Apparently the Vaillant 4 series is a UK only model that is made in the UK in the Glowworm factory. Having said that whenever I've looked inside the boiler I've seen no trace of any Glow Worm stuff. Unlike when I dig into a Mini Cooper and find BMW parts all over the shop. That's said, I am glad that the PCB and it's firnware is Vaillant, atleast I could use the VR33 and hence OpenTherm. Any way this update was to provide the Glow worm chap some hope. But looking at the PCB used within the Glow worm it doesn't look like the VR33 will naturally fit any way.
Evohome + Opentherm v Evohome + Boiler Outside Weather Compensation
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Originally posted by bruce_miranda View PostI have finally managed to get the Opentherm bridge to fire up my boiler on a Vaillant ecotec plus 438. I put back the jumper between 3 and 4, without this the boiler doesnt fire up. Once 3 and 4 is connected the boiler is expecting to see an analogue controller on terminals 7 8 9, otherwise it is constantly firing up. If i put a jumper between 7 and 9, the D.09 just shows me 0, which basically means that the OT bridge isn't doing anything. If instead I put a jumper between 7 and 8, the OT bridge is not only able to vary the target temperature but is also able to fire up the boiler! So it looks like a jumper between 7 and 8 is the equivalent of the 24V RT on the modern boilers.
Will report back just in case there's anyone else with a 624 with this circuit board...
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The Vaillant 438 uses 0020036861 PRINTED CIRCUIT BOARD and the Vaillant 624 uses 0020132764 PRINTED CIRCUIT BOARD. So not exactly the same. However if your PCB also doesn't have the 24V RT connections but instead has the 7-8-9 then you may be able to do what I did.
UFH valve needs to stay - will be controlled by a BDR91 and T87RF
HW needs needs to stay - will be controlled by the HW BDR91 and it's sensor
CH valve can be run off it's own BDR91 is the Hot Water S Plan configuration, or can be run off the Boiler Pump feed.
If all rads don't have HR92s, how will those rads call for heat?
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Originally posted by bruce_miranda View PostThe Vaillant 438 uses 0020036861 PRINTED CIRCUIT BOARD and the Vaillant 624 uses 0020132764 PRINTED CIRCUIT BOARD. So not exactly the same. However if your PCB also doesn't have the 24V RT connections but instead has the 7-8-9 then you may be able to do what I did.
UFH valve needs to stay - will be controlled by a BDR91 and T87RF
HW needs needs to stay - will be controlled by the HW BDR91 and it's sensor
CH valve can be run off it's own BDR91 is the Hot Water S Plan configuration, or can be run off the Boiler Pump feed.
If all rads don't have HR92s, how will those rads call for heat?
For UFH - I'll use the main evohome controller as the thermostat - I've already set that up, seems to work fine. Waiting for hot water kit and opentherm to set up the rest as you suggest. The rooms that don't have HR92s are the porch, downstairs bathroom and utility room. I'm happy for them to be set low via their traditional TRVs (or in the case of the downstairs bathroom just turned down as it doesn't have a TRV) so they'll get a bit of heat if other zones are calling. To be honest we have the porch down low, and the utility has all the UFH tails so the rad never comes on (great room for drying clothes in the winter though!)...
will report back more once all the gear arrives and I've had chance to set it up. Thanks for your help.
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Originally posted by Dan_Robinson View PostWhen you've finished monkeying around inside your Vaillant boilers, please don't forget your 26.9 and FGA checks.
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Whenever you take the boiler cover off you change it's behaviour, hence why there are two CO2 readings in the manual, also you could jam or puncture something.
Good move on using the Evohome panel as the UFH sensor, and you have a BDR91 for the valve in the box too. That was my learning to pass on, I now have a spare BDR91 and a spare sensor!
We built a pantry cupboard around our UFH manifold, to store stuff that doesn't like the cold e.g. Honey, Oils, etc. Same idea.
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Indeed, by very nature of getting at the wiring you are entering the realms of having to be deemed "competent" to work on gas carrying parts.
The only way to prove competence is to have carried out the ACS assessments. But hey, don't worry about it . What's the worst that can happen?
Much like other things in life, not knowing is not an excuse.Kind Regards - Dan Robinson (Jennings Heating Ltd)
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Originally posted by mdurkin View PostHi Bruce - I'll check the circuit board number, but it has the same 7-8-9 connections like yours, no 24RT etc, so at least in that respect seems similar.
