- posted 14 years ago
Combi/condenser boiler, solar-heated water supply to boiler inlet
averaging 35 degrees C (i.e. can be 20 degrees on overcast winter's
day, can quickly reach 65 degrees on a sunny morning).
Is there any way to estimate how much more gas is consumed in raising
the temperature from 35 degrees to 75 than if raising it to just 55
The reason I'm asking is that our condenser boiler always heats the
water to 75 degrees, despite its temperature control being set to 55
degrees or lower. It's not suppowed to kick in at all if the
solar-heated water feeder tank reaches 55 degrees, but it does.
The explanation we've been given is that the water pressure (20 litres
per min at the cold water tap) drops to 6.5 litres per minute at the
hot water tap, i.e. when it's passed through the solar-heated hot
water tank. The engineer says this means the water passes through the
boiler too slowly and so gets too hot. I can't quite believe this, as
surely when the hot water tap isn't turned fully on it'd have much the
same effect, i.e. reduced flow?
As far as I can tell, whatever environmental and cost-saving
advantages there may be in this system are being offset by wasting
what I assume is a serious amount of gas over-heating the water.