Fresh tank help needed

[Falcon]

I have a 2019 3791RD. I was told by the dealer rep that it had one fresh tank with two drains because it had a saddle-shaped tank over the axles. While sanitizing before our first use, I filled the tank and added bleach. While draining it the next day, I opened the rear drain and it drained normally. Then I opened the front drain and the pump started and shot water out the front drain under pressure. I had mistakenly left the pump switch on. I immediately thought I should shut it off but had forgotten the keys. I couldn't get to the battery cutoff either. I panicked thinking the pump would burn up when the tank ran empty. I crawled back under and managed to get the cap on while getting soaked. The pump built up pressure and stopped. Why is the pump connected to the front tank drain? The tank finished draining out the rear drain. When I got the keys, I turned off the pump and opened the front drain and about a cup or two came out and then stopped. I have been lied to about a "saddle" tank. What's the real story about this tank and the pump relationship to it? Dealer did not return my calls.

[rohrmann]

I’m thinking the second drain is the one for the ice maker in your residential fridge and with the pump turned on, there is pressure in the entire water system in your rig, the ice maker included. This is just like if you opened the hot and cold low point drains while the system is pressurized. Just like with most salesmen, was likely he doesn’t know what he’s talking about. Never heard of a saddle tank for anything in these rigs.

[RMcNeal]

As rohrmann said, the front drain is for the ice maker line, and pump kicked on to provide pressure for the demand created when the drain was opened. I have this same unit. The fresh tank is not "saddled" over the axles. It is actually behind the rear axle.
In addition to the ice maker drain in the slide where refrigerator is located, you also have low point drains in the convenience center for both cold and hot water. Either of those would also cause the pump to kick on from the draw as well.
One other thing...if you are draining the ice maker line intentionally like during winterizing, make sure you cut off the valve under the sink or you'll just drain your tank.

[speedster100]

Or is it the low point drain ??? I'm guessing they told him to open both drains when preparing for winterizing. The drain for the fresh water tank and the low point drains for the system... Opening the low point drain would immediately release the pressure in the whole system which would trip the limit switch on the pump to start it. The fridge drain would be alot slower draining off pressure......... just saying. Sure do wish they'd start installing a switch for the pump at the convenience centre...

[Falcon]

Are you absolutely sure this front drain is for the fridge? The back of the fridge is all the way on the outboard side of the left kitchen slide so that's a long way to run a drain line. If you are guessing that's one thing but if you know for sure then I believe you! My walk-through rep at the dealer didn't know much. Also, why do they refer to the hot & cold drains as "low point" when they are clearly a foot and a half above the tank drain?

[Tom N OH]

The forward drain that was under pressure from your water pump is definitely to drain the line going to the ice maker. It is simply at a mid point in the supply line. The low point drains are the lowest point in the pressurized side of your water system. The rear drain is to drain the fresh water tank, which is the lowest point on the non-pressurized side of your water system. I am 100% sure of this.

[triplebvalp]

Falcon, on our 2020 295RL, the front drain is definitely for the fridge, the rear drain is for the fresh water tank.

[Falcon]

Thank you. I understand all you said except the valve under the sink? Which valve and what does this do?

[Tom N OH]

There should only be 1 valve under the sink & it shuts off the water supply to the ice maker. There is also another valve close to the refrigerator. Usually behind the drawer below the oven. I had to remove the drawer & lay on the floor to reach that one in our 3811MS. When we got it, both valves were shut off & the drain cap underneath by the axles was loose. After I turned the valves on, I went outside & had water spraying all over from that cap, as you learned. I went back inside, turned the valve under the sink off, then went out, crawled on the wet ground & tightened the cap. Luckily we were on a concrete pad, so it wasn’t muddy. Just wet. Also, in case you haven’t figured it out yet, when the cup of ice shows on the refrigerator control panel, that means the ice maker is “OFF”. Cup not displayed means ice maker is “ON”.

