KW confusion (boilers)

[pennyasks]

Firstly thank you for the many, many times DIYNOT forums have helped in previous years without needing to post. But this time I'm struggling to find the answer.

We're replacing our combi boiler (no space for tank). We currently have a Vaillant AquaPlus which has a 15L extra power store and a DWH output of 36.9kw.

It's on the large side for a flat - top floor, two storey warehouse conversion with tall ceilings and large, single-glazed windows. Six rads, two towel heaters.

Five different plumbers have recommended five different kw output boilers:

21 kw
28 kw
27 kw
31 kw
37 kw

Only one has recommended replacing the boiler with a similarly powerful one with the extra 'power store'. They have all visited the property to inspect.

Obviously keen not to buy the most expensive if it isn't necessary - it seems like the current boiler we have might be excessively powerful. But the quotes from the experts have provided a range of answers and that's quite disconcerting.

In this instance, does it sound ok to replace boiler with a lower output model?

Your views and thoughts are very welcome!

Thanks,

Penny

 

[Steelmasons]

Are you happy with the performance of the vaillant aqua?

Central heating can be range rated down so hot water performance would be the important issue here , are you happy with the hot water performance when two tap outlets are used simultaneously?

If the gas supply is adequate for the 37kw combi you have @ the moment then I wouldn't hesitate to replace with like for like although not necessarily with a store.

 

[dcawkwell]

30kW boiler is more than enough for a flat.

Gives around 11 litres a minute of hot water.

 

[Steelmasons]

Doesn't really matter whether a house or flat as it will depend on the requirements of the individual , how many tap outlet and flow rate through sanitary outlets , a 4 bed house may have one occupant who is quite happy washing themselves down over one basin tap.

 

[ALEC1]

just go for the 937 ecotec, WITH a mixing valve on the hot outlet to ensure design performance is met...the average flat in london has a maximum heat loss of about 12kws...use vaillants compensation controls to give you optimum heating performance...

this does assume the gas pipe is up to spec and the mains flow adequate..

dont compromise on hot water performance it will drive you mad!

 

[Dan Robinson]

 

[bazdaman]

Weather Comp controls had no idea you was into that Alec

 

[newbuildinstaller]

Alec1 bingo people!!! Who had "compensation controls"????


EVERYONE!!!!!!!!!!!!!!!!!!!!!!!!!!

BINGO!!