Screened cable

[bernardgreen]

And HTF have they ended up with cables and protocols which can be corrupted by "spurious stuff"? It's surely not high-speed long distance. Do the OpenTherm crowd not have a clue?

if OpenThermÔ Protocol Specification v2.2 7 Februari 2003 is still valid then the OpenTherm physical layer ( signalling method ) looks bomb proof for use in domestic situations

That said that document does include

3.1 Medium Definition- Characteristics of the Transmission Line
Number of Wires : 2
Wiring type : untwisted pair *
Maximum line length : 50 metres
Maximum cable resistance : 2 * 5 Ohms
Polarity of connections : Polarity-free, i.e. interchangeable.
* In electrically noisy environments it may be necessary to use twisted pair or screened cable.

Is this a case of a system being pushed upto and then beyond its intended purpose ?

 

[magicmushroom666]

I tend to do them like this:

And then use some earth sleeving.
Some applications though its neater to crimp or solder into a normal bit of earth cable, especially if its got to run around a panel.

 

[ecowarrior]

"And HTF have they ended up with cables and protocols which can be corrupted by "spurious stuff"? It's surely not high-speed long distance. Do the OpenTherm crowd not have a clue?"

Multizone OT is volatile & sensitive at the best of times relying on Wifi (for the App) RF and good signal is critical. Making sure the signal isnt corrupted is just one more pre-emtive move to reduce nuisance faults. I use 12 & 16mm glands always with YY & CY cable into IP rated boxes (obviously lots of the controls are in & around potentially wet areas. I think between you all you have given me the idea I needed - a gland similar to armoured cable so I can clamp the screen use a washer with a tag & then a bit of earth cable to the connector block. The only down sdide to this is the CY for the OT is 2 x 0.5 so very small in diameter. I am not sure what your statement means nor who the HTF are and again 'long distance' is relative - some runs are perhaps 20M+. probably not long to you guys but when comms faults do arise its good to know its not due to incorrect cabling. One less thing to eliminate. Fault finding OT on a good day is bad enough as often all you can do is shout at it lol. Having said all that - when its working OT controlled heating will save the planet! Set points are just that - set- and modulating low flow temps ensure low flue temps & maximum condensation. As from April all boilers must be OT compliant (& I believe fitted with OT controls). This of course wont happen as there is no OT police but if any of u need a boiler after April make sure you get a OT control stat (with or without the App) As a foot note I would rather not use a armored cable type gland as it will be really clunky but instead deal with it inside the IP box. This pic is not an OT application but gives an idea of the scale of heating electrics (small!) Thanks for all you ideas.

 

[ecowarrior]

if OpenThermÔ Protocol Specification v2.2 7 Februari 2003 is still valid then the OpenTherm physical layer ( signalling method ) looks bomb proof for use in domestic situations

That said that document does include

3.1 Medium Definition- Characteristics of the Transmission Line
Number of Wires : 2
Wiring type : untwisted pair *
Maximum line length : 50 metres
Maximum cable resistance : 2 * 5 Ohms
Polarity of connections : Polarity-free, i.e. interchangeable.
* In electrically noisy environments it may be necessary to use twisted pair or screened cable.

Is this a case of a system being pushed upto and then beyond its intended purpose ?

Yes thats the killer - if you dont use screened and u get an issue - it might just be the cabling causing the issue. The CY is pence more than YY and as someone mentioned as a % of the overall bill its nothing.

 

[ban-all-sheds]

none of us have yet asked the questions that really need to be asked before anyone could really decide what type of termination might be appropriate for the OP's application.

STP?

 

[ban-all-sheds]

Umm...

between you all you have given me the idea I needed - a gland similar to armoured cable so I can clamp the screen use a washer with a tag & then a bit of earth cable to the connector block.
.
.
.
As a foot note I would rather not use a armored cable type gland as it will be really clunky

I am not sure what your statement means nor who the HTF

That's "How the **** have they ended up with..."

'long distance' is relative - some runs are perhaps 20M+.

That's no distance at all, way under uncountably large numbers of networks which happily carry data at gigabit speeds without being easily corrupted.

when its working OT controlled heating will save the planet!

I have a feeling that working is what it might often not do once lots of people have it, particularly in high density housing.

This pic is not an OT application but gives an idea of the scale of heating electrics (small!)

Surely surely surely that cries out for an enclosure with a DIN rail and through terminals?

 

[ban-all-sheds]

The CY is pence more than YY

And shielded Cat6/6a?

 

[ban-all-sheds]

if OpenThermÔ Protocol Specification v2.2 7 Februari 2003 is still valid then the OpenTherm physical layer ( signalling method ) looks bomb proof for use in domestic situations

When they started it there was already a long established bomb-proof set of standards for the physical , link etc layers.

 

[ban-all-sheds]

As from April all boilers must be OT compliant (& I believe fitted with OT controls)

Brilliant.

