danfoss room stat - wiring problem?

[andyb123]

Hi all

Fitted a danfoss room stat yesterday as a replacement for a honeywell room stat the was faulty. When i turned the room stat up to call for heat, boiler fired and ran normally. Got a call today that the fuse has blown after the boiler had been running for around 2 hours or so.

The only thing i can recall that was not normal was the roomstat seemed to be set incorrectly. When the room stat was set at 30 degrees it turned off, and when it was set to 10 degrees it turned on. I think i must have wired it wrongly.

Im going to go back and check to see what ive done.

From looking at the diagram (Y plan)

Red should go to 1 (live)
Yellow should go to 2 (switched live)
Blue should go to 4 (neutral)

Is this correct? (only three wires coming from wire to wiring box red, yellow, blue)

thanks
andy

 

[jackthom]

hi, which model thermostat is it ?

 

[picasso]

What model of danfoss stat ?

 

[andyb123]

Its a danfoss RMT230 room stat. This was the only thing that wasnt right. I had to fit a new 3 port valve which operates ok, a pump and a cylinder stat.

 

[jackthom]

Post deleted. Confused by Danfoss wiring diagram.

 

[andyb123]

Just spoke to the customer and the fused spur has gone, the rcd has tripped and the programmer is dead. I think maybe there is a bit more to it than the room stat

 

[matt1e]

Hi all

Fitted a danfoss room stat yesterday as a replacement for a honeywell room stat the was faulty. When i turned the room stat up to call for heat, boiler fired and ran normally. Got a call today that the fuse has blown after the boiler had been running for around 2 hours or so.

was this for a customer?

The only thing i can recall that was not normal was the roomstat seemed to be set incorrectly. When the room stat was set at 30 degrees it turned off, and when it was set to 10 degrees it turned on. I think i must have wired it wrongly.

then took payment and walked away?

Im going to go back and check to see what ive done.

From looking at the diagram (Y plan)

Red should go to 1 (live)
Yellow should go to 2 (switched live)
Blue should go to 4 (neutral)

Is this correct? (only three wires coming from wire to wiring box red, yellow, blue)

well at least you are going back so credit to you and lesson learned and yes andy those are the correct connections
make sure you do not have anything connected to term 3
jackthoms' post above is a typo, he means it looks like your switched live is connected to term 3 (which would make it work in reverse) not should be

are you sure the 3-port is wired ok?

Matt

 

[andyb123]

Thanks Matt

Im pretty sure that the £ port valve is wired correctly as it works when either the heating or hot water is selected, or both.

I think it could be to do with the room stat as this works in reverse; ie 10degrees setting is 30 degrees, and 30 degrees setting is 10 degrees.

I will double check the wiring.

Could this blow the circuit breaker fuse, the spur fuse and blow the programmer? Why does it operate for 2 hours and then blow?

Cheers
Andy

 

[picasso]

Bit of guess work here but I think you have neutral connected to 2 and are using 1 and 3 as the permanent and switched live, the thermostat would work backwards and when the stat switched it would connect neutral directly to live blowing the fuse.

 

[andyb123]

Thanks Picasso

So by checking and ammending the wiring should sort this out? Why though would it run for a while and then blow? I had been testing the room stat by moving the dial to click on and off which would turn the boiler on and off

thanks
andy

 

[picasso]

You have to check that the thermostat connection correspond to what you think they are, ie is blue actually neutral ect, if the fuse is blowing after 2 hours try turning the cylinder stat down and see if that causes the fuse to blow.

 

[andyb123]

Thanks Picasso

I did the same with the cylinder stat that i did with the room stat; turned it up and down so the stat clicked to turn the boiler on and off as per normal.

If either or both stats were incorreclty wired would they then blow the fused spur, rcd and programmer if they both turn the boiler on and off when calling for demand?

Andy

 

[picasso]

You need to trace all the wires back to the junction box and double check each one is in its right place, if you still have trouble with fuses blowing you can then fault find with a bit of confidence .

 

[andyb123]

Thanks picasso

will give that a go. I understand it difficult trying to diagnose in the forum, hopefully just a mistake with the wiring

cheers
andy