Water tank replacement - my options?

snic104

Section62 said:

snic104 said:

...so does it sound like I already have a direct invented cylinder, like you suggest?

Unless the hot water cylinder is leaking there's not much point in changing it.  The 'eco' option is to avoid throwing away something completely serviceable just to have something 'new'.

Thank you, I'm learning so much nd I really do appreciate everyone taking time to answer.

I had initially assumed that the tank would be inefficient due to its (perceived) age, but if it is serviceable then I'm very happy with that! 

Section62

snic104 said:

Section62 said:

snic104 said:

...so does it sound like I already have a direct invented cylinder, like you suggest?

Unless the hot water cylinder is leaking there's not much point in changing it.  The 'eco' option is to avoid throwing away something completely serviceable just to have something 'new'.

Thank you, I'm learning so much nd I really do appreciate everyone taking time to answer.

I had initially assumed that the tank would be inefficient due to its (perceived) age, but if it is serviceable then I'm very happy with that! 

No, immersion heaters are close to 100% efficient.  If one of those is faulty it is a relatively easy and cheap job just to change them.

The cylinder will be less than 100% efficient because some of the heat will escape from the cylinder into the surrounding air.  The foam insulation on the cylinder is designed to reduce the rate of heat loss.  Because the cylinder is inside your living space (not the loft) then in the cooler months, the 'lost' heat is helping to keep the flat warm.  A brand new cylinder will likely have better insulation, but the amount you'll spend on one will take years to recover in terms of electricity savings.  If you felt more insulattion was needed then relatively low-cost insulation blankets are available.

Frankly, other than checking for leaks - and having the facility to isolate the supply - there isn't much wrong with what you have.  Other than trying to find out why it currently isn't working.

snic104

Section62 said:

snic104 said:

Section62 said:

snic104 said:

...so does it sound like I already have a direct invented cylinder, like you suggest?

Unless the hot water cylinder is leaking there's not much point in changing it.  The 'eco' option is to avoid throwing away something completely serviceable just to have something 'new'.

Thank you, I'm learning so much nd I really do appreciate everyone taking time to answer.

I had initially assumed that the tank would be inefficient due to its (perceived) age, but if it is serviceable then I'm very happy with that! 

No, immersion heaters are close to 100% efficient.  If one of those is faulty it is a relatively easy and cheap job just to change them.

The cylinder will be less than 100% efficient because some of the heat will escape from the cylinder into the surrounding air.  The foam insulation on the cylinder is designed to reduce the rate of heat loss.  Because the cylinder is inside your living space (not the loft) then in the cooler months, the 'lost' heat is helping to keep the flat warm.  A brand new cylinder will likely have better insulation, but the amount you'll spend on one will take years to recover in terms of electricity savings.  If you felt more insulattion was needed then relatively low-cost insulation blankets are available.

Frankly, other than checking for leaks - and having the facility to isolate the supply - there isn't much wrong with what you have.  Other than trying to find out why it currently isn't working.

Thank you, that's really good to know 

Bendy_House

snic104 said:

There's currently just me in the flat, and I'd be happy with shower-only, however, I may be looking at renting it out in the next year or so (but no definite plans as yet to do this) As it's just a 1-bed flat it would be better suited to a single person or a couple.

Yes ideally I'd like to put the tank (or a replacement of some sort) in the loft so I could make the kitchen bigger. 

Photos attached - I hope they're useful! The brass tap above the floorboards  is where the water supply enters my flat. The red wheel- valve feeds into the tank and the white valve feeds the electric shower. 

Cool - that seems pretty clear. Unlike the water - yuck :-)

Ok, your TOP PIC - it's good you know where the rising main comes in to the flat, 'cos that stopcock valve is what you shut off first in the event of a leak.

Q - is that valve easy to turn? It should currently be set to FULLY OPEN, AND THEN CLOSED OFF A HALF-TURN (anticlockwise to open). This is so that it's fully open = max flow, but then closed a half-turn from 'hard' open to make it less likely to seize.

Q - is the floorboard damp underneath it? If so, it's likely dripping very slowly, which should be easy to sort.

The cold mains then splits using a tee, with one branch heading up to supply the cold tank, and continuing off to the shower via the white valve. The bottom branch goes through the floor and presumably heads to your other cold taps - ie kitchen and bathroom.

 

SECOND PIC. That red wheeled valve looks to be on the HOT FLOW from your cylinder. The hot water supply always comes out the top as that's where the hottest water is found (hot water rises, just like hot air). If you shut that valve off, you'll stop the hot water flow to your taps.

NB: Usually you DON'T have a valve on the hot outlet from a hot tank, just in case the hot tank overheats, say due to a stuck immersion thermostat. If the water boils, where does the expansion go? I don't know if that rule applies to these combination tanks - DOES ANYONE HERE KNOW?

