Vaillant EcoTec plus and Room Themostats

[plumbinguser]

Hi

I have had a Vaillant EcoTec plus installed (not combi even though it has a knob for water side - this is not used).

There are two room thermostats that go to a (non viallant) control box which appears to "control" the boiler by doing the equivilant of simply pulling the mains power from it by a relay (as explained in a simple way to me).

Is this is valid way of controlling a boiler (seems a bit crude to me) or has the installer made a mistake?

Please reply as I am concerned about the medium to long term reliabilty of the boiler.

 

[stevetheplumber]

boiler should have permenant live at all times if its wired to remove all power from boiler then it is wired incorrectly boiler needs permanent live for several safty features
with a conventional boiler as this is its normall to run all external controls via a junction box the room stats probably controll seperate motorised valves for the heating zones and there will be a third for hot water control
the trlays are integral to the motorised valves and its these that controll the boiler switch supply

 

[plumbinguser]

Thanks for the reply.

There are zone valves (one upstairs, one downstairs and one for central heating cylinder). These go to some kind of control box but I was informed that this was simply same as turning off the power. (There is also a 3 zone timer)

There does not appear to be any other connections and with what was said I pesumed it was the equivilant of wiring to a relay and then to the boiler (thus removing power).

What are the trlays to the motorised valve? When heat is demanded do the zone valves have power onto them all the time?

Looking at http://help.tradingdepot.co.uk/heating/honeywell/cm-literature.pdf it looks like the control systems do indeed use relay output to switch live power to and from the boiler so this must be common? (again I would think this had bad effect on long term operation)

Sorry for long winded questions but I am concerned (I am trying to get a wiring schematic from the installer but so far not much luck)

 

[doitmyself]

There are zone valves (one upstairs, one downstairs and one for central heating cylinder). These go to some kind of control box but I was informed that this was simply same as turning off the power. (There is also a 3 zone timer)

Two heating zone valves and a HW zone valve is called a "S-Plan Plus" system. Do your components, e.g control box, say "SmartFit"? This system does use relay switching. Normal systems switch 240v directly.

When heat is demanded do the zone valves have power onto them all the time?

Yes the thermostat applies voltage to the valve motor which opens the valve. As they are closed by a spring, the motor has to run all the time to keep the valve open. The motors are designed for this.

 

[plumbinguser]

The control boxes are from Salus wireless receivers (one for downstairs and one for upstairs{actually two zone valves connected to the upstairs one as old house and they said it was best way to easily split it}) model RT300RF and thermostat on hot water cylinder. They disappear into a double socket sized unit that has no information on it (possibly just a terminal connecting block?). There is also a Horstmann ChannelPlus H37 Series 2 programmer.

The boiler has a link that could be used but I don't think they have (just mains on/off at the boiler by the relays).

Ideally I would like the system to be changed as there is no frost protection as calls from the thermostats are blocked by the timer. I would also like to be able to use two room thermostats that have their own time and date and can be set for multiple heat at different times of the day (rather than when timer lets it through). The hot water would need some kind of timer.

These would be magically wired to provide the boiler with either its power or with the corret link inside it.

Problem appears to be lack of wireless that takes more than one (from the information on the websites anyway - forums here tend to like Honeywell). Any suggestions would be welcome

 

[stevetheplumber]

The control boxes are from Salus wireless receivers (one for downstairs and one for upstairs{actually two zone valves connected to the upstairs one as old house and they said it was best way to easily split it}) model RT300RF and thermostat on hot water cylinder. They disappear into a double socket sized unit that has no information on it (possibly just a terminal connecting block?). There is also a Horstmann ChannelPlus H37 Series 2 programmer.

The boiler has a link that could be used but I don't think they have (just mains on/off at the boiler by the relays).

Ideally I would like the system to be changed as there is no frost protection as calls from the thermostats are blocked by the timer. I would also like to be able to use two room thermostats that have their own time and date and can be set for multiple heat at different times of the day (rather than when timer lets it through). The hot water would need some kind of timer.

These would be magically wired to provide the boiler with either its power or with the corret link inside it.

Problem appears to be lack of wireless that takes more than one (from the information on the websites anyway - forums here tend to like Honeywell). Any suggestions would be welcome

if there is a link between terminals 3 and 4 on the boiler then its wired incorectly which is negating several saftey features
terminals 3 and 4 should be connected by way of the relays on your motorised valves
the wireless stats make no difference as they are only used to open or close the power from the timeclock to the valve motor in which ever channel (hw or h)
so basic sequences is call from clock via stat to motor of valve when valve opens it closes the integeral relay which allows power from terminal 3 to flow to terminal 4
obviously this is duplicated for heating and hot water
wires which got to the relays on the valves are the grey and orange
without a permanent live to the boiler you will have no pump over run and possibly no overheat stat as on earlier vailants this cut power to terminal 3 but in not sure if its the same on the newer versions

 

[plumbinguser]

Thank you for the reply

I will ask them to remove the boiler cover in the new year and to check that the link has been removed and if not to have them rewire correctly.

From what I understand from your reply (please correct me if I am wrong) the signal is from timer/room stat to power the appropriate valve. When this valve opens it closes its relay which then is (supposed) to link or power across pins 3&4 on the bolier? So changing the wiring should be easy

 

[stevetheplumber]

Thank you for the reply

I will ask them to remove the boiler cover in the new year and to check that the link has been removed and if not to have them rewire correctly.

From what I understand from your reply (please correct me if I am wrong) the signal is from timer/room stat to power the appropriate valve. When this valve opens it closes its relay which then is (supposed) to link or power across pins 3&4 on the bolier? So changing the wiring should be easy

yes thats about it

 

[plumbinguser]

Thank you