[A/S] Tankless Hot Water Heater

["towner7" <towner7@xxxxxxxxx>]

If I may offer you yet a third option to consider>??

http://www.precisiontemp.com/RV-500Page1.html

This is the first and only instantaneous tankless water heater 
specifically designed for recreational vehicles.  It replaces 
conventional tank type heaters. 
It allows all of the RV owner's family to shower comfortably by 
producing endless hot water.  It is not limited to a few minutes 
supply of hot water as with low-end tank type units. 
Technical Data Sheet Type: Gas instantaneous, direct vent water 
heater designed for recreational vehicle and mobile home use. Full 
gas modulation temperature control. 
Dimensions: 13.5" Wide x 13.5" Deep x 14.5" High. Weight: 27.5 
pounds. 
Rough-in dimensions: Add 1/4" to above dimensions. For retrofit, see 
special directions. 
Clearances: Zero clearance top, bottom and sides. 2" in back for hook-
ups 
Construction: Modular, three assemblies; gas, electronics and water. 
Burner: High primary air, 12 element, atmospheric type. Aluminized 
steel body with stainless flame strips 
Heat exchanger: Copper fin tube type with wrap for cooling. 
Electronics: Plug in, works-in-a-drawer. 
Case and flue assembly : Galvanized with painted aluminum access door 
(polar white or colonial white; surface or flush mount). 
Mounting: One inch mounting flanges with corner pieces and door jamb 
included. Must be mounted in accordance with local codes or in 
absence of local codes, Manufactured Home Standard, Title 24 CFR, 
Part 3280 or Recreational Vehicle Standard, ANSI A 119.2/NFPA501C 
Hook-ups: Electric: 18-2 x 2' lead. 
Gas: brass 3/8" flare inside case rear or side accessible. 

Water: 1/2" OD copper tubing. Brass compression to 1/2" NPT elbow can 
be installed or as specified. 

 
Fuel: Propane at 11 WCI 
Capacity: 53,000 Btu input - 42,500 Btu output at maximum burn at 8.5 
WCI manifold pressure.15,000 Btu input - 9,600 Btu output at low burn 
at 1.2 WCI manifold pressure. 
(85°F temperature rise per gallon per minute continuous flow at high 
burn).
 
Fuel consumption: 2.55 lbs per hour at maximum input. ( At 2 GPM of 
water, 20 lbs of propane will produce over 940 gallons of hot water). 
Power: 12 VDC at 1 amp. Operating range is 9 to 15 VDC. 
Flue gas temperatures: Under 300°F. 
Water temperature: Factory set at 115° F. Can be field adjusted 90° 
to 135°F. 
Leakproofing: Case is sealed from interior of coach. Bottom is sloped 
to channel water out of unit. Hook-up plumbing is gasketed. 

Gas train:
 Burner is a 12 element high primary air, atmospheric type with 
stainless steel flame strips. Aluminum manifold with brass pressure 
tap. Orifices, brass # 71 x 12. 
Modulating valve: Solid brass conduit with 3/8" NPT ends. Control is 
non-intrusive into gas cavity using no seals, pushrods or diaphragms. 
There is a 5:1 gas flow ratio con-trolled by a magnetic field 
actuating movement of a poppet in and out of a fixed orifice. 
Gas Valve: Redundant solenoid with integral two stage regulator and 
1/8" NPT pressure tap. 
Water Assembly: Heat exchanger: Solid copper, fin tube type, 6 fins 
per inch with copper combustion chamber with 1/2 " tube wrap to cool 
assembly. 
Hook-ups: 1/2" OD copper tubes. 

Flow meter: Plastic rotary type with encapsulated magnetic rotor and 
Hall plate. 

Clear plastic observation port. 

Pressure relief valve: Approved, set @ 100PSI. 

All other hardware in contact with water is brass or NSF approved 
composites.
 
Controls: Microprocessor, controlling ignition, flame proofing, 
safety systems and electronic gas modulation temperature control. 
Control boards are mounted in a removable drawer, coated, with plug-
in connectors protected with an anti-oxidant compound. 
Ignition: Direct spark type with two 2.5 second ignition attempts. 
Flame proofing: Rectification, shutting gas valve off in .8 of a 
second if proofing fails. Ignition and proofing is effected by a 
single stainless probe at the burner. 
Temperature sensors: Three thermistors, one senses incoming water 
temperature (mounted on cold water line of heat exchanger), one 
senses temperature midway through heat exchanger (mounted in 
stainless probe with compression fitting on the heat exchanger), and 
one senses outlet temperature, (mounted to hot water outlet on the 
heat exchanger). 
Flow meter. Senses rate of water flow, (mounted on inlet water pipe). 
Temperature control: Maintained by microprocessor controlled gas 
modulation that de-livers output water temperature within ±2°F by 
sensing water flow rate and three tem-perature inputs. 
Safety Features: The Model RV 500 is pilotless. There is no flame 
unless water flow is sensed. 
Flame rectification: Gas valve shuts off in .8 of a second if there 
is a flame outage. 

Redundant gas solenoid. 

Electronic high temperature shut-off (two). 

ECO high temperature shut off @ 165°F with manual reset. 

Pressure relief valve at 100 PSI. 

Direct vent with combustion chamber sealed from inside of coach.
 
Model RV-500 Operation: When unit is powered, the microprocessor 
activates the gas modulation valve and per-forms component 
diagnostics. A green LED will flash for normal operation, red will 
indi-cate a malfunction, signified by different codes. The unit will 
remain dormant until the rotary flow meter senses at least .4 GPM of 
water flow. The gas modulating valve will be set to its ignition 
value, the spark will be effected and the gas valve will open. Igni-
tion will occur and the flame will be proofed. 

The microprocessor now reads water flow rate, and incoming water 
temperature, calcu-lates the required gas flow to maintain set 
temperature and sets the gas modulation valve to the proper setting. 
The water temperature is then monitored by the thermistors midway and 
at the outlet to make any minor corrections in gas flow. If there is 
any change in water flow or incoming water temperature, the 
microprocessor recalculates and makes any required adjustments. 

The unit continues to produce hot water until water flow is stopped 
and the burner turns off.
 
Approvals: Approved to test standard: ANSI Z21.10.3 1993 

NOTE: I'm in no way connected with this company~!!
ciao T7