CS92 insertion probe resistance/extending fly-lead

[skwerl]

Does anyone know the resistance range of the CS92 insertion probe? I want to know if it's possible to extend the length of the fly-lead as I can't see any mention, in Honeywell literature, of whether this is/isn't possible. Typical NTC thermistors operate with fairly high resistance so I expect a few metres of extra cable won't have any impact to the operation of the thermistor.

Would be good if Honeywell provided official guidance on the matter

[skwerl]

Does anyone know the resistance range of the CS92 insertion probe? I want to know if it's possible to extend the length of the fly-lead as I can't see any mention, in Honeywell literature, of whether this is/isn't possible. Typical NTC thermistors operate with fairly high resistance so I expect a few metres of extra cable won't have any impact to the operation of the thermistor.

Would be good if Honeywell provided official guidance on the matter

I will answer my own question. With my water currently at 37degC the resistance is approx 6.4kOhms.
1 metre of 1mm copper flex adds approx 17.2mOhms

i.e. it will make bugger all difference if I add some flex to extend the fly lead so I can install the CS92 in a more accessible (and signal friendly) place than my loft

[iaingore]

I need to do exactly the same as you discuss. how far did you end up extending the probe?

Al the best
Iain

[skwerl]

I haven't yet. I'm planning to put the CS92 and both BDRs in my utility room. I haven't built my utility room yet though!
I expect it will be about 20 metres of cable. Put it this way, 50 metres of 1mm T&E adds 1 ohm which represents less than .002% of the resistance
What I need to do at the weekend is take resistance readings across the temperature range as an NTC thermistor becomes less resistive as temp increases. I don't know by how much. I don't expect a lot but best to check. I'm also planning to take readings off the probe and then again when hooked up to a length of T&E or flex

Will post my findings

[Richard]

No problem extending the lead guys, just bear in mind this may affect battery life.