ash_hammond
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| posted on 29/11/17 at 12:56 PM |
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OT Heating Nest Thermostat Install
Hi guys
Heating question
I'm in the processes of swapping my out my Vaillant VRT 360F wireless thermostat to a Nest.
Currently the Wireless Vailliant VRT controls my ecoTec 831 boiler over the eBus connection from the controller box attached to the boiler.
(Vaillant Wireless Thermostat > Vaillant Controller Box > Wire from the Controller Box to the eBus connection on the boiler)
When the Nest is installed and connected, is it a just a case of unplugging the eBus connection from the boilers board? Nothing needs changing in the
software menus on the boiler?
When connecting the Nest HeatLink module to the boilers 24v RT terminals do I use:
Option 1
Common (Pin 2 on the HeatLink) and Heating Relay Normally Closed (Pin 1 on the HeatLink)
Option 2
Common (Pin 2 on the HeatLink) and Heating Relay Normally Open (Pin 3 on the HeatLink)
Image attached of the pin options
I think option two as an open relay to me by default suggest the circuit is not complete so the boiler is off by default. I assume if I get it the
wrong way around the boiler will either not fire up or do the inverse of what is being asked by the thermostat.
For completeness, the Heatlink will be wired to the boiler via a 5 core cable, so when the fuse spur for the boiler is turned off, the Heatlink will
also be dead and safe too.
Secondly, My boiler is booked in for a service next week so, once the HeatLink / Nest of is connected, the boiler will be serviced by a pro and then
left alone.
Cheers. Thank in advance.
.: www.mac1motorsports.co.uk | www.m1moc.com :.
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ash_hammond
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| posted on 29/11/17 at 12:58 PM |
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.: www.mac1motorsports.co.uk | www.m1moc.com :.
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rgrs
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| posted on 29/11/17 at 03:46 PM |
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Yes option 2
edited as i have just noticed that there are two pcb versions, earlier ones just use the 240v connections on pins 3 & 4
Later pcbs will be marked RT (adjacent to the mains connections)for the switched live.
You don't want to use the 24v terminals unless you run a separate cable (you shouldn't have both240v and 24v down the same cable
Yes you can disconnect the ebus wireless controller receiver with no effect.
hth
Roger
[Edited on 29/11/2017 by rgrs]
[Edited on 29/11/2017 by rgrs]
[Edited on 29/11/2017 by rgrs]
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rgrs
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| posted on 29/11/17 at 04:20 PM |
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Had you looked at the Valliant vsmart ?
It's plug and play and does the same as Nest but with more control over the boiler.
Its about the same price as well.
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ash_hammond
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| posted on 29/11/17 at 04:42 PM |
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Hi Roger,
Really appreciate your reply.
Since posting this I have found the errors of my ways, I now know you don't you the RT24 terminal to connect the heat link to. I was lead to
believe I need to do this as the Nest install guide said "24 volt system are the most common". When I saw the 24 volt terminal I thought
bingo. But yes than I simply a jumper to tell the boiler which type is being used. I assume assume the "Burner Off" jumper remains in
place? I have not opened up my boiler yet to check what version of the PCB is has. It was installed in 2013 so it may be the old one. I have done a
diagram if you don't mind confirming the intended install.
I only found out about the Vsmart after I had purchased the Nest via doing my research on how the Nest connected. I paid £150 for it on Cyber Monday
from Amazon. I could return it as it is has not been opened.
What other additional practical features does the Vsmart have over the Nest. I wanted the Nest 1 as a smart stat and 2 integration with Amazon
Alexa.
I know its grey area about me removing the boiler front but, the boiler is due for a service through its maintainance contract next month so, Once
I'm happy the Nest is in and installed correctly, they can then come and give the boiler a clean bill of health.
What size cable would you recommend for the link between the boiler and the heatlink. The boiler is currently fused at 3 amp so 1mm2 is 11amps rated.
These things tend to have tiny connectors and getting "chunky" cables is not possible. I always like to over engineer things.
Cheers
.: www.mac1motorsports.co.uk | www.m1moc.com :.
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adam1985
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| posted on 29/11/17 at 06:32 PM |
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The vsmart becomes part of the boiler electronics so it will let you know if there's a fault on your boiler. You can change the hot water
temperature, and time the hot water comfort mode from your phone. It can also weather compensate your heating system which nest,hive etc can't
do.
Download the app and use the demo mode to see if you like it, you will need a spare 3 pin plug by the boiler to plug in the receiver into. The room
thermostat part is wireless (I think the nest thermostat needs plugging in)
2 years warranty on all vaillant controls.
Edit to add
Vsmart works with Alexa
If it's the ecotec2 (buttons to change the temperatures) you can either use the 24v plug on the boiler and use the nest as a switch or remove
the 24v and ebus plugs and have a 240v switched live to RT
Ecotec (round control knobs to change temperatures) same as above but 240v to connection '4'
Leave burner off link in for all wiring options
[Edited on 29/11/17 by adam1985]
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ash_hammond
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| posted on 30/11/17 at 10:35 AM |
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Thanks for the reply Adam and Roger.
I'm a techie by trade as such, so I can see the benefit of using a Vaillant Thermostat with the eBus as I can imagine it will have better
integration with the boiler than the nest ever will.
It is my understanding that the Nest can also compensate for weather as it knows where it is located and it calls out to the internet for local
weather and makes the adjustment based it that, Agreed it is not "real time" as such. IIRC the Vaillant system needs an external
temperature do weather compensation in "real time" as such? Happy to be corrected.
I looked over the Vaillant Vsmart last night in demo mode, one thing I did like was the hot water boost function. However, I was of the understanding
that with a Combi boiler as such, there was no need to have an hot water schedule as it would heat water on demand? Or does it have a small tank for
the initial demand while the boiler has time to react and it is that you are controlling. The nest does have hot water control but I assume not
compatible with the ecoTec?
This is the same as my boiler
Looking at google images, the ecoTec1 PCB's do not have a eBus connector (happy to be corrected), my boiler is controller over an eBus
connection With that, I believe my boiler is the ecoTec2 given it has the plus and minus for temps also
This is my boiler and controller:
Happy to have a pros and cons conversation. The nest can be returned it is unopened and from Amazon on a £150 black friday deal. One of the mains
advantages of the nest is how simple it is to up and down the temperature for my folks when they are baby sitting. The amount of time they have
cocked it up is unreal and ended up with the heating on 24 degrees in "constant mode". Plus I like shiny things of which the nest looks
nice in comparison to the vsmart white box. Sorry. 
If I do go with the nest I will be wiring it to the 230v connector as the diagram above with a 3 core cable between the heatlink and the boiler with
the permanent live at pin 2 (common) the heat link jumped from the 230/40 input. This way I think the installer is neater and I'm not trying to
get two connector. I think you have both already said that is OK, but to be 100% the diagram above is OK as I will follow that to the letter. I like
detail.
Cheers
Ash
[Edited on 30/11/17 by ash_hammond]
.: www.mac1motorsports.co.uk | www.m1moc.com :.
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adam1985
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| posted on 2/12/17 at 02:05 PM |
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The above boiler is the original ecotec and does have ebus, weather compensation will change the boiler flow temp depending on outdoor and target
temperatures, this can only be done by the vaillant controls, nest can do it by opentherm but this isnt supported by vaillant so the nest can only
send the boiler a on\off signal.
IF you did get the vsmart you wouldnt need to open the boiler, that existing control runs on ebus so just disconnect it, wire it to the new one and
plug in.
[Edited on 2/12/17 by adam1985]
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