Sun Mar composting toilet help?

[Yankeesouth]

Ok...I need some help with composting toilet questions/concerns.  I have tooled around the internet and can't find an answer I would trust so I throw myself to you all.  Everything seems to be bias one way or the other.

Here are the facts:
•   Location will be western PA mountains; not exactly an arid or overall warm climate
•   Cabin to be used by 4 people, 3 being ladies only one tree pee-er, probably every other weekend from May-Aug with the occasional +3-5 guest weekends thrown in
•   Cabin may be used 2-4 weekends over the winter
•   Considering the Sun Mar Centrex 1000 or Centrex 2000, (electric models to heat the poop!)
•   http://www.sun-mar.com/prod_flush_cent1.html
•   http://www.sun-mar.com/prod_flush_cent2.html

Other than reading the Sun Mar site which boasts nothing but good things, I read a few blogs talking about horror stories of soupy poop and bad odors.  Does anyone have any experience in a similar climate with these or similar Sun Mar models?  What are the keys to making it work properly?  If anyone in PA or WV has one please chime in on your experience.  Thanks ahead of time!

[OlJarhead]

I use the Centrex 2000 AC/DC unit and actually love it

Here's the scoop:  My unit is located at 3200 feet in a location which can drop to -30 or below in the winter and even now in June will see temps in the 30's at night so definitely a harsh location.  During the winter it acts like a 'holding tank' because it's too cold to compost.  However with anywhere from 2 to 6 people using the unit we had no issue over the winter.  During the summer I'm always amazed at how well it copes with usage and we use TOO much water as the 1 pint flush toilet isn't hooked up to water so we have to use a bucket of well water to flush the unit.  We put in a large cup of water to start, flush and then flush again with another large cup.  This does mean more water goes into the unit but that's ok as it hasn't caused us any problems.

We run the AC unit as often as we can (or think about it) when there and the DC side isn't hooked up yet at all -- nor is the big stack plugged like it should be, or with the fan installed, like it should be.

I'll be getting the 12vdc fan installed soon though and get the stacks up much higher as we're now in a position to do so.

I've emptied only one drawer of compost from it in the last year!  I have another in the finishing drawer now to give it more room though I probably didn't need to do that yet.

My plan is to fully insulate the unit and maybe even provide a winter heat source other then the AC power as it uses way too much AC for my solar power setup (I'd have to add a LOT more power for that).  However, at this point I've had no problems at all.

I think it's a great unit.

One note of caution though:  In the winter be certain to insulate the sewage pipe and install a heat trace/wire to warm the sewage pipe in extreme cold weather to prevent icing -- we had a couple occasions where someone didn't make sure it was fully flushed and it froze over on us and had to be thawed ou.

After a year of using the unit I'm very happy with it.

[MountainDon]

Never any issues with odors with ours (self containered model).

Our issue is with our climate. Too cold most of the time for composting to work. Temperatures need to be above 50 F. If it drops below, the unit acts a a holding tank.

Regarding the 12 VDC fan in the 4" vent pipe. Installing the fane will basically mean there will be no venting unless the fan is running. SunMar themselves told me that. The fan blades will restrict the air flow more than a pair of 45 degree elbows in the 4" pipe. We left ours out and it vents fine.

[OlJarhead]

Never any issues with odors with ours (self containered model).

Our issue is with our climate. Too cold most of the time for composting to work. Temperatures need to be above 50 F. If it drops below, the unit acts a a holding tank.

Regarding the 12 VDC fan in the 4" vent pipe. Installing the fane will basically mean there will be no venting unless the fan is running. SunMar themselves told me that. The fan blades will restrict the air flow more than a pair of 45 degree elbows in the 4" pipe. We left ours out and it vents fine.

In mine it's required according to SunMar because we have both the 4" and the 2" pipes.  Apparently you have to plug the 4" pipe when using the 2" but not the 2" when using the 4"....AC vs DC operation.

[MountainDon]

That's interesting and conflicting with what I was told. Our model is the AC/DC. No mention of requiring to block the 4" pipe when using the 2" (AC only) vent pipe. In any event, no smells no matter what mode it is in. For the last 2 years it has been used strictly as a NE (non electric) model. No forced venting and no smells. I guess I'd try the 4" with the 12 VDC fan if there is any issue with not having enough venting without the fan. It really does work/vent well on it's own. Up on the roof you can feel and smell the draft going up the unobstructed, straight up, 4 inch pipe.

[OlJarhead]

That's interesting and conflicting with what I was told. Our model is the AC/DC. No mention of requiring to block the 4" pipe when using the 2" (AC only) vent pipe. In any event, no smells no matter what mode it is in. For the last 2 years it has been used strictly as a NE (non electric) model. No forced venting and no smells. I guess I'd try the 4" with the 12 VDC fan if there is any issue with not having enough venting without the fan. It really does work/vent well on it's own. Up on the roof you can feel and smell the draft going up the unobstructed, straight up, 4 inch pipe.

Mine vents well as is too but I thought the real purpose was to dehydrate the water and urine from the base -- though they say not to run the fan when gone for long periods as it would dry the compost out too much.

[Yankeesouth]

what if you put one of tose spinny roof vent fans on top?  well at least the two of you are having success, tat eases my mind.

[OlJarhead]

what if you put one of tose spinny roof vent fans on top?  well at least the two of you are having success, tat eases my mind.

