Having Opentherm error issues with navien LCB700 oil combi boiler.
Hi, I just installed my Wireless Receiver, temp sensors and rad valves etc this evening, its too hot to test thoroughly as my house is so hot today the heating cant come as the rooms are all too warm.
I managed to set one room half a degree warmer than it was (set to 25deg when room was at 24.5) and the boiler came on, water pump only and circulated warm water from the internal heat store - burner didnt light (this feels correct to me as there would have been very low demand for heat) so im assuming all is working fine.
HOWEVER
im having some intermittent (sometimes every 2 mins other times it goes half an hour or so) opentherm errors displaying on my boiler NAVIEN ERROR CODE 783 sometimes these last a few seconds and the boiler screen just flashes red then clears and the error can be viewed in the logs. other times the error will stay on screen for some time and its even cuasing the central heating to erroneously turn on which would bwe sending hot water round a short circuit as all the rad valves would be off in this hot weather.
the errors i could live with - but the boiler turning on when it shouldnt is a real worry.
how can i debug this - how can i find out what opentherm requests the tado is making when the error is displayed on the boiler. i really dont want to have to wire this up in relay mode and lose the modulation opentherm provides... i need log files so i can work out whats going on...
any help appreciated.
Edit: Temps have gone down a bit and managed to call for a 2 degree increase and the boiler started up as expected. so it does seem to be working. however the opentherm errors are happening every couple of minutes while its actually heating...
faulty, tado ? faulty boiler main board ? not compatible ? i dont know where to turn to diagnose this. neither the boiler nor tado seem to expose enough info to assertain the problem.
Best Answer
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I have now had what I understand to be a main release firmware from Tado for the Wireless Receiver.
this is firmware 181.0.
All firmwares after 101.2 and before 181.0 contain the bug where the opentherm message bitrate is too high for some (including Navien) boilers. I think most boilers are more tolerant of this too fast bitrate which is why the issue went for so long without being fixed.
I'm happy to say I've been testing this new firmware for a week and its working great. (Still with the issues that Navien need to fix though)
Thankyou to the engineer that worked with me to fix this - I did have to "go over the heads" of 1st line support to get someone with the appropriate knowledge and interest to get to the bottom of it but in the end its all working. I can only hope that there's some internal memo or training to help the 1st line support (and whoever they attempted to escalate it too several times) understand the difference between a typical "user error" type support request and my genuine "hey, I have a boat load of technical proof your software is faulty" request...
Anyway... can I now recommend the system with a Navien LCB700 Oil Combi... If you can live with DHW being stuck at 50degC (this is just hot enough in my house for the mrs to run a bath with the hot tap only and she just needs to top it off with a bit of cold before getting in). and your happy either leaving DHW on all the time or using the boilers built in front panel scheduler to turn it on and off then YES it does a fantastic job of modulating the boiler for CH purposes and I've lived in this house for 20 years with a bang/bang relay system and mechanical TRVs and I'm blown away how consistent room temps are compared to that old system. (must make sure the wireless receiver updates to v181.0 or later)
Now to shift my focus to the Navien engineers to try to get them to fix the DHW issues their end.
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Answers
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Have you asked Tado support whether your boiler is compatible? That might shed some light on it.0
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i chatted to a tech before purchase - he was confident it would work seeing as my nest controller was operating it correctly before that. I assume he knew that if nest could control it then so could tado.
having spent multiple hundreds of pounds in 5 or so seperate purchases im going to have a nightmare returning this whole setup if it doesnt work -
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It seems odd that it would work with nest and not with Tado. You could try adding an Opentherm gateway to see what’s going on.0
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I have a works do tonight so will get back on this Thursday evening - if i need to invest in a opentherm gateway to debug this i will... but first id like some reassurance from tado/navien that it should be working. I'm going to try and refit the nest and see if that does indeed still work.
