How do you keep your tanks from freezing?

[charles_m]

Hey everyone,
Im mapping out my grewater tank situation (no black water tank on my bus) and I am curious how you all deal with keeping your tanks from freezing?

Freshwater will be in the bus so no worries there. Id like to keep the greywater below the bus (outside) so Im wonderi g what everyone does to keep that from freezing up.

Ive seen heaters, but Im not thrilled about using power to keep my wastewater warm.

Has anyone experienced a frozen tank? If the tank is not full, is damage likely if it does freeze? My greywater will be 80 gallons.

[lornaschinske]

Yes, I have learned grey water will freeze. Only had it happen once (black also froze). This was in the Class C. Slapped a water bed heater on the bottom of the tanks (I could use one pad for both tanks) and built a temporary box out of rigid foam insulation (that one was the pink foam board). Valves were wrapped with pipe heat tape. Didn't freeze after that. In current location (NM) I have the grey bypassed and the black stays open all the time (I have a residential toilet). My supply and drain lines are heat taped and insulated. When I build the new tanks, they will have bypass valves on both (only 1" insulation as well, no heat pad). I fulltime and when in cold areas, am on full hookups. This is my last winter. Come the end of summer, I'm out of this state and heading for warmer climes.

[taskswap]

In our camper our grey water tank is very low to the ground and we can't get any insulation under it - I'm literally talking <6" here and a bump in the road would rip it out. We've lived with this issue for a while.

If you're concerned about your tank freezing because of STORAGE, it's super easy to deal with. You pour some RV antifreeze down there to protect the valve and just let it go. We've had this happen to us several times and it's no big deal, as long as it isn't completely full. The real trouble comes because you can't DUMP it until it all thaws.

During full-time usage I like Lorna's idea of the electric blanket. They also sell tank heaters designed specifically for this. The only differences between the two are that the RV-specific ones are 12V, and cost more.

You didn't say what your usage pattern would be, and that matters a lot. Access to electricity and the ability to dump regularly (or always - full hookups) changes the picture a lot. It's also important if you're more worried about damage than convenience. For example, if you want to go camping in the mountains where it might freeze, and you don't mind waiting a day in the valley before you can dump, that's a different story than full-timing in Alaska...

[drifted_cowboy]

Being on hookups makes it easier as we leave both tanks open and use lots of water to flush. Not very conservative but the alternative when we're traveling in the cold requires a combination of rv antifreeze, stock salt, and livestock water tank heaters. We've been completely frozen up 3 or 4 times and no damage as of yet aside from some connections working loose here and there.

I cant see that the branded tank heaters are much more than thinly insulated heating pads. I almost spray foamed one to the bottom of my tank but somehow didnt care to.

I park with my valves to the southwest and let the CO sun keep me fluid.

[mjmuckenthaler]

I have a similar problem. This is multi-layered thought so I will try to consolidate:

Quick facts: composting toilet / 30' bus / solar with 460ah battery but use 110vac everywhere through inverter_shore power charge or dedicated shore circuit / no "basement" or side storage (yet) / live in Kansas City where winter temps range from 0F to 40F any given week / 90% of the time hooked up to full service, but want to take on road trips / 42 gal fresh water mounted under the bed at the rear passenger side/ shower (to be installed as a wet-bath) and kitchen sink are on opposite sides and opposite ends

Problem: do I mount the grey tank inside the bus or under the bus? Biggest concern - freezing temps.

Train of thought: could run a bilge pump/water pump from sink area (front driver side) to back of the bus driver side under the bed on opposite side of fresh water? This would keep everything warm and not concerned about freezing for sink water. The problem is the shower. I'm 6'2" and cannot give up any inches to mount a pump under the shower but above the floor, so shower plumbing (whether to grey under or inside the bus) will be below the floor.

So, overall, what's the best way to design this to avoid freezing temps with the considerations of longevity, easy to moderate convenience for travel (understanding wind-chill) and eco-friendliness when possible.

Muck Bus,

[Twigg]

Originally Posted by mjmuckenthaler

I have a similar problem. This is multi-layered thought so I will try to consolidate:

Quick facts: composting toilet / 30' bus / solar with 460ah battery but use 110vac everywhere through inverter_shore power charge or dedicated shore circuit / no "basement" or side storage (yet) / live in Kansas City where winter temps range from 0F to 40F any given week / 90% of the time hooked up to full service, but want to take on road trips / 42 gal fresh water mounted under the bed at the rear passenger side/ shower (to be installed as a wet-bath) and kitchen sink are on opposite sides and opposite ends

Problem: do I mount the grey tank inside the bus or under the bus? Biggest concern - freezing temps.

Train of thought: could run a bilge pump/water pump from sink area (front driver side) to back of the bus driver side under the bed on opposite side of fresh water? This would keep everything warm and not concerned about freezing for sink water. The problem is the shower. I'm 6'2" and cannot give up any inches to mount a pump under the shower but above the floor, so shower plumbing (whether to grey under or inside the bus) will be below the floor.

So, overall, what's the best way to design this to avoid freezing temps with the considerations of longevity, easy to moderate convenience for travel (understanding wind-chill) and eco-friendliness when possible.