Nah, the diffuser works well and a 12vdc computer power supply fan (or similar size) glued in between a coupling and piece of pipe will work perfectly well and cost less then buying one from Sunmar.  They actually suggested it to me but I was buying the AC/DC model anyway and it came with it...then I put a nail through it (DOH!) and had to make one anyway...lol 

[CabinMom]

We have had our Centrex 2000 Electric for about 4 years and have had a lot of problems with liquid in the evaporation chamber. It is never dry and this causes strong urine smell around the unit. We have moved the "tank" closer to the toilet to reduce the amount of water required for flushing and improved the rock pit drainage but still have liquid and smell. Also, we cannot seem to get the right balance for better composting. Even after waste has been in the finishing drawer for several months it still looks "rich" as they say, and not ready for spreading anywhere. We use the manufacturer's bulking material and composting additives, no chemicals. We follow their recommended amounts and turn the drum according to their recommendations. Any suggestions?

[jenjody]

OlJarhead,
I am very interested in how you insulated and then heated your composter.  I was contemplating burying some foam insulation (the type with the reflective surface), layering a bit of sand, coiling in an eaves trough wire, more sand and then the composter, but I am unsure if that will be a fire hazard or wreck the composter.  Any suggestions?

[OlJarhead]

We have had our Centrex 2000 Electric for about 4 years and have had a lot of problems with liquid in the evaporation chamber. It is never dry and this causes strong urine smell around the unit. We have moved the "tank" closer to the toilet to reduce the amount of water required for flushing and improved the rock pit drainage but still have liquid and smell. Also, we cannot seem to get the right balance for better composting. Even after waste has been in the finishing drawer for several months it still looks "rich" as they say, and not ready for spreading anywhere. We use the manufacturer's bulking material and composting additives, no chemicals. We follow their recommended amounts and turn the drum according to their recommendations. Any suggestions?

Strange -- but I might have the answer....but first questions:

1.  Is it the AC/DC or just AC unit?
2.  Which bulking material?
3.  Using the valve for flush?

In our case we are using the AC/DC unit and mostly only use the DC fan.  With just the DC fan running I have to leave it on when the unit is not in use (at least a week or so) to dehydrate the bottom.  You also have to clean it out periodically to make sure the drain is not plugged -- but the drain is an overflow so theoretically not always in use.

We use too much water (I think) but that doesn't seem to matter too much though one of these days I'll get the water plumbed to the toilet to see how that does.

I use ONLY the Hemp bulking material at 1/2 scoop per person per day.  Seems to work well and I never notice a smell unless downwind of the too short stacks (my stacks are still too short because I haven't finished the install completely yet).  Otherwise we never notice a smell.

When I use the AC side I try to always have the DC fan running (except in extreme cold weather) because if I don't then the AC side can't actually work efficiently.

[OlJarhead]

OlJarhead,
I am very interested in how you insulated and then heated your composter.  I was contemplating burying some foam insulation (the type with the reflective surface), layering a bit of sand, coiling in an eaves trough wire, more sand and then the composter, but I am unsure if that will be a fire hazard or wreck the composter.  Any suggestions?

Mine isn't fully insulated.  In the winter I just know that it is a holding tank.

What I've done is I've wrapped the sewage pipe with a heat tape/trace (low wattage) and then wrapped it in pipe insulation and foamed the entrance into the composting toilet 'shed'.  FOr the composter I insulated the floor under it and then loosely insulated the walls around it (still not complete 100% yet) and then layer some over and around it.  This doesn't work to stop it from freezing but my thinking is that when I'm there in the winter and run the dehyrator/heater it will help keep the heat inside and therefore defrost it a little.

In the winter I just try to keep it from plugging up and don't worry about composting at all.  But then I don't live there!  If I did I'd have the unit inside!

What I do in the spring is I begin added composting material at roughly what I think I need (just take how many weekends I remember being there and add that much bulking material) and then I rotate the bin and run the AC side (and DC fan) all weekend (or week if I can) and keep checking on it to make sure I get a good balance of material.

After a month or so of good weather I fill the drawer and dump it about once a month.  I'm usually able to do that long enough that the unit is less then half full by winter.

So far I've had great luck with our unit.

[sweetfarm]

We have had our Centrex 2000 Electric for about 4 years and have had a lot of problems with liquid in the evaporation chamber. It is never dry and this causes strong urine smell around the unit. We have moved the "tank" closer to the toilet to reduce the amount of water required for flushing and improved the rock pit drainage but still have liquid and smell. Also, we cannot seem to get the right balance for better composting. Even after waste has been in the finishing drawer for several months it still looks "rich" as they say, and not ready for spreading anywhere. We use the manufacturer's bulking material and composting additives, no chemicals. We follow their recommended amounts and turn the drum according to their recommendations. Any suggestions?

We have the same unit and the same problems!  Have you figured out a way to reduce the liquid?  We are getting liquid out the overflow almost constantly.  The fan and heater are working correctly.  It just doesn't seem to get rid of any liquid.

[OlJarhead]

We have the same unit and the same problems!  Have you figured out a way to reduce the liquid?  We are getting liquid out the overflow almost constantly.  The fan and heater are working correctly.  It just doesn't seem to get rid of any liquid.

I rarely have this issue any longer.  The fix?  Leave the 12vdc fan on for a week to ten days after a stay (or more or less on all the time in the summer months).

When we dug up the french cesspit it was bone dry

[Squirl]

We have the same unit and the same problems!  Have you figured out a way to reduce the liquid?  We are getting liquid out the overflow almost constantly.  The fan and heater are working correctly.  It just doesn't seem to get rid of any liquid.

As OlJarhead suggested, it is usually a venting issue.

http://countryplans.com/smf/index.php?topic=12325.msg160191#msg160191

Sun-mar even responded to the question.  Their customer service may be able to give some suggestions too.