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Thread: Ideal Vogue & Opentherm via Honeywell T6 Lyric (wired version)

  1. #11
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    Is there really any need for flow temperature to go below 45 degrees ? I've experimented with very low flow temperatures to see how much heat is put out (mainly for working out an ideal flow temperature shut off point for frost protection purposes) and it doesn't seem like you'd get any worthwhile amount of heat in the 30-45 degree range, even to maintain status quo in warm weather. Modulating from 45-80 degrees should be more than enough, as that's a 2.4 to 1 heat output range assuming a room temperature of 20 degrees. Being able to modulate as low as 30 degrees seems to be only of academic interest.

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    Quote Originally Posted by DBMandrake View Post
    Is there really any need for flow temperature to go below 45 degrees ? I've experimented with very low flow temperatures to see how much heat is put out (mainly for working out an ideal flow temperature shut off point for frost protection purposes) and it doesn't seem like you'd get any worthwhile amount of heat in the 30-45 degree range, even to maintain status quo in warm weather. Modulating from 45-80 degrees should be more than enough, as that's a 2.4 to 1 heat output range assuming a room temperature of 20 degrees. Being able to modulate as low as 30 degrees seems to be only of academic interest.
    I guess every home is different, what if you have fan convectors, large rads or underfloor heating where you have a max flow temp of say 45C but then want it to modulate down to 30C. It needs to cover all scenarios really. Given the main information is the room temp this is most important. The boiler should then only lower as low as it needs to go, so if it can lower to 45C but still the temp is going up then it then can lower further down to hold that if it then sees the room temp dropping then it will correct it. You only need as much heat as the house is losing so the more modulation the better. My house for example, very well insulated, massive double rads in all rooms once the house upto temp I can get away with keeping the house at 21C with a flow temp of 35-40C especially in Autumn or spring. Limiting the min flow temp via the boiler pcb is quite a crude way of doing it. You should perhaps be able to set this yourself in the boiler menu similar to how you can set a max flow temp.

  3. #13
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    Quote Originally Posted by richardc1983 View Post
    Attachment 877

    Here it is
    The OpenTherm wires aren't running in the same cable as the 230v wires are they (as I can only see 2x wires going to the R4H receiver box, which I assume one is going to boiler and other is to the thermostat).

    Running OpenTherm wires in the same cable as 230v wires is a definite no no and must be run separately - this is known to cause issues!

  4. #14
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    Quote Originally Posted by richardc1983 View Post
    I guess every home is different, what if you have fan convectors, large rads or underfloor heating where you have a max flow temp of say 45C but then want it to modulate down to 30C. It needs to cover all scenarios really. Given the main information is the room temp this is most important. The boiler should then only lower as low as it needs to go, so if it can lower to 45C but still the temp is going up then it then can lower further down to hold that if it then sees the room temp dropping then it will correct it. You only need as much heat as the house is losing so the more modulation the better. My house for example, very well insulated, massive double rads in all rooms once the house upto temp I can get away with keeping the house at 21C with a flow temp of 35-40C especially in Autumn or spring. Limiting the min flow temp via the boiler pcb is quite a crude way of doing it. You should perhaps be able to set this yourself in the boiler menu similar to how you can set a max flow temp.
    You have a good point, I hadn't considered UFH, but is it standard practice to have UFH without a mixer valve of some sort to reduce the temperature from the main boiler/radiator flow temperature ?

    I have no experience with UFH so I don't know, but if the required flow temps are very low it doesn't seem that the system would work well with UFH demanding a low flow temp (even if the boiler could modulate that low effectively) and radiators demanding a high flow temp at the same time ?

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    Quote Originally Posted by DBMandrake View Post
    You have a good point, I hadn't considered UFH, but is it standard practice to have UFH without a mixer valve of some sort to reduce the temperature from the main boiler/radiator flow temperature ?

