Under Pressure

randen · 01-19-13, 05:14 PM

Well its happened, The bad luck part. So far the 3.5 ton homemade GSHP was keeping the shop comfortable without any problems. The two details left to tie up was; the loop still needed the propylene glycol. This would prevent the tubes going up the side of the building and in from freezing as well if it ever happened that we reclaimed so much heat from the ground loop as to cause the evaporator HX to freeze up. Also there was a tiny-weeping stubborn leak in a spot I needed to remove the HP to get at it. It was so small the little puddle dried on the heated floor infront of the unit.

I wanted to be professional with professional results. Pulled the unit out tightened the fitting. (it would seem the temperature cycles had loosed the fitting.) Repair made, re-installed no leak all is good. Now the proplyene glycol. Obtained some glycol from my new friend 80 ltrs for a 33% mix and actually drew it in with a vacuum pump no mess not a drop on the floor. Topped off the loop with the addition of water and pressurized the loop. Started the GSHP and purged the air (or so I thought) Ran the system for an hour checking the purge valve. no more air. HMM Somewhere out in the ground loop the un-known air bubble was waiting to cause a world of trouble.

Hind sight.: The system was running fine. I just left the ground loop pump run continuosly during the sub-freezing temps. Not expensive, maybe $20.00 worth of electricity per month. Although the little leak really bothered me I could live with it for a while. The other facet was, if I had a problem, the heat would be off when its cold and we had a big meeting to be held in the office latter that week. In the back of my mind "just leave it alone for now"

But I thought IT WILL BE NO PROBLEM, HA!!

Getting back to the shop, 4 hrs after the repair and purge--The biggest frost ball I have ever seen. The evaporator HX was froze beyond solid. That air-bubble hidding from me out in the ground loop made it in to the circulation pump stopping any flow. As the glycol hadn't had time to mix the water in the evaporator HX froze and burst my HX jacket.

My worst night mare had come true!!! As they say in the movies "now its become personal."

Frustration at 200% tore out the heat-pump again, evacuated the refrigerant and rebuilt the HX. All the while the shop is getting cold.

Remembering BradC talking about a 3 phase compressor coupled to a varible frequency drive VFD. This infinite control can soft start {LOW CURRENT }(no light flicker on start-up) and speed control the compressor for varible out-put. No start capacitor or relay required. Some VFD's have extra I/O for say circulation pumps. And being exposed to this type of VFD control now common in machine tools and the efficiency they have. This is the holy grail.

OK heres the new plan. Don't really have the time, but my bad luck has forced my hand. I have an inexpensive, new 5 ton scroll 208V 3phase compressor on its way to the shop and the original 3.5 ton GSHP still not assembled with the rebuilt HX awaiting the swap-out with a new compressor and VFD. For some reason 3ph motors etc. have a low value when it comes to resale price. I have seen industrial motors, 3ph. sell for $1.00/HP.

Brad C has been experimenting with Electronic Expansion Valves (EEVs). This coupled with the VFD. WOW. Varible compressor speed with varible expansion valve what could be better. Can you imagine a heat pump that will start slowly and quietly and ramp up to full capacity to bring on the heat quickly and slow to a more moderate speed as the heat is starting to flow reducing operating costs, or any desired profiles.

For now I had to install the little 2 Ton that of which was my first attempt at building my own GSHP. It will have its tongue hanging out running 24/7 and its going to be cold here in the next couple weeks. By the time I end up with my final unit all the soldering I've been doing I could have plumbed 3 houses.

The two photos, The 3.5 ton unit awaiting the 3phase swap out. The poor lowely 2 ton trying to keep things from freezing.

The pressure is on to complete and install the inverter drive homemade GSHP before the Canadian freezes

Randen

01-19-13, 05:14 PM	#1
randen Uber EcoRenovator Join Date: Apr 2011 Location: Strathroy Ontario Canada Posts: 657 Thanks: 9 Thanked 191 Times in 129 Posts	Under Pressure Well its happened, The bad luck part. So far the 3.5 ton homemade GSHP was keeping the shop comfortable without any problems. The two details left to tie up was; the loop still needed the propylene glycol. This would prevent the tubes going up the side of the building and in from freezing as well if it ever happened that we reclaimed so much heat from the ground loop as to cause the evaporator HX to freeze up. Also there was a tiny-weeping stubborn leak in a spot I needed to remove the HP to get at it. It was so small the little puddle dried on the heated floor infront of the unit. I wanted to be professional with professional results. Pulled the unit out tightened the fitting. (it would seem the temperature cycles had loosed the fitting.) Repair made, re-installed no leak all is good. Now the proplyene glycol. Obtained some glycol from my new friend 80 ltrs for a 33% mix and actually drew it in with a vacuum pump no mess not a drop on the floor. Topped off the loop with the addition of water and pressurized the loop. Started the GSHP and purged the air (or so I thought) Ran the system for an hour checking the purge valve. no more air. HMM Somewhere out in the ground loop the un-known air bubble was waiting to cause a world of trouble. Hind sight.: The system was running fine. I just left the ground loop pump run continuosly during the sub-freezing temps. Not expensive, maybe $20.00 worth of electricity per month. Although the little leak really bothered me I could live with it for a while. The other facet was, if I had a problem, the heat would be off when its cold and we had a big meeting to be held in the office latter that week. In the back of my mind "just leave it alone for now" But I thought IT WILL BE NO PROBLEM, HA!! Getting back to the shop, 4 hrs after the repair and purge--The biggest frost ball I have ever seen. The evaporator HX was froze beyond solid. That air-bubble hidding from me out in the ground loop made it in to the circulation pump stopping any flow. As the glycol hadn't had time to mix the water in the evaporator HX froze and burst my HX jacket. My worst night mare had come true!!! As they say in the movies "now its become personal." Frustration at 200% tore out the heat-pump again, evacuated the refrigerant and rebuilt the HX. All the while the shop is getting cold. Remembering BradC talking about a 3 phase compressor coupled to a varible frequency drive VFD. This infinite control can soft start {LOW CURRENT }(no light flicker on start-up) and speed control the compressor for varible out-put. No start capacitor or relay required. Some VFD's have extra I/O for say circulation pumps. And being exposed to this type of VFD control now common in machine tools and the efficiency they have. This is the holy grail. OK heres the new plan. Don't really have the time, but my bad luck has forced my hand. I have an inexpensive, new 5 ton scroll 208V 3phase compressor on its way to the shop and the original 3.5 ton GSHP still not assembled with the rebuilt HX awaiting the swap-out with a new compressor and VFD. For some reason 3ph motors etc. have a low value when it comes to resale price. I have seen industrial motors, 3ph. sell for $1.00/HP. Brad C has been experimenting with Electronic Expansion Valves (EEVs). This coupled with the VFD. WOW. Varible compressor speed with varible expansion valve what could be better. Can you imagine a heat pump that will start slowly and quietly and ramp up to full capacity to bring on the heat quickly and slow to a more moderate speed as the heat is starting to flow reducing operating costs, or any desired profiles. For now I had to install the little 2 Ton that of which was my first attempt at building my own GSHP. It will have its tongue hanging out running 24/7 and its going to be cold here in the next couple weeks. By the time I end up with my final unit all the soldering I've been doing I could have plumbed 3 houses. The two photos, The 3.5 ton unit awaiting the 3phase swap out. The poor lowely 2 ton trying to keep things from freezing. The pressure is on to complete and install the inverter drive homemade GSHP before the Canadian freezes Randen Attached Thumbnails