Hot water cylinder only heating top half of tank

[hannahHamilton]

Hiya, we had a new pressurised hot water cylinder fitted a few weeks ago even though its double the size of our last one we are finding we aren't getting any more hot water. So once the tank is full and the immersion has turned off and i touch the tank only the top half feels warm and the bottom half still feels cold. My theory is because the element / thermostat is half way up the tank its only heating to that? which seem pretty crap and a waste of the other half of the tank? basically to where the line is on the picture.

 

[PETE 123]

The tank bottom part would be heated from your boiler so no need to use electric.

 

[gmartine]

Yep, that immersion is only really for a quicker charge of half the cylinder or emergency/summer use when heating is not on. If you want a full cylinder of HW you've gotta heat it up using your gas boiler, should be cheaper tbf. Depends on type of energy tariff of course.

 

[hannahHamilton]

Yeah I think we have realised the wrong tank has been fitted as that's not what we want - as we have PV panels we want to use them to heat the water for free as much as we can. Our plumber knew this all along so i have messaged him. Thank you.

 

[John.g]

If the solar boost is electric then another immersion in the bottom of the cylinder might be more economical if large amounts of diverted power is available in the summer.

 

[gmartine]

Didn't see the iboost initially but it looks like installed wrong cylinder, it won't fully utilise your array with one immersion.

• Solar iBoost+ features connections for 2 immersions, switching between them automatically to maximise electric water heating systems.

 

[hannahHamilton]

Can you add another immersion / element to the bottom? or would it have to be a whole new tank?

 

[gmartine]

New cylinder I'm afraid, was the iboost already installed and connected to old cylinder with one immersion only and swapped over?

 

[hannahHamilton]

Yeas we already had the iboost fitted, so our plumber was well aware we had it and how we planned to heat out hot water.

 

[gmartine]

I'm trying to establish who knew what...

It's likely the plumber didn't know the iboost was capable of heating two immersions allowing you to heat a larger cylinder fully and just replaced like for like but with a larger version that you asked for, that really is the job of an electrician.

However it is possible to buy a larger cylinder 200 litres + with an immersion positioned at or near the bottom of the cylinder which is what he should've considered.

 

[hannahHamilton]

Our plumber knew we have a solar iboost and knew we wanted to use that to heat our hot water as much as we can. He chose one with the element half way up, we have a 180L tank, which if the element was just at the bottom it would be perfect. I assume we don't necessarily need double immersion just where the element is future down, on a sunny it heats very quickly so it would be capable of doing double im sure.

 

[fowlerboi]

I'm pretty sure you're looking for a unicorn.

To get what you want you either completely lose capability to connect the boiler or you use a destrat pump with the immersion a bit higher up.

I've never seen and still can't find a cylinder in which an immersion heater is lower than the coil or remotely close to the bottom when there is a coil. Even doubleimmersion indirect cylinders have the bottom immersion too high for what you want

 

[hannahHamilton]

Update - our plumber has fitted a secondary return pump (think that what he said it was called) which circulated the hot water within the whole tank allowing us to heat the whole tank using the solar iboost.

 

[Ben-gee]

I've never seen and still can't find a cylinder in which an immersion heater is lower than the coil or remotely close to the bottom when there is a coil. Even doubleimmersion indirect cylinders have the bottom immersion too high for what you want

Unfortunately I have!
Twin immersion with a coil, the lower immersion was below the coil- I was supposed to be changing lower immersion.
Once this immersion was removed the coil dropped down and made it almost impossible to put a new immersion in / the old one had failed where the coil had been resting on it - really bad design/manufacturing.
I Jerry rigged something to hold the coil up and told the custard that next time I would change the cylinder if I were him (it was quite old anyway)