What is OpenTherm / Weather Comp

[@kevincranfield5235]

that is a very good explanation of opentherm, however i would like to add that opentherm is a messaging protocol, sending packets of data to and from the boiler and controls, therefore the connections are very low voltage and cannot be tested with a regular multimeter. if wiring in opentherm it is a good idea not to use 5 core and have your mains voltage parallel to the opentherm cables, as voltage can be induced and cause a fault. bell wire is best. by using opentherm you benefit from a slightly more efficient boiler, but by it heating on one fire heat curve you also negate the boiler overcycling, which overtime will not wear out the parts, i.e fan stopping and starting, gas valve opening and closing etc etc.

[@vulcancontinental]

Couple of good points there. Yes the information is data packets which would not appear on a multimeter but with the system isolated electrically you could use the meter to test if the cable was actually in good condition. One point, polarity is unimportant with OpenTherm, two cores, connect to the correct terminals at either end and the control sorts out the rest. FYI Voltage is used room thermostat to boiler, current boiler to thermostat (when I say voltage and current it's chopped up into data packets). VERY important point about multi core cables, data should not be run with power, induction from the power cables can affect the data packets. I suggest running cables at least 50mm apart parallel to each other (although some cables are shielded). Running data across the power, say at 90 degrees, is unlikely to have an effect.

[@richardkingadi5511]

I was very glad to find this video, as I am about to commit to adding Weather Comp. to my 5 year old Worcester Bosch... I have my fingers crosses, as it is hard to know just how much the savings might be!

[@johnboddington]

Never fitted a Vokera, possibly never will, but David is great and I found that very interesting, Cheers

[@vulcancontinental]

That's kind and disappointing in equal measure

[@johnboddington]

Never say never! Looks a good boiler, but there are many other good boilers out there too now with good warranties and well priced. Not many Vokeras in my area at all (Wiltshire)

[@thisall4real]

my vokera 8 yr old. still going.

[@martynlewis4344]

I fitted a Baxi 800 working with a Nest on OpenTherm at my own house and its a massive improvement on the old system which was a Halstead Combi on 240 VAC thermostat switching. OpenTherm is way better than weather compensation, in my experience you ask the customers if their cold and the answer is usually "yes" especially if they are elderly.

[@AllenHart999]

Thanks for the feedback.

[@richardhodgson7443]

A video on setting up open therm and weather comp would be great please 👍

[@richardhodgson7443]

Also, is nest/hive similar to open therm? Are they essentially the same thermostat controls? Thanks, I am an inquisitive learner..

[@vulcancontinental]

@@richardhodgson7443 Nest has got OpenTherm embedded software, Hive has not.

[@joncoke8208]

Agree

[@bockersjv]

Great video and good to see information on this. I upgraded to a Nest Thermostat on my old boiler I wasn’t aware of opentherm. Then I had a new boiler fitted, Baxi 800, and my Gas Engineer told me about opentherm and its benefits, especially boiler longevity. It does take a while to get used to, especially when sometimes the rads are lukewarm. However the that room temps are constant and don’t swing between 18 and 22c, that they did when it was just set as simple on off, is important for general comfort. Early days but bills so far seem to be between 5 to 10% lower. The fact that it is more efficient and less emissions is of more importance to me. I used to think the Nest was overpriced but realised I was just not using it correctly. Hive does not have opentherm! Please do more on this subject, there is precious little information out there.

[@vulcancontinental]

I hope I'll be invited back to do more. Don't forget not all OpenTherm is the same. The short explanation I use is the language is the same but the words used are not always understood between different differing manufacturers products and definitely some manufacturers have used more of its capabilities than others.

[@LordJasonKing]

How do you wire the vokera Unica erp? sensor with a nest??

[@vulcancontinental]

@@LordJasonKing do you mean the external sensor or the OpenTherm BeSMART? In the terminal strip on the back of the control box there are six connections. We always use the same colours; black for standard room thermostat (24v), orange for external sensor and pink for open therm

[@vulcancontinental]

@@LordJasonKing I answered this but it seems to have got lost. The Unica i has a connector block with 6 terminals, we always use the same colours for internal wiring. Black is ON/OFF room thermostat (24v), orange is external sensor and pink is OpenTherm. The Unica HE is different. Ask again if it's the HE model you're looking at.

[@LordJasonKing]

@@vulcancontinental thanks so much. Wired the sensor in 😊. I've a nest 3rd generation. Can I set that up as an opentherm? I'm guessing it's wired as an on off. I'm sort of assuming that the opentherm goes to. Pink from the nest? Does opentherm compete or conflict with weather comp? Can they be used together?

