Sticking gas valve in furnace

When raising the thermostat setting so that the heat is supposed to come on, the gas valve sticks. I can free the sticking with vibration by tapping in the area.
Do I need an entire gas valve assembly, or can I just replace part of the switch? Would a service call be able to clean the valve?
TIA
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Orlandes wrote:

    First measure the voltage applied to the coil of the valve. (It could be as simple as a bad connection at the terminals) If it is there and tapping the valve makes it operate, the valve is bad. Replace it.
    The valve is not serviceable, it needs to be replaced if bad.
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Generally gas valves are replaced as a unit. They are not servicable. Any good heating service company should be able to replace the gas valve for you.
--

Christopher A. Young;
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On Tue, 20 Nov 2007 18:14:46 -0800, Orlandes wrote:

Tighten the screws holding the wires on the valve first. If that doesn't fix it have a tech replace it.
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wrote:

If the valve works otherwise on your current setting the valve works OK. Its the controls to the valve that needs work or replacing.
The valves are fixable. But by law no parts repairs are allowed even if done by a certified HVAC technician. A new valve costs CDN $185.
Call you gas company to do the checkup. Mine has the obligation to restore service (a functioning home heater or water heater.) There is no charge if no parts are used. Checking transformer voltages and wire connectiions, including fixing them is free. If parts are used he will only charge that part of the work. Or if he advises you to hire an independent service company you will know the exact problem that needs to be fixed by them.
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One more tip. If you think the valve is sticking use a rubber mallet and give it a good thump. The feed gas pipe to the valve is made from very tough black iron. The gas burner manifold that connects the valve to the burner array is made of as tough a material (mine is silver colored that is not paint). You can't dent either with a heavy hammer if you tried. A good thump on the valve won't damage anything and may just loosen the valve. That was what the gas company service guy did to my furnace.
In the end I replaced my furnace valve. But the actual problem was the old brittle plastic insulation on the 24Volt wires to the valve that had caused an electrical short. It was not visible as I had wrapped them with electrical tape and the wires looked OK. Once used the new valve could not be returned for a refund.
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Hey as long as we are on the topic of gas valves. Is there an adjustment for main gas flow under the silver screw on this one? Elsewhere?
http://farm3.static.flickr.com/2403/2053479619_631323b0cb.jpg
I put this in several years ago. The OEM part was NLA; this was the recommended replacement (which surprised me a little since the body size was different so I had to use a different nipple on the left and relocate the pilot line a little as well). Works fine but early on I had a few trips of the heat sensor attached to the draft diverter. Never had that happen before but then someone pointed out that they thought the flame size was a little bigger than in the past.
I throttled back the gas at the shuttoff and figured I'd check into further adjustments at the gas valve. I got lazy and just left it and it's been working just fine ever since. But of course that's not exactly right. Figured I'd ask before looking myself as someone will know.
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On Thu, 22 Nov 2007 03:44:20 -0000, Big Giant Head

The adjustment on the valve I am familiar with is for the size of the pilot flame. You can eyeball the flame to adjust to your idea for the best flame.. The valve I have is a Honeywell V800A1161, slightly different from yours. Right next to the pilot light knob is a screw with the words "Pilot Flow Adj" screw molded into the alloy body.
In the valve installation manual there is a "Pressure Regulator Adjustment" beneath cover screw (illustration). My furnace works fine. I am not about to fiddle with this adjustment. I believe if your furnace works leave it alone.
The other adjustment is the air restrictor orifice on the burner tube to adjust the air/gas mix ratio. The flame should be a clean blue flame.
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PaPaPeng wrote:

Just wanted to throw in my two cents.
If the gas line that feeds the gas valve is copper you may want to replace the gas line and maybe the valve.
When you have a copper gas line carbon forms inside the copper pipe and after awhile that carbon falls off and goes into the gas valve and cause the valve to act up.
The worse thing I have seen is the valve not closing.
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Moe Jones
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On Thu, 22 Nov 2007 03:44:20 +0000, Big Giant Head wrote:

