you have pointed out). The idea is that in the event of the switch carrying too high a load the fuse in the plug will blow, thus preventing the switch from melting.

If the sonoff is hardwired in, it's argued earlier it should match the capacity of the MCB. Great colourful row here in that regard.
https://www.google.com/amp/s/amp.reddit.com/r/homeautomation/comments/8h0hr7/boltr_sonoff_wifi_switch_cheap_aint_so_cheap/#ampf=undefined

In Ireland we don't have to argue about this because we have "The National Rules for electrical Installations", (ET101:2008). These legally enforced rules are very clear on this. Here are just a few relevant extracts on the subject:

431.1 Overcurrent Protection of Line / Phase Conductors

Means for detecting over currents shall be provided for each line phase conductor and shall cause the disconnection of the conductor in which the over current is detected.......

^^^ Of course the Sonoff makes up part of the phase conductor for a given circuit.

133.2.2 Current

All electrical equipment shall be selected for the maximum sustained current (r.m.s. value for a.c.) which it has to carry in normal service. Account shall be taken of the current likely to be carried in abnormal conditions and the period (e.g. operating time of protective devices if any) during which it may be expected to flow.

^^^So if a Sonoff is protected by a 20A MCB we can conclude that under "abnormal conditions" 20A could flow though it even though load should draw far less under normal operating conditions. Drawing 20A through a device that is only rated for 16A is inadvisable particularly when we consider that it is not CE marked :eek:

Ignore the above at your own risk.

---

In the electrical world there are simple cost effective ways that allow us to use devices that are only suitable for carrying small currents to switch devices that can safely carry far larger currents. Let's take an immersion fed from a 20A MCB. We can fuse this down to just 2A using a spur outlet which can feed the Sonoff device which in turn can switch a 25A contactor. This contactor can then switch the supply on and off to the immersion element. The supply to the immersion element will not be fed trough the 2A fuse. The Sonoff can even be installed local to the distribution board if desired. These ratings (2A fuse & 25A contactor) provide generous safety margins and are very cost effective.

I'm all for DIY but people need to be competent when working with a potentially lethal voltage. If in doubt get a professional in. You can also get some great advice and guidance here for free.

Make what you will of the above, but the contacter relay is probably the best and safest setup.

Agreed.

maxamillius

So folks, just before I press play on the nest I want to make sure I have it right in my head..

My current setup

Oil boiler
Single zone pumped
Timeclock on boiler used to fire it
Switched live from boiler to wall stat
Switched live from wall stat back to circulating pump.

When I turn stat up, pump starts, turn it down and pump stops.

Switch boiler off via sliding switch on front panel or when it times out.

Going to get the nest offer from electric ireland for 130eur

Install beside boiler,this will now take over from the boilers time clock.

I will then link the 2 cables at the wall stat.

The nest should then fire the boiler according to the schedules and the nest thermostat will control the pump.

Am I correct with the above? Is there actually any benefit to me installing this from an energy saving pint of view or does it just provide remote control etc?

Cheers,

punisher5112

I'm moving into the house next week, I have a netatamo but looking at this deal with electric Ireland as I'll be starting up as new customer.

Am I best signing up on the €200 cash back and then get a nest????

deezell

maxamillius wrote: »

.......Install beside boiler,this will now take over from the boilers time clock......

Cheers,

This is the only unknown. You will require the CH relay of the Nest heatlink box to be connected internally to the Live and Switched Live terminals inside the boiler, they should be on a terminal strip or inside the mains connector casing, and would have a link as there is no stat currently controlling the boiler. Otherwise trace the SL coming from the old timer and interrupt this with the heatlink relay, setting the old timer to always on. The pump should always come on with the boiler in your system as you have no gravity fed HW, so linking the old stat cables achieves this
In the future you can use the HW relay of the nest if you install a motorised valve on the CH branch, to give you HW only. This will only be possible if there is a clear separation of the HW feed and all CH feeds from the boiler on the flow and return. It's quite possible the HW cylinder coil is tapped off the flow and return at a random point in the plumbing, making it impossible to isolate all CH taps without re-plumbing. For the moment, get the Nest box wired into the boiler, and get the benefits of tighter and smarter heating control.

deezell

2011 wrote: »

...........So if a Sonoff is protected by a 20A MCB we can conclude that under "abnormal conditions" 20A could flow though it even though load should draw far less under normal operating conditions. Drawing 20A through a device that is only rated for 16A is inadvisable particularly when we consider that it is not CE marked.......

