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Have electric hot water - what to do, solar electric, combi boiler, unvented tank? Yes PigletJohn I now have my own thread ;)

(15 Posts)
RandomMess Sun 02-Nov-14 00:04:05

Have bought a house that we are not yet living in and about to do major conversion to make the basement area into a kitchen living space with showerroom.

Much to mine and the central heating engineers horror we discovered that the hot water tank is heated only with an electric immersion.

Central heating boiler is more than adequate for both the radiators we will require for the whole house and should do the hot water too.

There will be 3 adults, 1 just teen and 2 pre-teens living in the house and we envisage being there for at least 10 years until a couple of them have been kicked out flown the nest. This hot water will be required for hand washing, minimal dishwashing (have dishwasher), occasional baths - could be used for the basement shower or we could fit another electric one.

I have complete information overload

So my random thoughts so far:

Keep electric hot water and get solar electricity, dh works from home so we can make good use of day time electricity 7 days per week. Pros - no plumbing work required. Negatives - PigletJohn says in winter you often only get about 20% output from the panels, so is it worth the £6k outlay for solar electricity.

Remove storage tank and get a small combi boiler and just use it for hot water. Pros - install it in the roof space next to all the existing pipe work, instaneous hot water on demand. Cons - PigletJohn says expensive/non-sensical as already have a boiler that will do the job.

Unvented Cylindar - Pros get rid of all the tanks in a small double bedroom, efficient, mains pressure hot water. Cons - cost, lots of plumbing reconfiguration and PJ reckons we will need to lay a wider replacement water pipe.

Current gas boiler is in the basement at the back of the house, current tanks are on the 1st floor at the front of the house. Unvented cylindar could go in the basement but still at the front of the house not next to the boiler. Current boiler is 10 years old but a good one and fully functioning so don't want to replace.

Any thoughts/experiences/ideas of costs.

Even comiserations at having to make such a big decision having never lived in the house and having to make a decision very quickly would be appreciated sad.

PigletJohn Sun 02-Nov-14 06:53:14

Is it one bathroom, and one basement shower room?

With so many people you will need a large cylinder if you go that route, and I think two showers and at least two WCs that can be used when the bathrooms are being hogged.

If you currently have a cold tank in the loft, shower pressure in the basement will be quite reasonable (no pump needed).

Please don't put a boiler or cylinder in the loft.

Have you got lots of money?

No need to fit solar panels immediately.

Immersion heater is a money pit, and slow, if your only source of hot water, but a useful standby for when boiler is out of action

RandomMess Sun 02-Nov-14 16:39:18

There is an en-suite with bath only on the 1st floor - you could add a shower as well if we have the money to add on a dormer or move the bath (currently under eaves).

Ground floor wetroom with decent electric shower

There will be a basement wetroom with some sort of shower (well that is the plan)

Currently the cold water tank and hot water immersion cylinder are on the 1st floor in another part of the eaves.

No we don't have lots of money sad but would rather pay some more for decent showers running of gas heated water as I'm thinking that would be cheaper than running 2 expensive electric showers (or even 3 possibly?).

If we got a vented cylinder would it still be more sensible to locate that in the basement rather than replace the current one? Would you still leave the header tank on the 1st floor to improve the pressure?

RandomMess Sun 02-Nov-14 16:40:21

Both wet rooms will have a WC in them as well as the en-suite!

PigletJohn Sun 02-Nov-14 17:03:45

if you don't change to an unvented cylinder (yet), then a cold water tank in the loft will give better pressure than one on the first floor. A loft tank will give a good shower in the basement and a not very good one on the first floor. A first floor tank will give a pathetic and useless shower on the first floor.

The pressure does not vary according to the height of the cylinder.

There is no such thing as a decent electric shower. Look up the litres per minute delivered and compare that to pouring water out of a kettle.

You will need a much bigger cylinder than you have. If you are buying a new one, you might as well go for an unvented, which you could supply from a loft tank for a while, but it would be much better to replace the water supply pipe at the same time. It can go in any convenient position, but will be heavy.

If you replace the water supply pipe with a bigger one, and fit an unvented cylinder (or a combi or a storage boiler if you prefer) you will no longer need a cold water tank. You boiler, if it does not have a pressure gauge, is probably topped up from a small cistern upstairs or in the loft, about 450x300x300mm, and you will need that even if you no longer need the cold tank. This is the feed and expansion tank, and you can move it to a more convenient place if you want. It should be higher than your highest radiator or cylinder.

