Typical challenges faced in air removal in solar hot water system
Amongst some of the problems that comes in a solar hot water installation in a building is
the issue of air entrapment .
Air is trapped due to the inverted “U” shaped bends that are inevitable as the pipes move
up and down from one panel to another as shown.
The air entrapment can be easily understood by following sequence
To allow removal of this air the Air Vent valves are generally used by professional installers
as seen in the sketch below.
The same installation is depicted in a simpler sketch below where air is removed and pipe is
filled with water.
A challenge installers or service men face at site is inability to decide whether Air is actually
removed or not (functionality of Air Vent Valve). This becomes especially important when
there is complaint of poor temperature achieved in the hot water supplied to the units/
apartments. When such a situation of improper heating arises there are many causes apart
from Air entrapment!! Servicemen have to look for many causes which is time consuming
and extremely frustrating at times. Hence a quick method to verify the air vent’s
functionality was always needed.
Engineers then found a solution by fixing a small transparent pipe before the valve. If the
pipe is not filled with water it would mean that the root cause is improper removal of air
from system which is either because the Air Vent has been fixed in improper locations
(where all the trapped air is not reaching at all); or the Air vent needs some cleaning or
maintenance. But these transparent pipes had limited life due to the high temperature and
exposure to UV radiation from sunlight as most installations were in open areas.
Varie valves has introduced an innovative feature in their Air vent -a transparent chamber-.
One can actually see the level of water or air in the valve. If the chamber is filled with water
it can be inferred that the air in that segment of pipe has been removed completely. But if
there is no water level then the servicemen will know that root cause of improper heating is
air and stop looking for other causes. And fortunately , these valves are designed for hot
water as well as UV exposure ensuring long life.