For UFH - I'll use the main evohome controller as the thermostat - I've already set that up, seems to work fine. Waiting for hot water kit and opentherm to set up the rest as you suggest. The rooms that don't have HR92s are the porch, downstairs bathroom and utility room. I'm happy for them to be set low via their traditional TRVs (or in the case of the downstairs bathroom just turned down as it doesn't have a TRV) so they'll get a bit of heat if other zones are calling. To be honest we have the porch down low, and the utility has all the UFH tails so the rad never comes on (great room for drying clothes in the winter though!)...
will report back more once all the gear arrives and I've had chance to set it up. Thanks for your help.
I need to see what happens once the heating goes off later - make sure the boiler goes off. I had the impression it was running continuously but then I looked at the following:
I noticed that d.1 was set to 60 (60 minutes pump overrun) - I thought the boiler was never turning off, but I think it was this setting. The default is 5 minutes, so I'm unsure why the installers set it so high. Perhaps with just underfloor running the demand would be very low and not fire the boiler within a 5 minute window, but 60 mins seems very high. Anyone any thoughts on this?
Also - what does d.2 do wrt the fact there is an anti-cycling setting on the evohome controller. What are people setting this to - mine is 20 mins (the default).
I also noticed that d.9 seems to drop to 10 (rather than 0) - is that normal for evohome to send a setpoint of 10 via opentherm?
I also noticed that although d.25 is set to 1 (Hot water activation via eBus), that d.22 (hot water demand) is always 0 even when evohome is calling for hot water. I was also wondering about hot water priority - I had assumed that evohome might have had the intelligence to have this as an option - so to turn off other valves / TRVs when there's hot water demand. I'm assuming it doesn't, and that to achieve hot water priority I would need to wire the valves on a priority circuit?
Any thoughts on the above appreciated,
Cheers,
Matt
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I have HW Priority via a 2 valve bespoke system. The HW is on a standard motorised 2 port valve controlled by a BDR. CH has an inline power off open motorised valve. When HW is demand, the HW valve opens and the CH valve closes. Seems to work perfectly as my installer said it would.
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Originally posted by HenGus View PostI have HW Priority via a 2 valve bespoke system. The HW is on a standard motorised 2 port valve controlled by a BDR. CH has an inline power off open motorised valve. When HW is demand, the HW valve opens and the CH valve closes. Seems to work perfectly as my installer said it would.
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Originally posted by mtmcgavock View PostOr you could just simply provide power to the A port on the BDR91 Heating receiver from port C on the BDR91 Hot Water. (Providing you have two NC MV in your setup).
One other thing - my UFH is just off a BRD91 - just a zone valve. When the UFH comes on evohome opens the UFH zone valve as expected, but it also opens up the heating zone valve. Is this expected? I don't have the heating BRD91 double bound - I cleared it and rebound. Unless perhaps it's in the evohome controller where the binding is incorrect.
I was thinking that perhaps once a zone valve is set for 'heating' in the water kit configuration, it gets opened for any heating requirement - the TRVs calling or the UFH zone?
thoughts?
Matt
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That depends, or so I was told, on what is needed by the boiler to ‘inform’ the boiler of a hot water demand. Atag requires a 3 way diverter valve. This was a compromise/ cheaper way of avoiding the need to re-pipe the heating system from an original ‘S’ Plan.
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I have pump over run set to 20 mins which matches my maximum wait time, so that the pump never switches off unless there is absolutely no heat demand. Also 20 mins is enough time to have the heat slowly ramp down.
The OT bridge assumes all boilers are Heat Only, so having studied the eBUS messages in detail, I can confirm they never send the HW demand flag which would make your d.22 show as 1. The only way to do HW priority is by wiring the BDR91 and the motorised valves appropriately. OT Bridge goes from 10 no demand to 90 full demand. Some Vaillant controllers start from 0, some go from 10.
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Originally posted by bruce_miranda View PostI have pump over run set to 20 mins which matches my maximum wait time, so that the pump never switches off unless there is absolutely no heat demand. Also 20 mins is enough time to have the heat slowly ramp down.
The OT bridge assumes all boilers are Heat Only, so having studied the eBUS messages in detail, I can confirm they never send the HW demand flag which would make your d.22 show as 1. The only way to do HW priority is by wiring the BDR91 and the motorised valves appropriately. OT Bridge goes from 10 no demand to 90 full demand. Some Vaillant controllers start from 0, some go from 10.
Any thoughts on the heating zone BRD91 coming on when the UFH BRD91 comes on - is that expected? It's not the end of the world as most rads have HR92s fitted, so little heat will be wasted, I just wondered if it was normal.
Cheers,
Matt
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