Sorry for the late reply and if I was the cause of the thread being locked but thanks to the guys for the constructive replies. At least I can now get in touch with some fitters for quotes, knowing that what I would like is possible.
Using a combi boiler for central heating only replies to the guys who helped
- Thread starter shaky1105
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ffs using two boilers is ridiculous either install a fooking unvented cylinder or a system boiler , you still didn't answer my question but hey you know your still going to fit two boilers so crack on , simples 
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Sorry AGAS. With the other thread getting a bit heated, I didn't want to fuel the fire by replying until it'd cooled down a bit, hence the delay in me re-posting and I forgot you asked a question about water flow rate. Is this the "bucket test" ? If it is, I've just done one now with a three gallon builders bucket and it took 41 secs to fill it.
Can I ask why everybody seems to think that two boilers isn't a good idea ? I can't see why it would be but then again I ain't a gas fitter. I just thought that as long as whichever fitter ends up getting the job, as long as he gets paid there wouldn't be a problem.
As I said before, I just like the idea that if either goes faulty, I would only lose the water OR the C/H, not both. The main reason for posting on here was to see if it was possible as I had a lot of assistance from the guys on the electrical forum a few years ago. I wasn't trying to start an argument.
Thanks as always.
Can I ask why everybody seems to think that two boilers isn't a good idea ? I can't see why it would be but then again I ain't a gas fitter. I just thought that as long as whichever fitter ends up getting the job, as long as he gets paid there wouldn't be a problem.
As I said before, I just like the idea that if either goes faulty, I would only lose the water OR the C/H, not both. The main reason for posting on here was to see if it was possible as I had a lot of assistance from the guys on the electrical forum a few years ago. I wasn't trying to start an argument.
Thanks as always.
Not every one thinks it is a bad idea. The "professionals" on this forum may feel that way but then are they a truly representative cross section of the industry ?.
Every design of a combi has to be a compromise between high powered instant water heater and a much lower powered heat source for central heating. One function may operate at high efficiency but the other may function at a (much) lower efficiency.
That said bolers with variable geometry combustion chambers do operate efficiently at both functions but variable geometry chambers in a domestic boiler ? It will never happen. Far too expensive for the domestic market.
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What complete rubbish!!! There's no compromise, 40KW Combi for HW output & a good turndown ratio for CH. You're only a Google Warrior Berny boy, clueless!!
A 40KW Combi can give you roughly 16Ltr/Min & an unvented cylinder about 20Ltr/Min. What's 4Ltrs between friends??!!
We tend to be considered by those in the know to have more appreciation of the niceties of our field.
Muppets like you are, however, considered to be an irritation that does nothing but propagate the kind of bullschit that leaves largely unhappy customers with expensive bills for remedial work.
Sorry you got caught up in a cat-fight, some of the guys on here need to go find somewhere else to play rather than ruining otherwise useful threads.
You've still not said (as far as I can see, and I don't blame you with all the fuss going on) what boiler you have now. This will affect the boiler/water heater you can have, as your gas meter has a maximum capacity and the maximum output of all the appliances in your home must be taken into consideration.
You have around 19-20 litres per minute coming into your home by the look of it, so to take advantage of that and get usable hot water at that flow rate you need a big boiler, but if you already have one big boiler then you can't have another due to the aforementioned gas meter capacity, and there is nothing you can do about that. You'd end up with a small capacity water heater with a hot water flow rate where you could pizz faster, which would be rather disappointing. If you're concerned about the possibilty of breakdowns (and it really shouldn't be much of a worry, the right boiler will be very reliable and have same-day or next-day warranty repairs attached) you could go for a small unvented hot water cylinder in your loft, which would have an electric immersion as backup, and a boiler capable of reheating it quickly. It would behave like a combi, give you a great flow rate, and give you the peace of mind of both a long warranty (10 years is possible) and electric backup
So yes, what you're proposing could be done, but I don't think it's anything like the best option
True, but the 10Ltr/Min multipoint you recommended would be farting at thunder filling his bath.
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How is there no compromise? Do you design boilers? All boilers have a peak efficiency at a particular power point, just like every other device on the planet.
Oh, here we go!! Another Google Warrior, no mate I don't design boilers & as installer, neither do manufacturers!! Most boiler designs are so poor they must be designed by a Primary Skool kids.
So crawl back under your stone.
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