In the electrical world there are simple cost effective ways that allow us to use devices that are only suitable for carrying small currents to switch devices that can safely carry far larger currents. Let's take an immersion fed from a 20A MCB. We can fuse this down to just 2A using a spur outlet which can feed the Sonoff device which in turn can switch a 25A contactor. This contactor can then switch the supply on and off to the immersion element. The supply to the immersion element will not be fed trough the 2A fuse. The Sonoff can even be installed local to the distribution board if desired. These ratings (2A fuse & 25A contactor) provide generous safety margins and are very cost effective.

All very good advice. The Sonoff relay on Amazon here is clearly CE marked.

https://www.amazon.co.uk/Sonoff-Consumption-Monitoring-Appliances-Compatible/dp/B06XSD6PD6/ref=sr_1_fkmr1_3?s=electronics&ie=UTF8&qid=1549203819&sr=1-3-fkmr1&keywords=sonoff+16a+relay

The idea that a device with a max of 16a is not protected by an MCB of 20 is a bit vague. If a hard wired Sonoff has a single fixed load, (is not connected to a load of plugs say), it can only really experience rated load or perhaps a short circuit, which will trip an MCB long before it would burn out the contacts. A real world example. Electric touch hobs with four or five rings power each ring with internal relays. these are rated as low as 10a on some models for small 1.2Kw elements, maybe 16a relays for the larger elements. All these relays are fed by the hardwired mains from a 32a MCB, far in excess of the individual current rating of any one relay. There is no onus on the hob manufacturer to individually limit the current through any relay to its design value. Hob elements can and do fail abnormally, perhaps a short circuit is possible in its design, and when this happens the relay should take down the 32a breaker. The point is the relay is rated way below the MCB which supplies it and all the others, but well above the 5-10 amps of any individual ring. My only reservation for a hardwired sonoff is the 16a rating is too close to the 13a required by a typical 3Kw immersion (but these only draw 12a at 230V, 3Kw is at 240V) There is the risk of someone wiring this to a dual element immersion (bath/sink) which could have total requirement greater than 16a if both elements were on, so stick with the contactor.

On a final note, once you use a contactor there is no need for a Sonoff at all as the contactor can happily be operated directly from the HW relay of your chosen smart stat, Tado, Nest, Hive, heatmiser etc, and timed by its schedule. This was illustrated in a wandererz post.

Stoner

Mod note.

In the interests of safety and best practices let's stick to the position that a device needs to be protected with suitable switchgear.

So a 16 amp sonoff is not fully protected by a 20 Amp device.

You need to protect it and it's cabling with a device at or below it's device rating

On that basis this is not a debate.

There is nothing vague about this position.


Yes there are circumstances where short circuit protection is provided upstream by switchgear devices rated higher than the device being protected.

In Industry that is usually addressed via risk analysis carried out by engineers for specific devices used under defined conditions. There are usually tests and and papers with independent input supporting these positions provided by suppliers to support engineering practices with PI insurance to standover such installations.

We don't have that here or anything close to it here.

So in the absence of same we follow the device ratings and fuse suitably.

We can argue this here all day but it is generally not recommend to connect a device rated below 20 amps to a 20 amp automatic breaking device without adding in suitably rated additional inline device protection (and isolation for maintenance).

So please all continue to discuss iot elements here but please follow the direction given here.

