Question on water system capacity

[pvstoy]

I bought a 2015 FWC Hawk flatbed and I like to know how things work and such not. Been sanitizing the water system, found a o ring leak on one of those quick connect fittings to the indoor shower.

But what I found that filling the tank with both valves open will also fill up the hot water heater. And with both valves open the water pump just pumps in a endless loop. I did run a quart out the sink hot water faucet.

Ok onto the question. FWC list that it is a 20 gallon fresh water system. I put in 18.5 gallons when water went out the vent and filler tube.

Is it your experience that so-called 20 gallons include the hot water heater volume? I guess I was expecting to have some where around 26 gallon capacity.

Just getting opinion as it is what it is.

 

[longhorn1]

20 gallon fresh water plus 6 gallon hot water tank for a total of 26 gallons. You can't really drain the water tank completely so there will always be around 2 gallons left. Congrats, jd

 

[pvstoy]

Compleatly drained the whole System and could only put back 18.5 gallons

 

[pvstoy]

Alright I have miss calculated. on removal, and you are right it drains slow, with both valves closed I got 19.5 gallons out. Then opened the two valves and water was moving out of the hot water heater to the tank very slow and it sped up when I opened the relief valve. I then drained 5.75 gallons. So appears getting to know the system all seems as I expected it to be. Cheers!

 

[longhorn1]

Alright I have miss calculated. on removal, and you are right it drains slow, with both valves closed I got 19.5 gallons out. Then opened the two valves and water was moving out of the hot water heater to the tank very slow and it sped up when I opened the relief valve. I then drained 5.75 gallons. So appears getting to know the system all seems as I expected it to be. Cheers!

The drain pipe is approximately 2" above the bottom of the tank, which allows 2 gallons +/- to remain in the tank.

 

[Bombsight]

^^^ That's a messed up system. Why wouldn't somebody who designs a water tank design it to where it could be fully drained? That's essentially a health safety issue.

 

[rando]

It is a practical issue - the drain fitting is on the side of the tank, and needs to be a little away from the edge of the tank so it can have some wall thickness for the NPT threads, which leaves a little bit of tank below the drain fitting. You can get almost all the water out by parking on slope to drain the tank, or by leaving the drain open and driving. When you turn right (on my Fleet anyway) the water sloshes to the left end of the tank where the drain fitting is.

 

[Old Crow]

The discussion brought to mind one of captainphx's photos of the water tank in his 2012 Raven. He took the photo because of a leak at one of the sensors but it also shows us the fittings.

(click to enlarge)



Note- The photo comes from this Water Tank Leak thread. I cropped it a bit for this post.

I've always liked this photo as it shows the fittings spin-welded into the tank, the water-level sensors, the wire loom for the sensors, wire colors to each sensor, etc.