100KW gas boiler for domestic install!

[infromthecold]

In from cold has keen confused - 100,00 btu not 100KW 30 kw will do his place
on a system boiler set up. 100kw will light up over 1600 60 watt light bulbs
- old type !!!!!!!!!! or 100 1 bar lecky fires

Hi
That's exactly what I thought but installer and now worcester TSM have said that not the case. So, with all the advice from everyone on here and my initial concerns I have another instaler scheduled to survey.
I am amazed that a representative of the manufacturer can give such poor advice :-(

 

[doitmyself]

Used whole house boiler sizing method which came out at 23kw

You said earlier that you were considering a combi boiler as you had only one bathroom/shower. Is this still the case?

If it is, the size of boiler is really determined by the hot water requirement, which depends on the maximum incoming cold water flow rate. You can easily check this at the kitchen sink cold tap using a bucket marked in litres and a watch with a second hand. Time how long it takes to fill to the top mark (usually 10 litres); then convert this to litres per minute. The required Hot Water output of the boiler is at least 2.5kW per litre/minute; i.e a flow of 10 litres per min will require a 25kW HW output.

You can ignore the 2kW allowance for HW if you have a combi boiler.

As for the advisability of having a combi boiler, don't forget that all taps, hot and cold, as well as washing machines, dishwashers etc are fed from the one source: the incoming cold main. So there could well be a reduced flow rate if more than one tap etc is in use at the same time. If you have a garden tap, you can do a basic test to see what the effect will be. Repeat the flow test, but this time with the garden tap full open. You will then find the reduction in flow rate.

 

[M77]

Would a 100kw boiler even modulate down to 32kw?

 

[Centralheatking]

so you could thank us all talk to the organ grinders not the monkeys

Hi
That's exactly what I thought but installer and now worcester TSM have said that not the case. So, with all the advice from everyone on here and my initial concerns I have another instaler scheduled to survey.
I am amazed that a representative of the manufacturer can give such poor advice :-(

 

[infromthecold]

so you could thank us all talk to the organ grinders not the monkeys

Many thanks go to all who have participated on this thread.
Without professionals like yourselves willing to share your knowledge and experience folk like me are in the dark.

Many thanks once again for everyone's help.