If it gets too particular I'll ask that a separate thread is generated on the electrical forum as it's going off topic for this forum.

2011

deezell wrote: »

All very good advice. The Sonoff relay on Amazon here is clearly CE marked.

Agreed, in fact the Sonoff from all sources has a CE markings on them. The question is, do you believe it?
As it happens many Chinese products have the "Chinese Export" mark on them. This is abbreviated as "CE" in similar lettering to the CE marking that we require on electrical and electronic goods sold within the EU. Some sceptics may think that this is do it in order to confuse, I'm sure that couldn't be true :rolleyes:

See link.

Have a quick Google about Chinese electrical & electronic goods going on fire, it is quite alarming, as is the their history of counterfeiting :eek:

The idea that a device with a max of 16a is not protected by an MCB of 20 is a bit vague.

Really it's not.
If a device is designed to continuously and indefinitely supply 16A it should not be pushed beyond that under any circumstances.

If a hard wired Sonoff has a single fixed load, (is not connected to a load of plugs say), it can only really experience rated load or perhaps a short circuit, which will trip an MCB long before it would burn out the contacts.

That is factually incorrect. Abnormal or fault conditions can be broken into 2 main categories:

1) Short circuit condition which you have mentioned. When analysing this breaking capacity should be considered.

2) Overload condition which it would seem you have not considered. Most domestic installations use B type MCBs, when we look at the B characteristic (see below) for these units we can see that at 1.45 times the rated current it can take almost an hour to trip.

This mean that 29 amps would be flowing through a device that is rated for no more than 16A for up to an hour :eek:
In summary: It can be dangerous to advise against the stated position of a manufacturer.

A real world example. Electric touch hobs with four or five rings power each ring with internal relays. these are rated as low as 10a on some models for small 1.2Kw elements, maybe 16a relays for the larger elements. All these relays are fed by the hardwired mains from a 32a MCB, far in excess of the individual current rating of any one relay. There is no onus on the hob manufacturer to individually limit the current through any relay to its design value.

You are comparing apples and oranges.
The internals wiring design of an appliance is not comparable with an external wiring system. With respect tot eh appliance, there is an onus on the manufacturer to ensure applicable European Directives including the Machinery Directive 2006/42/EC. This will have been tested extensively and certified by an independent governing body. This is not the case with the external wiring design, so very different.

When designing a wiring system compliance with ET101:2008 is not optional.

Hob elements can and do fail abnormally, perhaps a short circuit is possible in its design, and when this happens the relay should take down the 32a breaker.

I would not be as concerned by short circuit conditions as I would expect a disconnection time on < 0.4 seconds. My concern would be an overload which you have not even mentioned.

On a final note, once you use a contactor there is no need for a Sonoff at all as the contactor can happily be operated directly from the HW relay of your chosen smart stat, Tado, Nest, Hive, heatmiser etc, and timed by its schedule.

Alternatively a number of Sonoff devices when installed in line with best practice could switch zone valves with dry contacts supply a run signal to the boiler at a fraction of the cost.

Edit: Just noticed that I crossed posts with Stoner. Agree completely, I think that it is best to take this discussion to the electrical forum. In the interests of safety this is not up for debate on this forum, but can be debated on the electrical forum.

maxamillius

deezell wrote: »

This is the only unknown. You will require the CH relay of the Nest heatlink box to be connected internally to the Live and Switched Live terminals inside the boiler, they should be on a terminal strip or inside the mains connector casing, and would have a link as there is no stat currently controlling the boiler. Otherwise trace the SL coming from the old timer and interrupt this with the heatlink relay, setting the old timer to always on. The pump should always come on with the boiler in your system as you have no gravity fed HW, so linking the old stat cables achieves this
In the future you can use the HW relay of the nest if you install a motorised valve on the CH branch, to give you HW only. This will only be possible if there is a clear separation of the HW feed and all CH feeds from the boiler on the flow and return. It's quite possible the HW cylinder coil is tapped off the flow and return at a random point in the plumbing, making it impossible to isolate all CH taps without re-plumbing. For the moment, get the Nest box wired into the boiler, and get the benefits of tighter and smarter heating control.

