Are heated skirting boards any good for use with heat pumps?
Posted by Tasha Kosviner on 24 March 2014 at 9:13 am
Radiators or underfloor heating? That has been the traditional question asked among those considering installing an air or ground source heat pump.
But should we consider a new contender on the market?
A study in Sweden has found that heated skirting boards are significantly more effective than ordinary sized panel radiators at heating a room and that they are a particularly effective partner to heat pumps.
The study, by the KTH Royal Institute of Technology in Sweden, found that heated skirting boards had a heat transfer ability that was 50 per cent more effective than traditional panel radiators.
Heated skirting board is simply an aluminium casing with hot water pipes running behind it. It is used to line the walls of a room in place of traditional skirting.
While there are a number of products on the market, this study used Discrete Heat’s ThermaSkirt which some of you may remember seeing turned down for investment on Dragon’s Den in 2008.
This system was found to be more efficient for two reasons:
1. Its low position means there is a better distribution of convective heat throughout the room
2. Its low position means it is exposed to colder air, increasing the thermal gradient in the room
In technical terms, the study found that radiant baseboards have a higher mean heat transfer coefficient, of 12.6W/m2 compared to 8.4W/m2 of conventional panel radiators.
Since to work at optimal efficiency a heat pump generally needs to warm water to slightly cooler temperatures than conventional heating systems, general practice has been to increase the size, or number, of radiators used. By using heated skirting boards it is possible to increase the surface area of your heat emitters without the need for outsized and unsightly radiators taking up wall space in your rooms.
However, you need to be careful. Some experts have warned that depending on the size of your room, you may find that the surface area you’re able to achieve with heated skirting boards is not sufficient to heat the room at the more efficient, lower flow temperature. In addition, in an older property, you may find that draughts around the edges of the room negate the benefit of the lower profile skirting. Assuming a room is well insulated, there may be an optimum sized room at which heated skirting is more efficient, otherwise you may still find that oversized radiators are your best bet.
The aim of the Swedish study was to design a valid equation for the heat output for all skirting board heights and excess temperatures as the present equations are limited to certain heights and a specific temperature ranges. The results showed that the heat emission increases by 2.1 per cent per cm of height of the heated skirting board, and that doubling the water flow only increases the heat emission by 4.5 per cent. The paper concluded that heated skirting boards should be used at a maximum possible height and with the current guideline value of 100 Pa/m for waterside pressure loss for the system design.
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