macerator in winter camping

[booster]

I am confused a bit about the pic of the tank connection.


The piece shown looks to be tig welded, so the only way it could be brazed would be if it was flanged an then, probably, silver brazed from on the inside of the tank.


IMO that is not a bad way of doing it, although it does have the water and brazing alloy contacting each other. I haven't looked into it but depending on the silver brazing alloy, some might be concerned about leaching.


Essentially all the tanks in the factories are was in were TIG welded to the stainless tanks, or a stainless flange welded on, or bulkhead fitting used with gaskets.


I am thinking of having a tank made for ours to add a small water tank in the rear now that I have space the AGM batteries in place. I have pondered the construction method a lot, and silver brazing was on of the options on the list to check out, with the more surefire welded flange with bolt on mating flange and gasket. Same would apply for an access hole to be able to clean the tank if needed, probably combined with a fill port high connection.


Are the tubes supported internally at all to prevent bouncing? Hard to tell for certain on the drawings.

 

[GeorgeRad]

I am confused a bit about the pic of the tank connection.


The piece shown looks to be tig welded, so the only way it could be brazed would be if it was flanged an then, probably, silver brazed from on the inside of the tank.


IMO that is not a bad way of doing it, although it does have the water and brazing alloy contacting each other. I haven't looked into it but depending on the silver brazing alloy, some might be concerned about leaching.


Essentially all the tanks in the factories are was in were TIG welded to the stainless tanks, or a stainless flange welded on, or bulkhead fitting used with gaskets.


I am thinking of having a tank made for ours to add a small water tank in the rear now that I have space the AGM batteries in place. I have pondered the construction method a lot, and silver brazing was on of the options on the list to check out, with the more surefire welded flange with bolt on mating flange and gasket. Same would apply for an access hole to be able to clean the tank if needed, probably combined with a fill port high connection.


Are the tubes supported internally at all to prevent bouncing? Hard to tell for certain on the drawings.

My tanks were welded including heavy-duty stainless-steel NPT fittings. Level sensor was attached to a flange with gasket. TIG welding could be more damaging to a seamless tubing potentially causing its galvanic corrosion, brazing is done at lower temperature.

One item on my project list is to improve freezing prevention on the fresh water tank by running copper tubing touching stainless steel tank form outside, currently I have rubber hose with hot coolant running through it in close contact with the tank and never had a problem, so my copper tubing left on a shelf.

 

[booster]

My tanks were welded including heavy-duty stainless-steel NPT fittings. Level sensor was attached to a flange with gasket. TIG welding could be more damaging to a seamless tubing potentially causing its galvanic corrosion, brazing is done at lower temperature.

One item on my project list is to improve freezing prevention on the fresh water tank by running copper tubing touching stainless steel tank form outside, currently I have rubber hose with hot coolant running through it in close contact with the tank and never had a problem, so my copper tubing left on a shelf.

The corrosion thing is one that I have been looking at in TIG vs silver.


With the right filler to match the SST alloy, weld are generally very corrosion resistant from what I have seen over the years we never had issues with them. You tanks are probably 302/304 type alloy which isn't hardenable.


All bets are off if you use the direct hardening SST alloys in the 400 series. They are magnetic and less corrosion resistant in general and weld effected areas can be a problem.


With silver, I would worry about galvanic corrosion.


Of course the tank would have to contain an electrolytic liquid which probably likely in the various drinking waters and waste tanks.

 

[avanti]

You guys are way out of my league when it comes to welding minutia. ����*

The tanks are either 304 or 316 stainless -- not sure which one we ended up with.

 

[avanti]

Are the tubes supported internally at all to prevent bouncing? Hard to tell for certain on the drawings.

They are captured by the baffles. I am guessing that they are spot-welded at the point of contact, but I don't really know for sure.

 

[booster]

They are captured by the baffles. I am guessing that they are spot-welded at the point of contact, but I don't really know for sure.

The heater stuff is very interesting to me in how they did them, as I dealt tanks heaters, and all the problems they can have, for so many years.



You do have the advantage of the tank and tubes looking to be of similar heat expansion coefficient and that is a big advantage. Downside comes from the temp differential the heater can see compared to the tank skin pressure. Loop heaters do tend to develop cracks caused by the combination of heat expansion and being tied down too tightly so they can't expand and contract. The brazing would indicate some worry about cracking as the joints are much less likely to crack, AFAIK. The other side of it is if they allowed to move they are often rubbing on something and wear holes in themselves or what they are rubbing on. Making it mobile probably amps up the rubbing wear potential.