Think I’ll take the plunge and get it ordered, appreciate all the advice you’ve provided!

deezell

maxamillius wrote: »

Think I’ll take the plunge and get it ordered, appreciate all the advice you’ve provided!

Thanks. And I promise not to say the S word again.

Stoner

deezell wrote:

Thanks. And I promise not to say the S word again.

The mod advice was not manufacturer based or personal preference. I have Sonoff devices in my house.

This issue relates to recommending a small change to the advice here to allow for the safe and responsibile means of device protection and isolation for maintenance.

There are DIY people reading these forums. It's a reasonable request and not a challenge to anyone's intellect.

The inclusion of protective devices for cable, devices and isolation of circuits is not part of a game of one-upmanship nor a demonstration of knowledge.

2011

@ deezell: As previously stated if you would like to debate this matter a thread in this forum is not the place for it. We have no problem with you starting a thread on this very matter in the electrical forum. No more off topic posting please. Thank you.

deezell

2011 wrote: »

@ deezell: As previously stated if you would like to debate this matter a thread in this forum is not the place for it. We have no problem with you starting a thread on this very matter in the electrical forum. No more off topic posting please. Thank you.

👍

deezell

maxamillius wrote: »

Think I’ll take the plunge and get it ordered, appreciate all the advice you’ve provided!

This is as good as I can find on the GEM boiler. Connector strip at the top back, there should be two of these terminals with a link, meant to go to a thermostat. connect the Nest Heatlink box CH Com and NO to these.

see image here

bonnieprince

I have a heating system with gloworm flexicom 30sx with three zones (downstairs, upstairs and hot water) and I am looking to change my heating controls from a Sauter T37 programmable timer with 2 robus wired thermostats to either a Drayton Wiser or Tado setup. I have checked the panel behind the Sauter and it looks it is suitable to connect to the extension kit/heat hubr. I would plan on getting TRV's over time when budget allows etc.
Any recommendations or advice would be very welcome.

deezell

bonnieprince wrote: »

I have a heating system with gloworm flexicom 30sx with three zones (downstairs, upstairs and hot water) and I am looking to change my heating controls from a Sauter T37 programmable timer with 2 robus wired thermostats to either a Drayton Wiser or Tado setup. I have checked the panel behind the Sauter and it looks it is suitable to connect to the extension kit/heat hubr. I would plan on getting TRV's over time when budget allows etc.
Any recommendations or advice would be very welcome.

The panel behind the T37 has an 8 terminal receptacle, pins 1 and 2 are the mains, pins 3-8 are the On/Off connections for HW, CH1 and CH2 respectively. The Tado ext kit plate looks similar, but is only the same for the first 6 terminals, (standard UK 2 zone), mains, HW and CH, the remaining three terminal are for analogue/digital boiler control.
The Drayton wiser three channel receiver also use a similar looking back plate, but does not supply any 'OFF' terminals for the three zones, it's wired over 5 terminals, Mains in on 1 and 2 followed by three 'ON'
terminals, HW, CH1 and CH2. on 3, 4 and 5, with 6 unused.

You have a few options.

With Tado, by far the simplest is to replace the Robus with 2 wired Tado stats. set the Sauter to always on on CH1 and CH2 and use the Sauter to time HW.

Alternatively, if you want Tado control of HW, you require the Ext kit. You will need to remove the Sauter, wire HW on and CH1 on to the Tado ext Kit base, and wire CH 2 directly to the mains Live of the Ext kit. Tado stat for CH1 can be wired in place of CH1 Robus, or this can just be be removed and hardwired on, and the Tado stat for CH1 can be located anywhere and will control CH1 wirelessly back at the EXT kit. Tado stat for CH2 will be wired in to replace CH2 Robus.