Lets take a system hopelessly crippled by 20th century legacy issues, which isn't "open" in ways that actually matter, and enshrine it in law in the 21st.

 

[Doggit]

And shielded Cat6/6a

Cat 5 should also be fine, and with the pairs being twisted to cut down on noise, you may not need to earth the shielding.

 

[bernardgreen]

Yes thats the killer

Are you refering to my comment

Is this a case of a system being pushed upto and then beyond its intended purpose ?

The "heating professionals" have created a lust in customers for over complicated and often in-necessary "Must Have" features. Hence the system is forced to do more than it was ever designed for. Made worse by the fact that too many "heating professionals" do not have the necessary knowledge to work on the equipment.

 

[bernardgreen]

Quoting from this
Expanding the functionality

The OpenTherm communication protocol is primarily designed to control modulating heating appliances. As stated above, the protocol offers expansion possibilities which enable the manufacturer to build extra functions into their control devices or appliances as well as the basic function which is compulsory for all OpenTherm implementations. As such they can distinguish themselves from other suppliers and increase the freedom of choice for installers and consumers.


Of course, one must ensure that these extra functions – which are not included in the OpenTherm Protocol Summary’s minimum specifications – are also communicated in a standardised fashion. The Technical Commission of the OpenTherm Association monitors this and ensures that standardised functions are added to the Protocol Summary.


Here are some functions which have already been standardised in this way:
– setting and reading tap water temperature
– switching tap water on and off
– reading the outdoors temperature
– reading malfunctions
– weather-dependent control

Yet the physical data transmission used ( 5-8 volts Binary Zero, 15- 18 volts Binary One ) with power supplied to remote modules ( Slaves ) from the central controller ( Master ) has been in use for more years ( decades ) than OpenTherm has been around. I recall it being used in the 1970's as the comms system for a warden call system in sheltered housing.

 

[ban-all-sheds]

Indeed, just as I said - not "open" in important ways, and hampered by 20th century legacies.

 

[ecowarrior]

Ok so thanks for all your reply's - it seems argument is a necessity and not what I was after but: The pic was to give you a clue as to the type of enclosures used in most domestic and light commercial properties and that metal Din rail boxes are seldom required. I was not trying to enter a dick swinging competition. It was a test rig I did as a 'sparky' for a customer friend using the items I had in my van. Not sure what 20th century legacy means or what it has to do with OT, but I do agree that plumbers/installers are woefully under-educated when it comes to wiring a S plan never mind anything slightly challenging. I dont think installers try to over complicate things - quite the contrary as most struggle to wire an on off stat. OT on a combi is as easy as on / off or Tpi but on a system boiler with a cylinder or anything with multiple zones it becomes a whole new ballgame. Endless households have spent thousands on new 'fancy' condensing boilers to have them set to run at 80deg to never condense enough to get the trap damp. There is nothing " hopelessly crippled by the 20th century legacy" in the installs I provide? I will look into Cat 5 type cables but none of the kit I use ( apart from Rhiani sequencing software) has this option. I personally think that properly sized Weather comp is as good an option as fault finding is much easier. However ramp up time can be long under these controls & customers complain the rads are cool even though they are themselves warm? Sometimes you can't win. As always I appreciate all your input.

 

[SUNRAY]

"And HTF have they ended up with cables and protocols which can be corrupted by "spurious stuff"? It's surely not high-speed long distance. Do the OpenTherm crowd not have a clue?"

Multizone OT is volatile & sensitive at the best of times relying on Wifi (for the App) RF and good signal is critical. Making sure the signal isnt corrupted is just one more pre-emtive move to reduce nuisance faults. I use 12 & 16mm glands always with YY & CY cable into IP rated boxes (obviously lots of the controls are in & around potentially wet areas. I think between you all you have given me the idea I needed - a gland similar to armoured cable so I can clamp the screen use a washer with a tag & then a bit of earth cable to the connector block. The only down sdide to this is the CY for the OT is 2 x 0.5 so very small in diameter. I am not sure what your statement means nor who the HTF are and again 'long distance' is relative - some runs are perhaps 20M+. probably not long to you guys but when comms faults do arise its good to know its not due to incorrect cabling. One less thing to eliminate. Fault finding OT on a good day is bad enough as often all you can do is shout at it lol. Having said all that - when its working OT controlled heating will save the planet! Set points are just that - set- and modulating low flow temps ensure low flue temps & maximum condensation. As from April all boilers must be OT compliant (& I believe fitted with OT controls). This of course wont happen as there is no OT police but if any of u need a boiler after April make sure you get a OT control stat (with or without the App) As a foot note I would rather not use a armored cable type gland as it will be really clunky but instead deal with it inside the IP box. This pic is not an OT application but gives an idea of the scale of heating electrics (small!) Thanks for all you ideas.View attachment 131746

Good god above what a mess.
And there is mention earlier of a professional job!