Help me pick a boiler

[morethanacondiment]

Ok, local independent plumber is coming this week to change our inefficient old boiler (with clanking pipes, CH feeder thing right above our heads, and heat-leaking hot tank that takes up masses of space in the middle of a little kitchen) to a combi boiler.
We were planning to go for a Worcester-Bosch 32CDi, resiting it from the kitchen to the downstairs shower room. Upstairs, we only have a grotty bath that's in the eaves, so currently can't have a shower attached. Our grand plan (within 10 years) is to redo that bathroom to allow us to add a shower in (3 kids, so thinking separate bathrooms for adults and children would save a little sanity).
Plumber says we'll need a 42CDi to run two showers, but mains flow is too low so would also need an accumulator (big tank in the little loft). It'd be another £1200 for him to fit that.
DH and I are vigorously debating this I think we'd just get used to not showering at the same time (our jobs mean we're likely to always get up hours before the kids and they can take turns - it won't kill them), we'd have to cut wine something to afford the bigger cost, and I worry that then we're going to be paying to run a much bigger boiler for this occasional two-shower event. He keeps muttering about future-proofing.
We need to call the plumber back this evening. Can anyone give us any perspective?!

So we have opted for a combi Vaillant 937 - we have one bathroom and two shower rooms. It replaces an older combi. A builder suggested a boiler with a hot water tank would be better, but that would have involved ripping up the bathroom as well as more expense. It's just the two of us at the moment, but we're aware a combi might not be ideal in years to come. We're happy with the choice we've made - the 937 is meant to be Vaillant's 'best' combi, although the installation isn't finished yet so I can't vouch for it! There is usually always a compromise...

I'm not sure even powerful combis can run two showers at once - hopefully pigletjohn will be along soon to clarify / correct! We have a Worcester Bosch 34cdi and pleased so far. Just the one bathroom though.

I'm sure you're right - I expect we won't be able to run two showers at once on our new combi boiler. But it seems the OP's concern is whether she 'should' install the capability to do this. In the end, husband and I decided the upheaval and extra costs at this point in our lives outweighed the benefit of being able to run two showers etc at once, but that was based on our particular circumstances. If we stay in our house long term then we will reconsider for our next boiler replacement - hopefully this won't be until at least 2025 though!

you don't need to change the boiler to add an unvented cylinder. Any boiler, combi, conventional or system, can heat any cylinder.

p.s.

if you have insufficient flow, consider running a new, larger plastic supply pipe all the way to the pavement. It will be simpler than an accumulator, and I think more satisfactory. It might or might not be cheaper.

Thanks all, now we both have more bits to include in our argument!

In terms of future proofing, you will one day (before you know it) have 3 teenagers in the house. There is no telling whether they will be shower-dodgers or wallowing water wasters, but if you have 3 of the latter, you're going to need the biggest boiler and hot water tank you can fit/afford.

You only want the hassle once, so I would do it now.

Sorry, actually came on here to say - if you live in a hard water area and have a water softener, make sure the plumber knows. Some types of boilers are incompatible with water softeners.

Of the 3 who came and quoted for our new boiler, the first never asked if we had a water softener, the second asked and explained why, and the third, I told with my new found knowledge. HTH.

It's interesting though - I think trying to ensure two teenagers can shower / bath at the same time is a relatively new thing. I wasn't a teen THAT long ago, and I can't remember feeling particularly hard done by if I wanted to shower when somebody was in the other shower. And I was the sort of teen who found various things to grumble about...!

It's a lovely option to have, but I don't think it's something that should be seen as a 'must have' if there is a limited pot of money available. Clearly a combi would be impractical in a house with four en-suites for example, but that isn't OP's particular situation.

I should add that the teenage me would have been horrified if she knew I would later spend so much time weighing up the merits of various boilers. Hmmm.

Haha, Filigree, I'm on annual leave next week and when colleagues if we were doing anything nice, I had to play it cool and not scream "we're FINALLY getting a boiler!". The teenaged Condiment didn't care where water came from
CQ, your post just made me think that a water tank with a finite supply of hot water might be the more frugal option. As it is, they're 5,3 and 1 and all bath together - perhaps we could sustain that indefinitely?!
We do both want a combi rather than a tank, so if the 42CDi may not be up to the job, I think we'll go for the small boiler and manage.