DIY Maintenance Instructions
Please refer to the sketch below when following the maintenance instructions below:
Air Handling Unit Filters
These filters form part of the hot air central heating system, but are included as they play a part in the heat pump system's efficiency.
There are two filters in the air handling unit; one located in the discharge ducting, the other in the air return system. These filters remove any airborne particles that may have been picked up from the various rooms in the house; the particles consisting of dust, smoke, pieces of fluff and insects.There are a few specialist types of discharge air filters that remove most of the dust mites some people are allergic to. These are known as HEPA filters and are referenced in the website section at the end of this article. However, the table below gives a good selection of filters available for family members who may be allergy sufferers. A typical HEPA filter is also shown below. (Please click on images to enlarge.)
(a) Before replacing or cleaning the air filters, the power to the hot air heating system and the heat pump system should be isolated.
(b) A disposable face mask should be worn over mouth and nose.
1. The filter is accessible by removing the housing lid usually held in place by two spring clips or screws that can be loosened and released using a screwdriver.
2. The filter can now be removed and bagged tightly for disposal.
3. The new filter is now fitted and the covers clipped tightly into place.
The majority of air filters are disposable and should be changed at least every three months. Permanent, cleanable filters should be cleaned every one to three months after being removed as per the disposable type. They are usually made from fabric and can be cleaned using a vacuum cleaner hose. The vacuum cleaner bag should then be discarded and a new bag fitted.
Coil Circulating Pump Filter
A layout of a typical filter is shown below. (Please click on image to enlarge.)
(a) Before changing the filter, the power to the system, including the circulating pump should be isolated.
(b) Rubber gloves and eye protection should be worn when handling the filter.
Please use the maintenance sketch along with these instructions:
1. The filter is isolated by closing the valves V2 and V4 and opening the drain valve V3 letting the pressure of the system.
2. The filter housing lid is usually fitted using stud bolts, and these are removed slowly in case any pressure remains in the system, allowing the lid to be lifted clear.
3. The lid mating face with the housing has a rubber gasket or ring fitted and this should be renewed. The manufacturer will be able to supply a new gasket/ring to fit on reassembly of the filter housing.
4. The filter is now accessible and can be lifted clear of the housing. Remember to wear disposable gloves when handling the filter as the circulating fluid contains antifreeze and anticorrosive inhibitors.
5. Immerse the filter in a bucket of warm water and use a wire brush to clean any debris/algae collected in the mesh.
6. Dry the filter and ensure it is clean before refitting into the housing.
7. Replace the rubber ring and stud bolts, ensuring they are tight.
8. Shut the drain valve V3, then open just a fraction before opening the valves V2 and V4. This will fill the filter housing with the operating fluid, any air being expelled through the valve V3, then shut V3 after a few minutes.
9. Inspect the filter housing for leaks and if none evident, start the circulating pump; then inspect the housing again for leaks.
The circulating pump filter should be cleaned every three to six months, a new rubber gasket being fitted each time.
This completes the DIY residential geothermal maintenance for the homeowner; but remember to check the levels of refrigerant (this is usually evident from a small sight glass or glass window on the compressor). Also check the temperatures and pressures as noted in the O & M Manual. It is imperative to have the whole system checked and serviced once a year, by an experienced engineer.