Help me not blow up my house

So, the gas solenoid on my 11-year-old Goodman NG furnace has stuck closed twice recently.  Both times I got it to function by cycling the power on the gas valve itself.  I also had cycled the power on the main furnace, not just the valve.  It's been working fine for about a week now.

I had an HVAC tech from the company who did the original install come out and look at it.  He claims a number of things:

1. Cycling the power on the furnace clears any diagnostic codes that might have been stored.
2. Behaviour as I described is consistent with a dying solenoid in the gas valve.
3. Cycling the power on the gas valve (or furnace) will radically shorten the lifespan of the valve.
4. It's going to cost me almost $1000 to have them replace the valve.

My thoughts are as follows:

1. That's possible; I have no way to know.
2. That's why I tried resetting the valve itself.
3. This I highly doubt and it smells like hooey to me.  If the solenoid is dying, it's dying, but turning it on and off shouldn't hurt it.
4. I think I need a second professional opinion on that, which I plan to get.

The valve assembly itself looks to be somewhere between $110-$140 for me to buy.  It's got gas in and gas out via a union and a compression fitting.  I have  wrenches and I know how to test for a leaking connection.  There are a couple spade connectors to move over.  I know where the main supply valve is to the house.

How hard can it be?  How likely am I to blow up my house if I try to replace this myself?  Is that a stupid way to try saving $800?

In reply to Duke :

I presume you have a shut off valve at the furnace? If so, I’d totally DIY it. 

Do it. 

If it goes well, life will get better. If it goes poorly, life will get better. 

If you video it, you can be a YouTube hero either way. 

Pete Gossett said:

In reply to Duke :

I presume you have a shut off valve at the furnace? If so, I’d totally DIY it. 

Yeah, there's a 1/4-turn shutoff right at the furnace.

SVreX said:

Do it. 

If it goes well, life will get better. If it goes poorly, life will get better. 

If you video it, you can be a YouTube hero either way. 

Everybody's a comedian!

Changed the gas valve in my Ameristar furnace two years ago with no issues.

Use the proper sealant, soap-test the connections, don't be an idiot and you'll be fine.

A $90.00 part plus a an hour of my time and I had a working furnace again.

I would DIY it for sure. As mentioned, use the right sealant ( I would assume pipe dope?) and hit with the soapy water to be sure.  If it does leak, you will get a smelly warning.

How people who cant fix E36 M3 afford to live I do not understand. Just this last month I have had to snake out a sewer line and replace a start relay on the fridge. That would have been better part of a $1000 bill out of my pocket had I called the trades. Actual cost was just over $100 for both jobs.

Just spent the savings on Molvo parts!

Pete

REPLACING THAT VALVE WOULD BE LIKE DROPPING A BOMB ON THIS CITY. 

NOHOME said:

I would DIY it for sure. As mentioned, use the right sealant ( I would assume pipe dope?) and hit with the soapy water to be sure.  If it does leak, you will get a smelly warning.

 

Pete

What he said.  I replaced the regulator on my gas stove myself after dire warnings not to from the appliance guy. The piece was about $45 and it took all of 30 minutes including an overly cautious number of leak checks. 

A house blew up in St. Paul today, the cause hasn't been determined yet but considering what's been reported so far I suspect it was a gas explosion...just sayin'.  Make sure you know what you're doing.

I just recently replaced my gas fireplace.  Just make sure to use the right thread sealant and check all the fittings for leaks.  If you use teflon tape, make sure it's the yellow stuff.  

stuart in mn said:

A house blew up in St. Paul today, the cause hasn't been determined yet but considering what's been reported so far I suspect it was a gas explosion...

Turns out the explosion in St. Paul was captured on video from a convenience store security camera down the block.  It was pretty impressive.  https://www.youtube.com/watch?v=XB7uc2hCuss

I once paid a plumber to install a gas shutoff valve for a dryer, where there previously was only a capped pipe. He didn’t even shut off the gas, just unscrewed the fitting and replaced it. The gas line pressure inside the house is very low. 

I would proceed with saving $800. 

Use Rectorseal on the external pipe threads, none on the internal, and don't overtighten the black pipe into the gas valve.  Gas valves are aluminum and you can split the threaded portion if you go too tight.  Make sure you have two sets of pliers and back up whatever you are tightening or loosening.  I changed out one on a water heater for a customer last week and I only charged $100.  Took all of 20 minutes including writing the bill. 

If there are any flexible lines that have flared fittings, do not use any thread sealant on the threads or tapered sections.

Just an fyi.

If it leaks, tighten it further, if it still leaks, there is something wrong.

Thanks for all the input, folks!

Go for it, Duke.  Residential gas pressures are in the 3-4 psi range, so doing it safely is pretty easy.  Gas isn't as deadly as everyone things.  Yes, it is an explosive hydrocarbon gas, but it also needs exact concentrations of air/fuel to explode like that house in the video.  Pros still use the open flame/lighter test to check for leaks.

I recommend pipe dope (the white teflon paste), install the valve, tighten the NPT fittings, and use a spray bottle of a household cleaner like 409 or simple green to spray on the joints to make sure there are no bubbles.  That's what I did when I converted my old house to a gas stove; just added a tee, ran 8' of black pipe, and shoved it up through the kitchen floor.  No one died.

Wrong.  Residential gas pressure is in the range of .5psi or less.  Its so low its actually measured in inches of water column it can lift.  One psi can lift 27 inches of water.  Just set gas pressure for a Modine heater and factory specs wanted to see 12 to 14" of water going in and 10" under full fire.  Most residential systems work in the 7" and under range.

Just as closure for this thread:

Ordered the part shortly after this discussion and kept it in inventory.  Of course this meant the OE valve continued to work fine for another month.

After it quit again on New Year's Eve, I smacked it with a wrench to get it open, ran the house up a few extra degrees, then shut off the gas.  Replaced the valve by removing the whole manifold so I could disconnect it on the bench.  The installer put the supply union in a stupid place but I go that apart too.  The old pipe dope was like Locktite so I really had to horse the connections at the old valve to get it apart.

Once it was apart I cleaned up all the threads and applied fresh NG-rated pipe dope.  Installation was the reverse of removal, as they say.  Leak tested twice with soapy water and we've been in business since then.

Pro estimate: $980

Actual cost: $121.75 + 45 minutes of my labor

In reply to Duke :

This calls for a beer!

tr8todd said:

Wrong.  Residential gas pressure is in the range of .5psi or less.  Its so low its actually measured in inches of water column it can lift.  One psi can lift 27 inches of water.  Just set gas pressure for a Modine heater and factory specs wanted to see 12 to 14" of water going in and 10" under full fire.  Most residential systems work in the 7" and under range.

yeah. At my house we are regulated at 1/4 psi. I installed a backup generator last spring so I was looking into our gas supply with the utility. 

Nice work Duke!

Nice work. I’m only good at blowing up bathrooms. 

What the hell kind of pro charges a grand for changing a valve?

That's service call E36 M3, in and out, parts and an hour of labor.

I’m In reply to Grizz :

Precisely why I told them to berk themselves. 

Labour, plus the minimum 1 hour truck charge, plus travel time, plus environmental fees...