Opentherm is opentherm right - it should work - tado is opentherm, my boiler has opentherm???
how can i tell if the opentherm connection errors are physical / link layer OR data layer i don't know if there's a physical issue with the voltages / ampages being transmitted and received or if its interference or a software issue and the tado is transmitting garbage or if the tado is sending valid opentherm commands and requests and the navien just doesn't know what to do with those. etc etc etc
It seems everyone is just using opentherm on a wing and a prayer and none of the systems give out any meaningful error codes or logging to debug it when it doesn't work.
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Still hoping to find another TADO=>OPENTHERM<=NAVIEN user in the community here somewhere. I switched the boiler back to my nest opentherm controller and played around increasing and decreasing thermostat temps and the boiler behaved as expected - and most importantly no errors. When i switched back to Tado opentherm i got about 10 mins of use before the errors started flooding in again.
Support say it should be working, and are looking into it - but you cant beat someone with the same or similar setup to give you there words of wisdom.
Ive ordered an OTGW so if support dont get there first ill hopefully be able to give them a nudge with some data
Just really need to get this sorted before winter is here...
Any help or ideas of things to try would be great.... Is there a way to access opentherm logs from the tado api ?
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got myself an Opentherm gateway.
With the opentherm gateway in between my tado and the boiler - it all works fine - all the errors are gone from the boiler (presumably blocked or corrected by the gateway)
any suggestions as to why ??? I have 2 theories.
- the opentherm signal from the tado is not to spec or faulty in some physical link layer way. I have confirmed the voltages are very slightly out of spec with my oscilloscope low voltage is 7.2v and high is 15.4v but it is this .2v out of spec on the low voltage enough to cause all the errors I get on the boiler. The opentherm gateway is obviously then retransmitting the messages in spec (i havnt measured this with the scope yet)
- the opentherm gateway in "gateway" mode is correcting or blocking some of the opentherm messages that the boiler doesnt understand thus preventing the errors.
anyone got an idea how to narrow it down ive attached the opentherm gateway logfile - near the end i switched it from gateway mode to monitor mode and you can see normal communication just changed to the tado transmitting the same messages over and over and getting no response from the boiler. (based on the behaviour, my gut tells me its because the out of spec voltage, but my brain asks is my boiler really going to sensitive to that .2 of a volt error.
Any help, info or suggestions gladly received
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Hi Roycruse,
Did you get the Tado system to work correctly and are you happy with it now?
We're just about to have a Navien 700 oil boiler installed and looking at having a Tado system.
Thanks
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Tado are replacing my wireless receiver as it is suspected to have a too high bitrate on the opentherm interface (see this discussion here https://www.domoticaforum.eu/viewtopic.php?t=14111 )
I will update here if the new unit solves the problem or just suffers from the same issue.
My Tado is transmitting opentherm at around 0.92ms per bit and opentherm is supposed to be 1ms per bit. That said the spec does allow for some leeway.
The best diagnosis we have so far is the tado is too fast and the navien not tolerant of this. Your mileage may vary.
Once I get the new Tado unit I'll re measure everything and see if I'm in the same boat or not.
HAVING SAID ALL THAT.
If your a tinkerer - putting an opentherm gateway in between the two fixes the timing issues and provides a working system that is really good. (ive got 4 room and 6 smart valves) The tado calls for lower or higher CH flow temp based on the demand from the rooms and radiators.
DHW is also able to be switched on and off but the navien is ignoring the temperature requests from the tado and gets locked on delivering water at 50deg c but i think this is a uk law anyway.
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An update on this...
Tado eventually replaced my wireless controller and initially the replacement worked. BUT an hour or so later it firmware upgraded to latest firmware and stopped working again. so somewhere between firmware version 47.3 and 140.6 they broke the opentherm bitrate timings !!! trying to get Tado to escalate this to a development team is taking its time... at leazse i now have proven to its a software issue so its fixable - just need to wait and see if tado will put the effort in to fix it.
