Plumbing! Shower pressure- Unvented tank?

[Wwe175]

Any explanation, personal experience, would help please.

The problem
Poor shower pressure in our standard 1980s 4 bed detached house, 2 bathrooms. All original plumbing - hot water tank in airing cupboard, cold water tank in loft. Showers gravity fed.

Suggested solution
Plumber suggested a new unvented hot water tank. He says that is better than shower pump for both bathrooms.

Questions

1. will cold water pressure be enough? I understand the idea we are improving the hot water pressure by installing the new unvented tank, but what difference would this make to cold water pressure in showers? Am I misunderstanding?
2. loss space in airing cupboard? Is new unvented tank huge? I use airing cupboard to dry clothes currently.
3. boiler related question - current boiler is a Worcester Greenstar condensing boiler. A neighbour (not a plumber!) said they replaced theirs with a combi boiler and the pressure in their showers is now great.

Any comments welcome. Thanks!

In relation to 3, Are both showers in use at the same time frequently? If not a combi will sort this based on personal experience similar to your neighbour.

I had the same set up as you with pathetic water pressure in our only bathroom. Boiler needed replacing and went with a worcester combi in october and the shower pressure is now insanely good. My understanding is that a combi would only struggle here if there's multiple showers in use at the same time. Bonus has been getting loads of extra space back in the airing cupboard once the water tank came out!

Thank that is useful!
Both showers in use at same only rarely.
Did you leave your boiler in same place when you installed the new combi? Is your airingcupboard now unheated? Or did you put a little radiator in when you took out hot water tank?

A combi boiler probably increases the water pressure because it heats the water directly from the cold mains feed, which is at higher pressure. The good news is you will probably get higher pressure for 1 shower. The bad news is if you turn say two or more on at once, or someone is running hot water for washing dishes at the same time someone else is running a shower the boiler may not be able to cope with the heating requirements unless it is very powerful.

Unvented tanks - what they are is pressurised hot water tanks. The hot water tank is driven by the mains cold water pressure. If your mains cold water pressure is good then the unvented will work well. If it isn't then not so well.

My opinion is unvented tanks are the gold standard for hot water delivery. Provided your mains cold water pressure is good you should get tons of hot water at good pressure and you will not suffer any of the problems you will get with combi boilers which have a limit on how much hot water they can deliver at once.

An unvented cylinder will not take up much more space than a current vented one. I would say the major issue with installing unvented is that your hot water pipes may not be up to the job of handling the increase in pressure caused by the unvented cylinder. So you could get banging. Or maybe leaks which would be additional costs to rectify.

My guess is the installation of an unvented cylinder would be less than that of a new boiler.

Finally, if you do get a new cylinder it will probably have immersion heater backup. What this means is if your boiler breaks down you can still get (expensive) hot water. If you have a combi boiler you lose this facility.

Wow GasPanic, really good summary and thanks.
We won’t know if the hot water pipes can handle the pressure before installation of the unvented cylinder. It’s a risk. If we lose our nerve, we would have to have shower pumps, which won’t be as good ..

We've had a pressurised hot water tank for years now, and it is absolutely brilliant. Great showers with a really reliable high pressure. Originally we just had a new tank and kept the same boiler and it wasn't very expensive, then when we had a new boiler we moved the tank (and now the airing cupboard has a small electric radiator) and the new one is sleeker than the previous

Yes the boiler went in the same cupboard in our small downstairs lootility no problem. The airing cupboard is 'unheated' technically but has hot water pipes running through the bottom so warms up when the heating is on. It's in the actual bathroom so we may remove it and put a freestanding shower cubicle in the space eventually.

We were also offered the higher pressured option of the unvented cylinder and if we had more people in the house or intended to do a loft conversion we might have gone for this. Our pipework is old but functioning well in a late 1920s property and on balance we decided not to take the risk of big leaks with only the one full bathroom in the house. Cost was also a factor; combi plus all labour and removal old stuff was 4k, unvented would have been 6-7k.

We priced up an unvented system and it was around £6k, 4 bed house with 2 bathrooms. There is a D2 (?) discharge pipe that has to be taken into consideration so it depends where your tank is.

We didn't go for it in the end. We already had a 10kw electric shower for the main bathroom so there is always a hot shower on tap, but our cold water is main pressure to all taps except the bloody en-suite where there is a cold water header tank. We know this is to balance the gravity fed hot water.

We have just installed a pumped shower, Mira Platinum and it is lovely. The pump is in the loft and there is a slight hum from it when the shower is on but that was less than £1k to buy but we installed it. I did watch the cold water feed tank when Dh showered to work out how fast it was draining down compared to cold water in.

Thanks everyone. I think I understand the issues better now and can ask the plumber intelligent questions!
I'm still undecided. There are only 2 of us living in the house, but we do have fussy visitors every few months!

Also a 19802 4 bed 2 bath house here. I changed to an unvented cylinder 4 years ago due to pressure issues, plus there were issues with the loft tank which would have needed replacing. And I needed a new boiler.

Plumber recommended the unvented system as it would solve the tank issue, the pressure issue, and would work well with the new boiler.

He said combi boilers are better with a smaller house and he didn’t recommend it for me. Yes, the new cylinder does take up a lot of room, but luckily I have a double airing cupboard, so not so much of a problem.

It definitely solved my pressure problem, and also the advantage is that it makes the upstairs water drinkable - so if you need a drink in the night, no trekking to the kitchen!

We have a 1970s house which was redeveloped before we bought it and we have an unvented cylinder in the loft.

Having only previously lived with combi boilers, I think it's fantastic. With a combi, it's not just running two showers which can cause issues it can be ANY two uses. At my DM's the shower turns cold if someone washes their hands somewhere else or runs the kitchen sink. If you try and do anything while the washing machine is on, the pressure is poor.

I honestly think our system is amazing. We can run the dishwasher, washing machine and shower all once.
The only downside is that the inbuilt immersion has never worked, but that could just be our unit.

Thanks ScoobyDoesnt. Did you have any leaks from the pipe work after the unvented cylinder was installed?

And thanks BlueShed. Time to go for it I think!

I had a very similar setup in my old place — gravity-fed showers, cold tank in the loft, and an old vented hot water cylinder. The pressure was always disappointing until I finally switched to an unvented system.
To answer your question: yes, an unvented tank can make a big difference because it uses the mains water pressure for both hot and cold supply, so the showers get balanced pressure. You’ll only notice an issue if your incoming mains pressure is already too low — which a plumber can easily test for you.
Space-wise, the unvented tank is usually a bit larger, but you can still use the airing cupboard for light storage or drying if you plan it well.
I also looked into a combi boiler, but since I’ve got multiple bathrooms, it didn’t make sense — water flow drops when two showers run at once. The unvented tank has been much more consistent.
If you ever face hot water flow problems again, I’d recommend checking out this Water Heater Repair guide — it helped me understand a lot about balancing water systems at home.