    I have no experience with UFH so I don't know, but if the required flow temps are very low it doesn't seem that the system would work well with UFH demanding a low flow temp (even if the boiler could modulate that low effectively) and radiators demanding a high flow temp at the same time ?
    I guess you can use mixer valves (if you have mixture of rads and UFH but on a modulating boiler with ALL UFH you would just set the max flow temp and then you have zone valves which behave like radiator TRVs reducing flow as rooms come upto temp. On the Ideal Vogue boiler you can have 2 zones on it so you can have one for UFH and one for Radiators, both controlled by the boiler so no need for mixing valves as the boiler does all the work.

  6. #16
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    Quote Originally Posted by richardc1983 View Post
    I guess you can use mixer valves (if you have mixture of rads and UFH but on a modulating boiler with ALL UFH you would just set the max flow temp and then you have zone valves which behave like radiator TRVs reducing flow as rooms come upto temp. On the Ideal Vogue boiler you can have 2 zones on it so you can have one for UFH and one for Radiators, both controlled by the boiler so no need for mixing valves as the boiler does all the work.
    Multiple OpenTherm thermostats can't work together so Vouge couldn't do this on its own - evohome is the only system I know that can incorporate multiple and differing technologies under OpenTherm control.

  7. #17
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    Quote Originally Posted by The EVOHOME Shop View Post
    Multiple OpenTherm thermostats can't work together so Vouge couldn't do this on its own - evohome is the only system I know that can incorporate multiple and differing technologies under OpenTherm control.
    Luckily I dont need that setup just simple radiators (6) and a nice shiny Vogue!

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    Having spent more time than I can ever remember trying to find an installer who understands Opentherm - with very limited success - I am coming around to the view that this is a technology too far for Mr Average Householder. I just want something that is install and forget. The couple of quotes that I have received seem to have factored in the cost of return support visits: hardly, a great vote of confidence in Opentherm.

  9. #19
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    Quote Originally Posted by HenGus View Post
    Having spent more time than I can ever remember trying to find an installer who understands Opentherm - with very limited success - I am coming around to the view that this is a technology too far for Mr Average Householder. I just want something that is install and forget. The couple of quotes that I have received seem to have factored in the cost of return support visits: hardly, a great vote of confidence in Opentherm.
    I agree, the lack of knowledge is because of the lack of info out there. My installer said he wont ever fit one again cos of the issues I have had. No where in the book for the boiler or the manual does it tell you how opentherm works or what to expect. It has something about weather compensation but that's a different control method. It also doesnt state you have to leave for 7-10days and that by the 10th day you should start to see better performance. The technology is great but unfortunately the knowledge out there is poor.

  10. #20
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    Quote Originally Posted by richardc1983 View Post
    My installer said he wont ever fit one again cos of the issues I have had. No where in the book for the boiler or the manual does it tell you how opentherm works or what to expect. The technology is great but unfortunately the knowledge out there is poor.
    This is the same installer who has installed your receiver incorrectly though? Sounds like he hasn't bothered to research the technology first and then moaned after this has cost him money? Thankfully this shows a dying UK installer mentality and is not the mind-set of every installer in the UK, otherwise we would still be fitting gravity circulation and houses without thermostats.

    Opentherm is a great technology and has potential to do amazing things going forwards. There is no 'manual' for OpenTherm as it should just 'work' out of the box - OpenTherm Boiler + OpenTherm Thermostat = Perfection? Well, it would be if the boiler manufacturers stopped playing with the OpenTherm protocols.

    However, you must appreciate this is 'new' to the UK and we are currently behind our European brothers. I have learnt lots more this year about how OpenTherm works and should be implemented correctly. Also best practice for OpenTherm heating system design away from the design guides of 50 years ago.

    There are people out there who are very knowledgeable about heating design and OpenTherm (*cough*). From my experience, people who buy 'specialist' technology from the cheap online outlets then moan at the manufacturer when they don't get great support and backup at consumer level is typical.

    Our business tries to bridge this 'gap' but like flying a plane, it is something I would like to do but doesn't mean i should and a level of knowledge, training, experience and understanding is required.

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