Glycol Additives for new Ground Loop commissioning

knobby44

Hello. I have a Geothermal system that I am just filling with glycol. I have the radiant side filled and working with my backup Combi Boiler with 30% Dowfrost HD, so that side works great.

I'm getting ready to fill my ground loop (~115 gal capacity) and going to add 35 gal of Dowfrost (30%) and 70% DI water ( I got this for about 10% of the going cost) and wondering if there are additives that I can/should put in the system to make it closer to Dowfrost HD (both use Dipotassium hydrogen phosphate @ 4%-6%). I did see HVAC-1 as a recommendation at 4% solution to glycol, but can't find that in small containers which seems to be 40-50% Tetrapotassium Pyrophosphate and 5% proprietary inhibitors (if it's even available any longer). (need about 1.5 gal)

My system is a 4T heat pump with about 20ft of 1" copper between the non-pressurized pump station and the Heat Pump with a couple brass fittings and the rest is HDPE gound loop (5x 750ft 3/4" HPDE) and manifolds.

Thanks for any suggestions.

hot_rod

sentential, Rhomar, Nobel and other small “blenders” use Dow as their base and add their own additives. They may know if their boosters are compatible in jwith Dowfrost

Jamie Hall

Make sure that ground lop is pressure tested and certified leak gith — I'd want it to hold at least twice the relief valve pressure for at least 24 hurs.

Why? Because if you get that glycol into the ground in your area, you are going to have a big cleanup for really big dollars.

knobby44

https://forum.heatinghelp.com/discussion/comment/1893508#Comment_1893508

Jamie, that is why I held off on that side until now, I had a leak in 1 of my 5 lines, I hit it with the backhoe early on and missed it. I found the leak with air from one side and water from the other to pinpoint the leak with a very sensitive ground probe microphone and fixed the leak.

It has held 50psi for 2days and ready to fill.

So, in this case, being a ground loop, if there was a leak for some reason in the future, then the Dowfrost (food grade) might be the better choice?

Jamie Hall

Yep