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Old 01-29-18, 09:11 AM   #2
Lurking Renovator
Join Date: Jan 2018
Location: Sofia
Posts: 9
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Since it will be a low-temperature heating system,it will require very large radiators to compensate for the lower temperature of the water.That means a lot of money for radiators and a lot of space for them.So i decided to convert AC indoor units to be used as radiators because of it's fans (forced convection) and because i can get them almost for no money.I got one of these indoor units (luckily its 12000BTU also) in my basement with ripped off electronics,so the fan doesn't have speed control-it's just running at max speed,or not running ,but that is not a problem-I'll make simple VFD later.The only thing that i have made is just soldered 2pcs 1/2 NPT brass bushings on it's pipes to connect it to to the tank and the pump.
As i said pump-i found a cheap GRUNDFOS UP 25-50 130 80W single speed,so i bought it.The connecting pipes are PEX-AL-PEX 20mm diameter (about 3/4") insulated with 9mm rubber piping insulation.The tank is insulated with 5cm of mineral wool.Temporary i've covered the wool with nylon bags,to protect it from soaking with water,but later i'll wound it with aluminum tape.
I was wondering to buy a expansion vessel but the pressure rises only slightly when the water is 40C,so to volume also,and i don't think it's really necessary to have one.
So sipmplified the setup is water tank-pump-indoor unit.
Finally some pictures,and in the next post i'll explain my idea about electronics and about custom control for the AC (which i tested and works) and the results from the first run.
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