combi versus conventional boilers

[Doctor Drivel]

Please eff off you are a plantpot.

[John Rumm]

As I said - some can - most can't.

Why, do you want it?

[Doctor Drivel]

So you did.

[The Natural Philosopher]

Hmm. Most houses are fused around 160A..thats 15KW more or less...

Not enopugh? no. You are probably right.

Need that bank of car batteries we were discussiong earlier elsewhere..;-)

[Frank Erskine]

160A? Mine's only fused at 80A...

[The Natural Philosopher]

Sorry, Mistype. 60A not 160A..

I THINK the incoming is good for 100A, which puts peak draw in the 25KW area.

More than that and you need three phase ;-)

[John Rumm]

No, just thought that next time I get spam from Argos offering a free sample pack I could fill your name in. Seems a shame to waste it.

[Doctor Drivel]

You did. You are a Chav.

[Dave Plowman (News)]

Think most are actually 100 amps or less - unless they have been designed for electrical space heating.

But 160A at 230 volts is 37 kW. ;-)

You'd not want to commit the entire capacity to one task.

It's most amusing how he on this thread deprecates the use of a storage system (which as an added advantage gives easy provision of a backup for hot water in the guise of an immersion) in preference for an on demand combi. Which is small and inexpensive. Then after what passes for a thought for him recommends one with an internal store - and wants it backed up by an electric heater in it. Thus re-inventing the storage system. But one too small to be of much use while making the boiler itself larger and more expensive. I can only conclude he was scared by a storage system as a child. Perhaps his father - at who's knee he learnt all his expertise - bypassed the immersion thermostat in an attempt to get it to heat up more quickly. Boiling storage systems are quite scary for an intellectually challenged child.

[Doctor Drivel]

Please eff off as you are a total idiot and known plantpot!

[ARWadsworth]

Or better still I could just add a cylinder and zone off the existing combi to heat it. If done properly I could use the cylinder just for the bath and leave the rest of the hot water running off the combi.

Adam

[Doctor Drivel]

Make it a combi cylinder - combined cold water tank and cylinder. By the time teenagers come along probably a state of the art high flow combi would be better. for you.

[Ed Sirett]

You must have some infatuation for the word combi. A combi tank (often known as a Fortic tank) does indeed combine a rather small CW storage cistern with the HW cylinder. The usual problem is that they are installed at about the same level as the bath and so give little or no pressure to the DHW pipework. Installed in a loft they would work fine except then they'd be subject to freezing when the house is empty. So all in all they are not an ideal solution to adding a conventional gravity DHW back into a home.

[Doctor Drivel]

Integration of any sort in small British homes is a good thing. Elimination is even better.

They do? They can have large cold water cisterns too. Have look:

This can have the cold services taken off it too. Have a 22mm maons pipe to a 3/4" ballcock.

They are heavily insulated, moreso than a normal cold water storage tank.

They are!! Maybe not in your mind. The link I gave you can do all the hot and cold services and a combi boiler can heat it and provide the high pressure shower(s).

Think of the combi cylinder/tank as an unvented cylinder - and they are about the same size. No tank in the loft. High lower pressure flows and high pressure DHW flows via the water section of the combi boiler. A combi cylinder and a combi boiler for the showers can be a great and better alternative to an unvented cylinder - and cheaper and no explosion:

Ed, at least try to think about these things.

[<me9]

Mine's only 50A.

[Paul Kelly]

In message , Doctor Drivel writes

Yes it did sound like a relaxed sort of troll - sorry I do not post enought to be on my guard. It was a genuine enquiry.

Obviously conventional and combi have their own supporters and it is still a live subject after all these years - glad I do not have to make decisions now.

But I will tell my daughter how wrong she is.

Now here comes the troll:

Could it be that those who are in favour of one sort or another are simply justifying their own decision. A bit like my car is great because I have one.

In any event thanks for all the thoughts - very enlightening. The spirit of usenet is still alive!

[Dave Plowman (News)]

Not really - it's simply impossible to get the same flow at the same temperature of say 60C from a combi as you can from a half decent storage system. And when filling a bath this can make a real difference to the time you have to wait. It's also easier to design a storage system so you don't get so much interaction when other taps in the house are used.

Of course this may not matter to some, but it's as well to be aware of it since prats like dribble simply lie about their flow rates. And quote the upper end models as being representative. I've never quite worked out why he feels the need to tell lies so often.

[Doctor Drivel]

It is a matter of getting the best solution for the needs, not pushing a whim. Those who say only a tank and cylinder is the way know sweet nothing about heating and water systems.

She is not wrong at all. Take note of professionals like me, not know-it-all amatures.

Those who say one thing and only that will do, know nothing of the industry.

The point is that if you have good mains pressure and flow a combi should be the first on the list in an assessment. They range from small one flat jobs to large three bathroom models and a plethora of models between. They do deliver the DHW, and save space in small UK homes. They are improving all the time and some the latest models are superb. Like any other product, price usually dictates quality and reliability.

Read my posts on the subject.

[Dave Plowman (News)]

Why do you assume everyone lives in a rabbit hutch like you?

[The Natural Philosopher]

I think that is probably the case.

When I built here, I had no idea what was good bad or ugly. I did the research, talked to the BM's heating engineers, talked to the builders and plumbers, and arrived at a solution that suits ME.

I would happily recommend a combi for a small flat, with maybe two adults maximum.

I would not recommend a non stored solution for bigger households. The combi gets huge, expensive, and still can't do the peak flow rates.

A pumped cold water tank solution gets noisy and expensive, but if the mains pressure is crap, it works better than a pressurized HW setup.

Likewise if the mains pressure is good, a pressurised system turns out as cheap as a decent pump and gravity system, and its a lot nicer.

Nowhere is there a 'best' solution'. Just solutions that fit differing circumstances.

I have yet to see any advantage to a heatbank with a combi tho. Or two combis.