Shielded comms cable

[HughF]

ASHP is going 20m up the garden, total cable run from controller (Carel, I think it's on rs485) to unit is probably more like 30m. I need a suitable cable for running this back to the unit. Ideally I'd use the same cable to extend the flow/return temp sensor, and the DHW tank sensor. Planning direct burial of the swa for power, then the comms cables into some 50mm ducting.

 

I don't really want to use cat5, although I do have outdoor rated stuff, I'd prefer something stranded, with slightly larger csa. Does anyone have a link to something half decent from Belden (or other) that I can get from RS/Farnell/Mouser/Digikey?

[joth]

If you want to put other signals down the same bundle I'd suggest shielding around each pair rather than the bundle as a whole. And twisted pairs. CAT6A U/FTP ticks those boxes and is thinker csa than cat5(e), however it's (almost certainly) solid core rather than stranded. 

 

>Ideally I'd use the same cable to extend the flow/return temp sensor, and the DHW tank sensor.

Oh, do you mean one length of cable carrying all these functions, or a separate piece of it for each sensor? If the latter just 2 core shielded maybe sufficient. Something like RS 827-4133 (which was suggested to me for another HVAC controller) 

 

[HughF]

I'll need a cable for the 485/carel network, I'll use cat6 ftp for that (thanks for the recommendation), a cable for the call-for-heat jumper (I can use SY/YY for that) and one cable each for the dhw tank sensor and buffer/flow/return temp sensor.

 

4 cables...

 

EDIT: Temp sensors are 2 wire... so a 100m roll of 2 core screened, and a roll of cat6 ftp...

Edited September 11, 2023 by HughF

[HughF]

Edit: 5 cables, one for the 3 port...

[joth]

22 minutes ago, HughF said:

I'll use cat6 ftp for that

Note I suggested CAT6A as that definitely has larger cores than CAT5E.  CAT6 can be just the same core size as CAT5E ( but has tighter twisting and thicker internal filler  iirc) 

 

[HughF]

5 minutes ago, joth said:

Note I suggested CAT6A as that definitely has larger cores than CAT5E.  CAT6 can be just the same core size as CAT5E ( but has tighter twisting and thicker internal filler  iirc) 

 

Understood... I have rj11 breakout PCBs for each end which have screw terminals.

 

I could use one CAT6A for the comms, and the other one could easily do the two sensors and the call for heat... That makes good use of a 100m length of cable from TLC-Direct...

Edited September 11, 2023 by HughF

[JamesPa]

6 hours ago, HughF said:

ASHP is going 20m up the garden,

As a matter of interest, split or monobloc and if the latter what pipework are you planning on?

[HughF]

Monobloc (no space indoors for an indoor unit, although I would have gone split if I had the space), using hi-line eFlex 2x32mm from Ingoodnic.

 

Ingoodnic are marginally cheaper than LoCO2 heat which was the other supplier I got quotes from. If you’re buying this stuff you want to use the product with bonded in place PU/PIR insulation, not the stuff that is unbonded. The latter will cause issues with the hot pipe expanding along the length and causing havoc with your end terminations.

Edited September 12, 2023 by HughF

[MikeSharp01]

You can get RS485 twin pair cable if that helps. Over 30m there is almost no chance of any problems with RS485 although terminating resistors will help. I use this stuff . You can also use this cable to run your sensors all screened and drained.

[HughF]

6 hours ago, MikeSharp01 said:

You can get RS485 twin pair cable if that helps. Over 30m there is almost no chance of any problems with RS485 although terminating resistors will help. I use this stuff . You can also use this cable to run your sensors all screened and drained.

Nice cable, thanks. Stranded too, which I like. I've just pinged an email to Chris at CoolEnergy asking for confirmation on the Carel pLAN wiring requirements so should be able to spec a suitable cable once I hear back.

[HughF]

"

At the PCB end, there is actually some screw terminals just above the RJ11 jack, this is 4 pins for the power and data so you can use this one end and disregard the plug.

 

For the screen end, you can use a RJ11 adapter with 6 pins, from memory the two outer pins are live and the 2^nd two outer pins are neutral. The middle pins are + / - data. (Carel double the power cables up to overcome volt drops on the prewired cables) A standard CAT6 cable is normally fine for upto 30m runs though."

[HughF]

I went with belden 9505 alternative - ideal stuff... Foiled, drain wire, 5 pair, tinned, stranded...

 

Going to use two runs of that, one for the pLAN connection (RJ11 at each end) and one for the temp sensors and call-for-heat.

 

I just need a nice way to get it out of the duct, and into the side of the ASHP. I'm thinking I'll use a rubber duct end cap, into 20mm rigid conduit, stainless jubilee clips, then a conduit bend and a panel fitting.

0900766b813d85c8.pdf

Edited September 18, 2023 by HughF