Replacement for a hot water cylinder

[Yellow Fang]

It looks like I will have to replace my old immersion heater. It's making a constant drip from behind somewhere, so I've switched off the water. Ideally I'd like to replace it with something very green, like solar, woodchip or an air source heat pump, but living in a flat in a conservation area in the middle of town, does not make these viable. I suppose solar might be possible as I live on the top floor, but I wouldn't want to battle with the council and deal with the legal rammifications with the freehold, and anyway, I don't have the time and money.

I was thinking of electric instantaneous hot water heaters. They don't seem enormously expensive to buy, but they look like you need one for each hot water tap.

I am also considering highly insulated, dual immersion cyclinders. The lower immersion element does the main part of the heating using economy 7 while the top immersion element tops up the water temperature during the day if you start to run out. The thing is, my hot water usage is quite light - mainly just washing up and washing my face and armpits. I occasionally have a bath, but more often I use the showers at a leisure centre.

Lastly, I am considering gas multipoint boilers. I have a gas fire, which I hardly ever use, but the gas supply has never been connected up to a boiler. My mum says gas boilers are more expensive, need to be checked annually, and are less reliable. From a green point of view, gas boilers are better than electric heaters. Turning natural gas directly to heat is more efficient than turning it into electricity and then into heat. Gas boilers only heat the water you actually use too. OTOH, gas is gradually becoming more expensive, is running out in the North Sea, and cannot be decarbonised, while in theory electricity can.

I studied an MSc in Renewable Energy and still don't know which is the best option. I probably should have studied plumbing instead. I have not found sites such as Energy Saving Trust that helpful. Most other websites are commerical, so want to promote their products. Some are technical, using terms such as vented/unvented, direct/indirect, single, twin and dual immersion. Some systems are suitable in one sort of household, but totally unsuitable in another. Some hot water systems are combined with space heating, which appears to make it shed loads more complicated and expensive, but I am only interested in hot water.

 

[Archie_tect]

You need a simple and small gas combi boiler... you only heat the water you need and the cost will be low compared to electric heating, because you don't use much. That way you can get rid of the hot water tank completely and you get the benefit of mains pressure hot water if you fit a thermostatic shower over your bath which will be more efficient than a bath anyway.

Solar heating would be great as you're on the top floor but you'd need to replace the existing cylinder with a three coil cylinder and with the amount you'd use it it would be expensive to install and you don't sound as if you want the hassle especially as you'd need a top-up heat source anyway.

 

[Yellow Fang]

Aren't combi-boilers space and water heating? I don't want the space heating. British Gas quoted me £5000 for a combi-boiler system because they insisted on selling it with radiators and everything. What about the servicing requirements for gas boilers? I gather they're supposed to be inspected yearly, though I expect that's rare.

 

[Andy_R]

For a start, never ever to go British Gas for an installation. They charge so much more than anyone else, and tell you what they want to install, instead of asking you. Go to your local heating engineer and explain what you need. Probably get an installation for less than £1000 - remember that combi's, like all boilers, whilst having the option of space heating don't have to use it (who uses heating in the summer?). Alternatively, what about a gas water heater like this one heater - all it does is heat water (guess the name gives it away), with no provision for space heating.

 

[Zoiders]

I have a dual immersion cylinder in my flat which is a new build with all the efficient features - I was lairly about it at first as to be honest emersion cylinders used to be a bit pants but it's become a huge money saving feature because it's so well insulated.

It heats quickly for odds and sods usage and two hours will give you a tank full that stays hot for two days.

As someone who only showers and washes up it's a very good option indeed.

 

[MacB]

It is a bit of a minefield and I wasn't convinced by the recommendations according to home and occupancy. Against the perceived wisdom/advice I chose a combi boiler ,along with new rads, pipes, etc, total of 13 radiators, I think our overall bill came to a bit shy of your British Gas quote.

The only difference is the hot water, the radiators are heated as they always were, it's just hot water on demand rather than via storage tank. Our appliances are cold fill so no useage there, both showers are electric so the only time the water side is used is for a bath or filling a sink. Our bills came down significantly following this change, impossible to break it down, ie what was not heating excess water and what was down to the condensing boiler.

Also in the back of my mind was the idea that the boiler is effectively a plug and play part. In theory another boiler, running on a different energy source, could just be slotted in.

 

[asterix]

I am also considering highly insulated, dual immersion cyclinders. The lower immersion element does the main part of the heating using economy 7 while the top immersion element tops up the water temperature during the day if you start to run out. The thing is, my hot water usage is quite light - mainly just washing up and washing my face and armpits. I occasionally have a bath, but more often I use the showers at a leisure centre.

In France we have a 200L water tank with a heating element. It is extremely well insulated and we re-heat it for a couple of hours each night. No idea how economical it is as we haven't had it long. 200L is easily enough, we'd get by with half that and no need for daytime top up. IIRC the whole thing was 180 euros. special offer. A very simple system.

 

[Brains]

I'd go with the gas fired combi boiler option.
You only heat the water you use

Combi boilers have a life of 15 +/- 5 years, it depends on how hard the water is in your area.

