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Solar air heating: is it worth it?

By Richard Keech

2018-08-14

Do solar air heaters or coolers live up to their promise?

At face value the idea of having a device which uses sunlight directly to heat air in winter seems like a good one.  It’s the idea behind a number of products on the market that promise really high-efficiency heating for low cost. We can lump these together in the category ‘solar air heating’.  Solar air heaters sometimes claim thermal efficiencies greatly in excess of that possible with a solar PV panel.

Continue reading “Solar air heating: is it worth it?”

Efficiency and Air Displacement

By Richard Keech

2018-08-12

Some systems used for heating and cooling depend on air displacement.  Understanding what this means is valuable, because systems like this are usually inefficient.

So , what do 1) evaporative air conditioners, 2) fireplaces; and 3) solar air heating systems have in common?  Answer – their normal operation usually requires air displacement.

Evaporative aircon
Evaporative cooling and wood fires both involve air displacement

Continue reading “Efficiency and Air Displacement”

Hydronic heat loss in one picture

by Richard Keech

2018-07-12

I thought this picture neatly shows the limitations of passive panel-based heating such as hydronic or column heaters. The thermograph shows most of the heat convecting to the ceiling, allowing much of it to be lost before it can reach the occupants of the room. This is one of the main reasons I never recommend hydronic-panel heating.  In-slab hydronic doesn’t have this problem, but it does have other problems.

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Multi-head splits vs single-split systems

There’s some debate about whether the best configuration of split systems for multiple rooms is to have multiple single splits or to use multi-splits.

By Richard Keech  2018-06-18

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Multiple single-split systems can be an eye sore

Introduction

Increasingly split systems are used to heat and cool entire homes – not just single rooms.  The default way that split systems are deployed is what I call single splits – one outdoor unit piped to one indoor unit.  And repeat that configuration for each conditioned room.

The alternative, available from many vendors, is a multi-split. This configuration involves more than one ‘head’ unit for each outside unit.  Often a whole home might be served with only one (larger) outdoor unit, and heads in all bedrooms and living spaces. Continue reading “Multi-head splits vs single-split systems”