Repeating metallic ping near furnace

[Tad K]

First trip out with my new/used Casita! Dry camping, having a pinging noise every 15 seconds or so near the furnace, sounds like metal heat expansion/contraction but way too regular.

Furnace has been off but seems fine: turning it on gives blower and then heat, back off everything shuts down as expected and then back to pinging.

Earlier thread said could be converter but I’m not on AC. Brand new battery replaced by shop just after inspection. DC seems fine: lights, water pump, blower all good. Hard to enjoy the nice river with the pinging.

Any ideas most appreciated!

[Tad K]

I pulled the 7.5 amp fuse for the furnace a few minutes ago and the sound persists…

[Raz]

Could be the brake controller checking for a connection. Try unplugging.

[Tad K]

Good thought but I unplugged when I got here so I wouldn’t drain the TV batt.

I think I’ve identified all of the water heater noises (click on, flame, click off) so I’ve hopefully ruled that out.

The constant regularity stopped mid morning and now seems to be only every few minutes or so.

[floyd]

How about the water pump, maintaining line pressure?

[Tad K]

Water pump is a low rumble that lasts for a few seconds. This is a quick metallic ping almost like hitting one of the metal fins inside the fridge — the first night I thought it was temperature creaks on the fridge but it’s definitely on the left near the furnace.

Almost sounds like a slow drip on the fins of a window air conditioner… I’ll have to check how the water lines run in that area

[Tad K]

After a bit of spelunking I discovered that what sounds a lot like water on metal… is! The hot water line had a slow drip right on top of the furnace. Which also explains why I have less water than I thought I did. It doesn’t explain why the RV place that I payed for a thorough check over didn’t find it

Thanks for your suggestions and letting me bounce ideas around. Sometimes having to explain things makes me think through them more methodically. And hopefully this thread can help someone else with a similar situation!