Thanks All,
Here is an attachment from HEATCRAFT who makes the units. They use 4 defrost heaters and can arrange them for 230v/1p or 230v/3p or 460v/1p.
http://files.engineering.com/getfile.aspx?folder=39597903-cc4f-4609-9e29-54a1f34a4897&file=LSF200_wiring.pdf
Controls are seperate thru ssr and contactors.
But I did find out there are in fact 4 seperate heaters in a delta configuration for 3phase 230V heat. How in the heck is that done? Does this mean that not all the heaters are the same? Thanks, your humble student of reason....Joe.
Hello rcwilson,
Thanks for the explanation. I get it. I will reconfigure as 3 heaters in parrellel at a total amperage of 19.6 since this is what I originally planned for anyhow. The two outta three idea without re-terminating the three heater leads is not the way to go but I do appreciate...
Hello,
I'm in need of electrical help as I'm a Mechanical Engineer who knows enough electrical to be dangerous....if you know what I mean.
I have electrical distribution all set up for 230V 1 phase power to be delivered to resistive defrost heaters. The equipment unfortunately is designed as 3...
Our refrig systems are probably considered a little non-traditional. I am well aware of how the Alco HP valve works. The modulating hot-gas valve, not the Alco HP, is a motorized (Siemens SDR-3) and controlled from a little PLC (0-10vdc) with a room temp set point. We use a lot of hot-gas...
Thanks for responding.
I have both an Alco HP8 with 110 psi condensing pressure set point and a seperate modulating hot gas valve on a hot gas line from the compressor outlet to the distributor side port on the dx coil. Is it possible that for 134-a I should have higher setpoint specified...
Hello my fellow engineers,
Here is my problem. I have a small Copeland RACCU, R-134, 3HP. It is used to cool a dry room with a Munters dryer.
We use hot gas bypass into the dx coil in the room for modulation and heat because the room is to run at 77F. Well, I can't get enough hot gas to...
Hello, I too get into perfed ceilings in small(100-300) sq.ft. controlled temp. (CT) rooms. SMACA's HVAC System Duct Design has a table 14-17 on page 14.48 that gets into a a coefficient factor for doing calculations regarding pressure drop and air flow. We use Hunter-Douglas steel perf panels...
I know there are other losses assoc. with the air circuit
(ie: blowers, refrig coil, duct bends, intakes). I am just concerned with calcualting what would be the pressure drop thru a perf. pattern as a function of %open area. You see the volume above this perf. panel is essentially the volume...
What about the the "K" factor for perforated plate like is found in this following link?
http://www.inres.com/Downloads/HVAC_RR.pdf
Here is the real life situation I am dealing with: I have to blower modules facing each other in a room 11'deep by 7'wide.
They blow 1800 cfm each (0"SP blower...
hELLO,
I too am a relatively new ME to AEC/MEP but have been an engineer for 15 years. I do agree with you and have experienced "shock" at energy waste for indoor air quality.
I see that LEED's and "Green Building" philosophy is addressing this somewhat. I think we need energy "hawks" on big...
Accystan,
Your assumptions of the problem are correct.
I am glad you mentioned the "k" factor which is crucial when dealing with orifice obstructions in fluid flow. I will check if manufacturer of perf-ceiling panels (HunterDouglas) has such info. I, like yourself, wonder then if (K x...
Hello,
Here is the problem and what I think could be the solution based on the Bernoulli equation, but it seems too simple to be true.
We have say 1000 cfm(@0"sp) being delivered to a ceiling plenum of 10ft x 10 ft. with .50" holes spaced every 4". That means I have 900 .50" holes giving me a...
Hello fellow knowledge seekers,
We make custom hvac/refrig. system dedicated for particular close tolerance lab conditions. We match a ceiling mounted evaporator to the room load and to a Copeland condensing unit that has compressor, condensor, receiver pre-assembled.
The evaporator coil manuf...