[@louisvl10]

thanks for the breakdown of the modulation logic. im trying to build something with open source software and sensors with radiator electric valves per room to save some money. this is crucial information to figure this out, cheers :)

[@AllenHart999]

Thank You

[@joncoke8208]

Great video allan i always new about open therm and weather comp but was unsure what it actually did this has cleared alot up

[@AllenHart999]

👍👍

[@imranmajid1978]

Very well explained, please can you give some more examples of these types of thermostats and if they actually form a cost saving in real life.

[@vulcancontinental]

That'll be a long article I'm afraid and one where there's no definitive answer. You could buy an Aygo on the promise of 60mpg then drive like a maniac and get 40mpg.

[@dickie997]

The Vokera BeSMART is an open them controller

[@vulcancontinental]

@@dickie997 actually it is both OpenTherm or ON/OFF, just choose which of the marked cables to use

[@johnburns4017]

Weather compensation can work on OpenTherm, however some do not. Weather compensation: ♦ raises the boiler flow temperature when the outside temperature cools; ♦ lowers the boiler flow temperature when the outside temp rises. Weather Compensation is _feed forward_ control. That is, it anticipates the _coming_ heat loss, or heat gain, adjusting the heat input to the building to suit. eliminating a cold spot. A simple thermostat is feedback control, it only injects heat into the building after the inside has cooled. Some may have a room temperature sensor (called a stat for domestic use) to trim the final target room temperature off. If you have TRVs all around then no need for this. Weather compensation, as stated, keeps the boiler temperature as low as possible to maximise efficiency. Set up properly, they can almost eliminate boiler cycling. With a boiler that modulates very low, say going down to 3kW, it may hover the burner at around say, 3.5kW for long periods, with the burner never switching off. Perfectly matching heat demand.

[@kevincranfield5235]

nice explanation

[@vulcancontinental]

I can't help but add Vokera's OT can work with WC and can take the outside temp from a wired sensor, a RF sensor or download it from a weather station

[@kevincranfield5235]

This is an important issue as a lot of weather compensation is heavily relied upon the installer fitting the sensor correctly, as it is essentially a thermistor, thermostat resistor and the boiler relies on accurate information to best change the parameters, of the sensor is not facing the correct way or obstructed etc it can cause the whole system to go out of whack. I see this many time’s when on warranty calls, the installer just drills a whole through the outside wall of where the boiler is mounted and attaches the sensor, regardless of which way it is facing.

[@johnburns4017]

@@vulcancontinental _"download it from a weather station"_ This is becoming more common, eliminating the hassle of wiring and finding a proper sensor location on the north side of a building. I think Navien were the first in the UK with this function.

[@johnburns4017]

@@kevincranfield5235 Too many cowboys out there. Many are jobbing plumbers who just do not understand heating control. Downloading the local outside temp from a weather station is the best way for the stupid.

[@daleatkinson7901]

Great video Alan. Please do more of these videos 👍

[@guinnessdublin4669]

Very good clear explanation of this type of control, just one thing though does a Nest Thermostat for example take into account outside temperature when trying to reach inside temperature like a weather compensator does & both comply with Boiler Plus regs?

[@craignixon4468]

Nest can get approximate outside temperature from the internet and use this somehow? But most times o/s temperature is directly connected to boiler itself. I have a feeling that if you use opentherm the o/s temperature is for information only (its used with normal on/off thermostat)

[@1Monaghan]

Great idea from an efficiency point of view however the problem is when customers like to blast the heating hot to dry clothes on radiators then they you’re gonna get a phone call asking why the radiators aren’t heating properly.

[@kylejoel87]

Would love a video on how to set things up regarding weather compensation.

[@farukadam1696]

Very good explained about open therm boiler

[@scobeno1911]

Good video. My experience of weather compensation is it ain’t worth the hassle. Most new builds have it fitted to meet low energy rules but constantly get sent out to houses complaining that the radiators aren’t getting hot. People put heating on and expect radiators to get piping hot. Weather comp can stop this happening and end up having to disconnect it to keep customer happy. End users just don’t get the way it works and it isn’t explained to them in the first place. Just to add, as Alan says, read the instructions. Electricians should know better than to run the low voltage weather comp wire alongside the mains voltage cable, can cause interference and clearly states in installation instructions not to do this .

[@chocfinigan]

Fantastic and very well spoken.

[@SuspiciousAra]

Convince me to go opentherm again after a TADO wireless receiver's cr.ppy designed board burned completely because of the flaws in the power design and damaged my expensive boiler and now i have to use classic on/off RT to be able to have heat during winter. It is the case with every manufacturers, even Google nest. just wait a few years and you will see. Mine worked for only two years.

[@col4022]

Allen, any idea how much it would cost for a central heating installation for a 2 bed terrace house, theres 2 rooms downstairs and a bathroom. Would need a combi boiler, pipework and radiators + installation.

