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PHOENIX Residential Units


     The PHOENIX is now considered the state-of-the-art design of composting toilets. 



Read about the advantages of a Phoenix below:



The advantages of the Phoenix are many. 

  • It is easy to install:  smaller tank sections, no caulking, simple vent and toilet. 
  • It is easy to maintain:the access door to the compost is on the face of the tank, and removal of the compost is controlled by rotatable tines which control compost movement to the access area and keep material at the bottom of the tank uncompacted and aerated. 
  • A permanent medium provides secondary liquid treatment beneath the sloped bottom baffle. 
  • Air travels over the entire surface of the liquid to increase evaporation and aerobic conditions. 
  • The liquid is separated by the screened liquid baffle for easy removal; accumulating liquid can be removed with the hand pump and used to moisten the compost pile, and excess liquid canbe drained to a leach field or holding tank. 
  • Ventilation is provided by a low power DC fan operated by a small power supply or photovoltaic system.  Flexible 4" duct and rigid 4" PVC pipe are easily installed.  Continuous air baffles along the tank sides provide aeration of the compost pile and do not interfere with compost movement.  Their large surface area allows the insulated tank to be readily warmed with circulating air from a heater or solar collector. 
  • One or two toilets connect to the Phoenix with 12" diameter pipe.  Toilets are made from vandal-resistant polyethylene and ABS. 
  • ADA: The Phoenix dry toilet fixture is compliant with the Americans with Disabilities Act.  In addition, the Neptune Foam Flush and the new Jets vacuum toilet fixtures can be ordered with the correct height.
  • The Phoenix system is complete with all components necessary for installation, including a white contemporary toilet, a food waste inlet with a maple chopping block option, and the vent system; only the peat/wood-chip starter bed for the tank is not supplied.  Additionally, the package contains all maintenance tools needed: a door counter to tally use for public facilities, a compost rake, liquid recycling/removal pump, and compost tray.  Nesting parts allow shipping at class 100 rates from Whitefish, MT.  
  • Read on for even more advantages.


For an overview on the Phoenix, read this article comparing the Phoenix composting toilet to the original Clivus Multrum.

Phoenix Toilet Seat Using the Phoenix in 
Homes & Cabins
ACS manufactures three models of the Phoenix Composting Toilet for use in private residences. Several toilet-to-tank configurations are possible for each model, providing plenty of options for refits or new construction. 
Advantages of the Phoenix

Odorless. Aerobic decomposition and a ventilation fan ensure that there are no unpleasant odors in the toilet room, tank area, or around the building. Finished material is inoffensive. 

Waterless. No flushing saves annually up to 10,000 gallons (38,000 liters) of water per person. 

Rugged. Thick, tough, insulated polyethlene walls, and corrosion resistant fittings. Lasts a lifetime. 

Capacious. Accommodates families, guests, hordes of relatives, occasional occupying armies. 

Owner-friendly. Field proven design ensures easy maintenance. Finished compost is removed just once a year. 

Frost-safe. Freezing does not injure the composting process. Use of the Phoenix in cold weather can continue at a lower rate. Composting resumes when the system warms up. 

Energy efficient. A 5-watt fan is the only electrical load in residential units. 

Chemical-free. Composting uses a wide variety of organisms to biochemically decompose wastes. The only additive is a bulking agent such as wood shavings. 

Clog-proof. Items such as apples that stop up conventional flush toilets won’t clog the wide chutes connecting the toilet and food waste inlet to the Phoenix composting tank. 

Non-polluting. Wastes are totally contained in the Phoenix. No cracks, no leaks. A long, uniform, retention time ensures a stable, biologically benign end product, reduced 80&endash;90 percent in volume, that can be easily transported or disposed of on-site. 

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Phoenix Residential Models

Phoenix residential packages contain all of the components necessary for an installation except for the wood shavings starter bed for the tank, and the 4-inch (100mm) rigid vent pipe. Every package includes a Phoenix tank, one toilet with three feet (910mm) of chute, a complete ventilation system, a manual liquid respray system, a compost bin, rake, and installation and operating instructions. 

Capacity. ACS manufactures three residential Phoenixes. Capacities range from two to eight persons. The capacity of the Phoenix system greatly depends upon the temperature of the compost pile. The rate of composting is significantly influenced by temperature: the warmer the tank, the faster the composting. Warm tanks have a higher capacity than cold tanks. Our capacity ratings assume a minimum tank room temperature of 65F (18C), our minimum recommended temperature. Below 55F (13C), composting is very slow. 

The R-199 “cabin model” can be used continously by two persons. 

The R-200 accommodates four full-time users. 

The R-201 accommodates eight full-time users. 

Models R-199 and R-200 can be upgraded by adding a midsection. 

Phoenix Models 

Peak use. The Phoenix’s large volume allows it to accommodate peak use well in excess of its nominal rating &emdash; an important advantage in seasonal situations such as family reunions. The annual average use should not exceed the rating, but very heavy use over relatively short periods is handled easily.  

