Boiler choice if new combi

[FantaIsFine]

Hi

I am having extension done and my downstairs shower room plan is all around having washing machine and (stacked) tumble drier in it.

By chance to do with a conversation about power shower pump options having come up, came a look at the bathroom upstairs (system boiler, cylinder) which are in a big cupboard space as it is.

Suggested was to think about a new combi boiler in which case without cylinder > wm could go upstairs > shower room I'd configure differently. Also apparently improved water pressure all around the house and I apparently wouldn't need a new power shower pump to take downstairs.

The plumbing has all gone in under the floor downstairs already. Movable blocks.

I don't remember if I already discounted boiler/cylinder option for some reason in the first place and I'm nervous both about the idea of cost/ feasibility of last minute changing the new plumbing as well as cost of a total change to all existing plumbing.

Any opinions about what you would do would be amazing!!! I don't even fully understand a change or implications

TIA 😊

I wouldn't go for a Combi in a new build because gas boilers are due to be outlawed. Heat pumps cannot provide as much heat as a combi boiler, so they can't be used on mains water pressure. Future houses are likely to need a pressurised cylinder.

That's probably relevant info I should have given...

2 bed Victorian cottage 1 occupant (me). Cylinder over 20 years old and boiler about 3

A system and cylinder usually gives better water pressure in bigger homes than a combi, so you can have one person say having a shower and the other doing washing up with no effect on pressure. That's why we have one. Has your plumber talked about the difference between them?

I would happily take a combi in a smaller home but I can't see how it would improve water pressure over your current setup? Perhaps someone else knows better though!

Combi is great because your hot water is at mains pressure. It'd work well for the life of the boiler. BUT if gas combi boilers do get banned you'll need to refit to make space for a pressurised cylinder in future.

How long do you plan to stay? If less than 10 years a Combi would be good.

Gosh. Can they really insist that you rip out your combi for a cylinder in future? Or is it just that you won't be able to put in a new combi after a certain date, but can still use the old one until it carks it?

I truly appreciate the replies - I am troubled enough by this I'm awake at 4am :-)

@rollercoaster1920 that is AMAZING to know to ask about. Also to ask TW about whom I currently have some extremely negative opinion in the first place to do with water meter siting and an ongoing debate and who are calling me back tomo. [Actually that's a whole other thread I should probably post]

Which to yours and @doodlesdoodleschnoodle points about mains pressure I'm on a shared inlet from the mains, common in my road. So my "mains" comes via my adjoined NDN and my stopcock is on the party wall. TW say their responsibility for my water supply stops at the point at which it enters my neighbour's property.

No intention of drip (hahaha literally) feeding, it's so hard to understand all the domino effects.

I need to speak to builder/plumber about options and config more fully. I haven't realised before I even need to think about some of these things. And perhaps for pressure regardless should be checking out with NDN in case there is something her side causing reduced pressure delivery to me.

For the showers I've been told by an independent heating engineer friend separately - just a phone convo opinion not truly professional capacity - my best bet is to replace my power shower pump 1.5bar which supports 1x thermostatic shower with a 3.6bar that will support x2 but not be able to use both at the same time. He never mentioned new boiler.

What I realise also I absolutely must check in the morning is to CONFIRM that my boiler supports the under floor heating since if it turns out that I need to replace it for that reason anyway, I will be VERY DISPLEASED if that is out of my control and past the point of no return ref shower room plumbing. Above friend told me yes on another occasion.

Again, thank you so much for replies. Feeling a bit like I've bitten off more than I can chew undertaking this project solo!!!

There’s absolutely zero chance that people with existing gas boilers will be forced to remove them.

at some stage it is likely that rules will come in to force meaning a gas boiler cannot be installed in a brand new home.

Worcester and get service annually for 20 year guarantee on parts

The water pressure will depend on the size of the pipe to your property. We recently had a new combi but needed to get the width of the water pipe to the property upgraded - digging up the drive! I would strongly suggest you check out the size of your pipe first. We had 15mm diameter and needed to upgrade to 25mm. 😞

You may find that if someone is running the shower, no one can get water from the tap.

We had a gas boiler replaced(4 years ago) i asked about a combi boiler but as we have two showers the plumber said to avoid a combi as if both showers are used atvrhe same time the supply to both would be reduced (not the pressure bu t due to the heating capability i believe)

May I please ask what that cost you? Might need it done at my gaff. Cheers, CA

I'd also love to hear what that cost! Had an overall pretty damning plumber report on ancient pipework and one of the verdicts was the same. Not sure about my own drive digging up status but definitely increasing diameters

Ideal logic ,got it from screwfix 7 years warranty and brilliant

In a smaller house I’d go for a Combi. We had a Worcester greenstar in our old house that I was happy with