Boiler swap

[Britlee]

I may sound a bit thick here but i have been a site plumber for 11 year and have never priced up for a boiler swap before. What i'm asking is what information is needed to work out which combi is sorted for a property.

Thanks Lee

 

[SimonJohns]

Mainly dhw output

How many bathrooms
Also location paying attention to gas runs
Fluing
Also suitability of combi

If they have a combi just do a like for like on kw providing they are happy with dhw output and not lookin to alter house

 

[Britlee]

Its a sealed system at the moment. I heard you can only run one bathroom on a combi

I have just got myself a flow cup.

 

[SimonJohns]

Its a sealed system at the moment. I heard you can only run one bathroom on a combi

I have just got myself a flow cup.

It's best not to run more that one but it can be done with special combis. Not really worth it thou

 

[Britlee]

is there a calculator for working out the kw needed for the CH. or can i fit the kw as the last boiler

 

[SimonJohns]

http://www.cityplumbing.co.uk/heatLossCalculator

 

[Britlee]

isn't that for radiators

 

[Britlee]

sorry just realised what i said what athickly Ii am. i need to add up each room which will give me the total. Hammer, Head and hit.

 

[SimonJohns]

Didn't want to say anything lol

 

[Britlee]

lol, i was just having a school boy moment. I have also just found out that i can not us * to hide bad language. My apologies to the mods.

 

[lolipop]

28 to 32kw normally enough general rule of thumb bigger the output the better dhw flow but remember you can t get out more than you put in ,use your flow cup

 

[doitmyself]

Even if you put in a combi boiler, the heating requirement should also be taken into account. If you don't you can end up with a boiler which is considerably oversized for heating.

Use the Whole House Boiler Size Calculator with the Domestic Hot Water Allowance set to 0. This gives the CH requirement. Make sure that the boiler can modulate below this - the lower the better.

If you want to check the output of existing radiators use the Stelrad Elite Catalogue. The page headed 40Δt is the correct one to use.