Electric Central Heating

[Quillan]

I have been looking around for information on these types of system (better known as Electric Wet Central Heating Systems) I have found some info but not a lot. They are electric powered central heating boilers normally with a storage tank. I was wondering if anyone else has looked in to them or even better installed one or has one installed (either here or in the UK). The benefits I can see are that they are around 99.8% efficient, maintenance free, use off peak electricity and are a direct replacement for gas or oil boilers.

So far all I can find on running costs is a 50/50 split between those that claim they are cheaper to run and those that claim they are expensive (these are users not manufacturers or installers who would of course be biased).

[Albert the InfoGipsy]

In effect you're running your rads off an electric ballon.

Dunno about the running costs, but they do have the advantage over most other electric systems of being adaptable in the future. If you decide in a few years to change the boiler to oil, wood or whatever then you'll have all the actual heat emitters in place.

If you already have the rads in place & want to go electric they are the obvious solution.

[Will]

I think that during cold periods you would still need to top up outside off-peak hours. The only system anything like that which I have seen is one where the electric 'boiler' (in effect a chauffe-eau) was used to supplement a heat pump, drawing heat from geothermal sources, and as such systems operate at a lower temperature than a standard wet system, they work best with underfloor heating, or, at a pinch, oversized radiators. This of course is expensive to install. but very economical in use.

The big benefit of electricity in France is that it is a much more stable energy source, in terms of supply, than oil or gas. Over 80% of France's electricity is nuclear-generated, and a fair bit of the rest comes from sources like hydro power. That means the generating cost is influenced far less than in many other places by the oil and gas markets. It is still expensive, kW for kW, compared with oil or mains gas, but less so than a couple of years ago. Electricity bills in France were a lot more than in England, but are now pretty close, and will probably become relatively cheaper. And as oil and gas rise in price the electricity in France will get still more competitive. Off-peak costs are lower of course.

So in the medium to long term view, electric heating looks as if it should be a sensible option in France. But who can really tell what is going to happen?

[sheldonrobbo]

hi quillan

search on the web for redring hotbox electric boiler.....its a form of halogen heater that will feed normal wet central heating rads....very economical to run and easy to install ....runs off a 13 amp plug

[Quillan]

I looked at the Redring Hotbox but the biggest only produces around 12,000BTU's which as it says is OK for small flats, boats and caravans. I have found a few UK manufacturers on the internet but they don't give much, if any, information on running costs. I know there are two types of unit. One just heats water as it pass's through and has no 'storage' tank which is suppose to be expensive to run. The other has a tank and can be 'charged up' on off peak then topped up during the day. They talk about economy 10 in the UK as being the best way to save money with these systems but I don't think we have anything like that in France (you get one or more 'top up' off peak times during the day).

In theory it should be good to use a system like this in France and help with the environment so seeing as they have been around for a few years in the UK now I would have thought I would have seen or heard more about them in France. I was also thinking that they might work well with TEMPO which we have.

I don't suppose anyone has a name for them in French so I can have a look at French prices?

[sheldonrobbo]

hi again quillan

don't think they will be available in france as redring bought the idea off a smaller company and have the patent on the system as far as i know ....forgot to say in my earlier post that it has limited capacity. However we are using it purely to heat bedrooms and bathrooms as we rely on a woodburner for heat in the main living area and kitchen.

 

[powerdesal]

The hotbox sounded very interesting until I realised that the biggest is about 3.5 Kw.

Not really an option for a 'normal' CH system. I'm still tending towards a log burning boiler, if I can ever get replies to my e mails!!!!

[Gluestick]

The of these Electric Boiler "Wet" Systems is a very large (depending on volume of house to be heated) water storage tank with a "Floating" inner tank.

The idea is that the tank -  which is super-insulated - is heated at night on cheap rate to circa 85 C.

The hot reservoir of water is thereafter circulated on demand via radiators and of course, for DHW.

The main problem is that to provide central heating throughout the day, in cold periods -  which after all, is normally when you want it! - the tank needs boosting as it's core temp drops beneath circa 50C. Expensive!

Most ethical manufacturers and specifying authorities admit straight off that users would normally require some form of back-up heating, such as a log burner, in main living rooms for the evening: at which time the core temp has reduced drastically.

I suppose if you could provide a simply massive storage tank then this would store sufficient heat energy for the day.

Like so many innovations, these systems work best with underfloor heating, as once the thermal mass of the floor is overcome, it sorts of ticks over. Any efficiences also assume a pretty high standard of insulation and thus heat retention.

Unfortunately, the real beauty of oil or gas is that this is if you like an "On Demand Stored Latent Heat at any time" system; hence their popularity and universal appeal and use.

 

 

[powerdesal]

Interesting idea Gluestick, build a super-insulated, massive underground storage tank then the only daily running costs would be the heat lost due to air changes, heat leakeage (function of insulation levels) and such like. The civil works would be awesome (and expensive) but it could (should) work. Cant imagine what the amortisation period would be.

The building insulation levels would be equally expensive, especially as a retrofit to a traditional stone house. Maybe its a thought for a new build project.

[Gluestick]

I have, philosophically, pondered for quite some time, Steve, that it would be technically possible to build a dwelling where the first and critical bit was a massive undergound "Utility Services" section.

