Filling fresh water tank also fills Hot water tank???

[JPHealy]

I have a 2018 greyhawk 30x. I have noticed that when I fill the fresh water tank the Hot water tank also fills. Why would that fill and has anyone else noticed that. I would assume when filling fresh water tank that would be the only thing filling. I verified I had the manifold in the correct position 1-6 to city fill fresh water tank.

[Dave55]

Maybe you had the water pump on and a hot water tap open. Just guessing.

[JPHealy]

No verified no water pump running. thanks, I noticed this earlier this season when drained everything including hot water tank but it into storage for a few weeks, then pulled it out to get an alignment done. I filled the fresh tank to add some real world weight to it. Drained the fresh water tank when I returned home. Three weeks later we go out to go camping and notice the hot water smells. Here it filled and remained filled when the fresh tank filled. I know to check now but doesn't make sense that that would fill. My last RV 2009 Holiday Rambler Arista I could fill the fresh tank with out issue. But that had a gravity fill system verses the manifold system on the Jayco.

[hoppers4]

That's the my rig works also. It not only fills the tank in that position, but also charges the complete water system. When I'm filling my tank I always open my kitchen faucet to hot to ensure my hot water tank fills up completely. When the water starts spitting from the faucet, my hot water tank is full and my fresh water tank is about half full. Just where I want it actually.

[JPHealy]

Thanks, I still think it is misleading but at least I am not the only one. I never thought that it actually pressurizes the whole system. I will start doing as you described.

[hoppers4]

Bear in mind that once the water system is charged, the fresh water tank will start filling twice as fast.

[Fr8Train]

Under normal operating conditions it should. If you don’t want it to fill the HWH, you’ll need to put it in bypass mode.

[cabinetmaker]

Never noticed this...but come to think of it mine does it the same. Thanks for the heads up!

[JPHealy]

Thanks for all the replies. This is one of those “now I know”.