Personaly I installed two boilers rather then one big one. I would imagine how many BTU out put you need that would dictate what size boiler one needed as one size does not fit all applications
In order to determine what size boiler you need, you will need to have a Manual J Load Calculation performed on your home.
a 462000-gallon boiler, unlikely to be found on the market :)
"Firstly you need to make sure you've got the right size boiler cover, as boilers do come in all shapes and sizes. Then empty the boiler and cover it. Then slowly refill it."
The relief valve should be at least as large (in BTU/hr capacity) as the input of the boiler. A 3.5 million input boiler would need then a relief valve to handle at a minimum 3.5 million BTU/hr.
You would need a 10 to 40 MMBtu/hr boiler for that size of a school. The larger the place you are heating the larger output of heat you will need.
what gas boiler alleviates the need for a cwsc
NONE a boiler is a boiler and a water heater is a water heaterSEE ASME section IV or the NBBI
A new boiler will cost about $3000 for a standard efficiency model, but for a more efficient boiler it can run up to $8000 plus. It is important to have a contractor size up your system. If you buy a more efficient system the boiler will not need to be the same size as your old boiler unit. Keep in mind that you location and seasonal demand will affect the price as well. If a contractor is super busy they will likely charge more since they have plenty of jobs lined up in the future.
output
In the combo boiler for the central heating? You need a small piece of hose (or it might have a permanent connection) to fix to the mains from the boiler. Then turn the taps near the boiler for the mains and the boiler. You want the pressure to be about 1.3 bar
depends on how many people live in the house. and if they all take showers at the same time. 3 people and below is a 30 gallon boiler 4 - 7 a 40 gallon would suffice anything above that you probably need a commercial boiler.. like an 80 gallon.
http://en.wikipedia.org/wiki/Boiler Should be everything you need to know