...and is it inefficient to over-specify a combi boiler?
I've read the FAQ No 34, which implies either the 831 or the 837 would work, but which would work best?
We are replacing the two rather old boilers (separate heating and hot-water) with a single combi boiler. I've settled on a Vaillant ecoTEC Plus boiler with a VRC430. However, I would sincerely appreciate advice on which ecoTEC Plus boiler is most appropriate/efficient for my house. The Energy Saving Trust's online calculator gave a figure of 18kW as the requirement for the boiler, which appears to sit within the ranges of all three of the ecoTEC Plus boilers:
824: 6.7-19.0kW
831: 8.7-24.0kW
837: 12.0-28.0kW
We've been told by a family friend (who is a retired plumber and couldn't comment on the latest Vaillant boilers) that we want a hot-water flow rate of at least 11 litres per minute, which discounts the 824 (@9.4 L/m). And given that there's only about £30 difference between the 831 and the 837 I would instinctively go for the higher rated model. Is this sensible? Or would that not leave the boiler enough “flexibility” to cope with anything but the coldest days and be less efficient?
As you can tell, I know very little about CH (this being my first house – very steep learning curve). Ultimately I will defer to my plumber as to which model is best, but I would like to have a (semi) informed idea as to what I want/need and why.
Thanks in advance for any help you can give.
Regards,
Dave
House details:
-Built in 1900
-End terrace
-solid brick walls
-2.5 bedrooms
-Small two-up two-down layout with small rear-extension
-Slate roof(s) with aprox 70mm insulation
-Sash windows
-6 radiators
-Thermostatic valves on all radiators
-1 bathroom (bath and separate shower [not power shower]) on ground-floor. Not unusual for both the shower and the bath to be run at the same time.
-2 occupants (happy with their first house, even though they need to replace the boilers and possibly rewire the entire house)
-Old heating boiler: Ideal W2000
-Old hot-water boiler: Main Medway
I've read the FAQ No 34, which implies either the 831 or the 837 would work, but which would work best?
We are replacing the two rather old boilers (separate heating and hot-water) with a single combi boiler. I've settled on a Vaillant ecoTEC Plus boiler with a VRC430. However, I would sincerely appreciate advice on which ecoTEC Plus boiler is most appropriate/efficient for my house. The Energy Saving Trust's online calculator gave a figure of 18kW as the requirement for the boiler, which appears to sit within the ranges of all three of the ecoTEC Plus boilers:
824: 6.7-19.0kW
831: 8.7-24.0kW
837: 12.0-28.0kW
We've been told by a family friend (who is a retired plumber and couldn't comment on the latest Vaillant boilers) that we want a hot-water flow rate of at least 11 litres per minute, which discounts the 824 (@9.4 L/m). And given that there's only about £30 difference between the 831 and the 837 I would instinctively go for the higher rated model. Is this sensible? Or would that not leave the boiler enough “flexibility” to cope with anything but the coldest days and be less efficient?
As you can tell, I know very little about CH (this being my first house – very steep learning curve). Ultimately I will defer to my plumber as to which model is best, but I would like to have a (semi) informed idea as to what I want/need and why.
Thanks in advance for any help you can give.
Regards,
Dave
House details:
-Built in 1900
-End terrace
-solid brick walls
-2.5 bedrooms
-Small two-up two-down layout with small rear-extension
-Slate roof(s) with aprox 70mm insulation
-Sash windows
-6 radiators
-Thermostatic valves on all radiators
-1 bathroom (bath and separate shower [not power shower]) on ground-floor. Not unusual for both the shower and the bath to be run at the same time.
-2 occupants (happy with their first house, even though they need to replace the boilers and possibly rewire the entire house)
-Old heating boiler: Ideal W2000
-Old hot-water boiler: Main Medway