Have you ensured the gas valve is turned in the correct direction when descaling a tankless water heater?
Asked by Hilda Franklin 
2 weeks ago
Last Updated: November 4, 2024
When descaling a tankless water heater, should I focus on turning the gas valve in the opposite direction before getting started?
It all comes down to the specific tankless water heater specifications provided by the manufacturer.
If the manufacturer requests to shut off the gas, then definitely.
To prevent damage or excessive wear on the burners, remember to disconnect the power cord before stopping the water inlet and outlet to allow the water and vinegar mixture to descale the tankless water heater for about an hour annually.
The gas won’t flow into the unit without electricity to open the internal valve for the burner and igniter to work.
The instructions can be found in the manual.
If you need help, consider contacting a plumber.
How else can someone acquire new skills if they don’t ask questions?
To clean it, you’ll need a plumber to set up a water inlet and outlet, unless they’re already inside, which is highly unlikely. Leave the gas valve as is; simply turn it off or unplug it.
Oh, I don’t think so. Do you see those valves at the bottom? They have ports attached for connecting to descaling equipment
Actually, my eyesight isn’t the best 😄
Haha, I’ve got you taken care of! lol
Just disconnect the unit. – a plumber
Feel free to turn that valve on or off, it won’t make a difference either way.
Just disconnect the 110V power cord.
Attach your bucket and pump to the marked cap on the red valve set (hot side), and connect a return hose to the cap on the marked blue side.
Turn all four valves to close the incoming water (2) and hot water to the house (1) lines. Then open the descale ports on both lines (3 and 4).
Your descaler will flow from the bucket through the coils in reverse, and then back into the bucket for recirculation. After finishing, disconnect the pump and open the blue inlet port (2) to flush some water through. Remove the bucket and hoses and return all ports to their original positions (1 and 2 open, 3 and 4 closed).
Run your shower with the hot water valve fully open for 5 minutes to eliminate any remaining residue. Return, plug in the hot water heater, and ensure that your hot water is working again.
No action is necessary with the gas line.
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So, first things first, track down the gas installer and reconsider that decision. Are we seriously looking at a 2-foot cantilever dangling from a 6-foot unsecured drop, relying on some flex at the tankless unit? And let’s not even get started on the lack of support for the water lines. On the bright side, the condensate drain does have an extra opening in the T. Also, he opted for 2 additional short pieces and couplers instead of a single length of pipe. Is that a combination of soldering and sharkbite fittings on the tee at the cold inlet? Sounds like this might be a joke post.
I could use some help here, I know I’m not dumb, but I’m struggling with these valves. I can tell which way they’re supposed to turn, but they just won’t budge.
Only needs to give the valve handle a slight twist until it’s perpendicular to the gas line. It should turn easily by hand.
I appreciate the help – the valve was stuck. Even though I consider myself quite strong, I had to remove the screw and use pliers to turn it all four ways. It’s tricky since they’re not situated on a stable section of the pipe.
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I didn’t put it in myself! But I did manage to remove the limescale. However, when I tried to flush out the chemicals as directed, I got some really dirty water coming out from the city supply when I opened the main valve, and that ended up going through the water heater! 🤪😢
Hey, do you happen to have a water softener?
Nope, not for me.
You might want to consider getting one, along with a whole house charcoal filter. It can help prolong the life of your fixtures and system.