It's all Plain to Sea

[taulepton]

[jellis]

I second that!

[mrhobbithhnet]

My apologies for no response to all your 'shout outs' - I've been on the road, and was out of the loop for awhile. I'm back at my home now and getting somewhat caught up.

WRT to 3 phase computer control motors, drives, PLC's, etc, I should have included the vendor of choice as far as we've found. Excellent tech support and pre-sales support (for the newbies out there)

Check out Automation Direct Their product line includes everything needed for automated mechanical system drives and controllers. The interesting thing with these folks is their pricing. $230 gets you programmable speed, direction and power ramp control in a 1/4 hp 3 phase inverter duty 230 VAC motor. And you power it all from standard single phase 110 VAC input.

1/4 hp 230 VAC 3 phase motors are in the $130 range.

1/4 hp 110 VAC single phase input to 230 VAC three phase output Controller/Drives for these motors are manually programmed or with Programmable Logic Controllers for dynamically controlling ramp up speed, direction and speed.

There is a catch though - they don't handle 3 phase Fans. I've looked into what that means... and from what I can see, if you want a completely controllable and automated fan system you will be looking at finding a housing and fan blade to add to the setup. That could be another project all together unfortunately. The beauty of fans is that some blade designs allow for moving air both ways, so you could have a reversible flow in the UACT with fans. I can be done with blowers too, but that would involve damper systems.

Personally, the thing that makes the most sense for bigger houses is to use a squirrel cage blower with a belt drive. They are available cheap used or new, with and without motors, so you'd just be looking at adding or swapping out the motor. Swamp coolers boxes come to mind for this. Always lots of them kicking around, they often lose their functionality as coolers, but are still great as blowers that can move a lot of air.

This kind of design direction as it applies to SHCS is only a really interesting choice if your systems are very large, needing to move a large amount of air (1/2 hp blowers can move over 5000 CFM at 0.0 SP and sometimes real cheap - check out this one for $170 from Graingers. In such cases, it does not make sense to run fans full tilt at all times when set points are reached. It makes more sense to build in speed control so you can ramp up the speed in relationship to the soil temp/air temp differential.

Two speed motors used to be the norm for speed control (hi speed for day time charging, low speed for night time heating) but being single phase, have another set of downsides... they run hotter, wear out faster, have start switches and capacitors that wear/burn out, are less efficient.

If you have a nice big old used swamp cooler box handy, a 1/4 hp variable speed inverter duty 3 phase motor with a 110 single phase to 230 3 phase drive would set you up nicely with 1000 to 4000 cfm for about $230. PLC control is only another $110.
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