[@dickie997]

I would like to add that WC and OT make a boiler comply with Boiler + regulations.

[@richardnixon8410]

so would you have the baxi weather flue sensor and an open therm together on the same system ?

[@MrHandsomejackuk]

so is it possible with opentherm to actually monitor all the boiler parameters using it... for instance is it possible to see boiler flow and return and dhw actual temperature pump speed and any other parameters of the boiler... i have a baxi 224 and thinking on getting a nest but not sure it will show me all these parameter ?

[@virginsim8024]

Really good explanation. Thanks

[@AllenHart999]

You are welcome!

[@dontcare32123]

Great video and very informative. I have an older Ideal Logic Combi 30, recently wired for OpenTherm and I was wondering if you can tell me if I need to fit a link wire across the room stat/timer connections? Ideal state it doesn't need a link wire but I notice Allen installed one with his Ideal Vogue Max OpenTherm installation and I have read of other Ideal users installing them with OpenTherm, hence my confusion. Thanks.

[@LordJasonKing]

Can you have opentherm on a nest and have weather comp also? Do they compete or conflict?

[@Chaos43075]

Should TPI be used in conjunction with Opentherm or simply Opentherm on its own?

[@stuartcarr7717]

Allen I use hot water tap the turn it off the boiler seems ages to turn off

[@joemurgatroyd7174]

david you bloody legend

[@johnboy1232]

Very well explained, thanks.

[@puddle_puddle]

My new-ish build came with a weather compensation. Absolute crap - Unless it was litterally freezing outside the radiators never got hot enough to get anywhere near comfortable inside. I would go for opentherm if I had the option, but I don't with this boiler.

[@AllenHart999]

Thank You

[@brendanwallace4661]

What Vokera model is Dave talking about?

[@shaunwalsh6354]

I’m having a Viessmann 100 35kw boiler installed with a Nest controller, and I believe it has open therm so is there an benefit to fitting an outside sensor and using weather compensation?

[@owenattewell3910]

Thanks for the video, In what situation would you recommend each form ? Weather comp seems ideal for a property that has had a full heat loss calculation done on the property, is on a modern designed system? Would you agree WC is proactive in operating As OpenTherm is a form of Load Compensation but would it be more suited to houses that haven't had the system upgraded (newer rads etc) as it is more reactive in operating Just open to learning more which would be better recommended

[@vulcancontinental]

Very tough question. Oddly the more oversized the system the better WC can be exploited. I have my own views on effectiveness but I'll back off and say the EU with ErP data rate WC as 2% improvement and OpenTherm on a modulating boiler as 3%. Both combined as 4%. So much depends on circumstance, occupation patterns, customer expectations, structure etc. Even whether an existing boiler can accept WC or OT and if so in OpenTherm's case, is it compatible with a particular boiler.

[@owenattewell3910]

@@vulcancontinental I agree that there are too many factors to directly say one is better than the other. This might sound like a stupid question but I can't get an actual answer for it......can you use both on the same system or will they conflict . Unless they are the same brand and designed to work with each other

[@vulcancontinental]

@@owenattewell3910 I can only answer for Vokera and say yes you can use both; don't even need a sensor with our BeSMART, just download the weather although I think a sensor is better personally. I honestly can't say X% will be saved and anyone who does say that I'd ignore. The EU say 2% with WC, 3% with OT and 4% if both combined; is this accurate, who knows, too many variables, what boiler, what control, what construction, what were the customer expectations?

[@vulcancontinental]

@@abhisheka1849 I'm not familiar with Heatmiser but OpenTherm can certainly work with multiple zones, I'm in the middle of testing another brand, not Vokera, at the moment. Our own BeSMART works with multiple zones but we would not support it on another brand boiler so it's not worth you experimenting. The latest boiler, the Vision Plus, can operate dual zones at different temperatures although we're not really releasing details yet. OpenTherm can drive cascades of boilers, it's just finding the right combination of control and boiler that work together.

[@glamour9617]

Is there any possibility to connect opentherm to worcester boiler?

[@thisall4real]

How much (roughly) does opentherm save v standard codensing boiler running open/close relay? 10%, 20%????

[@lorenzotaurino]

Can the tado termostat modulate according to the outside temp?

[@plumbertime]

Isn’t it funny how years on, the best way and cheapest. is still don’t have a room stat and just turn the boiler stat down in summer and slightly higher in winter if needed. It’s also the cheapest as you only turn it on when cold!

[@vulcancontinental]

The best monitor of temperature is yourself so you're right in a way but you have to want to make the effort, most people want to do less and government regs. want to take lazy humans out of the equation so they legislate for theoretically more automatic efficient controls and the having the most effect for the least expense or inconvenience. They also know high fuel bills can have an effect on the balance of payments and who votes where if the the voter feels poor.

