Replacing immersion heater

Goldiemum

Hi. I have an old immersion heater and both heating elements need replacing. The tank is probably over 30 years old.
I've had a quote from trusted plumber to fix it which is under £300. He did mention that as the tank is old, and they can split, is probably very scaled up inside, I may want to think about replacing it with an unvented tank which will cost just over £1000. 
I really don't know what to do so some knowledgeable opinions would be greatly appreciated.  

nofoollikeold

1. An unvented hot water cylinder may only be installed by someone with current "G3" registration.  There are a number of firms providing registration including "NAPIT" and Gas Safe.  The fact that someone gas a Gas Safe registration does not necessarily mean they are qualified to install or maintain an unvented system.
2. Depending on the layout of the property, installing an unvented cylinder can involve considerably more work than replacing a vented cylinder.  
3. Unvented cylinders should be serviced annually by someone with the G3 qualification.
4. To achieve decent performance, you need a dynamic incoming mains pressure of around 2 bar, and a flow rate of around 20 litres per minute.  
5. Installing an unvented cylinder may require the replacement of WC inlet valves as the system operates at higher pressure and the old valves may not cope.  
6. Removing an old immersion heater can cause the cylinder to split.  However, replacement on a like for like basis is likely to be far cheaper than installing an unvented cylinder.
7. The advantages of an unvented cylinder are hot and cold water at mains pressure without pumps.
8. The main disadvantage (apart from cost) is that if there is a mains supply interruption, you will have no hot or cold water.  

stuart45

£1,000 sounds really cheap, unless he means that's the cost of HWC.

Albermarle

An unvented hot water cylinder may only be installed by someone with current "G3" registration.  There are a number of firms providing registration including "NAPIT" and Gas Safe.  The fact that someone gas a Gas Safe registration does not necessarily mean they are qualified to install or maintain an unvented system.
2. Depending on the layout of the property, installing an unvented cylinder can involve considerably more work than replacing a vented cylinder.  

£1,000 sounds really cheap, unless he means that's the cost of HWC.

Something does not quite 'add up' 

Jonboy_1984

That seems suspiciously cheap, I was getting quotes of £1500-£2200 in a flat where all the plumbing for the entire property was within two back to back rooms in 2012.

twopenny

I had my ordinary immersion replaced with another ordinary but updated copper + insulation. It was 20yrs old and tiny leak at bottom. I decided to replace while I had a good plumber there to do it.
My neighbour whose house was also 20yrs old had hers flood. Also replaced with the same one.

If you don't especially want or need something more I'd say just replace the tank and elements. 
Do you have a thermostat on it? Might be worth having that replaced while you're at it and know it's all working.

I'd also get another plumber for the quote and just wait and see if he suggests anything different.

I seem to remember£500-600 plus labour about 3yrs ago

ThisIsWeird

Goldiemum said:

Hi. I have an old immersion heater and both heating elements need replacing. The tank is probably over 30 years old.
I've had a quote from trusted plumber to fix it which is under £300. He did mention that as the tank is old, and they can split, is probably very scaled up inside, I may want to think about replacing it with an unvented tank which will cost just over £1000. 
I really don't know what to do so some knowledgeable opinions would be greatly appreciated.  

Hi Goldie.

As said above, I think the obvious first step is to get other quotes and opinions. 

I take it your current cylinder is 'vented'? If so, current prices are around the £300 mark for these, and the job of replacing it should be pretty straight-forward.

If you are happy with how it performs, then that is bound to be cheaper than going 'unvented', even at the suspiciously cheap £1k quoted by this plumber. Unvented cylinders start at roughly double the 'vented' price, will require a G3 installer, significant (tho' not complex) changes to your plumbing pipes, and a decent mains flow and pressure rate to drive it. And annual services henceforth.

And then there's the option of a new immersion heater at around £50.

Yes, vented cylinders are susceptible to damage when trying to release an old immersion element, but that's not to say it cannot be done. Also, if your plumber is suggesting it may be full of scale, that suggests you are in a hard water area, so a plus here is that the cylinder is unlikely to be corroded/eroded, so should still be pretty strong.

Most plumbers would, I think, at least have a go at removing the old immersion, whilst safeguarding themselves by turning off the cold supply to the cylinder (but still leaving it full of water for strength), and fitting a drain hose 'just in case'. Then they'd at least try and remove the old element. 

Anyhoo, first step, I'd suggest, are other opinions and quotes.

Pivotal

If your a competant diyer, its not a hard task

I bought an element today £25 (was £34) & a spanner £2.50 (was £5), had some joint sealant on hand (£5 tub?) bit of garden hose & a small screwdriver

- it took longer to empty the airing cupboard than to replace the element, maybe a leisurely 2 hours

Plenty of video help online

knightstyle

One thing I used to do was to crack the seal, turn the old heater a tiny bit before emptying the tank.  Also if the heater is in the top then no need to drain completely.

WIAWSNB

Old thread, but useful pointers.
Replacing immersion elements is a perfectly possible - but very scary - exercise. 
The thin copper walls of vented cylinders are quite easy to distort if the immersion is forced too hard. The cylinder is stronger when still filled with water, but that carries the risk of a resulting flood.
In reality, they are unlikely to actually split or tear, but simply crease around the immersion hole. But, get a hose on the draincock, check it opens easily, shut off the cold feed, and be ready to drain and mop up should the worst happen.
Then it's well-fitting spanner, and 'shocks'. Hold the spanner in place firmly, add as much undoing force as that holding hand can apply, and thump the lever repeatedly anticlock using a rubber mallet. That is the best way. Build up the impacts as needed. Stop if you sense any movement that isn't the element turning...
If, instead, you try and twist it off just by hand pressure, you run a much greater risk of distortion.
Once slackened, drain the cinder enough.
Clean up the hole, and I'd use silicone grease to lube the new thread and both sides of the fibre washer.
Failing that, partially drain, and blow torch the cylinder's collar. Repeat.