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Nest stat with a Webasto Thermo Top C


Markblox

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Hi all,  one of my first posts, if not the first.  First trip in my first NB today but that's not the subject.  

 

I saw a good ~YouTube vid showing how to replace the controller on a Spacher with a Nest and thought: That's cool, I will get one.  Now, on the Spacher there is a live, a Negative and a switched live which is the call to heat.  On my Webasto with the 1530 controller it turns out there are four wires, Pos & Neg and also two black wires.  These are all terminated into a small Webasto socket which plugs into the 1530 controller.  I know one of these blacks will be a call to heat and that one will go to pin 1 on the actual heater, although belling that out would be fun as there is a hospital silencer in the way so knowing what one of those at the controller end is the call to heat would be very helpful.

 

 And what about the other black wire? what is it for and where do I connect that into the Nest base? Position 1 (satisfied, normally closed maybe).  Obviously don't want to start messing around cutting plugs off.

 

Does anyone know the answer to this? I have contacted the Tech dept but they just pointed me to the circuit diagram that only showed one black.

 

 

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Have a poke around the wiring loom connecting the heater to the switch. You may find two wires joined together to allow a timer/thermostat to be connected. That's what I found with our Mikuni heater.

One question: whilst I was able to find a 12V timer/thermostat, all the controllers required 230V. For us that would require having the inverter on all the time just to power the controller. Is the 'Nest' you've found 12V?

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Not to mention you will need a decent internet signal 24/7. I didn't bother with either Nest or Hive for mine as both require 230v and permanent internet.

My heating is controlled by a garage door switch* using txt messages. It has worked well for 8 years.

 

 

* Similar to this

https://www.ebay.co.uk/itm/RTU5024-GSM-Gate-Opener-Relay-Switch-Remote-Control-Wireless-Door-Opener-/353236387943?

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Thanks for your input.  I bought the Nest because I saw a YouTube video showing it working at 12V DC on an Eberspacher but couldn't get it working on my Webasto.  Google support said it wouldn't work because the Heat Link unit need 230V.  Now, I can see why most would want to avoid that path for various reasons but I am about to put an extremely large solar array on the roof and 600Ah of Victron lithium.  Also, most years I will probably be hooked up in a marina for two of the coldest months so I am not bothered about relying on the 3KW inverter working,  and in that unlikely but possible scenario I know how to get it going on 12V.  

The instructions say the heat Link should be connected to the Nest via a positive and negative DC connection and only connected wirelessly if it is on a stand and plugged into a socket via a micro USB.  I went back to support and asked if I could power it up from a local 12V DC lighting circuit (un-switched!) and then connect wirelessly to the Heat Link.  They said yes and it works fantastically.  Previously,  I would have to run to the stern and turn it on or off.  

One thing I am aware of is to avoid short cycling as I want reliability. 

Thank again for your input and I hope this helps someone in the future.

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  • 1 year later...

I helped a neighbour with an old fashioned thermostat for their Webasto. There are two types of wiring looms that Webasto have. One type is manual and has three wires going to a thermostat and these are easy to integrate a different thermostat, like a Nest in to. The other type has four wires and these use a Webasto specific data bus, called W-Bus and will be much much harder to fit a non-Webasto thing to. Have a look in the manual for your specific model of Webasto to see which you have, then check the wiring colours. The colours used are not intuitive; black is not ground, for example. It was a while ago, so I can't remember any more.

Fortunately, the neighbours had a model with a a dumb three wire plug, but the boat builders had given them a manual for a 4 wire W-Bus model heater! Once we had worked that out, the thermostat was easy to fit.

Jen

Edited by Jen-in-Wellies
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Hi, the Nest works well but beware, the nest base requires 230V, so may not be suitable for most of us.  I'm quite happy as I have an extremely large solar array and a large lithium battery but most of us wouldn't want an inverter running 24/7/365.  If you are able to go that way it's very nice to be able to heat the boat remotely and have a warm boat to wake up to.  We have no coal/woodburner on board.  The actual nest itself can be wired to 230V or 12V but as I have said, the base must be powered by  230V and the wires from the existing timer also goes to the base so therefore must occupy the position that your old timer occupied.

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3 minutes ago, Markblox said:

Hi, the Nest works well but beware, the nest base requires 230V, so may not be suitable for most of us.  I'm quite happy as I have an extremely large solar array and a large lithium battery but most of us wouldn't want an inverter running 24/7/365.  If you are able to go that way it's very nice to be able to heat the boat remotely and have a warm boat to wake up to.  We have no coal/woodburner on board.  The actual nest itself can be wired to 230V or 12V but as I have said, the base must be powered by  230V and the wires from the existing timer also goes to the base so therefore must occupy the position that your old timer occupied.

Also requires a permanent internet connection on the boat, despite having free unlimited 4g it's not something I leave on when away from the boat for a while.

Hence my earlier suggestion which gives the same nice warm boat on arrival. And the noal timer takes over once on the boat.🌞

I use Hive here at home so appreciate how it all works.

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I can see arriving to a warm boat might be nice, but is it really worth all the agg of setting up these high tech systems?

