SIT 630 EUROSIT

In most case the thermocouple is a separate part and not part of the gas valve .

Possible defective gas valve.

The thermocouple has to warm up before the unit will go on.

Problem is not thermocouple:
Thermocouple should be finger-tight plus 1/4 turn
Overtightening will short thermocouple against gas control valve, and solenoid switch will not open, and no gas will reach pilot once red button is released.
Tip of thermocouple has to sit in the pilot flame.
If pilot flame will stay on, then thermocouple is good.

Problem is not solenoid switch.
The gas control valve solenoid opens and closes gas supply to gas control valve.
On mechanical gas control valve, when you push down the red button to light pilot, then you are opening the solenoid and letting gas flow into gas control valve.
When heat is applied to thermocouple, a small electric current travels to gas control valve, and this causes solenoid to stay open.
If you extinguish pilot, then no current travels to gas control, and solenoid clicks off.
You can hear it click, and this is how you test it.
However, since you are getting gas to pilot light, then the solenoid is not the problem.

This leaves 4 possible problems:
1) Bad gas control valve thermostat.
http://waterheatertimer.org/pdf/How-to-replace-water-heater-gas-valve.pdf
2) Inadequate gas pressure. Call gas company.
3) Dirty combustion parts. Clean the burner with wire brush and water.
4) Clogged air intake on FV water heaters: Rheem FV gas water heaters have glass vial that will break if combustion is slowed by clogged air intake.
http://waterheatertimer.org/How-to-repair-Rheem-TRD.html
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

If pilot stay lit, then thermocouple is working.
If pilot will light, then you have gas. If pilot goes out when pilot button is released, then thermocouple is next suspect.

Thermocouple tip must sit in pilot flame.
The pilot light heat applied to two different metals inside thermocouple causes small current.
The current travels back to gas control valve through copper line.
If the gas valve receive this current, then a magnetic switch stays open and allows gas into the gas control valve.
The magnetic switch is on the end of the red button you push down when lighting pilot. Essentially the red button is an override to the magnetic switch.
If the gas control valve does not receive the current, then the magnetic switch does not stay open when you release the red button.
When replacing thermocouple, note that it is not screwed very tight into the gas control valve. Finger tight + 1/4 turn. If it is overtightened, then the small thermocouple current shorts out against the gas control body.

The tank size dosn't matter all you need is a feed line This looks like a spicific tank appalaction but just feed it remotely with a normal propane tank and a feed line and save your self the head ache as long as it dose what you want it to do ist cool

I'm in the middle of this right now. Y'all don't know what you're talking about. The thermocouple you can buy at the local hardware store has a different thread (fine) from the Eurosit TC (coarse) and doesn't fit. Now I'm trying to source a Eurosit TC. Any suggestions?

next to the pilot there is a connector with a long copper tube. it is normally that and most decent plumber shops stock them.

If your pilot light will not stay lit when you release pilot light button then chances are that your thermocouple is bad. Make sure that the tip of thermocouple is directly in line with pilot light. Tip of thermocouple should be cherry red if it is properly placed. If pilot will not stay lit then replace it. If you aren't sure about placement of thermocouple you can heat thermocouple with a seperate heat source. If you do this and pilot light stays lit then reposition thermocouple in pilot flame. If it still won't keep pilot burning then replace thermocouple. Hope this helps. Thanks.

We had a problem keeping the pilot light to stay on, and this site recommended that it could possibly be the thermocoupler that was causing our problems also. We ordered the thermocouple, put it on,hooked it back up and it worked great! Thank you so much.
ordered thermocouple from www.masterparts.net