NEST 3rd Gen > Hot Wanter Tank

[Bucki82]

Hello There

Currently my old Honeywell has got a BOOST option for hot water. Not sure what does in reality!!

Does boiler go over 70c to heat up the water tank or does it activate the Coil Immersion ?? There is this immersion to the water tank and not sure how that is controlled!??

So, how will NEST control the hot water in the tank? Will it know its temp? How will it know it/ hot enough? Ultimately, how will nest control the electric immersion?

Besides, my aim is to have Opentherm with PDHW hot water priority. ???

 

[Deleted member 267285]

Nest won’t control the hot water temperature in your cylinder - that’s the role of your cylinder thermostat if you have one. All Nest would do for hot water is act as a programmer, the learning part I think is just the room thermostat. You could start by confirming if you have a cylinder thermostat and a y plan or s plan.

 

[Bucki82]

Nest won’t control the hot water temperature in your cylinder - that’s the role of your cylinder thermostat if you have one. All Nest would do for hot water is act as a programmer, the learning part I think is just the room thermostat. You could start by confirming if you have a cylinder thermostat and a y plan or s plan

Hello

No there is no thermostat on water tank.
So how do I operate the Coil Immersion?
Also what does BOOST on controller do, or used for or how it does operate?

It is S plan indeed.

I am aiming for Opentherm with PDHW.
Got myself TADO EU model but apparently can't do what I am planning to do but NEST does.

Now I realized tank has immersion and wonder how that will come to play after all.?


Btw how will Nest know the tank is hot enough? How will it stop when satisfied and what sets the level of satisfaction anyway?

 

[stem]

The immersion heater is an electric heating element inserted into the hot water cylinder and when switched on it heats the water inside. [Imagine it as being like a big kettle] It has nothing to do with the boiler, its associated controls and plumbing. It is totally independent of it. Generally immersion heaters tend only to be used now to provide hot water during a boiler breakdown. Its thermostat is underneath the top cover.

If you follow the cable from the immersion heater, it usually terminates at its controller, which may be a simple on/off switch or some sort of timer device.

Can you be more specific about the "Honeywell" with the "Boost" button with a photo or provide the model number. I don't ever recall seeing a Honeywell product with a boost button. However I guess there are dozens of different models about so I might have missed one or two. A boost button is normally associated with an immersion heater controller, it switches the element on for a short period to provide a 'boost' if you run out of hot water. The example below is a Horstmann.

If you do have an S-Plan system there will be a motorised valve controlling the flow of hot water from the boiler to the hot water cylinder. The cylinder thermostat opens and closes the valve to maintain the set temperature of the water in the hot water cylinder. The thermostat should be about one third of the way up from the bottom of the hot water cylinder and look something like this:

This thermostat would still be required if you went to a Nest. As per @CBW Nest only provides on/off control of the water heating and not temperature control as it does with the central heating part.

 

[Bucki82]

Hey Sem

Ur right, it doesn't have a booster.
Probably got confused with other things.

I know NEST has a boost option and what does it then? Works faster, or increases temp or what?

As for water tank, I know it has two zone valves both are NormallyClosed and have a level which goes left - right.

Cannot recall seeing a device on the tank tho.



My ultimate goal is to have Opentherm and HotWater Priority. Thought TADO (EU model) can do that but apparently not - been told.

They said NEST can do this.
Actually there is a YouTube video from UrbanPlumber demo NEST with Opentherm and PDHW

On top of that, I am still not sure how this all works in the end. Will NEST then control the CH and then just have a simple on/off to boiler?

Will I then regulate the CH temp via Nest app instead of walking to boiler?

 

[amcluesent]

>They said NEST can do this.<

Not sure who 'they' are but as you've watched Urban Plumbers video, you'll have seen that Opentherm and Hot Water Priority requires a system boiler which can accept separate calls for CH and for DHW and run at different outputs. Plus, the valving to CH and unvented tank needs to be suitable. So the whole system needs to be designed for hot Water Priority

 

[stem]

I've only ever installed OT with a combi. The OT terminals from the controller connect to OT at the boiler simples!

With S-Plan, the controls normally only open & close the motorised valves, and that's all they do, the controls are not electrically connected to the boiler. It's then the motorised valves that have a simple on/off switch inside that starts the boiler and pump when the valve opens, so, not the Nest (or any other controller for that matter). There are some boilers that can now provide OT control with S-Plan as per @amcluesent but will need additional wiring. Unfortunately I haven't had any experience of these as yet. Hopefully someone that has will be along shortly to advise, but I guess they will as a minimum need the make and model of your boiler to confirm its suitability.

 

[Bucki82]

Hello

Correct, it is a System Boiler.
Also have ordered the NO zone valve for CH.

They is referred to internet folks.
Cannot find anybody who is a living proof to say that TADO (EU MODEL) does Opentherm and PDHW, just like NEST is able to.

As you can imagine, NEST has a lot of connectors on the controller whereas TADO has a RELAY: COM NC NO and Digital / Analog connectors.

I am not an expert but again just going to what people have shared online. I prefer TADO as it also has smartTRV and sounded best advanced thermostat outhere but yeh ...

I hope I get to the bottom with this as now have a boiler but not working due to this wiring etc.

 

[stem]

There are several types of TADO for the various types of installation, this example is for the wired thermostat and shows OT control. But this diagram is with a combi (ie no motorised valves)

 

[Harry Bloomfield]

I know NEST has a boost option and what does it then? Works faster, or increases temp or what?

Boost simply brings your hot water cylinder up to temperature, then switches off or back to normal operation. Handy for when you plan to have a bath, but outside of a time when your system is set to not heat the water at all.

 

[Bucki82]

There are several types of TADO for the various types of installation, this example is for the wired thermostat and shows OT control. But this diagram is with a combi (ie no motorised valves)

View attachment 282313

Yeh would be easy on combi boiler!
I got system boiler Ideal Vogue Max s18

Also the Tado EU model is only one supporting OT but then how I connect CH / HW PDHW is a puzzle.

Does this video make sense to you and can it be simplified to understand?

I now have ordered NEST 3RD GEN.
In the video it's Ideal Vogue boiler, whereas mine is Ideal Vogue Max. How can I find out whether it will support PDHW ???