Just replaced my boiler

[Andy Hall]

They can't do. IMM already told us that combis have no disadvantages......

.andy

To email, substitute .nospam with .gl

[IMM]

They don't. They see it as having high pressure showers, spacs saving and high convenient in having instant hot water that never runs out.

You haven't a clue what you you are on about. Just read my posts. If you are stuck, which you certainly will be, ask me to clarify for you.

Correct.

[Dave Plowman (News)]

Only if they believe your partial information. And that of other plumbers who just happen not to mention the disadvantages.

My idea of clarification would include both pros and cons. Yours is that of a double glazing salesman.

[Dave S]

That's the crux of it really, IMO. Maybe Adam (sorry, IMM) is correct and a combi can serve the needs of the majority of households. That doesn't mean that a combi is the *best* system for them all. If the financial outlay required is significantly more than sticking with a storage system, then I would think for most people it would *not* be the best system.

In my last house I fitted a basic combi. The existing boiler had expired, and both the HW cylinder and CW tanks would have needed replacing, together with the lead plumbing that connected the two. I had a very old (low power) electric shower, and the cables weren't rated high enough to install a high power electric shower. There was only myself and my lodger in the house, we rarely took baths, were unlikely to both be drawing hot water at the same time and the house was short of storage space. In that situation, a basic combi could meet our needs wrt HW provision, was the cheaper option, required less work to install and freed up an extra cupboard. There was little contest.

In my current house the situation is different. I'm married with two young children who often have baths and there are two bathrooms with showers. We find the airing cupboard useful, and are not short of storage space. Were our boiler to die tomorrow, I can see no advantage in replacing it with anything other than a conventional boiler.

Dave

[Dave S]

Even though they are the worst case example? Had a water seal split just after warranty expired. Was discovered by my buyer's surveyor - another month and it would have been the purchaser's problem. Can't comment more since I don't own the property anymore - worked fine while I had it, though. Dave

[Ed Sirett]

Apart from one or two notable exceptions the PDBs are fairly reliable relative to the other bits.

One of the aspects of modern boilers is that a dodgy sensor can really confuse the PCB. The PCB is at the bottom of the causes for every fault but the usual suspect pump/fan/sparker are at the top.

[Dave Plowman (News)]

Indeed. I was trying to keep things simple for IMM's limited understanding of things electric or electronic, and express reservations about relying totally on self diagnostics.

Same as any basic processor - without the input information, it can't output the correct instructions.

[IMM]

Is it? Any figures? What percetage have failures? Stop making things up.

Where did this one come from!

[IMM]

In flowrate terms they are, but fine for many applications.

[IMM]

And that they can.

High usage, then other methods must be looked at. If you have 4 teenage girls and 2.5 baths then maybe other solutions must be looked at.

Are you on about your Modena again, or combi;s in general across the flowrate range?

Ah the Modena!

Sounds familiar.

A high flow storage combi would suit those needs and also release needed space in the airing cupboard. The heat there can be provided by a small rad on the wall. The tank in the ooft would go releasing storage space up there, and maybe the combi could go up there too releasing more space in the house below. You also have instant hot water at any time, and hot water that will "never" run out. Also no power shower pumps and high pressure mains showers to boot. I see many advantages. It doesn't take much to see them. A win, win, all the way along.

[Dave Plowman (News)]

I have a good teacher...

I just knew you wouldn't understand.

Relative.

[Dave S]

Can you tell me where I can get 0.5 of a bath? It could possibly fit into my ensuite - could be quite useful.

You said that the needs of the majority of people (you quoted a figure of 90%) can be met by a combi boiler. Obviously, in some cases a basic combi would meet the needs, in other cases a higher flowrate combi would be appropriate. What I am saying, is that if the cost of going for a combi solution is significantly more than staying with a storage system, then I would think the combi based solution is not the *best* solution.

We don't need more space in the airing cupboard

I don't want to have to run the heating just to warm up my airing cupboard

We are not short of storage space (as I said previously).

I've never managed to run out of hot water.

But if you already *have* a shower pump, then not needing it is no big deal.

No, it's not that simple, because apart from what I've said above, there are many more factors to also take into account:

If my boiler dies tomorrow, I could replace it with a conventional boiler. The job would be about as straightforward as a boiler replacement could be - drain system, remove old boiler, install new boiler (probably with flue exiting the existing hole), minor pipe alterations to connect to new boiler, commission boiler. All this done in the utility room with minor disruption to the household.

If I go with a combi-based solution, considerable changes to the plumbing would be necessary, even if siting it in the same place as the existing boiler. This would entail lifting many floors and running a lot of new pipework. Hence considerable disruption to the household and considerable expense on top of fitting the boiler itself. Were I to put the combi in the attic as you suggest, the disruption would be even worse because the gas supply would also need to be re-routed.

So, although a combi-based system could meet my needs as far as HW provision is concerned, I do not see it as the best system in this case because there are no significant advantages and several disdvantages. If I were looking at a complete new installation, I would certainly re-evaluate and might decide differently, although in that situation, other factors may come into play (eg, I would probably be contemplating underfloor heating rather than radiators).

At the end of the day, a solution which /meets the needs/ is not necessarily the *best* solution available nor the best solution for the person concerned.

Dave

[Dave Plowman (News)]

That's it in one. If you have an existing storage system and don't need the extra space a combi might liberate, there is no point in ripping it out and fitting a combi - as getting truely equivalent performance from one will cost dearly.

Of course, IMM is so rich that money doesn't matter - especially other's money...

[Dave S]

Snip drivel..

Oh - so having failed to convince that your solution is best for my needs, you now want to convince me my needs actually meet your solution!!

[IMM]

Unless you live in a mansion, which I doubt, you will always need more space. British homes are "small".

[Dave Plowman (News)]

Yours may well be, but then you love modern boxes.

[Andrew]

In article , Dave Plowman (News) writes

So adopt the usual IMM solution - buy two houses, fit two combis in each, a win+=4 solution.

[IMM]

You are getting it at last. My oh my!