My choice would be a new water supply pipe, and a 250 or 300 litre unvented cylinder standing on the basement floor, close to the boiler. Get a cylinder with an upper and a lower immersion heater, as a standby for when the boiler is out of action. If you think you might one day get solar panels, you can use it to heat the cylinder on sunny days.

If you have electric heating of the cylinder, there is no point in getting an electric shower.

RandomMess Sun 02-Nov-14 17:29:51

The cold water tank is in the loft as such as it's a chalet bungalow grin

Yep I don't like electic showers sad

Does the distance between the boiler and the unvented tank matter much?

How much are we looking at for the purchase and installation of an unvented tank - I mean take off the complicated replumbing and new water pipe what is the starting price?

Also if we have the unvented tank fitted now and then wait a while to redo the main water intake will still work, just have a rubbish pressure? We could survive on the seperate bath and electric shower in the short term if we had to.

RandomMess Sun 02-Nov-14 17:31:09

I think the distance between the boiler and tank would be around 16' unless we also move the boiler - but then I reckon you would end up forking out for a new boiler too ££££££££££££££££££££££££££££££

PigletJohn Sun 02-Nov-14 17:53:45

the cylinder doesn't have to be next to the boiler but remember you will have insulated pipes running between them. You can have an airing cupboard round the cylinder, but they are so well insulated that it will not get very hot..

Yes you can run an unvented cylinder off a tank if the water pipe has not yet been changed, though I would do the pipe first, as you will otherwise have the extra cost of testing and commissioning the cylinder again.

It might cost more than a thousand to buy and install an unvented cylinder.

It might cost a few hundred to lay a new water pipe. But for people who have lead pipes, there might be a subsidy. It will probably take longer to do the pipe than to install the cylinder.

RandomMess Sun 02-Nov-14 17:58:38

I guess I will ask my basement builders to replace the water pipe for me as they will have the necessary stuff!!! House was finished in 1960 so I suspect unlikely to have a lead pipe?

Being positive getting rid of all the existing tanks means there will be a much better scope to have a master doulbe room and en-suite up there eventually...

PigletJohn Sun 02-Nov-14 18:14:59

Ask for a 32mm plastic pipe, all the way from the meter to the place where the cylinder will be. Ask for a stop-cock at the cylinder end, and another (with an iron hatch) in a pit just inside your boundary. Mention that the water co will want to inspect it before the trench is filled in.

Ask for the feed to the cold taps, and the feed to the cylinder, and a stub for garden taps, all to come off the 32mm pipe, and the connection to the cylinder to be made in 22mm copper (that way none will reduce flow to the others, like it would if they went down to 15mm copper). If they say a smaller pipe "will do," say you'd prefer the bigger one.

The difference in cost between 20mm, 25mm and 32mm plastic pipe is trifling, though the bigger stopcocks are more expensive.

When you are feeding two bathrooms and a kitchen, it is best to run a 22mm copper pipe, and tee off for each room. A bath should have a 22mm pipe, though a basin or shower should have 15mm. The point is that a smaller pipe reduces the flow. Each size down has about 50% less capacity that the previous. Due to the thickness of the walls, plastic pipes measure bigger on the outside diameter than copper pipes of the same internal bore.

Some budget installations save a couple of pounds by using 15mm copper pipe when 22mm would be better. The trouble and expense of changing later is vastly greater than using bigger pipe in the first place.

RandomMess Sun 02-Nov-14 18:41:44

Cheers, yes in previous houses we've had larger pipes installed for this reason. I'm going to have wine and sob about the additional expense!

RandomMess Sun 02-Nov-14 19:03:59

Can we not run a shower using 22mm hot & cold pipes for maximum flow?? I'm sure you said we'd get a decent shower direct from the unvented boiler?

PigletJohn Sun 02-Nov-14 19:05:41

unvented cylinder]

yes, if you want.

Bath taps are bigger, and deliver more water than shower mixers.

It may knock you over.

Waswondering Sun 02-Nov-14 19:09:08

Just, whatever you do .....

Make sure any submerged pipe work is sound when the basement is excavated. Do check for cracks in waste pipes etc.

Then make sure your basement is properly tanked, against water ingress and damp.

I speak from the heart!

RandomMess Sun 02-Nov-14 19:24:30

Oops I meant cylinder!!!

Very little excavation to do thankfully (already have huuuge garage & storage rooms underneath that are 99% dry) and no currently submerged pipe work - yes we're having it fully tanked grin hence the poverty!

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