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Thread: Evohome + Opentherm v Evohome + Boiler Outside Weather Compensation

  1. #181
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    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.

  2. #182
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    Quote Originally Posted by bruce_miranda View Post
    I 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.
    Bruce - just a quick to say thank you for your post above. I have a 5 year old Eco Tec 624 that seems to have the same circuit board. I've just installed the VR33, waiting for the opentherm bridge and hot water kit to arrive - similar setup to you with zone valves calling the heat currently. Am hoping to leave the zone valves in place (UFH, CH, HW), remove the switched live from the valves to the boiler, and use the opentherm gateway to call for heat if anything needs it. So your information about the pins to bridge is incredibly useful. I'm hoping in this configuration I can still use the CH zone valve as currently i can't bind it - sounds like I need the hot water kit before it can be properly used as a zone (not all rads have HR92s).

    Will report back just in case there's anyone else with a 624 with this circuit board...

  3. #183
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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?

  4. #184
    Automated Home Ninja Dan_Robinson's Avatar
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    When you've finished monkeying around inside your Vaillant boilers, please don't forget your 26.9 and FGA checks.
    Kind Regards - Dan Robinson (Jennings Heating Ltd)

  5. #185
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    Quote Originally Posted by bruce_miranda View Post
    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?
    Hi 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.

  6. #186
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    Quote Originally Posted by Dan_Robinson View Post
    When you've finished monkeying around inside your Vaillant boilers, please don't forget your 26.9 and FGA checks.
    Hi Dan - assuming you're talking about the gas checks - I wouldn't touch the gas side as I don't have experience nor the tools required to check things afterwards. That was all done by the plumbers who to be fair were pretty good at plumbing. Problem is the plumbers left a fairly crippled set of controls (didn't use the vaillant wiring center so no hot water / heating temp differential, no hot water priority even!!) - my discussions with them about evohome suggested I was better off doing it myself. Not sure if this is common, but the plumbers were pretty vague on the controls, but great at the plumbing itself. There was talk of a friend of a friend who does the specialist controls stuff, and the guys got their boss in to do the wiring as it stands right now.

  7. #187
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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.

  8. #188
    Automated Home Ninja Dan_Robinson's Avatar
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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)

  9. #189
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    Quote Originally Posted by mdurkin View Post
    Hi 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.
    OK - I'm up and running. Jumper between 3 & 4 definitely required, as per Vaillant instructions when using ebus controls (which is what in effect I am doing). I'm less sure about the 24V controls. I don't think they do anything - the boiler fires up with or without, and the Vaillant instructions just say not used in the UK. I wonder if there is a European manual somewhere that would show how to wire them. I've left 7 & 8 with a jumper anyway for now.

    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

  10. #190
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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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