Robertshaw-Grayson series 7000 control valve

[davec]

Hi,

I recently purchased a vermont castings model vf25t free standing vent free LP gas stove with a robertshaw-grayson control valve. (Model 7000MRB-4-LC-LP)OK I got it at a yard sale but for 50 bucks I figured what the heck. I disassembled, cleaned and touched it up. I got everything hooked up, checked connections, etc., lit the pilot. I turned it on low, had a good flame, and it stayed on for about 3-4 minutes, then went out. I heard a valve click. Any thoughts on what could be going on? The pilot is good, all other gas applances in house are OK so the pressure is good. Maybe the thermocouple or an internal thermostat? Any suggestions out there would be helpful. Thanks, davec (1st time)

[HayZee518]

the millivolt generator is a skinny copper bulb that sits in the flame. a very small copper capillary goes from this bulb to what looks like a pellet at its end held in place by a small hex headed gland nut. this capillary has no gas inside but a fine insulated wire that goes from the tip to that bead that goes into the valve. Inside the valve is a small electromagnet with a spring and a cylindrical iron pellet and a neoprene seal. the millivolt generator when it's heated produces a measurable DC voltage around 740 millivolts. It is strong enough to actuate and hold the electromagnet within the valve open. when it loses is heat the snap you hear is the valve spring action closing the valve. I'd say replace the millivolt flame detector.

[davec]

thanks HayZee,

do you think this is an item that is easily obtainable? easy to replace?

[HayZee518]

yeah, should be no problem. the part that goes in the flame has two nuts on it so you can vary its height. the other end has a gland nut ohhh, about 3/8 " - a regular open end wrench should fit it. it may be smaller - I'm not sure. mine is 3/8" for my portable propane heater.

[HayZee518]

To view a list of the Robertshaw model numbers for valves that are being recalled, please check the scroll down menu below. If you have one of these products, please call our recall hotline at 1-800-232-9389, or register for the recall online. Please note that some original equipment manufacturers may not be represented. To confirm whether or not your valve model is affected, please check the valve label for the Robertshaw model number. Affected model numbers can be seen in the drop down list below next to the sample label. Please note that any millivolt natural gas valves with date codes between 0306 and 0436 that have been converted to LP fuel are also included in the recall.
this is a list from robertshaw about recalled gas valves.

[HayZee518]

go to the robertshaw site with your model number to find this list.

[davec]

HayZee,

Thanks, not on the recall list..too old...1995
Will investigate the thermo couple and ODS

davec

[davec]

hayzee,

Took apart the pilot assembly and found the small screen in the inlet side was bent over on itself. also took the other end apart and the small orifice (maybe .010") was dirty. blew it out reassembled, and the pilot has been on for an hour or so already...so thats good. thanks again

davec

[HayZee518]

I'm glad that what little we contribute will help you out. Now if I can get my car to stop overheating we'll be on second street!

[davec]

check the thermostat, flush the radiator...thats my little contribution

[holzee]

use compressed air to clean out air intake ports on my vf25 NG and it works great. No more shutdown. Pilot looks normal pilot shoot out straight instead of up onto logs. i have a url of where to go to for this info but it will not let me post it right now because i'm new. no parts needed. spry air into and around pilot and into valve. stove must be off.

[psuce]

I stumbled across this forum while researching what appears to be the same unit. I bought it new in the mid 1990's and never had a problem. Never heard of any recall until now. Not sure how to proceed but I will email my information to Robertshaw and see what happens. However the problem is the pilot is hard to keep lit at times while other times it lights but shuts down after a period of time. Sometimes it operates with no problem at all. I had it cleaned and a local shop told me the pilot assembly may need to be replaced. However, I have noticed a correlation between how the gas valve behaves and the operation of the unit. When the black pilot or control knob that I turn to light the unit operated "freely" it functions fine. However, at times it fees "sluggish" or "gummy" when turning it and then I can expect a problem. I don't want to be replacing parts that do not need replacing. I also don't want to be replacing parts one at a time. I just want "one and done" so to speak. Any thoughts on this. Thanks.

[Dan O.]

Never heard of any recall until now. Not sure how to proceed but I will email my information to Robertshaw and see what happens.

Here's a link to the recall. Sorry I can't help with your problem.

LINK > CPSC, Robertshaw Controls Company Announce Recall of Certain Models of 7000 Series Gas Control Valves

JFYI

Dan O.

[HayZee518]

valve

do you have a meter that will measure 750 millivolts?
if you remove the thermocouple's end that goes into the valve there's a small gray colored button. measure across this button and the external copper cappilary with the bulb in a flame. if no voltage then the thermocouple is shot, get a new one. if there is a voltage around 750 millivolts [thousandths of a volts] then the pilot valve components are burnt out, the magnet inside the valve.
you mention sluggish on the pilot valve. could be gunk inside and below the turn valve.
that red button is a piezo igniter.

[psuce]

Dan O ........... Thanks for the information. It was more than what I had.

HayZee .......... I do have a meter that I think can measure this.I will have to break the unit down to do so which is really not a big deal. The whole valve thing just has me perplexed since it is hit or miss with the sluggishness. Also, I can tell by the feel of the knob on the valve even before I light the pilot if I am going to have an issue. When it is acting sluggish, I have to pull on it lightly to get it to turn to light the burner. When it is operating smoothly, it pops right out and I can turn it to light the burner. Go figure. All last week if was giving me trouble. This weekend I have had the unit running for more than 18 hours with no problem. Of course when I went to fire the unit up, the knob felt quite smooth. That is even before the pilot lights and heats the thermocouple. Therefore, I have to believe that the thermocouple is not the problem. I will check it anyway. Also, you mention "gunk" in the valve unit. Can they be cleaned??

Thanks