Most routine maintenance for geothermal heating & cooling systems can be performed by homeowners if they choose. If they’d rather not, just give us a call to schedule an appointment. Refer to Homeowner Maintenance section of your heat pump Owner’s Manual. Here are some items that require routine attention to keep your system running at peak performance:

Air Filter

If some or all of your system includes forced-air heating or cooling, then you should periodically check the air filters for each air handler.

If your heat pump is combined in one encasement with an air handler which is connected to ductwork – a common furnace replacement, then you’ll likely have pleated air filter(s) which should be replaced periodically. Frequency will depend on factors such as system usage and airborne particulates in your house. Every six months is a reasonable starting frequency; adjust based on experience. Air filters can be purchased directly from:


MERV 11 pleated filters are recommended for all Geostar packaged – heat pump/blower combination – units. 2-inch width for Sycamore, Aston, and Cypress models; 1-inch for Magnolia Plus.

If you have a washable air filter, check every 3 months or so and clean with mild detergent and water as appropriate… after removing it from the unit.



If you have a hydronic (or water-to-water) heat pump which provides heated or chilled water to one or more remotely-located air handlers, check the air filters on each air handler and clean or replace as appropriate.

Multiaqua hi-wall air handlers are ductless, but they still have air filters. Check your owner’s manual for instructions to remove and clean the air filter.

Hydronic ducted air handlers also have air filters. Depending on the manufacturer and model, they may be washable or disposable. Check these at least every six months, as well.

Flow Center Water Level

If your ground (or water) heat exchanger is a closed loop, you have a flow center which is the interface between your heat pump and loop, and manages the loop flow rate through the heat pump. If the flow center is NP – non-pressurized, check the water level in the reservoir once a year and add clean water to within five to six inches of the top. If the water level has dropped by half since the last annual check, call for service… as there’s likely something amiss. Caution: Ensure that no water spills onto the pump(s) mounted on the outside of the flow center encasement.

You can access the reservoir by unscrewing the cap on the top of the unit. Note that you may be able to do this while the system is running, depending on the relative elevations of the loop piping and flow center. If water begins to leak out the top when you loosen the cap, immediately re-tighten the cap; retry after disconnecting the power to the unit and closing the isolation valves on both sides of the flow center. Make certain that the isolation valves are re-opened before re-connecting power to the unit.

If the water in the reservoir drops below the level of the pump intake, air will be sucked into the pump cavity and water flow will be disrupted. When this happens, the pump will immediately become very noisy. If allowed to persist, the heat pump will generally shut itself off within a few minutes to protect itself from overheating. Warning: Both the heat pump and flow center circulating pump(s) can be irreparably damaged if this condition is allowed to persist.


Load Side Hydronic Pressure

If you have a hydronic – water-to-water – heat pump, check the pressure gauge on the load side – the piping that distributes heated (or chilled) water to air handlers and/or other heat emitters (e.g. baseboard). Appropriate hydronic pressure will be dependent on the elevation difference between the highest point in the system and the pressure gauge. For every 10 feet of elevation, add 4.3 psi of gauge pressure… then add 5 psi . For example, if you have an air handler in the attic which is 25 feet above the gauge, the hydronic pressure at the gauge should be no less than ~18 psi; otherwise, call for service. If gauge pressure is above 25 psi, you’re at risk for water leakage through the pressure relief valve(s), typically on the buffer tank.

Condensate Drip Pan, Drain Line, and Pump

If you have air conditioning, check your condensate disposal system at least annually. Beneath the air coil in your air handler is a pan to collect condensed water vapor during the air conditioning process. After disconnecting power to the air handler (which may mean to the heat pump if you have a packaged water-to-air unit), check and clean the pan, drain, drain pipe, and condensate pump (if you have one). These can be a haven for mold and/or algae growth. A mild solution of bleach will generally remove both. In between annual cleanings, if you notice water puddles during air conditioning season, check if the condensate removal system is clogged or if the pump is working – it’s activated by a float in the reservoir.

Air Coil

This is a network of metal (typically aluminum) fins and tubes that delivers heating or cooling to the blower of an air handler. Generally, it should not need maintenance or cleaning unless the air handler has run for a significant period of time with a very dirty air filter or none at all. If there is dirt or debris build-up on the coil, call for service as you don’t want to risk damage to coil during cleaning.

In Geostar water-to-air heat pumps, the air coil is located behind the air filter. Hydronic air handlers often use an A-shaped coil mounted below the blower (in a vertical unit).




If you have a flow-through drip-style humidifier on the duct system, check the specially coated metal or plastic screen for hard water build up annually. Clean or replace as necessary.




If you’re ever in doubt, give us a call. We service what we install!

Also, read about dehumidification and inadvertent use of auxiliary electric resistance heat.