Advice please??? Replacing Baxi Solo 2RS 40

[walsall]

We have had our Boiler since the house was built 12 years ago cold water and, 4 beds; we plan to add two more rooms downstairs that require 3 or more radiators. Have noticed over the last few years the heating system takes along time to warm up and even then it struggles to heat the house. I belive the boiler is equivalent to 11.7kw. We have 11 raditaors - 2 are double.

Have had a number of plumbers but there are conflicting opinions. We are not to bothered about having hot water available instantly, but do want a warm house. The siting of the boiler will not change.

Questions

What type of bolier should we purchase? or is the existing one okay. I have been advised that I can keep the existing, buy a minimum of 15kw and a web site says I need a 30kw when i completed their questions.
The plumbers have said that our boiler is a d rating?.Would I need to change the existing 11 radiators?- they appear to be functioning- but I am not sure if it is the boiler or the radiators that are not giving out heat.


Any advice would be helpful

 

[gas4you]

I think a 30Kw boiler is way over the top.

A guess, as I have not seen your house, would be a 18Kw boiler.

Your boiler may be struggling to heat the house because of sludge etc in the radiators and pipes, or it could be that the pump is failing.

Yes your boiler may be band D or slightly less. In fact i would say you would be lucky to achieve 65-70% max efficiency with this, whilst a new boiler, properly set up on a clean system will give at least 90% efficiency if it is band A.

Couple that with new controls and a new fast recovery HW cylinder and you would be on your way to saving at leat 1/5th on your heating gas bill.

I never advise changing radiators at the time of a boiler change, but point out that there is a very slight chance of a leak developing in a rad or 2 after power flushing and that repairing this is not included in the quote.