My Closed Loop system is 8 years old. Last winter the system struggled to maintain interior heat during low outside temperatures. My service provider suggests doing Purge, Flush, and Fill of the glycol loop. Does anyone have experiences in the typical costs to perform this service?
Hi and welcome! What led your service provider to conclude that flush., purge, and fill the loop was the cause of your discomfort last winter? Eric
Eric - a couple of things ocurred. While I am not a technical expert I understand the following: - the electric backup heat was engaging way too frequently so they performed a diagnostic test of the glycol and determined that the glycol was not allowing proper heat transfer from the Geothermal. - there was cavitation noise that seemed to point to air in the loop that should be purged. The cavitation noise has continued through the summer. They feel that a Purge is in order and while doing the purge it makes sense to flush and redo the glycol. Hope this is clear.
The heat pumps, when operating, will pump a certain amount of heat, as predetermined by its sizing. If that heat is not enough, your heat pump is likely not sized big enough. Plain and simple. If there is too much glycol in the loop, affecting heat transfer, or air, it can affect the capacity of the heat pump to a certain degree, maybe up to 15% in extreme cases. It would simply take the same amount of heat out of the glycol mix, and with an impaired heat transfer, would chill down the glycol more. The heat pumps are rated at 32F entering water temp (EWT), and quit operating below 20F EWT. The 12F difference between heat pump operating happily and quit working (and yours did not quit working?) can influence capacity by about 15%, not more. Thus, the heat pump is either not operating at capacity, or does not have the capacity. Measuring the heat extraction takes 2 minutes and will tell the technician if the refrigerant circuit is operating as specified. What was the flow, and what was the delta temperature between incoming and outgoing water temperature? What is your brand and model number?
Eric- Thanks Very Much for your points. As a result I contacted another service company as a second opinion. They quickly determined the issue to be that the Standing Pressure was 0 psi. He repressurized the system to 40 psi and immediately the system responded and has been working very well. Also tested the Delta T and that is fine. Summary: no need to perform the purge, flush, and refill. Thanks for your help.
Non pressure in a pressurized system being the reason for lack of capacity? How would one explain that?