 

Perhaps I'm getting too old for these new fangled systems, but I just get the heating going when I get home (I live aboard) and I don't think I suffer unduly. 

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Just now, blackrose said:

I can see arriving to a warm boat might be nice, but is it really worth all the agg of setting up these high tech systems?

 

Perhaps I'm getting too old for these new fangled systems, but I just get the heating going when I get home (I live aboard) and I don't think I suffer unduly. 

Except using the "gate opener" is not high tech just a txt message to send for on and off. Its sooooo simple.

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1 hour ago, blackrose said:

I can see arriving to a warm boat might be nice, but is it really worth all the agg of setting up these high tech systems?

 

Perhaps I'm getting too old for these new fangled systems, but I just get the heating going when I get home (I live aboard) and I don't think I suffer unduly. 

The gate opening system is very simple, is wired no differently to a simple timer, takes a sim card and once set up is useful for not only warming up the boat before you return, but also turning it on when you are away and know theres going to be a severe frost....we switched ours on and off whilst in Venice when the UK was having a very cold spell.

3 hours ago, Jen-in-Wellies said:

. The other type has four wires and these use a Webasto specific data bus, called W-Bus and will be much much harder to fit a non-Webasto thing to. Have a look in the manual for your specific model of Webasto to see which you have, then check the wiring colours. The colours used are not intuitive; black is not ground, for example. It was a while ago, so I can't remember any more

The 4 wires (2 black, one brown and one red) are not all needed, one of the blacks isnt needed and the other one is linked to the positive red at the controller....brown is the negative.

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15 minutes ago, blackrose said:

 

But don't you need to wire it into the Webasto control box?

Nope as @matty40s explained

On an eberspacher its even simpler just take a 12v supply from the loom wire to the Open relay contact, break the yellow wire and wire the heater side to relay common and the controller side to the relay closed contact.

been running mine like that for 10 years, I have recently replaced the origional one with one that monitors battery level / power and temperature as well and txt me when they are at concerning levels ;)

 

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47 minutes ago, matty40s said:

The 4 wires (2 black, one brown and one red) are not all needed, one of the blacks isnt needed and the other one is linked to the positive red at the controller....brown is the negative.

I know. That is the simple wiring system on some models. A Thermo Top C should be of this type, so possible to interface with another thermostat. If it is a W-Bus model, like the Thermo Top Evo, there will be green and yellow wires in there too. The OP needs to make sure it is one of the simpler models, unless they want to get involved in reverse engineering the Webasto comms to fit an non-Webasto accessory.

Jen

Edited by Jen-in-Wellies
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If its anything like the Eberspacher comms it can be ignored as the comms is only to run what is on the display and diagnostics, the switching is still done by +12v onto a terminal at the heater.

 

If its not this module should interface it.

https://www.ebay.co.uk/itm/Webasto-W-Bus-Functions-Module-/124147753763?

Edited by Loddon
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Thanks for all the advice. Loddon's solution seems attractive and considerably cheaper than the Webasto text version (nearly £300) but marina signal may be a problem. Shame about the 230v but probably best way to go in absence of an alternative 12v option. 

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On 30/01/2022 at 16:32, Loddon said:

Nope as @matty40s explained

 

 

But he said "The 4 wires (2 black, one brown and one red) are not all needed, one of the blacks isnt needed and the other one is linked to the positive red at the controller....brown is the negative."

 

So it sounds like you do need to wire it into the controller?

 

I have wi-fi on my boat but the phone signal is non-existent in my area. I use the phone over wi-fi inside the boat but it doesn't seem to work for texts. No doubt texts to the boat from elsewhere would be even more problematic.  

Edited by blackrose
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14 minutes ago, David Mack said:

So how does your wi-fi connect to the Internet if you have no phone signal?

 

Through an antenna on the roof and a wi-fi router inside the boat. There's good Three wi-fi signal but very poor mobile signal outside the boat which fails completely inside the boat.

Edited by blackrose
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41 minutes ago, blackrose said:

 

But he said "The 4 wires (2 black, one brown and one red) are not all needed, one of the blacks isnt needed and the other one is linked to the positive red at the controller....brown is the negative."

 

So it sounds like you do need to wire it into the controller?

Nope, those are the wiring loom coming from the Webasto itself

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6 minutes ago, matty40s said:

Nope, those are the wiring loom coming from the Webasto itself

The one I did, I wired the thermostat in to the loom between the existing Webasto controller and the Webasto itself. All the controller does is send a run signal to the Webasto, according to whatever times you've programmed in to it. Done this way, the thermostat sends the run/don't run signal instead, by connecting two of the wires. I can't remember which two though.

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1 hour ago, matty40s said:

Nope, those are the wiring loom coming from the Webasto itself

 

Ok, but the point is you do need to wire it into the Webasto electrics, whether that's at the controller or somewhere else?

 

Anyway, there's only so much gadgetry I want on my boat. Every system one installs generally presents its own set of issues and I'm sure if I installed one of these things the next problem would be receiving texts in my poor signal area. For me just having a central heating system onboard my boat is advanced enough so I'll stick with manual operation of my Webasto. As I said, I'm not suffering unduly by having to return to a cold boat for half an hour.

 

 

Edited by blackrose
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