Here would be a complete water and sewerage processing unit, recycling used water and reprocessing into two discrete systems: potable and the rest. Additionally one would have a massive rainwater storage tank, storing all the precipitated water from roof, outbuildings and land drainage.

The sewerage processing would process out methane (which has been achieved for a number of years in India, e.g. and produces sufficient low-pressure gas for cooking.).

Another section - depending on geographic location - would "Store" cold, by virtue of using huge freezer blocks filled with various liquid chemicals, energy sourced from solar collectors and acting like a gas, kerosoene or electrically powered 'fridge using heating coils instead of compressor. Solar air conditioning on demand! After all, the places where one needs it the most tend to have the most solar energy potential!

Heat would be stored using either solid or liquid medium.

Energy would be captured from solar radiation and wind source, as well as a heat pump from geothermal source/s and stored.

Ergo, pretty cheap to run!

But, as you say, the amortisation period would be pretty excessive. [:(]

I am sure, however, that such approaches on a group, rather than sole basis will be increasingly used in new builds; sewerage processing and water in particular.

 

[Quillan]

I have found some boilers, well three, all English plus a forum type website with people from councils discussing them with regatds to using them in rentable accomodation and private houses.

The companies I found are Fifas, Aptech and Heatwell two of these have boilers that push out about 40,000BTU. They all seem to claim that only town gas is cheaper (but only under certain conditions). But then they would make these sort of claims I guess.

With fossil fuel prices for ever going up and France only using little fossil fuel for heat, light and power I am thinking that perhaps this may be the way to go. Especially if you do not have access to town gas.

One of the above websites claims an annual bill for an all electric 3 bed house of around £700 but it does not say which year [:D] .

These system runs radiators and not underfloor heating by the way and they all claim they can be fitted in to a small space.

The forum type website is http://www.est.org.uk/housingbuildings/localauthorities/information/forum/index.cfm?Start=1&ty=1&topic_id=38  which s the Energy Saving Trust. There a collection of interesting comments in the thread there.

[Nick Trollope]

Here I dive in with a bit more maths...

IIRC (and it was a long time ago) a modern, well insulated 3 bed house in this part of Europe needs about 35,00BTu or 10KW/hr - assuming a direct electric heater is 100% efficient (near enough), then this will cost (at todays rate about 110c/hr to run duing the daytime or about 40c/hr at night) - perhaps 20€ a day. BUT, as no heat transfer system can be 100% efficient (oil or gas or coal or even electric), then perhaps we are looking at an average of (say) 23€/day for 6 months of the year = over 4grand! On this basis, £700 (1000€) would get you about enough to boil a kettle and cook toast continuously...

What's more - without any margin for "comfort", 10KW would give you nothing (from an average, rural supply) to run the rest of the house.

If you want to save the planet, then there is no alternative to geothermal (but all you will save is the planet - no prospect of saving money). If you want to save your pocket, then there is no alternative to a woodburner.

Discuss (again)

 

[Gluestick]

Good old Nick!

Some pragmatics here.

All the data I have seen - from the manufacturers of course - seems to tell the same boring tale of something for nothing, with the basic laws of physics being ignored.

Next it will be free heating, from an alternator powered by a perpetual motion machine............

[Chancer]

Nick

My 3 bedroomed house in England has a similar rated boiler but it is only running for a couple of hours in the morning and say 6-8 in the evening.

The 35000 btu is needed to very quickly raise the temperature in the morning but even then the thermostat cuts in and out after a short while, the system is only ever running at full load when replenishing the hot water cylinder after a bath or topping up the temperature when the stat cuts in.

For the same house if you used say panneau rayonnants you would of course need an equivalent 10kw but I bet it would not warm up anywhere near as quick.

I am following any discussion on these new systems with interest, I have just moved in to the first of the flats that I am building/renovating. It is about 38m2 and I have a total of  4.9KW of storage heaters plus the 1220w ballon de chauff, but they only would charge for a maximum of 8 hours.

Even in the current cold snap the heaters are not taking on a charge for the full 8 hours, I know this because I was running the washing machine on the same heures creuse asservissement and it was tripping my main disjoncteur, I have now fitted a timer which switches it on after 5 of the off peak hours and it no longer trips.

As I am writing this I realise that it is probably the ballon that is switching off  so I will have to investigate further but don't like getting up in the night to take current measurements. Certainly after a few hours of charge I only have to turn down the input charge control a little bit to hear the thermostat disconnect, I will investigate further.

[bejay]

The difficulty with off peak electricity is that you reduce the cost but use the same amount of energy. This in the long term leaves us at the mercy of the provider.

This is a UK perspective for which I apologise but it is clear from all sorts of existing legislation that the main thrust is to develop low energy housing ("....move to zero carbon construction for new houses in ten years" is one phrase that turned up). Even if international fuel prices were to settle and remain steady then taxes or fuel duty can be used to increase the cost. The first obvious increase could be in VAT on domestic energy.

As we speak we are training energy inspectors, at the moment their role is trivial, advisory, optional  and only applies to the sale of properties but its a start!

Industry won't mind, it will generate all sorts of business opportunities. President Clinton some years ago described energy conservation  as a  trillion dollar industry.

bj

[Gluestick]

And, of course, if a vast majority of electricity consumers switched to an Off Peak Tariff, then "Off Peak" would change to daytime!

Core rule of the free markets.

And if a vast majority of homes junked their gas, oil, wood whatever heating, then the markets would react; again.