What size combi for my daughters house.

[nickjaxe]

Hi all....my first post.....talked my daughter into seeing about a new modern gas boiler to replace to very old one she has now.

Its the type that has a separate electric water heater....parts are very hard to find for it.

She has had a few prices and one guy said she needs a Worcester 32Cdi condensing condensing combi boiler.....

Her house is a quite compact well insulated 3 bed detached house....way smaller than my 1930s solid brick semi no cavity walls.

We have a 25/30si which looks way bigger then her old boiler.....heats our house fine.

Is a Worcester 32Cdi condensing condensing combi boiler not a bit on the big side for her.....she needs to keep the cost down.

Thanks all....Nick.

 

[gmartine]

Boiler size cost difference isn't that significant but it's common for engineer's to oversize in part for the ability to provide hot water at a decent rate but to the detriment of the system's overall efficency.

Your instincts are probably correct as you describe her home as compact and well insulated and smaller than yours albeit also detached, an engineer should ideally calculate the heat loss of the property to provide an accurate specification.

 

[ShaunCorbs]

Also depends on cold water flow rate as he maybe trying to match them but with Worcester’s you can down rate them in the installer settings (heating side)

 

[nickjaxe]

Also depends on cold water flow rate as he maybe trying to match them but with Worcester’s you can down rate them in the installer settings (heating side)

Thanks guys....more to it than meets the eye then.

 

[Scott_D]

I believe you can range rate the heating output on the 32cdi so the heating side shouldn't be an issue.
A 32kw combi will give better hot water performance than a 25/30

 

[Riley]

Don’t these only range rate down to 7 or 8 kw likely still too big for property heating wise