Nest contactors running radiant UFRH

Danroonie

I am working on heating a 3 room cabin in PA. There is 200 amp service - so plenty of juice to heat it.

The house will only be occupied 1/2 the winter - and internet is available, so an app can tell the 2 nests to call for heat so the homeowner can turn up the heat on the way to the cabin. Each zone has UFH (under floor electric heat) and a less desirable - but fast acting in-wall electric heater (aux) 240V 20 amp. The nest has an aux setting. I got feedback from this forum recommending the contactors but I wanted to get final feedback on the setup. See diagram

HVACNUT

I would change the transformer to a 50va max and fuse it. Do you know the current draw from the two relay coils, and if the Nest can handle it?

ratio

We covered that in another thread.

Danroonie

HVACNUT said:

I would change the transformer to a 50va max and fuse it. Do you know the current draw from the two relay coils, and if the Nest can handle it?

Per ratio's earlier suggestion - the transformer is serving 2 zones- so essentially 50va is available minimum per zone off the 100 va transformer - I've updated the diagram since it was vague. Where would you put a fuse? What would it protect? Thanks!

BobC

i would fuse the output of the transformer, start with a 2a slow blow (might have to go up to 3a) so it doesn't pop on inrush current.

Bob

Danroonie

BobC said:

might have to go up to 3a) so it doesn't pop on inrush current.

MT0100C has a built-in holder- So 3amp slow blow like this? From amazon I looked at the tech sheet on the seimens site- but it didn't say if 5mm x 20mm is the right size. Tried to get it unsuccessfully at supply Cooper Electric and NAPA auto.

Thanks Bob and Ratio