For the Drayton wiser, its just a case of replacing the Sauter base plate with the Wiser receiver baseplate, and wiring in the mains and the three Zone ON terminals. The two Robus can either be removed and their two wires joined together (if it's a three wire Robus with an 'On' indicator lamp it will have a third neutral wire which should be taped up, this also applies to the wireless Tado CH1 install above). You can just leave the two robus in place and turn them up full to make the connection to the zone valves. The Wiser stats connect to the Wiser hub wirelessly and can be located anywhere in the Zones.

Drayton 3 channel base plate and wiring
https://www.draytoncontrols.co.uk/sites/default/files/WEB%2015-03-18%208987%20Wiser%20Instructions%20ISSH.pdf
Sauter T37 base plate and wiring
https://www.plumbase.co.uk/link/1/h034221_26641_t.pdf
Tado base plate and wiring
https://www.diynot.com/diy/media/dcaed0b9-cbe2-4098-97c9-d2483babf3a0.102027/full

bonnieprince

Thank you so much for this input! Really appreciate your help.

I know there is approx. €200 price difference from what i can see between the Drayton and Tado. I have a lot of apple devices so was leaning towards homekit compatible system but don't know if that is a deal breaker or not.
What would you recommend?

deezell

bonnieprince wrote: »

Thank you so much for this input! Really appreciate your help.

I know there is approx. €200 price difference from what i can see between the Drayton and Tado. I have a lot of apple devices so was leaning towards homekit compatible system but don't know if that is a deal breaker or not.
What would you recommend?

Both can do TRVs also for later upgrades. Tado has the edge on versatility, but fir Wiser you can create stuff like geofencing on IFTTT, apps already written. IFTTT is also compatible with Homekit, so should be possible to marry Homekit and Wiser. Wiser looks a simple install, and it's priced well for 3 zones/ two stats. It also handles OpenTherm for suitable boilers. I'm impressed with it on paper, but I've not used it. It's a cinch to install coming from a 3 zone controller also.

dball

With s tado tvr I stalled we have s room we don’t use that much this time of year. But to keep the damp and condensation out I put the TVR Setting to 14 degrees for a cpl of hours. Seems the tado is having difficulty with this and the room goes up 18/19 degrees.

deezell

dball wrote: »

With s tado tvr I stalled we have s room we don’t use that much this time of year. But to keep the damp and condensation out I put the TVR Setting to 14 degrees for a cpl of hours. Seems the tado is having difficulty with this and the room goes up 18/19 degrees.

What is the graph for this room showing? is it reaching 18/19 degrees on the graph? are there active calls to the TRV as the temperature rises (darker grey) or is the colour under the graph the light background grey. There are two possibilities
1. The TRV is not fully closing the valve, easily checked if the rad is heating though the TRV shows off.
2. during the day the room will easily heat to 18 degrees just because of heat leakage from adjacent rooms and hallway, plus sunlight entering via window will warm a room greater than outside temperature.
Setting the TRV to 15 will not force the temperature down, unless the house in general cools to near this overnight, or the room is a particularly cold room, say a corner room with older insulation.

reignschaos

Evening
I just used the tado app, and noticed it looked like the V3+ app. On checking my app was updated 2 days ago. Did anyone else get this upgrade? Note I didn't pay for the V3+ app!!!

j_lennon18

reignschaos wrote: »

Evening
I just used the tado app, and noticed it looked like the V3+ app. On checking my app was updated 2 days ago. Did anyone else get this upgrade? Note I didn't pay for the V3+ app!!!

Mine (on Android) is still on the old V3 style. It was last updated Feb 11th. No pending updates for me. Version is 5.4.0.

I don't think I want the new V3+ yet because I think it has removed 1 feature I use the last time I looked into it.