Any adjustment on the valve isn't going to make much difference. The flame is determined in large by the orifice in each burner.
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Meat Plow wrote:

Well is there an adjustment or not? If not does it seem likely that replacing the gas valve would result in a different rate of flow? Seems odd that one would have to change all the orifices as the result of valve replacement but then again, while this was the recommended replacement, it's not exactly the same as the original.
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On Thu, 22 Nov 2007 16:59:06 +0000, Steve Kraus wrote:

Your valve appears to have a gas pressure adjustment. I just couldn't say that all do. The brass screw is the pilot adjustment. I would recommend you have an HVAC guy adjust the gas pressure but if you must, remove the silver cap screw and turn the inside adjustment screw counter-clockwise for less pressure, clockwise for more. Do it while the burners are lit.
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wrote:

First off, you and your "gas company service guy" are idiots !!!
Telling someone to grab any kind of hammer and whack a gas valve is not only idiotic, but downright criminal. You want to help him blow up his house ? the fact that the valve had a malfunction is reason enough to not dick with it, and just replace it with a new one. you want a fucking half ass repair job or one that's done right ????
Secondly, if you had an "electrical short", you better hope a fuse opened up somewhere. If it didn't then you got more issues. Let me guess, the "gas company service guy" replaced the fuse with a loose bolt off his truck (it fit the fuse holder perfectly right?).
So let's recap. It's a miracle your house is still standing - after - gas guy whacks valve with big hammer, electrical wires smolder without popping fuses.
you need to buy a freakin lottery ticket ! your luck is amazing.
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I agree with that. Well, maybe a gentle tapping to nudge away any dirt that came in with the gas. If the problem totally goes away then fine but really, this is the most critical component and if there's even the slightest chance that it will get stuck open it has to go, no question about it. Lives are on the line.

Dunno about that. There isn't necessarily a fuse on the low voltage side and a short there isn't necessarily going to trip or blow anything. But it's also possible the he didn't really mean short but rather an intermittent connection.
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wrote:

Hey if you are so nervous about working on gas installations go find some other line of work. One of these days you'll die of a heart attack because of a strange click while you are working on one.

It will be a very brave or foolhardy homeowner who will stike his furnace valve hard enough with a steel hammer to damage something. The chances are he'll be too scared to tap it hard enough to unstick the valve (a very light rubber disk on a teeter totter requiring a milligrams force to open. Its normally closed). So how much do you make every time you scare some poor home owner with a sticky valve that could have been unstuck with a THUMP of a RUBBER mallet. $300? More? If not a rubber mallet then use the handle of a large screwdriver. The force delivered is pretty modest no matter how hard you strike.

A fuse on a 24 volt line? Why do you think they use a 24 V system in the first place? Hint. Inherent safety for just this very instance of a wire short. Anyway short means no juice to the valve. Valve never opens. No gas. No heat. No danger of a gas leak explosion. You don't know your basics.

The 24 V wire insulation had degraded from age (25 years) in a hot environment (near the burner array). These things happen. And also a lot of more weird furnace malfunctions in many ordinary households. You don't hear of houses blowing up all over the country. This is because there are many interlocks and strength built into the system to prevent ham handed fiddling that will result in a gas explosion. Lots of unknowledgeable people do try to save themselves from price gouging by people like you. The built in furnace safety features have taken into account such amateur attempts at fixing.
There's nothing much in items the homeowner or the service guy can fix anyway. Just the thermostat, the 24V transformer (correct voltage output?), the integrity of the associated 24 V wiring and of course the sticky valve thing. Other parts like the fan, the motor, etc. are mechanical and any problems are obvious and non critical (ie no linkage to a possible gas leak.
My advice is to try a few simple steps first. Its not always possible to get a service guy to come promptly. And the ability to understand how the furnace works and what one can do for oneself avoids a lot of anxiety as to when to call the service guy and as to what is a reasonable charge for the work involved.

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