I have a Hydro-Tek Mega-Tek unit and a non-pressurized horizontal closed loop which was installed in 2006. For the first 10 years we had no problems with this system, but for the last several winters I have a problem where the unit can't keep our house at 70 degrees during winter days when the outside temperatures drop below 20 degrees Fahrenheit. I have had numerous different hvac companies and techs out and they all say the unit is operating as it should, but that the ground loop has become too cold. In early November, the ground loop's temperature was in the low 50's, but now in early-mid January it has dropped into the mid 30's. I don't understand why the ground loop's temperature is dropping. I am not losing any fluid from the ground loop, but the ground loop fluid has never been replaced / flushed to my knowledge either. If a loop isn't loosing fluid what else could go wrong with the loop so that isn't working as well as it for the first 10 years of it's life? Any ideas?
Mid 30's is not "too cold", it is normal. Mine is running at 37*F right now. The loop temps always drop throughout the winter and rise in summer. Did the numerous companies give you any specs on the operation of your heat pump? What was the entering and leaving air temps? Does the Mega-tek unit make hot water also? Not the desuperheater.
You will loose efficiency when loop temps drop. If it's not keeping up your heat strips should be kicking in, if you have it connected that is. If it worked fine before you could have air in the loops. Why don't you get it flushed and purge of any air?
Shouldn't we diagnose a problem first before we suggest any corrective action? Capacity of the unit is not influenced very much by air in the loop. Air can capitate a circulation pump, shutting off flow to the heat pump, but then the heat pump locks out. Reduced capacity is either a dropping loop temperature, or is a issue with the refrigerant circuit. Your loop does not change over the year much, thus refrigerant circuit is mostly the culprit. The refrigerant circuit can easily being checked by measuring the amount of heat extracted, with a pressure gauge and a temperature gauge. The pressure drop on the source side with tell you the flow, and in combination with the temperature delta will tell you the amount of heat being extracted from the water and put into the house.
I want to thank each of you for responding to my post and I apologize for my delayed reply to each of you. I would have to double check air temps again, but I believe the temp at my registers is in the low 80's. How would I get air in my loop if it's not pressurized and my fluid level is not changing? I have burped the circulating pumps after they were installed before or could that be the cause? All the techs say the unit is working properly except one tech who said the unit is cycling through single, dual and aux heating phases rather than staying in the correct phase. Could this refrigerant circuit be the cause of this possibly excessive cycling or could that be attributed to a bad thermostat or a bad ECM which causes the unit to cycle through the three heating phases? Any other thoughts are appreciated. Our weather is supposed to hit the single digits this weekend which makes me fearful of another weekend of temps in the low 60's in the house. I am happy to share my phone number if anyone would be willing to chat about this problem with me or walk me through any testing as outlined above. I could post it on this thread if that's allowed or if someone emails me their number at zkc.alex@gmail.com then I could call them? Any help is appreciated. Thanks, Alex
