What is the work range of millivolt gas valve ?

[shinnecock]

My gas fireplace is with millivolt gas valve (Robertshaw 7000MVRB-5-LC, 770-826-497) .It was installed 2 and half years ago, but we use it only few times. Now the pilot is burning, but no gas burning. I have checked ON/OFF switch and installed new thermopile (750mV). But it still no gas burning. I try to use 1.5v battery to instead of the thermopile, and then gas is burning immediately.
I am thinking to use an AC-DC adapter with 1.5 v out to to instead of the thermopile. Is it OK for long time operation? What is the work range of millivolt gas valve ?

[HayZee518]

NO, NO, NO! The thermocouple is a safety device! Substituting a battery in place of it will get you going, but if you lose your main flame YOU ARE GONNA HAVE A BAD EXPLOSION if a spark is generated!
Get rid of the battery and find out why the thermocouple ain't working!

[shinnecock]

Thank you, HayZee518. One more question

Mr. HayZee518, thank you for your advise.
But I have one more question: in my case, is the gas valve difective and have to install new one?

[HayZee518]

The main gas valve is basically a mechanical device with one electrical device - the main gas solenoid. If this burns up the pilot flame will light but the main valve won't open.
The millivolt generator, the thermocouple, is just what it means milli volt is a thousanth of a volt. .001 volt is one, one thousanth of a volt. This is different than a battery which is 1.5 volt. see the difference?
You may even have burnt up the solenoid valve by applying the battery to the solenoid.

[shinnecock]

Thank you Sir, I fixed the problem. Finally I found the connections of wall switch wires with valve are fake. The valve and thermopiles (old and new) are OK. I think 1.5V battery can work with millivolt gas valve. Thermopile can produce 750 mV,1.5v is only 2x750mV. I think we can use 1.5v battery to test millivolt gas valve. but you are right, it is not safe for normal operation.

[SSN596]

I have to correct your logic here because I sense a "6 o'clock news item" coming. Even if you have a pilot generator, which can produce 750 mv OPEN CIRCUIT, many gas valves run off a thermocouple which produces less than 100mv OPEN CIRCUIT. NOW, the current which a pilot gen. or thermocouple can deliver into a solenoid circuit is quite low, compared to the potentially very high short circuit current of a battery. You could easily test a defective valve as being "OK" with your method. Please do not mess around with gas valves.

[Phelps]

Admirer of handyman: Boy, you sure know an awful lot about a lot of things!

Handyman: Ya. Just enough to be dangerous.

[dmillerp]

Different Issue, Gas won't turn off

I have a millivolt valve on our gas fireplace MVK-NQM for a Surefire. Just bought Feb 2008. Just started using fireplace this years after a couple uses, noted the pilot light blew out.

When I lit the fireplace and turned the manual dial for gas, it immediately started and WILL NOT TURN OFF (without manually turning dial). We have a remote control to go with it.

My gas/electrial guy says I need a new valve. What I can't understand is how the valve would be set to stay 'ON' if it failed and not 'OFF'.

Any ideas?

[HayZee518]

most valve for ON is just for the pilot valve. If the pilot valve is stuck internally, loss of flame will not close the pilot valve. the thermocouple for the pilot gas electrically keeps the valve open but if a slug for the valve is jammed in some way losing the pilot flame will not close the valve - I'd say replace the whole valve.