It has been determined by an AC & Heating repair Co. that my natural gas smart valve that lights my furnace burner needs replacing. It will light the pilot, but will not stay in the open position very long to light the burner. Sometimes I get lucky and it will light for maybe an hour then for whatever reason cycle closed but pilot still lite. I can hear it clicking and the burner will fire up and back off repeatedly. So the repair guy wanted $659 dollars to replace it, I asked how much he was charging me for the valve and he said $450!!! I still have all the manuals so i looked up the part and they are readily available online, for $150 - $200. So I have found a direct replacement, which seems easy enough to replace just threads on so my question is this: the pressure regulating setting is set at 3.2 in WC (inches of water column), being I dont have a way to measure what the current valve is set at is 3.2 in WC okay? Sorry for the long post leading up to such a short question. Thanks.

 

You can pick up a manometer(instrument for measuring gas pressure) at a local supply house or find one online..However, they generally come set from the factory and all you need to do is thread it on and rewire it...be careful with the pilot tubing and brass fitting for it as it is very easy to crossthread when re-installing...Is it a Robertshaw or Honeywell valve?

 

It is a Honeywell valve. So i assume i connect the manometer to the valve at the pilot tube to measure the pressure? thanks mrinaldi

 

On most Honeywell gas valves, there will be a hex key plug on the gas outlet side of the valve. That is where you thread in the fitting for the manometer tubing..Oh yeah, may sound idiotic, but make sure you turn gas off before removing and installing new valve Lemme know when your back up and running...one other tip...when applying pipe thread compound "pro-dope" or equivalent, use sparingly on the threads..Just enough to evenly coat the threads..Ive seen guys use to much on the inlet side of valve and end up clogging that screen causing problems...

 

mrinaldi, thanks for the help. The heater has begun working on its own again. maybe a loose connection? I did some research on the valve and maybe my tapping on it worked? Another theory I have and I could be way of, is that since we had the cold snap here in houston more people were using their gas furnace causing a gas pressure issue. From what I gather, the valve needs 3.5in WC to properly operate. Could gas pressure be similar to water pressure, when more people use it the pressure goes down? I'll keep an eye on it and try to find a manometer this weekend and see what i get.

 

A gas valve that doesn't work properly is a scary thing, to me. I mean, this is in your house, right? With all your stuff in there? Your dog? Maybe a wife and kids?

If you can get a direct replacement for the valve for $150-200, buy it and pay the guy with the tools and knowledge/experience to put it in correctly. Then you can stop worrying about it.

I'd be worried.

 

You should pay a pro.diyand uhave no warranty.smart valves have problems.replacing the fan timer board is a good idea as well.,so is the igniter senser. The valve needs set to whatever the furnace manufacturer requires.

 

I'm going to suggest you have a look at the sensor that tells the system the main burners have lit. It's a millivolt thermocouple (I think) that provides the control board with an electrical signal that says "all is well" and to continue supplying gas to the main burner.

If the board "thinks" the burner hasn't lit, it shuts off gas to the main burner. It sounds like in your case, after a short while, the system resets and tries another light.

The fact that SOMETIMES the system lights properly, suggests to me the sensor might be dirty. If you can find it, try wiping it off. It will probably look like a "probe".

The control board itself can be faulty too - that's a relatively expensive part.

Don't ask me specifics about Honeywell - I don't know them. I just know how some of the safety features are designed.

- Jack

 

There's a joke somewhere in here involving "manometer".

 

X2 what Jack and Janet said

 

I pretty much concur. Flame sensors are know to fail. Often times you can just clean them with a piece of scratch cloth and they will continue to work for years.

Unless it's a pretty simple set up, which usually isn't the case if you are dealing with something called a "smart valve", you are better off leaving repairs up to a tech. Not only because you could increase the risks of a major problem, but also, a tech is going to follow a set of proceedures to determine the fault. If you do something that could give a false reading it might take the tech longer to find the actual fault and will probably cost you more.

 

I wasnt the op. I do hvac for a living ...........i wont even get started on the smart valves too much to say!!!!!!!!!!!!