Heating houses from under

Ruapehu Bulletin, Volume 10, Issue 482, 20 April 1993, Page 6

Heating houses from under

Low temperature heating is normally supplied by warming up the structural elements of the building such as the floor

or the ceiling etc. As some of these have the ability to store heat this should be considered and made use of.

There are tfiree major sources: floors, blockstorage units and ceilings which may be used individually or in some com-

bined form, possibly even with radiant or convected heat. Floor heating and block-storage heating have the facility to store heat in contrast to ceiling heating which has little storage capacity. In particular they permit the use to a greater or lesser degree of special tariffs and controls offered by the electricity supplier. The design of the installation should take account of this factor. On night-rate tariffs electricity supply is only available for specified hours during which time heat is stored to be released during the rest of the day. In a domestic dwelling where maximum heat may be required in the evening, night-rate with afternoon-boost is preferable. In commercial buildings such as offices and schools, night-rate only may be successful. Any storage installation when first energised takes time to become truly effective. BlockTum to page 7

Storage

From page 6 storage has to store heat over-night so needs to be tumed on the day before. Under-floor heating may require a few days or, in the case of a new installation, a longer time to reach full potential. During the heating season they should not be switched off either for periods when the rooms are unoccupied or due to warm days. The slow recovery time of these heaters makes this undesirable. Thermostats correctly installed and set will prevent waste. The thermostat can have an over-riding or 'set-back' device which could be an advantage for weekends or longer periods enabling a basic amount of heat to be retained in the structure so that recovery time needed in anticipation of full occupancy would not be long. The structure of the building is very important. Timber framing has much less heat-storage than solid concrete or even concrete-blocks. The amount of glass present can seriously affect not only heat-storage but also heat-losses, for glass is a very poor insulator. Double-glaziflg cari be a big help as is the provision of additional heat-insulation in walls and partitions as well as under-flooring.