combi vs conventional

[IMM]

The so-called reliability is negated by have two of them.

Depends on what model you buy. Some restrict it a hell of a lot.

[Dave Plowman]

Only if IMM is on holiday.

[Bob]

I think combis are a handy compact solution for small flats. Anything bigger and you're better off with a conventional system, or a thermal store if you want mains pressure hot water and would like to free up the space in the roof.

If I had to replace the hot water tank as well as the boiler, I'd be looking at thermal stores for sure.

Bob

[IMM]

Nonsense. Read this thread. There are high flowrate combi's available. You obviously don't know of these.

Getting better, or put the thermal store in the loft and free up space in the living areas.

Or a high flowrate combi.

[IMM]

But then you have TWO to go wrong. 3-way "diverter" valves are essentially

2-ports.

[Lurch]

On Fri, 18 Jun 2004 09:10:56 +0100, "IMM" strung together this:

Why is it worse, it makes wiring simpler and gives more flexible control options.

I'm not married, but nonetheless, I'll get straight onto the leaving the family bit. Thanks for the tip.

[IMM]

Two valve to go wrong. With a combi, there is no wiring.

that is understanbdable.

[Dave Plowman]

Well, you apparently don't read this group where internal 'wiring' problems are a prime cause of boiler failure. Or are you recommending some non electric boiler with a clockwork timer?

[Christian McArdle]

Yes, two valves, each costing 30 quid, rather than a 3 port valve modified just enough by the combi manufacturer for the express purpose of being able to charge 150 quid for it.

Christian.

[Bob]

Make that two _easily accesible_ valves, in most cases.

Apart from leaving myself gasping on the floor due to not turning off the mains before putting some tape round the connector block, fixing a broken 2 port valve motor was a breeze.

Bob

[IMM]

Or £40 or £50.

Combi's use diverter valves and not all are £150. There are combi's that do not have 3-way valves at all. A conventional system needs valves.

[IMM]

Yes, stuck behind a cylinder.

[Tony Bryer]

And £10-12 to fix if it's just the motor - which IME it usually is.

[mike ring]

"Christian McArdle" wrote in news:40d2b0ba$0$289$ [e-mail]:

AAAaaaaaarrrrgghhhhhh!

mike

[Lurch]

On Fri, 18 Jun 2004 13:44:04 +0100, "IMM" strung together this:

I wish I'd have known that when I fitted my combi, I had to wire it into the mains and fit a temperature controller. I'll not bother with all that malarkey next time and just connect the 'mains in' terminals to the room stat connections and hopefully it will self power itself somehow. Come to think of it, I'm going to go and disconnect it from the mains now, it's using electricity up as we speak, if there's no need for it I'm not paying for it.

[Andy Hall]

Would you like to see the copies of letters to and from the water supplier? Email me your address and I will be pleased to send you copies.

Rubbish. The cost of the water softener can easily be offset against the cost of cylinder replacements. When I replaced mine a couple of years ago after 20 years, the inside was still pristine.

The cost of salt is more than offset by the savings in detergents and shampoos. I have posted full details of this previously.

The issue is the lack of the storage element as you well know,

It is a question of location as well as of size.

So what.

This discussion has also been done to death before. The incremental space is negligible as is any additional heat loss with a properly insulated cylinder. I presented calculated numbers on these on previous occasions.

One still cannot get a quart from a pint pot....

Get away.

You know full well that that comment is utter crap. System boilers are widely available with large ranges of modulation.

Cylinders do not take up any more space than the equivalent storage capacity built into a combi or CPSU.

This is of course unless you have perfected the technology to compress liquid phase water.

This is rubbish too. The cost is negligible as you often point out when proposing ridiculously large amounts of loft insulation.

This depends upon your definition of "high flow rate". I would not consider 22lpm at 40 degrees to be high flow rate.

So you're saying that there are no disadvantages at all? You really have been drinking the Koolade, haven't you......

.andy

To email, substitute .nospam with .gl

[Ed Sirett]

The FAQ does contain an extensive and fair spectrum of opinions and views on this matter. Doubtless such a spectrum will also become apparent in this thread!

I agree with your list. I estimate the 'half-life' of the heat in a Grade 3, Part L compliant cylinder to be around 24 hours. [1] The major issues in my experience. a) Customer preference (they may well already be very pro or anti combis) and it is just not worth reducating them if they have already made up their mind. b) Customer preference after being informed about the significant issues. Backup yes/no. Cylinder space needed. Yes/No. Fast bath filling Yes/No.

[1]The water cools to "off then chill" (say 30C) if we go away for 48 hours with the HW off. It is, however, really important to pay attention to details like lagging the draw-off and vent pipes for a metre or so from the cylinder.

[Ed Sirett]

I add my support for this view. The issue of HW backup during a boiler failure is a valid issue too. Also building the HW storage system from multiply sourced generic components rather than relying on the boiler manufacturer is bound to have a some value.

Also the foundations for extending the controls should the house become extended or a user wish to add zones.

[IMM]

An in-line electric instant heater can be installed.

I fail to see where. A combi is designed by exerts to get the best efficiency.

That can easily be done with a combi. If a house is extended the same issues apply to any system conventional or combi. If an extra bathroom is added you can always add another combi.

You say you are a pro. Are you sure?

[IMM]

You obviously have not a clue.