Edit: there is apparently an expansion pipe which comes out the top of the hot cylinder, passed upwards through the cold water tank above, and is open there above the cold water level. If the worst happens, boiling water will spurt up that tube, and fresh cold water enter the bottom of the hot cylinder as normal. The cold tank on top should also have an overflow pipe on it - this will be on its side, and at least an inch above the max level of the water inside.

Q - does that wheeled valve turn ok? Again, its setting should be FULLY OPEN, AND THEN CLOSED OFF A HALF-TURN (anticlockwise to open).

In that same pic you can see a 'draincock'. This is used to drain the contents of your hot and cold tank, say before removal, or to change an immersion element, or to - ahem - clean the cold tank... You push a garden hose on to the splined spigot, run it outside or into a drain (eg bath?), and unscrew (anticlockwise) that squared nut. (Don't undo that nut fully or it'll pop out... Give it, say, 5 turns.)

The second pic also shows that the tank is sitting on a (hopefully strong) shelf, and it's this height that provides the hot water flow to your taps. It is barely high enough to do this, but presumably does work 'ok'?

BOTTOM PIC. That's your ballcock, and is what keeps the cold water level constant.

Q - If you gently press it down into the water, it should start to fill - does it? Ideally you'd have a small isolating valve on the pipe that supplies this, so you can shut off the water to it without having to shut off the whole cold water supply (at the moment, you'd need to turn off that main stopcock.)

Scummy water! Not really a surprise after a good number of years, but it's why you don't drink from the hot tap... What is access like to that cold tank? Would you like to know how to clean it out?

Bendy_House

Looking at the pic below, these are:

1) The cold rising mains supply to the top cold water tank. It would be ideal to have a valve on there, but hey.

2) The hot water flow out of the hot water tank. This supplies your hot taps, and goes via that red wheeled 'gate' valve (which I'm not sure should be there...).

3) Hidden under the insulation is the cold feed from the top tank to the bottom of the hot tank. It goes in the bottom, as the cold water is heavier and stays near the bottom.

4) Is the 'booster' immersion element that will only heat up around a third of your hot tank. This is normally only used to 'top up' your hot water if need more. Bear in mind that this will almost certainly be at full electricity rates, so not cheap to do. But, it's a smaller quantity. Inside that black casing should be a thermostat set to around 65oC, so this 'should' prevent your water from getting too hot, or even boiling if the switch is left on for too long.

5) This is the main immersion element and is used to heat up the whole tank, overnight (or whenever) on cheap-rate electricity. It, too, should have a thermostat in it.

4 and 5 will likely be going to two different power supplies, with 5 only coming on at off-peak timings when leccy is cheaper, and 4 being available for top-ups at all times, but bear in mind it'll almost certainly be a lot more costly to run.

If you want more info on how these cylinders work, they are often referred to as Fortic cylinders, and Google is full of it. Lots of cut-throughs and diagrams. :-)

Bendy_House

Ok, what doesn't work to do with your hot and cold supplies in your flat?

It's unlikely to be anything major, and should be easily sortable. That means you shouldn't need to replace that tank, which is good news as it would likely cost around £500+ to replace, once new immersion elements and stuff is included.

So, the only valid reason to replace it - assuming it's actually working ok (now't really to go wrong) - is if you really do want that extra room for your kitchen. If you do decide to replace it, you could choose a slightly smaller tank, say 90 litres, or even less if you plan to lose the bath. This should make installation in the loft a lot easier.

Section62

Bendy_House said:

 

NB: Usually you DON'T have a valve on the hot outlet from a hot tank, just in case the hot tank overheats, say due to a stuck immersion thermostat. If the water boils, where does the expansion go? I don't know if that rule applies to these combination tanks - DOES ANYONE HERE KNOW?

Back into the feed tank, just as it would with a conventional vented arrangement.

Not having a valve on the outflow side of the cylinder has nothing to do with the tank overheating - since all the pipes downstream of that point will be terminated with taps/valves that prevent water flowing out freely and don't provide a means of pressure release.

The usual practice is to fit a valve on the supply side, which means the cylinder can be isolated to allow inspection and/or replacement of the immersion heater(s).  There's no need for an isolator on the outflow side because the feed side one already does that job.

With a combination cylinder there's the small feed tank of cold water which usually can't be isolated from the hot, hence it may be useful to have a valve on the outflow side to isolate the hot water for maintenance work.

plumb1_2

In the pics it looks like there’s no cold water in the tank, faulty ballvalve as my earlier post.
If there is water in the top tank, then faulty gate valve, it will need some of the water drained down from the cylinder to replace it.

Bendy_House

Cool - I amended my post to add that I found out there's an expansion pipe built in - it goes from the top of the hot cylinder, up through the cold tank on top, and opens above the water level. Makes sense.