[triplebvalp]

Originally Posted by Falcon

Thank you. I understand all you said except the valve under the sink? Which valve and what does this do?

The valve under the sink not only passes water to the ice maker ( when open ), it also allows you to drain the ice maker line. So, to properly drain the ice maker line, the valve next to the stove needs to be open, the valve under the sink needs to be open, and the low point drain valve needs to be open. Normal operation of the ice maker would have the valve next to the stove open, the valve under the sink open, the low point drain valve closed.

[RMcNeal]

Falcon, I have the same unit, a 2019 3791RD.
On my unit, you have a drain on the ODS side rear of the axles that protrudes through the coroplast. This is the fresh tank drain.
Under the ODS kitchen slide, I have a white flexible hose that feeds water to the icemaker. No specific "drain", but you can unscrew and disconnect this to drain the icemaker line under the slide for winter.
I also have low point drains in the convenience center, both blue pex (cold) and red pex (hot).
The valve under the kitchen sink is tee'd off the blue cold line feeding the sink and goes back down below the floor. This feeds yet another valve located behind the panel at the rear of the cabinet between the stove and fridge. This valve connects the water supply to the ice maker in the slide. In order to get water to your ice maker, both the valve under the kitchen sink and the one between the stove and fridge must be on.
To drain this line for winter, since it is exposed under the slide, you must turn off the valve under the sink and drain the white flexible line under your kitchen slide.
Do you have another drain line?

[Falcon]

RMcNeal, yes, there is another drain dead centerline under the unit and about a foot ahead of the front axle. Dealer rep told me this was a second drain for the fresh tank, it most certainly is not. I'm still waiting to hear back from Keysyone tech rep. For winterizing, I would open both the interior valves feeding the ice maker, then disconnect the line under the slide AND open this forward mystery drain. I was under there just today and saw the line you mentioned under the slide, not terribly difficult to get to. Would this for sure get any water that may already be in the ice unit or would some air pressure be required to assure it is empty?

[RMcNeal]

If you are only using compressed air to winterize, you can leave both valves open and and open the line under your slide to blow out any air.
If you are using antifreeze, close the valve under the sink when winterizing. Open the valve between the stove and fridge and drain all water from the line under the slide. Otherwise, you'll get antifreeze in the ice maker.
I just went out and checked. I do not have anything in front of the axles except the black plumbing pipes for gray and black tank drains. Is your drain like the one behind the axles? Mine is just a short white hose with a screw on cap which drains the fresh tank.

[Falcon]

RMcNeal, I was just thinking would it be better to have antifreeze or water in the ice maker when it gets down to zero? I need to be confident that draining will leave the ice maker protected.

[RMcNeal]

I've been in -7 degrees and just draining and blow out with air is all I ever do. Dont use antifreeze in water lines at all. I have poured some in black and gray tanks though.

[ejerni]

Originally Posted by Falcon

I have a 2019 3791RD. I was told by the dealer rep that it had one fresh tank with two drains because it had a saddle-shaped tank over the axles. While sanitizing before our first use, I filled the tank and added bleach. While draining it the next day, I opened the rear drain and it drained normally. Then I opened the front drain and the pump started and shot water out the front drain under pressure. I had mistakenly left the pump switch on. I immediately thought I should shut it off but had forgotten the keys. I couldn't get to the battery cutoff either. I panicked thinking the pump would burn up when the tank ran empty. I crawled back under and managed to get the cap on while getting soaked. The pump built up pressure and stopped. Why is the pump connected to the front tank drain? The tank finished draining out the rear drain. When I got the keys, I turned off the pump and opened the front drain and about a cup or two came out and then stopped. I have been lied to about a "saddle" tank. What's the real story about this tank and the pump relationship to it? Dealer did not return my calls.

We have the same model with rear living room. I purposely closed the 2 grey tanks. When the kitchen sink backed up in it, I opened the #2 tank and it drained, same with the shower and sink . I pulled the #1 tank and it emptied.