Honeywell 5-wire zone valve wiring (to Nest)

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Hi All

I'm trying to replace Honeywell thermostats with Nest. I don't do this professionally (something similar-ish) but have a fair amount of experience. The wiring centre is simple, Neutral, Live and Earth and six wires from three existing thermostats (two each).

I think the valves are Honeywell V4043H, and it's only "think" as the labels have been removed, so it has just been a case of matching them visually. They have 5 wires each:
Green
Brown
Blue
Orange
Grey

The manual for the V4043H, only has example wiring, but I tried (in brackets is what I connected them to on the Nest)

Green -> Earth (Earth)
Brown -> 3 (Call for Heat)
Blue -> N (Neutral)
Grey -> L + 2 (Common)
Orange - > Nothing

With that, the Nest won't open the value (the mechanical lever is just loose). Strangely, when the call for heat stops, the value tries to close (even though it's already closed).

There's only a certain number of combinations; trial and error is tempting but risky :D

Long shot, has anyone got any suggestions or is familiar with this type of valve?

Thanks in advance :)

* The attached picture shows the wire colours - it's another wiring I've tried, which seemingly does nothing!
 

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I'm no expert, but I hope your pipes are copper and cross bonded, because that valve is not currently earthed!
You need a proper earth connection for a start.
 
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Get someone that knows what they are doing, that is complete *******s, the orange never goes anywhere near the nest
 
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Not quite
Green -> Earth (Earth)
Brown -> 3 (Call for Heat)
Blue -> N (Neutral)
Grey -> L + 2 (Common)
Orange - > Nothing
it is
Green -> Earth (Earth)
Brown -> Activate valve
Blue -> N (Neutral)
Grey -> Common
Orange - > Normal open contacts
So the Brown and Blue open the valve and the Grey and Orange activate the boiler they connect to a micro switch inside the motorised valve, so the valve opens first then the boiler and pump fires up so it does not push against a closed valve.

from three existing thermostats
As far as I am aware only EPH do thermostats that can be configured as master/slave, I may be wrong, Nest in USA do sensors so it can monitor the temperature in 4 rooms, but these it seems will not work with the European versions.

There are two types of motorised valve this type 1661751010574.png controls a group of radiators, and this type 61dmtMm13BL.jpg allows individual radiator control, although they can be grouped together where more than one radiator in a room. The main difference is this valve 1661751010574.png is on or off, (digital) there is no graduated control, where this valve 61dmtMm13BL.jpg slowly opens and closes (analogue) so works far better with a modulating boiler. The whole idea with a modern gas boiler is it does not turn on/off, but until the minimum setting is reached, it turns up/down.

The EPH thermostat can be set as master/slave so one thermostat connects to boiler with OpenTherm and the others open and close the old type 1661751010574.png motorised valve, plus tell the master when the boiler is required to fire up, seems up to 10 can be fitted, however there is little need for both types in one system, the old wax TRV head is used to stop rooms over heating, but linked TRV like Wiser, Tado, and Evohome mean the old type motorised valve is not required, so it is in the main an either/or situation.

Theory one could put a simple on/off thermostat in every room wired in parallel and a wax TRV head, so when room cools the boiler fires up, but easier to simply use linked TRV heads.

Nest is designed for Open Plan homes and hot air central heating, i.e. a home where one single sensor is enough to control whole home, most other "Smart" systems use multi-sensors dotted around the home, the question is normally how few can one get away with, the TRV head shown cost me 2019 £15 each, they do not connect to any central hub, so you need a wall thermostat on a lower floor, in an area with no alternative heating, and no outside doors and normally kept cool to switch boiler off when weather warms up, it all depends on the home.

Main point is you can control warm up speed with the lock shield valve, but you can't control cool down speed, so want a room which cools down quicker than the rest. This is normally the hall, but in my case hall cools too slowly.

So one has to sit back and design the system, the people who do this for a living are called heating and ventilation engineers, and engineer in UK means some one trained higher than level 3, HNC, HND, Degree etc. Although I am an engineer I am an electrical engineer, not heating and ventilation, but do recognise their skill.

In the main their skill is to work out the minimum controls you need, any tom dick or harry can install a linked programmable TRV head in every room connected to a central controller, at around £60 each for the TRV heads, an expensive exercise, and likely only need two or three TRV heads linked, the rest can be cheap ones like shown.

So your problem now is to decide if Nest Gen 3 is near enough for what you want, or do you want a proper control? I am a fine one to talk, as also using Nest Gen 3 in on/off mode to control when my boiler runs, I was bought as only two wires main house to where boiler is, and Nest Gen 3 allows me to control DHW and CH and keep the Display/Thermostat powered up, ideal would be run new wires, but that is not an option, so for me Nest Gen 3 is near enough engineering.

For you likely Drayton Wiser would be better, it comes in three versions
1661753744921.png
the latter designed for three zone valves, plus also has about the best TRV heads, unfortunately the OpenTherm module is only for the one channel version, but it does as you can see work with three channels, if you want OpenTherm then looking at EPH, some boilers you can only use their make of thermostat connected to the ebus, and much depends on existing wiring, and if you can install new or not, I have floor panels not boards, so lifting to fit wires is not really an option.

My cure (hope it works) is to replace doors and windows with better quality, I hope then a single wall thermostat will work, fingers crossed.
 
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Might be helpful enough not to injure/kill yourself and or damage the equipment.
I didn't find it helpful at all - just interpreted it as a typical internet comment.

I was simply just trying to find out what the wires did, ericmark provided that and much more.

Thanks all
 
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I didn't find it helpful at all - just interpreted it as a typical internet comment.

I was simply just trying to find out what the wires did, ericmark provided that and much more.

Thanks all
Well stick with ericmarks advice then , good luck
 
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