Ls and Lr on the ufh manifold is an un-powered relay. So the UFH thermostat tells the manifold it needs heat, the manifold closes the relay labelled "Boiler". That should then send a voltage back to SL/Lr at the combi boiler and ask it to turn on? Is this right?
So effectively it will bridge...
The 1st thermostat, (21 Landing Thermostat), I have wired to S-plan connector 4, which goes to the combi boiler SL/Ls. It that right or would I connect it to connector 1 or does it not matter? Is SL/Ls on a boiler a permanent Line or does it ever switch off? I don't ever want to lose power to...
Hi I am training to an electrician.
I am working as an electricians mate.
I have been asked to draw a wiring diagram, would anyone check my diagram and see if there are any obvious mistakes please. We will be wiring it Friday, obviously it will be checked by the electrician I am working...
So say if I measured Zs at 1.3ohms and looked at the table in the OSG and it said it should not be greater than 1.1ohms, should I be concerned? Or just ignore the OSG and use the values in BS7671
1.37 x 0.96 = 1.31
OSG says 1.1
I guess what you said to start with is the reason, they are using different conductor tempertures for their calculations, or something.
Thank you for your time, why they do not print the same information frustrates me, it makes learning very confusing.
I still do not get it, so why does the OSG say 1.1 again?
Calculation in OSG
32 x 5 = 160A
230 x Cmin 0.95 = 218.5V
218.5 x Ctemp 0.96 = 209.2
209.2 / 160 = 1.3 ohms
You know your stuff, your math is spot on!
You are correct in saying BS7671 gives values of max Zs permitted max operating temp is not exceeded (Note 2).
You are correct in saying that values in OSG are given based on ambient temperature.
I agree that Cmin and temperature correction values are...
It is interesting you mentioned 0.96 as a correction factor.
page 58 of BS7671 Note 1, states they used a correction factor of Cmin 0.95 to account for the potential voltage drop of the supply.
Is it a temp correction value or do you think BS7671 has accounted for Cmin and the On-Site-Guide...
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