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Old 02-06-18, 08:56 AM   #10
Ron342
Apprentice EcoRenovator
 
Join Date: Feb 2010
Location: Maryland
Posts: 120
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Great work, guy!!!
First though, spend the time with your son. You and he will be glad you did regardless.
As to the defrost, with the humidity and temps you have, you'll need it! Older heat pumps had a simple spring loaded vane in the airflow over the coil which, when the coil iced up, senses the lesser flow and triggered a microswitch to start defrost but I think the vane itself would ice up. we Newer ones I think use ambient air temp and humidity sensors but our wizard from Spain, Actaurio, did it with micro pressure sensors to detect blocked flow by sensing before and after the coil. I think it was simple and inexpensive - check out his post on that.
On your pump regulation, you can simply throttle the output of that type of pump to reasonable amounts with out much loss to test it but a bypass or vfd would be better long term.
For a shell and tube exchanger, I have good results with HVAC copper coiled into 3/4 or 1 black poly pipe. If you have the copper and poly in the same diameter coils, you can easily back coil the copper into the slick poly pipe and it's easy and cheap. Here's some pics.
When you do the Arduino hardware and software, please use beginner descriptions! Some of us love it but didn't grow up with it!
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