 

[Yellow Fang]

For a start, never ever to go British Gas for an installation. They charge so much more than anyone else, and tell you what they want to install, instead of asking you. Go to your local heating engineer and explain what you need. Probably get an installation for less than £1000 - remember that combi's, like all boilers, whilst having the option of space heating don't have to use it (who uses heating in the summer?). Alternatively, what about a gas water heater like this one heater - all it does is heat water (guess the name gives it away), with no provision for space heating.

Yes, gas multipoints look like a good option.

 

[ASC1951]

You need a simple and small gas combi boiler... you only heat the water you need

+1 for a small combi. Modern ones are very reliable - I have had my Vaillant for at least a dozen years and I've had it serviced a couple of times, once needing a new thermostat and last week a new top-up pipe.

... and you get the benefit of mains pressure hot water if you fit a thermostatic shower over your bath which will be more efficient than a bath anyway.

Showers are hugely more efficient than baths. You need at least a foot of water in a bath (before you get in!), whereas a shower with the plug in put about an inch and a half in my bath by the time I had got bored.

 

[Canrider]

Another +1 for the combi. We did well before the kids with a cylinder as we could completely predict when we'd need hot water and ration the heat accordingly. The only complaint I'd have is it can take a while for the hot water to work its way through the pipes to the tap, so a lot of (fresh, clean) water goes down the drain before the hot comes through.

 

[Archie_tect]

Another +1 for the combi. We did well before the kids with a cylinder as we could completely predict when we'd need hot water and ration the heat accordingly. The only complaint I'd have is it can take a while for the hot water to work its way through the pipes to the tap, so a lot of (fresh, clean) water goes down the drain before the hot comes through.

Everyone should minimise the waste of hot water in the pipes by insulating the hot water pipework as much as possible including the joints, it's fiddly but worth it.

Depends on the length of the pipe runs but in a flat shouldn't be too bad.

 

[Bobtoo]

We got a combi installed in our last house and I swore I'd never have another. It was installed a foot from the kitchen sink and the bathroom was on the other side of the wall. I thought it couldn't be better. Wrong.

It had some sort of pre-heat device so as soon as you turned the tap on you got scalding hot water, but then you got several litres of cold water while it sorted itself out. If you turned the tap off, even for an instant you would have to go through the whole process again. Incidentally it burned gas all the time it was pumping cold water through, god knows what it did with it.

I strongly believe that a correctly sized and well-insulated tank system is a better solution all round.

 

[asterix]

In York we went for a combi/condensing boiler and it slashed our gas bills. The downside is the wait for hot water to come through. We were also told (by British Gas) our gravity fed shower would have to be replaced. We had several quotes* and the cheapest one said he didn't think we'd need to replace the shower and also came up with the best pipe routing option, so we went with him. He did an excellent job doing everything neatly and tidily. I'd had a combi before and the newer one is a lot better - much improved hot water supply.




*the British Gas one was ridiculous, for one thing why did they 2 people? Why did they have an expensive computer? And why did they spend more time trying to get us to take out a loan than discussing the system? Maybe the last question answers the first 2. They were easily the most expensive.

 

[wildjetskier]

It looks like I will have to replace my old immersion heater. It's making a constant drip from behind somewhere, so I've switched off the water. Ideally I'd like to replace it with something very green, like solar, woodchip or an air source heat pump, but living in a flat in a conservation area in the middle of town, does not make these viable. I suppose solar might be possible as I live on the top floor, but I wouldn't want to battle with the council and deal with the legal rammifications with the freehold, and anyway, I don't have the time and money.

I was thinking of electric instantaneous hot water heaters. They don't seem enormously expensive to buy, but they look like you need one for each hot water tap.

I am also considering highly insulated, dual immersion cyclinders. The lower immersion element does the main part of the heating using economy 7 while the top immersion element tops up the water temperature during the day if you start to run out. The thing is, my hot water usage is quite light - mainly just washing up and washing my face and armpits. I occasionally have a bath, but more often I use the showers at a leisure centre.

Lastly, I am considering gas multipoint boilers. I have a gas fire, which I hardly ever use, but the gas supply has never been connected up to a boiler. My mum says gas boilers are more expensive, need to be checked annually, and are less reliable. From a green point of view, gas boilers are better than electric heaters. Turning natural gas directly to heat is more efficient than turning it into electricity and then into heat. Gas boilers only heat the water you actually use too. OTOH, gas is gradually becoming more expensive, is running out in the North Sea, and cannot be decarbonised, while in theory electricity can.

I studied an MSc in Renewable Energy and still don't know which is the best option. I probably should have studied plumbing instead. I have not found sites such as Energy Saving Trust that helpful. Most other websites are commerical, so want to promote their products. Some are technical, using terms such as vented/unvented, direct/indirect, single, twin and dual immersion. Some systems are suitable in one sort of household, but totally unsuitable in another. Some hot water systems are combined with space heating, which appears to make it shed loads more complicated and expensive, but I am only interested in hot water.

If its any use to you I run a property refurb company and if you need some independent advice I will happily send my heating engineer along to advise/recommend you, no obligation whatsoever, just some friendly CC advice.