Pilot fine but no main flames - valve?

If this is a standing pilot unit ( pilot all ways on) then replace the thermo device in the pilot flame as it is not sensing that the pilot is on hence not allowing the gas sol to actuate the main gas valve when heat is called for by the thermostat ( those sensors do get crudded up which may be all that is wrong. I always use to keep a new spare hanging close by the appliance for this particular reason.) It may also be a combination of dirty/ bad sensor and a dirty pilot ( colder flame than it should be hence low voltage output/ too high a resistance).

The SIT thermocouple do have a unique thread. I'm not familiar with that external solenoid. Is that anything you've seen, daksy?

On a second look, the SIT valve is the type which has a built in tstat. The external solenoid must simply be operated by the wall switch, the SIT valve should be turned up fully. It's a very simple valve. If the pilot remains lit, there's not much else going on. Be sure the knob is turned all the way to call for heat.

I'm not one to throw parts at a problem, hoping to hit the right one. First, on the SIT630 gas valve, be sure the thermostat is turned all the way up. When turning the knob, there should be a point, when the thermostat calls for heat, you will hear a slight click and you can feel the valve open. The 630 valve also has 2 test ports. One to test inlet pressure and one to test manifold pressure. I would make sure I have pressure at the inlet. Just because you hear the 530 solenoid click, don't assume it is opening.
You could also try a slight tap on the side of the 630 valve with the handle of a screwdriver. If the valve is stuck closed, this will jar it open, sometimes. With everything calling for heat, just a light tap.

One other thought, the 530 solenoid, which I have said I am not familiar with, is stamped 3VDC. That indicates there is battery power somewhere. Find and replace the batteries. Most likely to be near the wall switch.

Charliebarns said:

all good points! I did try with the pilot lit, dial cranked to high and wall switch on I gave it a whack on the side several times but no go. The wall switch is hooked up to a 120v -> 3vfc transformer that appears to be providing a sufficient amount of power (measured 3.2vdc at the solenoid).

I have not, however, heard the click while turning the dial. In fact, when I went to work on this problem I couldn't get the dial to turn. I thought I was missing something like having to push it in. I eventually got it to turn and since then has seemed to loosen and turns ok - but no click. I'll try that again today.

Thanks

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It's been awhile, but, I recall there being a plastic stop under the knob that, if forced, will break. It's supposed to hold closed with the pilot. Once closed, the knob turns freely. Try resetting the valve by turning it back to OFF, wait 5 minutes, then relight the pilot.

This is the plastic tab which will break if the knob is forced. I thought I had one of these in my old parts box. I believe this one is for LP, although it's not stamped as such.

These are the test ports I spoke of. The lower is inlet pressure. Upper is manifold pressure. The screw is only to be loosened, not removed. The inlet side will be charged if the solenoid is open. The manifold only when the valve opens.

The 630 sit gas valve is Uro valve made in Italy. The thermo coupler has a flat spot on it there is a number that has to match up for it to work and the threads are different. The only thing serviceable is the thermo coupler and the cut out block if B vent solenoid. The is a 630 sit group valve for each natural gas and liquid propane. There is a sit. valve that is motor driven for a remote control and a sit 630 modulating flame model with small tube about 20 inches with a bulb on the end for thermostat control. There is a lock out on this valve if pilot goes out. You have to wait 3 to 5 minutes to reset to clear gas out of stove and burner before you can turn knob. It looks like some body forced knob to turn on striped the gears.
Go to this link www.woodmanspartsplus.com they have all kinds of sit valves give them all the numbers on the valve and thermo coulper etc. I had to replace my thermocouple on my 630 sit modulating vave and pilot tube. they wanted the thermocouple number witch I could not read bad stamp on one number. The worked with with me to get the right part.Can even send pictures. I do not know what solenoid is for ask them see if they know.

Charliebarns said:

I managed to find the exact valve brand new. In reading about setting the output (manifold) pressure I came up with a question. I see some valves have a flow adjustment screw and some have a pressure regulator screw. My old valve (and new) has a pressure regulator. Do you set it the same way as the screw? Attach my manometer to the manifold pressure and make sure it reads 3.5 bars (as per label on valve)? Is it common to have to set them or is the factory setting pretty close?

Thanks!

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I did a little checking yesterday on that, too. It appears some are specifically for LP and some are for nat gas, while some are convertible for either. If you can find the exact match, go with that. The pressure regulator should be factory set. I always check. On some appliances, the manifold setting is critical. On your log set, not so much. Just be sure it is between 3.5" - 7". Also, I noticed you said bar. Just to be clear, you're setting inches of water column, not bar.
Be sure to test the system back to the shut off, as you've broken the connections. Set your manometer on the inlet side, charge the line, then shut the supply valve. Hold the pressure for 30 minutes. You should see <.5" drop. Any more and you need to find the leak with leak detector. Mix some dish soap and water and apply to connections. Also check the pilot connection by depressing the pilot valve and looking for leaks at the connection to the valve.
You can do it. It's not rocket science, but, you have to check. No shortcuts. One gas explosion can ruin the whole weekend.