Muck Bus,

Mounting the grey water tank above floor level is a little more involved. You have to pump the water into it from a sump, which itself can freeze.

Good insulation around the tank will keep it from freezing in all but a prolonged, very cold spell. If you are on shore power you can prevent that with a heating pad under the tank.

[Skoolydoo]

Go to a farmers co-op and get a tank heater, you live in KC area should be a in one of the out lying towns like belton or oak grove

[yello]

I am interested in the hot water circulating pump method to keep fresh water and possibly gray water also, from freezing. Mentioned by Nat but I can't quite see how it works.

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[DSchwiz]

On my mind as well...

What about if you are going with solar?

Anyone out there keeping from freezing without shore power?

Insulation enough?

[family wagon]

Originally Posted by yello

I am interested in the hot water circulating pump method to keep fresh water and possibly gray water also, from freezing. Mentioned by Nat but I can't quite see how it works.

Add a valve (manual or automated) on the hot water side so that the regular water pump can pull water out of the fresh tank, run it through the water heater, and dump it back into the fresh tank. That'll allow the water heater to put heat back into the fresh tank and keep it above freezing.

As for the gray tank: if you didn't mind throwing away good water and filling the gray tank faster, you could dump some of that hot water into the gray tank too. Otherwise, maybe a heat exchanger -- for example, route that line that dumps the hot water back into the fresh tank in a serpentine shape under the gray tank. It'll transfer some heat into the gray tank on its way back to the fresh tank.

Originally Posted by DSchwiz

Anyone out there keeping from freezing without shore power? Insulation enough?

Insulation only slows heat loss. Either by luck or by design there must be a source of heat to make up for what's lost. With thoughtful design one could keep above freezing using only solar heat. I did just that with a passive solar shed I built as an experiment 6 years ago. Indoor overnight temperatures dipped to about 35° F even in the coldest part of the winter in Salt Lake City (routinely 10° F or below); the only time I worried about things freezing in there was when we'd have several days of inversion. That brought heavy cloud/smog cover and reduced the solar heat gain the design depended on. Not only did this design stay thawed without grid power, but it didn't have any kind of mechanical systems for moving heat at all. It was just carefully insulated, had windows on the south side to take in solar heat during the day, and had thermal mass (concrete floor) to store that heat. The thermal mass absorbed heat so the air temperature wouldn't spike during the day and it slowly released heat through the night so things wouldn't freeze.

[Jolly Roger bus 223]

Heat trace tape and insulation will solve it but you have to decide what voltage you can or will have to energize them.
Another one a lot of people don't think about is the shower P-trap under neath holds water so it will need to be protected as well.
For a kitchen sink drain going to a grey tank inside shouldn't be a problem as long as you keep yor tank dimension at no more than 22"s tall because a normal/comfortable sink top is 38-40"s.
Minus the depth of a standard kitchen sink at 8" the drain cup at 2-1/2" and the depth of a standard off the shelf trap at 3-1/2" which leaves at 24" to the center of your drain connection to start your slope down to your tank connection. The standard slope is 1/4" per foot or 1" drop in 4'.of pipe.
There are things you can do to get the sink drain higher.
I like 40" as a countertop height.
They also make shallower sinks as short as 4"s and you can use a handicapped accessible tailpiece off of the sink drain cup and build your own shallower trap.
And I did this in mine for my sink?
My bus has is setting high in the back because of the lack of weight so I ran my drain at 1/8" per foot or 1" every 8' because I know that once I add the water weight to the back of the bus then it is probably going to squat enough to give me a 1/4" or more.
But that also means I have to make sure the bus is close to level and not nose diving in a camping spot which most people try to do anyway.
There are other trap options like drop sewer gas traps to replace loosing the room of a p-trap. But in my mind they have specific places to be installed because the block so much of the drain opening especially the small ones.they catch almost any thing that goes down the drain that is not water.
Worse than a bathroom sink pop up that catches everything and a shower grid strainer that catches all of a ladies long hair. You could almost forget a strainer with them cause they are going to catch everything and you will be in the piping trying to clean them?
Sorry I went on. Little rant ? My experience with them is in a commercial use setting and I can't say that they don't do there job when used in the right situation but in my opinion they do not belong in a house,bus,building?
They were originally designed for swimming pools being drained into a public system after the skimmers and everything else and then they made there way into the floor drain world to eliminate the need for the room a trap but after all the mop string and whatever stops it up it has to be replaced/cleaned and depending on the placement of the original installer? Sometimes floors tore up pipe cut out?
If anyone does decide to use them then I would recommend a union of some sort on either side so that you can remove that section and deal with it in your hands and not in a bind trying to get to it.
Sorry,done

[PNW_Steve]

Originally Posted by DSchwiz

On my mind as well...


Anyone out there keeping from freezing without shore power?

My solution involves a full tank of diesel and a compass.

Point the bus South and apply the throttle until the danger of freezing has passed.

[Jolly Roger bus 223]

You'll never find me in that situation and if I have to deal with it one time I have some torches to heat things up that for some reason I never forget at home?

[yello]

I have at least a week before I get to plumbing but when I can look at this and mull it over. Especially the rants.. useful stuff. I like the serpentine layout of hot water defrost loop. With the big basement might as well add gray tanks there.



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