Is V3+ still missing 1 of the options around the manual control - Start/Stop: 1. Until next auto change 2. Timer 3. Until ended by user?

reignschaos

j_lennon18 wrote: »

Mine (on Android) is still on the old V3 style. It was last updated Feb 11th. No pending updates for me. Version is 5.4.0.

I don't think I want the new V3+ yet because I think it has removed 1 feature I use the last time I looked into it.

Is V3+ still missing 1 of the options around the manual control - Start/Stop: 1. Until next auto change 2. Timer 3. Until ended by user?

I sought clarification from Tado and I was upgraded to the new app because I added in a new Tado Radiator value which they said was a V3+ item - they also update the MyTado experience too btw.

By default auto assist was gone and the subscription option was available.
There was no option for existing customer to purchase once off from within the new app. Following my eMail to support they down graded me again. So it's basically 1 app with a flag indicating what to display, i'm basing this on the fact I didn't have to re-install the app or log out and in again.

The home page is nice, all rooms available with temp (in my opinion they should also include humidity on the tile), other than that I wasn't overly impressed.

Swipe was missing, increasing or deceasing the heat was done via a slider which was a huge tile with nothing on it to assist you in what it did, eventually worked out you slide it (i'm on android, so may be different on Apple). Not sure about the schedule/timer aspect, I saw it but not sure if it was configurable (based on other reviews it isn't).

Let's say after 24 hours of the new app I won't be rushing back to get it until it goes through at least another release cycle.

budhabob

deezell wrote: »

Your nest has a separate timer for HW and a second relay on the heatlink box which would normally be used to drive a HW zone valve, thus directing boiler output to the cylinder only. As you only have a single zone, you were looking for a way to fire the boiler as timed events to heat the HW, with the CH flow turned off. My first suggestion was a fake CH schedule, high to low temperature events which would turn the boiler on then off. I also suggested enabling the HW timer schedule, which translates to on off events on the HW terminals of the heatlink relay. These are unused in your system, but by crossing them to the CH terminals on the heatlink box you effectively have the equivalent of an on/off timer, which will fire the boiler as you require for the programmed intervals. Joining pins 2 to 5 and then 3 to 6 will achieve this.

Morning Deezell, we're finally pulling the trigger on the Bathroom renovation so getting this done at the same time. I had the plumber in last week, had the above printed off to talk him through. He said the electrician he works with is familiar with Nest, but did query whether he needed to connect a stat to the tank? He was wondering how nest would know when the water reached the desired temp.

reignschaos

I've a few troublesome TRV's and thinking of replacing them. As I have Tado ideally I would like a decent TRV that doesn't need the adaptor ring. Are the any make of TRV's that anyone would recommend?

Thanks

deezell

budhabob wrote: »

Morning Deezell, we're finally pulling the trigger on the Bathroom renovation so getting this done at the same time. I had the plumber in last week, had the above printed off to talk him through. He said the electrician he works with is familiar with Nest, but did query whether he needed to connect a stat to the tank? He was wondering how nest would know when the water reached the desired temp.

It wouldn't. When HW is controlled by a series of timed intervals, ( notches on the old mechanical timers), its guesswork as to how long an interval you fire the boiler for to supply sufficient HW when you need it. The HW will only heat to the system temperature of the boiler, say its set for 65°, so when the cylinder reaches this the boiler will cut off via its internal stat, and cycle at its max temperature, until the timed interval is over or the cylinder return heated wayer cools.. Better to fit a cylinder stat in series with the HW live to the boiler, then the boiler will turn off until the cylinder stat cools, and HW temperature can be set independent of boiler max temperature.The only reason for having timed HW at all is to save a few quid by not having a fully heated cylinder of HW 24/7, dissipating heat. (TURN OFF THE IMMERSION! as Des Bishop tells it). This was a big issue with badly insulated cylinders back in the day, but the modern foam encapsulated ones can be kept heated all the time with the stat calliing the boiler in small bursts to keep it topped up. Heat loss is so small that there's little saving in using a timer except perhaps for ling absences like holidays.