thermostat with contactor problem...help

[discjockeyr]

Dear All,

I have install an electrical underfloor heating in my new house and i have 2 thermostats that controls 3 zones each thru a contactor. the problem with both thermostats is that when the temperature rich the limit and the thermostats give the commant to contactor to open, immidiately the thermosta restart like something shiort the output of the thermostat and looses the time/date and programming. Did any one came across similar problem?
Thanks in advance

 

[Alan.P]

Sounds like the thermostats are losing their supply, a crossed wire somewhere, can you post a picture of the wiring diagram and the actual control wiring that you have.

 

[pjrich]

Sounds like you need to install a snubber accross the coil of the contactor. If you can advise the manufacturer & part no. of the thermostat(s) we can probably advise what you need to get.

Warm Regards,

Peter

 

[discjockeyr]

first i would like to thanks for your help both of you.
here is a drawing on how is my installation.
The thermostats are XSTAT by warmup

 

[pjrich]

I believe the current warmup xstat is manufactered by a company in Denmark (OJ) and my personal experience is that snubbers are not required with thermostats made by them. If it's an older warmup stat then it may have been made by Aube and in this case a snubber is most likely required.

I've had a look at the instructions for an xstat and it does not mention using a snubber, so I would suggest contacting Warmup to confirm if a snubber is required.

With regard to the wiring, according to the instructions I have for an xstat the connections should be:-

Term 1 - Power Supply - L
Term 2 - Power Supply - N
Term 3&4 - Coil of contactor
Term 7&8 - Floor Sensor
Term 6&7 - Floor Sensor 2 (if used)

Hope this helps.

Warm Regards,

Peter

 

[discjockeyr]

Thanks a lot for your help,

The connections has been made as your instructions. As i know the XSTAT are the latest thermostats that warmup supply but i don't know made of. I will try to contacr warmup hoping to received an answer. Can you tell me what excactly "snubber" is?

 

[pjrich]

A snubber is used to inhibit / reduce transient voltage spikes caused by switching of inductive loads (coil of contactor). It's these voltages that can cause thermostats to reset.

More info on snubbers here:- Snubber - Wikipedia, the free encyclopedia

Warm Regards,

Peter

 

[Uheat]

Great Advice, Thanks

 

[discjockeyr]

Thanks all of you for yours advice.
As is a little difficult to find snubber in my country i have create one. A 0.1μF capacitor in series with a 100Ohms resistor and hope that it will work

 

[Alan.P]

Let us know how you get on

 

[discjockeyr]

Hey there,

SUCCESS... I have made my custom snubber with a 100nF capacitor and a resistor 100 Ohms and the thermostats now working perfectly with the contactor. So, i would like to thanks everybody who advice me regarding this matter. THANKS

 

[pjrich]

Pleased you got it to work, if you ever need electric ufh in the future please contact us and we'll work out a deal for you:hurray:

Warm Regards,

Peter

 

[HowardM]

Contactors are well known for this, you can get hold of a relay that will eliminate the problem and they are smaller. with a contactor the break of the poles is not instant (1 before the other) so will cause feedback from the coil, the snubber is a fix, it is a big capacitor but you can still suffer on the odd occasion the resistor in place helps.

My advice don't use contactors they are big and noisy, get a 32amp relay instead, they fit in a standard back box lifetime similar to that of the thermostat and cheaper.

 

[discjockeyr]

yes, you are correct there is a lot of noice when on/off the contactor. can i find a 3-phase relay din rail to replace the contactors?

 

[HowardM]

Do you mean 3 phase or 3 pole, there are a few 3 pole available but a pain in the preverbial to install as you have to split the load (10 amps per pole), what is your overall load it watts/amps, maybe an easier way to sort it.

Need to know if you really mean 3 phase as this is totally diferent higher voltage higher risk but my guess is 3 pole as your problem is familiar.

Give me an idea of your wiring config I will try to help.

 

[discjockeyr]

Actually with one thermostat i am controlling 3 different zones (same big area as i have open plan house). those 3 zones came from 3 different phase but this does not matter. actually i need a relay with 3 different contacts. the loads are about 11Amps each zone. Please see below a sample drawing of the installation.
Thanks

 

[HowardM]

Hi,

In answer to your question there is always a solution, I am sure there is a 3 pole relay for your needs or you can adapt 2 relays and the thermostat relay to do the same job (but not the ideal solution), i will speak to a few people in the relay industry about your requirement and see if I can find a nationwide distributor for you. It is a shame you are over the 10amps per pole as it would have only cost about £15-20 max to sort out.

None of the above is suitable for a din rail but takes up (usually) the same or less space.

 

[discjockeyr]

Howard,
I apriciate your help.
technically what is the difference between the relay and the contactor?

 

[HowardM]

Basically not a great deal for the purpose you have, a contactor is more industrial in plain speak and will last longer if the load is not great however, it is not advisable for delicate hardware i.e thermostats, controllers, computers.

A relay is used in more delicate products such as thermostats, controllers, etc. there are two main types of relay, analogue and solid state, solid state will give you more clicks in its lifetime but not always the best for economy (replacement value).

for a dictionary assessment

Relay
An electrically controlled device that opens and closes electrical contacts to effect the operation of other devices in the same or another circuit.

Contactor
A magnetically-operated device, for repeatedly establishing and interrupting an electrical power circuit. It is usually applied to devices controlling power above 5kW, whereas the term 'relay' is ordinarily employed below 5kW. The terms are often used interchangeably.

Hope that helps

 

[HowardM]

Here is an example of a 11 pin 3 pole relay with connection block, the problem is it is only 30amp (10 amps per pole), If I remember correctly though this type is noisy but not as noisy as a contactor.

230v AC 11 Pin Relay 3 Pole

This is more like what you need

[DLMURL="http://cgi.ebay.com.sg/CUTLER-HAMMER-3-PHASE-3-POLE-RELAY-HEAVY-DUTY-30A-600V_W0QQcmdZViewItemQQitemZ150267549111"]eBay.com.sg: CUTLER-HAMMER 3-PHASE 3-POLE RELAY HEAVY DUTY 30A 600V (item 150267549111 end time Apr 02, 2009 11:32:45 SGT)[/DLMURL]

 

[discjockeyr]

Howard,

Thanks once again for your time and advice. Yes the 30amps will not be enough and the other one unfortunately is not din mounted. so i will search to see if there is a solution. in other case i would try to sealed the panel so to eliminate the noice.