Electric hot water tank and power shower

Akustik

Hi, I've recently purchased a one bedroom (all electric) flat and have quite a few questions about what to do with the current setup of the hot water installation.

I mostly use the hot water for showering. I have a washing machine and a dishwasher which are self heating and storage heaters (and normal ones) for rooms.

I'm not someone who has quick showers and I end up in a situation where my hot water cuts off completely and the power showers starts making weird noises. I've searched around and I believe this is caused by either the power shower maxing out its runtime or the tank running out of water and creating a vacuum because of the power shower pumping air.

Firstly, let's begin with the setup as it is now:
I have a Elson Opal electric hot water tank.
(diynot.com/diy/attachments/img_2113-jpg.168795/)
I also have a Aqualisa Aquastream power shower

The bottom of the water tank and the bottom of the shower are at around the same level - 130cm off the ground.

I had a plumber in for a different problem, he took a look and gave me his opinion. In his opinion, the power shower is not really suited to the type of boiler I have. My boiler being one with internal feeding tank. I'm not sure if that's the case (about the internal feeding tank). My property seems to have different water feeds for the bathroom sink and the kitchen sink (discovered when the plumber stopped the water).
He had two recommendations:
I get a gravity fed system with the feeding tank in the loft. I'm not too sure about this option as I don't have loft rights even though I have a hatch to the loft inside the flat.
I get a pressurised hot water tank which delivers mains pressure for hot water.

I'm more inclined towards the second option - pressurised hot water tank (or I think they're called unvented?). But, would this work with a power shower?
What kind of cost would I expect around all of this?

I also stumbled onto this by accident - mcdonaldwaterstorage.com/products/rectangular-hot-water-tanks#cubeflowelectriccombination
They seem to sell something that can straight up replace my current tank, but I'm not sure if they're any good as they seem to target council housing which would mean they're cost over performance?

Final question is around cost, how much would it be to replace the current tank with either option? I'm currently under shared ownership, so I'll not go ahead with this if it's too costly until I buy the whole property.

Tom99

https://www.diynot.com/diy/attachments/img_2113-jpg.168795/
https://mcdonaldwaterstorage.com/products/rectangular-hot-water-tanks#cubeflowelectriccombination

coffeehound

Hi, not what you asked, but: Do you know what temperature your tank's immersion heater thermostat is set to? The usual setting is around 60 degrees C, but as a short term fix, you could make your shower last a little longer by increasing this a bit. Perhaps increase it to 70 degrees and see how that goes. Obviously extra care is then needed to avoid being scalded by hot tap water, though.

Akustik

Thanks @Tom99 for helping with the links - second link should be HTTP though as they apparently don't have a valid HTTPS certificate

@coffeehound No, I don't as the heater is encased in a box and I have no idea how to get in there. There's also some sticks in front that you can't remove without unscrewing them. Not sure why this was done and I really hope I don't have some kind of problem with it because it'll be a massive undertaking to open that up.
I have also thought about increasing the temperature, but yeah ... see above

coffeehound

Ah okay. I just looked at the Aqualisa Aquastream specs and the maximum temperature for hot water is only 65 C anyway.

coffeehound

Just seen your photo. I'm not familiar with those heaters, but the thermostat setting is probably behind the black trims on ends of the heaters - ensure electricity is off before looking

Owain_Moneysaver

The rectangular style 'cylinders' have limited hot water capacity and combined with the small cold header tank capacity and the high demand of a power shower mean you will run out of water.

Replace with an unvented hot water cylinder, and remove the power shower and replace with a thermostatic mixer shower. I'd expect about £350 for a 120-150 litre unvented cylinder, but you might want to go larger if you have the space and can afford it. Labour costs will depend on how close to the existing location the new cylinder goes, and how easy it is to run the presure relief pipe to a safe place outside (or an internal waste pipe using a Hotun . Probably about £1000 - 1200 all in.

The alternative is to have baths instead of showers. Showering for longer than 10 mins - a bath is cheaper and uses less water.

Akustik

Owain_Moneysaver said:

The rectangular style 'cylinders' have limited hot water capacity and combined with the small cold header tank capacity and the high demand of a power shower mean you will run out of water.

Replace with an unvented hot water cylinder, and remove the power shower and replace with a thermostatic mixer shower. I'd expect about £350 for a 120-150 litre unvented cylinder, but you might want to go larger if you have the space and can afford it. Labour costs will depend on how close to the existing location the new cylinder goes, and how easy it is to run the presure relief pipe to a safe place outside (or an internal waste pipe using a Hotun . Probably about £1000 - 1200 all in.

The alternative is to have baths instead of showers. Showering for longer than 10 mins - a bath is cheaper and uses less water.

There's one thing I'm unsure of and I'll try calling the lease owner to check, but ... can this still work if the feed for the hot water tank is coming not from the mains?
The reason I ask is because after I moved in, I hired a plumber to fix something which required him disabling the cold water. He had to do this from outside the flat. When he did, the cold water in the bathroom could still run, but not in the kitchen. I can see that there are two pipes coming into the flat from outside. One would be the main which is very high pressure, but the other one is low pressure - presuming that is from a communal tank of some sort.
So, would I be able to replace the hot water tank with an unvented one if it's not fed by mains? Could that even be the case with the old one e.i. could you have a vented cylinder's cold water tank being fed by non-mains cold water pipe?

Owain_Moneysaver

You can have a vented or unvented cylinder fed by non-mains. It just won't be mains pressure.
Speak to a competent plumber who can see your installation. In some cases you will need a local header tank, in others you may not. 

Akustik

Owain_Moneysaver said:

You can have a vented or unvented cylinder fed by non-mains. It just won't be mains pressure.
Speak to a competent plumber who can see your installation. In some cases you will need a local header tank, in others you may not. 

Thanks. I will do when this quarantine thing is over