Black tank flush for two bathrooms

[rschaz64]

Hello.

I just started using my new 2020 3761FL and love the layout. Already starting to have questions, though.

This floor plan has two bathrooms; the main in the back and guest in the center.
I tried to flush the black tanks today and discover that the tank flush hookup only flushes the guest tank. (There is no other flush hook up that I have found.)

Am I doing something wrong or does this model really only have a flush on the second (guest) black tank? (Even if there is only one flush, wouldn’t you think it should be in the main black tank that is used on a more consistent basis?

Any advice would be appreciated!

Thank you, in advance.

Rick

[1retired06]

How did you confirm one tank did not flush? We have two toilets, different floorplan. Bedroom toilet flush was in the convenience center. Half bath flush was in a panel door on the side just before the axles. I use the word was because I rerouted so all are threaded rod pulls, eliminating cable pulls. Try looking underneath the trailer near the rear wheels, ODS side. You must have one somewhere, maybe inconvenient location. Surely Keystone would not have missed installing a flush. Hopefull someone with your same floorplan will jump in.

[mbjam359]

I believe we only have 1 black tank flush on our 2020 3931FB. Its a bath and a half.

[prndl]

I believe the OP is talking about the tank flush water connection and not the location of the pull handles.
When he used the words "tank flush hookup" was the giveaway.

[DQDick]

So far, all the two bath Monty's I've seen only had one flush. Doesn't make sense which one they choose in your case, but on the other hand most of us got by fine for years with out a black tank flush until they started to include them.

[grass man]

I have the 3931 and I noticed that also. You flush the tank and it seems like only the 1/2 bath tank fills with water. I usually set something heavy enough on the main bathroom toilet flush handle and fill some that way.

[Mikendebbie]

On our 3921 there are two hose connections down low in the convenience center. The left connection is the black tank flush for the front bath black tank. The connection on the right is the flush for the half bath black tank. No flush for the gray tanks.

Tank valve pulls for the front bath gray & black tank are in the convenience center. Tank valve pulls for the half bath/kitchen black and gray tanks have an access door about 6’ toward the rear from the convenience center.

[1retired06]

Originally Posted by prndl

I believe the OP is talking about the tank flush water connection and not the location of the pull handles.
When he used the words "tank flush hookup" was the giveaway.

You are right! Misunderstood. We can only flush the main. Options for the second could include refilling via a hose down the toilet and redumping or using a backflush blade valve at
the sewer hose connection. I use the old hose down the toilet method.

[dfroggatt]

My rig has 2 Gray and Black water Pull drains. One in main wet cabinet and second set near wheel wells.

In the Global connect panel, it registers levels in Black Tank 1, Black Tank 2, Gray Tank 1 and Gray tank 2.

What confuses me is that I do not have any specs that tell me the size of these individual tanks.

Black Tank 1 has a Spray flush valve. Black tank 2 does not. Why?

I frequently have issues in draining Black tank 1 (must be bedroom toilet).

Sure would like to know more details about these 2 black and gray tanks. Are they truly separate? What is the size of each? Hopefully someone in this forum can help me answers these questions. No manuals specify this information.

[AZ Traveler]

Originally Posted by dfroggatt

My rig has 2 Gray and Black water Pull drains. One in main wet cabinet and second set near wheel wells.

In the Global connect panel, it registers levels in Black Tank 1, Black Tank 2, Gray Tank 1 and Gray tank 2.

What confuses me is that I do not have any specs that tell me the size of these individual tanks.

Black Tank 1 has a Spray flush valve. Black tank 2 does not. Why?

I frequently have issues in draining Black tank 1 (must be bedroom toilet).

Sure would like to know more details about these 2 black and gray tanks. Are they truly separate? What is the size of each? Hopefully someone in this forum can help me answers these questions. No manuals specify this information.

I am assuming your model number you quoted is not correct - I have never heard of a 3139.

Your tanks are all separate and should be a little over 40 gallons each. No clue why Montana only does a single black flush line but that is the way they do it. You can alway run a hose to the toilet which will do the same thing.

You can always confirm which tanks go where by running water to them after they have been emptied and see which connection the water come out.

The level indicators are basically useless for black tanks - just plan on dumping them every 7 days or so.

Tell us more about the issues draining your black tank and maybe we can help.

[Ahdmeyer]

on my 3931fb i inquired at the factory and was told The second flush is the one behind the blu and red pex hoses. In my picture the one with the yellow hose end. i have put quick connects on them. The one is hard to get at
Al meyer
3931 fb

[RMcNeal]

As I understand it, you should be able to look up your model specs on Keystone's website. They list a 3931FB, I'm assuming that's yours, with 88 gal gray water and 88 gal waste water. That means each tank is half that, or 44 gal each.

[dfroggatt]

Originally Posted by RMcNeal

As I understand it, you should be able to look up your model specs on Keystone's website. They list a 3931FB, I'm assuming that's yours, with 88 gal gray water and 88 gal waste water. That means each tank is half that, or 44 gal each.

I am a long term camper. Keep tanks closed and periodically open Black (1 & 2) to drain (followed by Gray 1 & 2) once Black tanks are emptied.

I was periodically having difficulty draining tank 2 (half-bath). There is a flush valve that appears to only flush tank 1 (bedroom). So, not being confident tank 2 was being flushed, I installed a shut off valve on the water to the toilet, and adapted sink faucet to accept hose, which I use to flush tank 1.

I am not confident my thinking was correct, so I started searching websites to see if tank 1 and tank 2 were connected in any way, or if they were actually totally separate. I found no literature actually stating the two tanks were separate or their size. All relative information was conflicting.

[Ahdmeyer]

if the 2 tanks were separate would they have 2 differant black valves to dump?defrogatt is your setup like mine 2 posts above?
al meyer
3931fb
az

[Sumri]

I have a 2020 3761FL. We have 2 black tanks and 2 gray tanks. All four tanks have their own pull cable to open each tank individually. All four pull cables are located in a box on the driver side just forward of the drain connection.

[dfroggatt]

Originally Posted by Ahdmeyer

if the 2 tanks were separate would they have 2 differant black valves to dump?defrogatt is your setup like mine 2 posts above?
al meyer
3931fb
az

Here are my valves. 2 is one in rear, not 1.

[Ahdmeyer]

that is exactly the same as mine. , the fitting above the red and blu pex is other tank wash that is where i put the quick fittings on it is a bear to get a hose on. correct me if i am wrong but the white hose is the other tank wash correct and the one above is for the fresh water inlet.
al meyer
3931fb
az

[dfroggatt]

Yes, the white hose is the Tank Wash (I believe Tank 1, Bathroom) and the Blue hose is a heated hose for fresh water fill.

Thank you much for your feedback. I will now connect a hose to the Tank 2 Flush connector and see what transpires. Why they did not mark these .. I am baffled.

P.s., I have a quick disconnect on the Tank 1 line, I will now place one on the Tank 2 line.

[Ahdmeyer]

yes i agree it would not have taken to much to label them i found out on the montana tour when i went on it, i asked why no 2nd flush and found out then. like i said before i used these quick fittings to connect when using the flushes, the one is really hard to get the hose on, now it is easy. here
https://www.amazon.com/Connect-Fitti...20282791&psc=1 another small thing i did was add motion leds to the 2 front compartments. now open the door and they come on for a preset time and then go out. always looking for something new if anyone has any tips or tricks

good luck
al meyer
3931fb
az

[grass man]

Hi Guys, been following your comments. I have a question, so what is the "tank fill power fresh valve for. I have the 3931 it is set to normal flow now.

Thanks