I also wanted to update on the DHW... even though tado thinks its enabling and disabling the DHW on the lcb700... its NOT. the hot water just carries on doing what ever setting you have it on on the boiler ie off, always on, its internal scheduler, etc. Such a shame this isnt working but i think this is a Navien issue not tado (unlike the timing issue above which is definitely tado) so i have a support case open with navien which has been forwarded to the manufacturers in Korea :/
Central heating control though (with the opentherm signal corrected by my Opentherm Gateway) works great but unless your prepared to go down this hacker/tinkerer route I cannot currently recommend Tado with a Navien boiler and opentherm control. I really hope this situation will change with a firmware fix.
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Sorry, can't be of any direct help but similar sounding issues with an ideal combi using opentherm here (link below). Asked the community and got nothing, best guess OT isn't widespread enough in the UK. tado support were totally useless for me, but you have validated my thoughts to obtain an OT Gateway.
CH is now in use and does work as you'd hope with OT, only real problem we have is the boiler running at a requested 0 degrees every other day or so.
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Thought I'd post an update as its been another month. I'm finally getting the help I need from Tado, its a shame but I had to go over everyone's heads on the support department to get it to happen - but I now have a point of contact that has uploaded some trial firmware to my wireless receiver and fixed the comms issue. The test firmware unfortunately introduced additional issues so couldn't be left in place but I'm hopeful once he has ironed those out the comms between my Tado and Navien Boiler will finally work with and without the OTGW in place.
Turns out the bitrate was slightly faster than the opentherm spec of 1ms per bit on the Tado and the Navien is not tolerant of this (the spec only allows for up to 10% too fast)(I have separate support tickets open with Navien about this too). The Opentherm Gateway is tolerant of the too fast bitrate - it receives the too fast message from Tado and re transmits it at the correct bitrate and makes it work. Other brands of boilers may be more tolerant of this too fast bitrate and work fine and others may not be.
The remaining issues I'm having with DHW enabling and disabling and temperature setting is all down to the Navien boiler not doing what its supposed to - I have checked and triple checked against the opentherm spec that Tado is sending the correct opentherm commands and they are, so those parts of the problem are definitely for Navien to sort. Navien have just responded and are purchasing an Opentherm Test Kit to get to the bottom of my support requests.
I'll update again once I have a firmware version from Tado that does not require the OTGW to correct its signal.
Fingers crossed its not too far away :)
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Thanks for the updates0
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Do I buy the Tado now while its on offer ?
🤔So frustrating that it's taking such a long time to resolve. Well done roy for sticking with it !
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Its working on firmware up to and including 101.2 of the wireless receiver (which i had to buy from the uk Tado professional shop as its not sold in the uk to consumers https://uk.installers-shop.tado.com/products/wireless-smart-thermostat-starter-kit-v3-eu-version )
by default the wireless receiver will update to 140.6 which definitely doesn't work with the Navien lcb700
Id be interested to know what mainboard firmware your lcb700 is running as your boiler is presumably a bit newer than mine
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Same firmware version as yours. System was installed on Wednesday. On your last post Roy, are you saying that the Tado connection / TRVs work with the EU kit? I've seen the kit on professional site but presumed it had the same issues. Is there a way of stopping the Tado wireless firmware update?
Thanks
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yes, the eu combi kit works fine with the uk stuff like rad valves and add on thermostats.
no, unfortunately theirs no way for you to stop the firmware updating yourself - engineers at tado can but i dont fancy your chances of finding any first line support staff who will understand your plight.
The guy i was talking to said i would get an update this week - but i havnt heard from him yet. so will chase next week.
on top of this tado opentherm comms issue there are issues on the navien end surrounding DHW but if your happy with your dhw being locked to 50degC and leaving it turned on all the time or using naviens own timer on the boiler front panel then the tado opentherm works great controlling the CH.
overall im still not happy enough to recommend it as a solution just yet
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Hello, did you manage to get your hot water issue sorted?
Am thinking of installing an LCB700 Heat only, with Tado on OT. I imagine this will open another can of worms, wiring cylinder stat directly to boiler.0