[@mgbroadsterJ]

can I use open therm and weather comp on the same boiler .

[@LordJasonKing]

Alan. Can you use this with a nest?

[@ianmacdonald2566]

Hi Allen and David. Connected the nest to the Vision Plus with opentherm, is the no way to control dhw temperature? Also on the manual to enter combustion mode it asks to disable the connection by setting the parameter p8.03 to 0 but the parameter only goes to p5 any more info on this?

[@45graham45]

how do you enable weather compensation in a Baxi?

[@dannyhalliday4873]

Just out of curiosity, would a boiler that reaches temperature then goes off be more efficient that a boiler that reaches temperature but the modulates down but stay lit using gas. Surely a more efficient boiler is one that isn’t costing money to run as it’s turned off

[@johnburns4017]

Weather compensation at times is not the way to go. If you have say a Kickspace fan heater which require a reasonably high flow pipe temperature, weather compensation may reduce the flow temperature too low, not giving effective heating from the Kickspace. So, know what you are fitting and in what application.

[@marka4706]

good explanation

[@stephendoherty8291]

My view is sadly that WC is a total mystery to most installers. None have offered it as a worthwhile extra. Most gas boiler users south of Leicester or where the winter temp does not fall to near double digit cold temp. Yet Bosch-Worcester does not support Opentherm in UK/Ire even if Bosch can do it in Europe. How many boilers offer setback? From listening it would seem that condensing feature is only of use when the boiler is operating at a low effort and the return flow temp is lower to the higher outflow temp. Why is WC not standard fitting like mag filtering has become. Power flushing is still a rarity offered

[@kieransidhu]

Thank you!

[@paulhill1665]

Have weather comp, best thing since sliced bread, boiler seems to run on air,

[@vulcancontinental]

Glad you like it but I know other people whose life patterns, comfort level requirements (and budget) that have taken it out. Horses for course. Around a 2% saving may be possible I reckon.

[@paulhill1665]

vulcancontinental had a new boiler fitted at the same time, Vitodens 200, so difficult to say how much of the saving is due to the compensator, have warm radiators, rather than hot, is no issue for me, just happy with the savings.

[@vulcancontinental]

@@paulhill1665 the WC on that boiler is supposed to be very good, highly rated by it's fans and more importantly is adaptable as a basic version of WC is a really blunt instrument. I heard about an installer Monday who likes the 200, put WC on it for 6 month then took it out, just personal opinions. In my opinion the biggest factor isn't the boiler, isn't the WC or OT, it's what is replaced as that's the benchmark you're starting from and you can look for 10 - maybe 14% improvement on the new boiler alone.

[@paulhill1665]

vulcancontinental if a

[@JesusChrist108]

I literally needed to know this today and here we go ha

[@paulw4904]

Great explanations but these technologies are no good for 80 year old 6 stone ladies when they want/need the heating to be on full blast to keep them warm & comfortable I find.

[@vulcancontinental]

I get into arguments with guys who say they fit nothing but WC or OT. We are a service industry, the customer is always right. It's not my job to give them something they're not sure of or will worry them about cost or disappoint them. If it's within regs and they want it I'll do it but I always explain their wishes against 'if I lived here this is what I'd do' then they can have what they want and I've done my best for them.

[@songzhou]

One penny save is one penny earn

[@AllenHart999]

Thank You

[@rayjaken]

Hi! Thanks for this video. I am about to buy a Ferroli RRT 34 boiler, to control the hot water and heating in my flat. The installer is offering me the Ferroli Connect Smart WiFi, that I don't like at all. I want to install a Google Nest Learning 3rd Generation. I know that the Ferroli RRT 34 supports OpenTherm according to the instructions manual. But I have seen some comments online saying that, if you really want to get the most of this boiler, you'd better use the Ferroli thermostat. Can anyone actually explain what kind of things I can do with the Ferroli thermostat that I can't do with the Google Nest? Anyone out there using this boiler with Google Nest? Thank you all.

[@AllenHart999]

This is a Vokera

[@rayjaken]

@@AllenHart999 thanks. Do you know if Nest would work with Ferroli RRT 34 though?

[@Bro-ex3su]

👍

[@alexmeyer9873]

Is a nest considered a weather compensator?

[@davidvokera535]

To make things easier to understand and install the various weather compensation sensors on our boiler models I've made this presentation. Hope it helps. kzbin.info/www/bejne/iYiVi5aZot5pZtk

[@djh1437]

Yes..Demond headmaster

[@ianwelch8935]

Over Complicating , customer saving 3 to £4 a year ...

[@charlottehart4430]

👍🏼

[@veronicahart450]

👍

[@lucyyyy-v3m]

👍🏻