Suitable replacement boiler.

[Goinker]

Please excuse what might be a silly question as I'm a 'newbie' on here, but I'm shortly intending to replace a Worcester Bosch 230 RSF combi of about 1995 vintage. It's still doing it's job heating-wise, but hot water output is only around 8 litres/minute which isn't much good as I'm about to replace a bath with a shower which has a 'monsoon' shower head so doubt it'll be able to keep up. I like the supposed reputation of Vaillant, and wondered if one of the Ecotec plus range with the extra cylinders in the back might give me the 'back-up' for the shower, but I'm open to advice for a reliable replacement. Around 15 litres/minute hot water output would seem to be what I need., and a bit higher central heating output wouldn't go amiss. I'm an Electrician, but I'm required to do a fair amount of water plumbing as part of my job, although I won't touch gas work. My intention is to replace the boiler myself (I've done a couple previously) and just get a local Gas Safe installer to do the gas pipework and commission the new boiler. There is no filter on the system presently, but I intend to flush and fit one as part of the job. Any/all advice gratefully received.
Cheers,
Goinker.

 

[doitmyself]

I'm shortly intending to replace a Worcester Bosch 230 RSF combi of about 1995 vintage. It's still doing it's job heating-wise, but hot water output is only around 8 litres/minute

The flow rate is determined by the incoming cold water from the mains. Installng a larger boiler will not give you a faster flow rate.

If you have a garden tap fed straight from the mains, measure the flow rate (litres/min) using a marked bucket and a watch. Then repeat with the kitchen cold water tap turned full on . If no garden tap, just check at the kitchen tap. This will give you the incoming flow rate - the lower figure is the important one. If you want to increase the flow rate the only way is to replace the incoming mains pipe with something larger.

You size a boiler using 2.5kW per litre/min.

 

[GQuigley67]

if you have good mains pressure at your house, then you should get the flow rate the manufacturer states.

 

[Goinker]

I did do the 'tap & bucket' measuring method and got 12 litres/min, on the cold main but it varies according to time of day and local demand, so can be a bit more at times. (I live near the end of a lane which only leads to a farm). My power supply voltage and broadband speeds are also poor for pretty much the same reason, as I seem to get whats left after everyone at the other end of the lane gets what they need! I'm guessing there is some sort of restrictor in the boiler as 8 litres/min hot water is about the max at any time, so I assumed a boiler with more potential throughput might give me a bit more hot water, maybe even the same output of hot water as the cold main output since I doubt Severn Trent are going to up the pressure anytime soon! I still want to look at a replacement boiler though, so advice on the best/most reliable would be welcome. My thanks to you guys for your help so far.
Goinker

 

[GQuigley67]

28kw boiler would be suitable then