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Old 03-10-20, 11:13 PM   #7
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Got the heat exchanger coils inside the tank completed. I connected the refrigeration type copper tubing with flare fittings into the diy manifold. Although it looks like some sort of brain interface from the matrix, it gets the job done. I added some ball valves in case I need to purge air from that spot.

I also plumbed in the glycol reservoir and pump. I used a cooler that is about the right size & has a nice gasket on the lid. The pump is an off-brand 007 Taco, with 3-speed settings & high head I figure close enough. I haven't seen any issues Scott Davis has with his open reservoir as far as oxygen breaking down his glycol. If the iron pump will cause corrosion issues with copper is another question mark. I figure with easy access to the reservoir, this should be easy to monitor & switch the pump with a brass one later if necessary.

I also picked up a majority of the other materials now that the spring thaw has started. I decided to purchase premade underground insulated pex pipe used in outdoor wood boilers. Wrestling pex through 120' of drain tile wasn't worth the few hundred dollar difference of buying it done right. I was fortunate there is a insulated pipe manufacturer within a reasonable drive to pick it up.

As far as the collector goes, I decided to go with treated 2x6s with a full 4x8 space inside. 1/2" Treated plywood flush on the back, 1" polyiso sandwiched in the middle, then 1/2" osb on the inside for mouting the collector pipes etc... I also decided to go with 4 runs of pex-al-pex inside the collector instead of 3 to maximize heat collection. With the full 48" height, I can use 6" spacing

Major questions going forward: 1. Collector temperature probe placement? 2. How to control a pump for running water through the furnace plenum heat exchanger? I would like to have it only turn on when the tank is over 130f and when a dedicated room thermostat is satisfied. Two 24vac thermostats in series is no problem, but how do I relay the pump & furnace fan simultaneously? I would obviously like to still use the propane furnace to heat, but controlled by a different thermostat set far lower.

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Last edited by Daox; 03-11-20 at 12:40 PM..
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