Discuss Ufh contactor wiring advice please in the Electric Underfloor Heating Wiring area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
8
Evening all,
Doing a bit of forward planning for an extension with possible electric ufh. i Have worked out room will need 25m2 split between 2 matts 15 and a 10. 150w per square meter matts. I work out as about 16.3 amps in total. Only one stat so a contractorwill have to be fitted.. if Someone could point me in right direction with wiring to include contractor I would be most grateful. Normally I would take supply froom Db to double pole switch to stat then join cold tails and probes. Cannot get my head round contactor tonight. Do I need separate supply’s for stat and contactor, or supply to contactor then to stat via fused spur.
Simple to many I expect . Obviously a 2nd stat negates this problem
 
You won't necessarily need to have a seperate circuit as the only reason you are using a contactor I assume, is because the switching contacts of your stat are rated less than the connected load you have calculated. You will need a circuit suitable to supply your UFH load plus the negligible power consumption of your electronic stat. A 20A circuit would seem sensible in this case.

Wiring wise you will wire as you would normally but instead of connecting the output of the stat to the cold tails, you connect them to the coil of your contactor (A1 & A2) instead. You then put a supply L&N on one side of the contactor and connect your cold tails on the other side.
 
I realise contactors can fit in db on din rail or suitable enclosure adj to db. but are there any flush enclosures that are available. Only thing I can think of is a deep fast fix box with a module face plate which does not seem quite right to me.
 
I realise contactors can fit in db on din rail or suitable enclosure adj to db. but are there any flush enclosures that are available. Only thing I can think of is a deep fast fix box with a module face plate which does not seem quite right to me.
Be aware a contactor will clunk loudly every time it operates. A heavy duty relay will operate much more quietly, and be physically smaller too. A mercury displacement relay will operate quieter than the room stat.
 
Be aware a contactor will clunk loudly every time it operates. A heavy duty relay will operate much more quietly, and be physically smaller too. A mercury displacement relay will operate quieter than the room stat.
Modern solid state relays are silent in operation.
just have to be aware that when they fail, they fail ”closed” so a second method of isolating is important.
 
Modern solid state relays are silent in operation.
just have to be aware that when they fail, they fail ”closed” so a second method of isolating is important.
Yes I've never wanted to use solid state relays where a problem could occur during failure. Difficult fitting an overheat cutout to underfloor heating, though it could be done with thermistors, connected to a thermistor monitoring safety relay controlling a main power contactor. Bit overkill though! That said I abused a modern solid state relay recently, including deliberately shorting the supply across it blowing the 13A supply fuse several times. It's still working. A 16.5A load might require the SS relay to be mounted on a heatsink.
 
most essential requirement is deep pockets to pay for all that leccy just warming your feet.
 

Reply to Ufh contactor wiring advice please in the Electric Underfloor Heating Wiring area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock