Hi
The gas boiler is getting old and so at some point will need to be replaced and I am trying to calculate what size it needs to be for best efficiency.
The system is zoned with Zone 1 being 15KW of radiators, Zone 2 being 10KW of radiators, Zone 3 being a Centerstore Solar 300L unvented hot water cylinder (product code 176778) which is connected to the gas boiler (the solar side is no longer used).
I am trying to find out how much wattage the cyclinder requires from my gas boiler so I can size it and the radiators to work out what size the boiler needs to be.
I have read online that you need to allow 7KW for hot water but as far as I can find out from the product it says the coil is 18KW so I am confused as to what figure to use.
First question is what wattage do I need to use?
Secondly, if I had say a 30KW boiler (as hot water on only for 1-2 hours timed twice a day), then if all zones were on at once (say in winter) it would require 25+18=43KW which cannot be supplied, what would the system do? Would it simply take longer to heat the radiators and hot water or would heating the hot water drag the heat away from the radiators (the water from the boiler uses the same pipe for all zones)? Conversly in summer with just the hot water a larger boiler would need to get down to just 18Kw and not sure they can do that.
I would appreciate it if anyone has any experience of how I can get my head around all this.
Thanks
Colin
The gas boiler is getting old and so at some point will need to be replaced and I am trying to calculate what size it needs to be for best efficiency.
The system is zoned with Zone 1 being 15KW of radiators, Zone 2 being 10KW of radiators, Zone 3 being a Centerstore Solar 300L unvented hot water cylinder (product code 176778) which is connected to the gas boiler (the solar side is no longer used).
I am trying to find out how much wattage the cyclinder requires from my gas boiler so I can size it and the radiators to work out what size the boiler needs to be.
I have read online that you need to allow 7KW for hot water but as far as I can find out from the product it says the coil is 18KW so I am confused as to what figure to use.
First question is what wattage do I need to use?
Secondly, if I had say a 30KW boiler (as hot water on only for 1-2 hours timed twice a day), then if all zones were on at once (say in winter) it would require 25+18=43KW which cannot be supplied, what would the system do? Would it simply take longer to heat the radiators and hot water or would heating the hot water drag the heat away from the radiators (the water from the boiler uses the same pipe for all zones)? Conversly in summer with just the hot water a larger boiler would need to get down to just 18Kw and not sure they can do that.
I would appreciate it if anyone has any experience of how I can get my head around all this.
Thanks
Colin