|02-01-13, 05:32 PM
Join Date: Apr 2011
Location: Strathroy Ontario Canada
Thanked 191 Times in 129 Posts
5 Ton GSHP Build
I made an error infusing my ground loop with Propylene Glycol. The infusing part went well but the purging air completely out of the loop didn't. The circulation pump ingested that illusive bubble, cavitated and my evaporator began to freeze as the water/glycol hadn't had enough time to mix.
I know what your thinking, where was I.? I had watched that 3.5 ton for an hour. It was 6:00 o'clock and I decided to go home and come back to see how warm the shop got.
When I returned, the shop was getting chilly and there was a huge block of ice were my HX should be.
Long and short I wasn't carefull enough to ensure the air had left and my homemade 3.5 Ton GSHP suffered a terrible fate.
It made me grumpy. I didn't really want to do a rebuild when outside temps were dropping to -15 Deg C. I re-installed my old GSHP the 2.0 Ton. My first GSHP attempt. It keeps the shop +12 Deg C min.
The unit was ripped out and torn apart to rebuild the HX.
Well since its apart maybe we should think of improving the Heat Pump (put in TIM ALLEN'S "lets rewire that bad boy")
As BradC had been thinking of the advantages of a 3 phase compressor I had as well. So on the bench as I write there is a 5 Ton 3 phase 208 V scroll compressor (new surplus) (insert Tim Allen "Grunt") Taking the place of the old 3.5 Ton recip. The 5T is smaller dia but 2 in. taller
The 3 phase scroll is more efficient than the recip and can be controlled with a varible frequency drive. This will allow the heat/cooling output to be modulated with speed control. With this the compressor can be started with a ramping to speed and programmed to ramp in the early morn. hrs. and after my work is completed slow to keep the shop warm. There are a lot of possibilities. The VFD has relay out-puts to run the circ. pumps. The VFD should be here this coming week. But as we have 3 phase in the shop we can run it without the VFD.
This weekend a little more brazing and should be running in place early next-week