Vaillant vrc430, vr81, vr61

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I have just added underfloor heating as a second zone to an ectotec 831 boiler, but I'm having a few problems setting up the controls.

Originally, the boiler was controlled by a VRC400 and this worked well. while waiting to finish off the build, the radiators and underfloor heating circuits (each with a 2 port valve) have been controlled by simple thermostats and while this worked fine, I want to get back to a weather compensated system using vaillant controls.

The Vaillant helpline said a VRC61, will work with a combi boiler so I have upgraded to this, with a VRC430 and VR81 to control the underfloor zone. I have read people's thoughts on the vaillant helpline though!

The VRC430 and VR81 light up ok and going through the installation assistant opens the valves when activated from the system check screen. However, when I try to use it, the boiler now fires immediately it's switched on and while the zone valves are shut, so overheats and locks out. It seems like the boiler isn't being controlled by the system, although the valves are??

All the controls are new (read this should work with the later VRC430 software), but the boiler is about 4 years old). Am I missing something obvious??

Many thanks, Barry
 
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sounds like you've have missed something on the VR61 installation/setup if you say the boiler fires up but the zone valves remains shut.

have you tried running the system one zone at a time?
 
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I was under the impression that you couldent use the vr61 with the ecotec combis, something to do with a software clash, maybe they sorted it out.
 
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I did ask Vaillant about using the VR 61 with this specific boiler and they said it was ok. However, as I said, a quick look on here does tell you all you need to know about the reputation of them!
 
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I would phone them back and ask to speak to someone that understands their own controls, I went on one of their controls courses and the instructor had never heard of this problem.
 
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Thanks. I'll double check I've not missed anything on the installation assistant. Just seemed strange something is calling for heat as soon as it is switched on. Also seemed strange it should instantly overheat and lock out, as surely the automatic bypass should stop this happening, even is both valves are shut?
 
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I ran through the entire installation again and things seem to be working ok with everything talking to each other. As far as I know, everything was set the same?

The only remaining problem showed up when trying each zone in turn. The VR81 is controlling heating circuit 1, instead of 2, meaning there's no thermostatic control on circuit 1. The VR81 installation tells you how to map it to the right heating circuit address, but doesn't say at what stage you should do this. Changing it now makes no difference. Should this be done as soon as the system is switched on, before the rest of the install?

After 4 years use, I'm really impressed with the boiler and the old compensator worked really well, but how can something as routine as a 2 zone system be made so difficult! Not to mention expensive. I now understand why so many people don't bother with the vaillant controls.
 
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you can assign the VR81 to a heating circuit at anytime.

have you set a heating program for Circuit2 via the VRC430? set the VR81 to 'manual mode' and see i that get's your uhf going.

is Circuit1 working ok?
 
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Hi Joe

Both zones are working ok. The VRC430 is in the hall to control the rads, the vr81 in the extension to control the UFH. Problem is, the VR81 controls heating circuit 1, rather than 2. Looking at the installer level screens shows HC1 remote control = yes HC2 remote control = no.

I'll tried to assign the VR81 to HC2 but it wouldn't play. I'll try again, then it should be sorted, as everything else seems ok now, as I can control the UFH from the VRC430.
 
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Good news/bad news. The heating is now working faultlessly on both zones, complete with weather compensation etc.

Sadly, there is no hot water - doh! When tap is opened, the heating shuts down and the display shows there is a hot water demand, but the boiler doesn't fire. close the tap and the heating starts again as it should. It's going to be a bit frustrating to get this far and find the VR61 is really incompatible.
 
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The system is now up and running so I thought I should update the thread in case others search for the same query.

The VR61 will work with combination boilers, as confirmed by Vaillant. The problem was with the LP/ZP setting, which is set with the install assistant. This needs to be set to ZP and cylinder set to active for combination boilers.

I have to say, Vaillant Technical support couldn't have been more helpful in the end, even asking for a number they could ring me on to discuss!
 
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I want to add an UFH circuit to a vaillant 937 combi.
Vaillant have told me to use a low loss header in the circuit with a separate pump for the rad circuit. Has anyone had to use one?
 
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how many radiators do you have and how big is the area for uhf? low loss headers are normally used in commercial applications when running multiple boilers.

i would say simply create a 2nd heating circuit for the uhf then use a manifold for the zones.
 
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Since I posted last, I've had to have a bit of a rethink. I have 11 rads and about 30m2 of underfloor. While the system worked with the Vr81/61, it wasn't really suited to the combi. The lag between turning the tap on and hot water was too long, due to the system waiting for the motorised valves to close on the heating every time before firing up for hot water.

A second problem was the boiler cycling when the underfloor only was on. When the floor gets warm, but the room's not quite up to temp, the boiler was firing but only for about 30 seconds, as the demand for hot water from the underfloor was so small. I guess that's why they mention a low loss header?

However, the underfloor is in a very well insulated new extension and I found there's really no need to have the underfloor on before the rads in the morning. I now have the boiler and rads controlled by the VRC430 (as it always was) and the underfloor controlled via the motorised valve by the programmable thermostat that can with the system (John Guest). The underfloor pump unit has a sensor to detect if hot water is available, before the pump runs, so if the rads do shut off, the underfloor stops anyway.

Having been told the underfloor needed to be on a couple of hours before the rads and would need to tick over all night, the main problem has been keeping the place from not getting too hot! Even in the cold weather, the underfloor is only coming on for about 1.5 hours in the morning and is still warm in the evening.

The system now works a treat and I am over the moon with the underfloor, but I wouldn't recommend the VR61 for a combi.
 
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I have a Vaillant system boiler, VRC430 and VR61 with Unistor cylinder, one rad zone (1st/2nd floor) and 50 sqm of UFH (ground floor) on a second zone, with an Esbe mixing valve.

The UFH zone is controlled by the VRC430; the rads by a VR81 unit.

There is a Vaillant LLH and a pump for both the rad and UFH zones.

All works very well indeed. Look at the system config diagrams in the VR61 installation manual.
 

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