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Discuss boiler sizing! boiler sizing!!!!?! in the Boilers area at Plumbers Forums
Is this the one? Heating and Hotwater Industry Council » Domestic Heating Design GuidePlenty of calcs online.
Buy yourself the design heating guide it's the bible for all pro heating engineers and everybody should have one my man!
The version you have uploaded is out of date; the current version is below.I hope to have uploaded / attached a PDF copy of the Calculation method which was printed by the Energy Efficiency Trust.
Can somebody tell me the correct way to size up a boiler. Its going to be a unvented system. The house is quite big. Am i right in measuring up the radiator sizes in watts then adding up to get my boiler size?
Thanks
How do you know the existing rads are correctly sized?No...your not right!
Add up the kW from the radiators, allow additional 10% for heatloss from piping.
Add onto that the kW rating required by the HWS.
Should give you a kW rating of boiler.
On top of that, depending how you set up the system will determine what size of boiler you require.
How do you know the existing rads are correctly sized?
How do you know the existing rads are correctly sized?
I haven't gone deaf so there's no need to repeat yourself.
I was on an enforced break - thanks to the previous regime of moderators.
I think they were forced into the situation, due the advice you were giving, would cause the forum legal liabilities.
So you don't just use the size of existing rads; you rely on your experience to tell you if the rads are the correct size, and make adjustments if required!
From 25 years experience, sizing and installing heating system, I do give myself the pleasure, of walking into a room and deciding whether the radiator sizes are applicable to that size of room.
If you are referring to the calculator I posted the link to, I made it clear that this uses the latest version of CE54, which was produced by BRE. It is therefore not Baxi-specific (apart from recommending which of their boilers would meet the requirements) and gives exactly the same result as going though the calculations manually using CE54.
Oh well....good for you....you have your way - we have ours
Rad-sizing calculators always 'oversize' by 10% to 20% to allow for intermittent use, i.e heating only on for an hour or so twice a day; which means the house has to heat up faster. If the house is occupied all the time, there is, theoretically, no need to make any allowance. But the next occupiers might not be there all the time, so over-sizing is probably preferable. Oversized rads will, in any case, run at a lower temperature so the boiler will be condensing more often, which saves gas.
The version you have uploaded is out of date; the current version is below.
It is more detailed than the original version, so there are several online "whole house" calculators based on the current version. for example: Baxi Whole House Boiler Size Calculator
Can somebody tell me the correct way to size up a boiler. Its going to be a unvented system. The house is quite big. Am i right in measuring up the radiator sizes in watts then adding up to get my boiler size?
Thanks