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Residential Installation Options and Planning Guide

The area in which the tank is located should be at least 40 (1,000mm) inches wide. Five feet (1,500mm) of clear space in front of the Phoenix must be provided for maintenance. This area should also be at least one foot (30mm) taller than the tank. The surface supporting the Model 201 Phoenix should be flat, level and capable of supporting 4,000 pounds (1800 kg). 

Phoenix Diagram
1 - Centerline of chute must be at least 9 inches from wall.
2 - Centerline of pipe must be 12 inches from wall.
3 - Standard toilet installed on second floor.
4 - Gravity micro-flush toilet installed on second floor.
5 - 4-inch diameter vent pipe.
6 - 4-inch diameter pipe.
7- 12-inch diameter chute.
8 - Standard toilet installed on first floor.
9 - 1-in-10 minimum slope south of angle.
10 - 12 inches between tank top and ceiling
11 - 1.5-inch diameter hose.
12 - Vacuum-flush toilet installed on same floor as Phoenix.
13 - 60 inches between wall or door and front of Phoenix.
All Phoenix tank models are 39 inches (990mm) wide and 61 inches (1,550mm) long. Model 199, the cabin unit, is 55 inches (1,400mm) tall; the Model 200, 73 inches (1,850mm); Model 201, 92 inches (2,300mm). The unassembled Phoenix fits through an opening 38 inches (970mm) wide, the width of a rough opening for a 36-inch (910mm) door. 

Standard toilets connect to the Phoenix tank with 12-inch (310mm) diameter chutes that must be vertical (see drawing at left). One Phoenix tank can accommodate two standard toilets if they are located back-to-back. The toilets can be located several stories above the tank. The minimum clearance from the center of the toilet chute to the finished surface of the wall behind the toilet is 9 inches (230mm). 

Gravity micro-flush toilets provide an alternative for installations requiring a toilet not directly above the Phoenix. They connect via a 4-inch (100mm) pipe and require a one-pint water flush. The maximum horizontal offset from the Phoenix is 10 feet (3,000mm). The minimum slope is one-in-ten. 

Vacuum-flush toilets offer an alternative for installations requiring a toilet on the same floor as the Phoenix (see drawing at left). They connect via a 1.5-inch (38mm) diameter hose, and require running water and 12 or 24-volt electricity. 

Drain. Micro and vacuum-flush toilets increase the amount of liquid end product in the Phoenix. Excess liquid decants through the tank’s drain. 

The ventilation system mounts directly on either side of the Phoenix. Four-inch flexible hose screws into the fan housing, adapting to 4-inch (100mm) rigid pipe for exiting the roof. Roof supports and flashings adjust from flat to 12/12 pitches. In cold climates, insulate the vent pipe reduce frost accumulation and condensation. With high snow loads, the vent should exit near the roof ridge. 

Electrical loads. The only electricity required for residential Phoenixes is for the 12-volt d.c., five-watt ventilation fan (120 watt hours per day). 

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How Composting Toilets Function

Human and food wastes compost in the Phoenix’s oxygen-rich environment. The principle is the same as in a common garden compost pile: dehydration and digestion greatly reduce the volume of the organic material, the texture becomes moist and crumbly, and the long and uniform retention time destroys many pathogenic organisms. Offensive odors diasappear. 

A fan drawing air through the tank and up the vent stack assures adequate oxygen for aerobic decomposition and odorless operation. A bulking agent (wood shavings) increases liquid drainage, aeration, and provides additional carbon. Manually rotated tines control the movement of material to the bottom, keeping fresh waste from contaminating the finished compost during its removal through the lower access door. 

Liquid filters through the compost pile and is further stabilized in the well-aerated, permanent liquid treatment medium in the bottom of the tank. Continual evaporation usually prevents needing to drain or otherwise remove liquid from the tank. 

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Graywater Treatment Options

Several options exist for treating graywater. Treatment systems that utilize natural biological processes require less energy, and are simplier and more reliable. 

Health department approval. Graywater disposal systems usually require local health department approval prior to installation. 

Conventional septic system/leach field. Because of graywater’s lower flow volume, reduced oxygen demand, and lower suspended solids, the size of the septic tank and field can be reduced significantly. Alternatives to the septic tank, such as a roughing filter or forced aeration system, can enhance treatment before infiltration. Leach water can be used to irrigate nonfood plants. 

Constructed wetland. A diverse collection of aquatic plants is grown in a layer of gravel in a lined shallow trench. The root zone of these plants provides an aerobic environment for bacterial treatment of the flowing graywater. Treated water infiltrates the soil from an unlined portion of the trench. Nutrients can be recovered through biomass removal. 

Aerobic infiltration bed. A coarse organic cover isolates the treatment area while allowing air exchange and providing a large surface area for biological activity and freeze protection. Increased longevity and significant nutrient recovery can be effected by alternating between two beds. In cold climates, the treatment can occur within a greenhouse. 

Surface irrigation. Graywater can be spray irrigated on non-food plants. Treatment occurs in the biologically rich topsoil layer. Nutrients are recovered in the biomass. 

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