Your builder probably has done these in the past so probably has all that figured out so it will be interesting to see how they work and hold up to the rigors of the road.



Your heat loop will be pretty cool compared to some I dealt with, though. Under 150*F? A max temp difference isn't bad, when compared to much hotter systems.

 

[GeorgeRad]

The heater stuff is very interesting to me in how they did them, as I dealt tanks heaters, and all the problems they can have, for so many years.



You do have the advantage of the tank and tubes looking to be of similar heat expansion coefficient and that is a big advantage. Downside comes from the temp differential the heater can see compared to the tank skin pressure. Loop heaters do tend to develop cracks caused by the combination of heat expansion and being tied down too tightly so they can't expand and contract. The brazing would indicate some worry about cracking as the joints are much less likely to crack, AFAIK. The other side of it is if they allowed to move they are often rubbing on something and wear holes in themselves or what they are rubbing on. Making it mobile probably amps up the rubbing wear potential.


Your builder probably has done these in the past so probably has all that figured out so it will be interesting to see how they work and hold up to the rigors of the road.



Your heat loop will be pretty cool compared to some I dealt with, though. Under 150*F? A max temp difference isn't bad, when compared to much hotter systems.

I talked in the past with Isotemp Marine Water heaters folks from Indel Webasto about the safety of drinking water from their marine water heater and was told how their heater was constructed. First of all, they claimed it is very safe. They use matching stainless steel for hydronic tubing and for tanks, they use seamless tubing exclusively. Applications are similar to Avanti’s tanks with the exception that marine heaters are used to heat water for use by folks. Marine water heaters are very popular in boats with engines using coolant and I never heard of anyone being poison by mostly used ethylene glycol.

In my van I take some precautionary steps:

1. I use polypropylene glycol for Isotemp heated by Espar D5 furnace
2. For drinking I only use cold water which bypasses the Isotemp heater.

 

[GeorgeRad]

...........................

In my van I take some precautionary steps:

1. I use polypropylene glycol for Isotemp heated by Espar D5 furnace
2. For drinking I only use cold water which bypasses the Isotemp heater.

I became aware of spelling mistake on my post, likely result of MS Word overcorrecting, coolant is propylene glycol. Polypropylene is plastic from polyolefin family.

 

[andrewtschneider]

I am slowly beginning to see the virtues of a cassette toilet. It is entirely in the heated area. But that would be a retrofit. You could draw water from a small tank inside the van. I am impressed with all the creative solutions out there!

 

[GeorgeRad]

I am slowly beginning to see the virtues of a cassette toilet. It is entirely in the heated area. But that would be a retrofit. You could draw water from a small tank inside the van. I am impressed with all the creative solutions out there!

Some cassette toilets have integrated flush water tanks, some can draw flush water from RVs’ main water tanks. https://thetford.com/us/portable-and-rv-toilets/cassette-toilets/. I have Thetford C400 with an integral water tank with level indicator.

 

[avanti]

Many Class-B black tanks are entirely inside the heated van (they form a pedestal under the toilet). This leaves only the dump plumbing to freeze-protect. This is very easy compared with protecting the fresh and grey tanks.

I would strongly recommend you try to rent a cassette-equipped van before you commit to one. I did, and did not find the experience at all pleasant.

 

[jojobafanzi]

I've been trying to figure out the best way to use the black tank on my 1999 RT 170 when camping in below freezing temps. I usually just flush with pink antifreeze and that works fine, but it requires a lot of antifreeze, which is costly and takes up a lot of space.

I'm wondering if I can use a gallon of water to flush the toilet, then use a portable macerator pump right away to transfer to a small portable holding tank (ideally something very small with, say, a 2 gallon capacity), then dump that in a pit toilet. When using my regular gravity dump, I always need to fill up my black tank all the way to make sure that everything empties out, to avoid blockages -- would a macerator allow me to successfully dump a tank after a single use?

I'm late to this discussion so I have not read all the responses yet. I'm in NY as well and I use the 170V all year. I winterize the van because these are just not designed for freezing temperatures. I bring in the portable toilet in winter and we use the vehicle for daily driving and some overnight trips.