Glycol recharge

AirborneTrav

I recently inherited a large snowmelt system that services balconies, patios and a garage apron. The system is 8 years old, and the existing glycol was borderline when I tested it with strips. Based on mechanical drawings, I have estimated about 80 gallons worth of glycol. The piping is primary secondary, with 3 load pumps pumping out to 6 manifolds in a very large (18,000 sq ft) and extremely nice house. Because the manifolds are located in main living areas (ie kitchen) of this very nice house, and also in hard to access areas (ie behind cabinets,) I am very hesitant to purge at the manifolds for fear of making a mess. There are purges at the return of each manifold loop, so my first thought is to go loop by loop, flushing with water first then pumpin glycol, again loop by loop. Is this the best way to do this? I can't think of a much better way. Anyone out there have experience replenishing systems like this? Thanks for the help.

hot_rod

It will take some time and planning to drain, flush and refill this system. Hopefully there are plenty of isolation valves in the mechanical system to break it into small zones for purging.

Your biggest challenge will be getting the water out of all the lines after you flush. It is a good idea to run the system with water and a cleaner chemical, especially if the glycol went bad.

You may need a fairly good sized air compressor to blow out all the water after the flush.

You might add some additional purge valves and hose connections in the mechanical room after the drain.

If you have enough purge pump hp you should be able to purge multiple loop manifolds without connecting hoses at the manifold, risking a mess. A 1/2 hp high head purge pump should be able to do most radiant manifolds up to 12 loops.

Hard to say the best approach without seeing all then piping and manifold runs. Bid plenty of hours for a major job like this.

If you can buy at least 5 gallons of straight un-blended glycol. Then you can add some to boost the freeze protection if needed after the final fill.