hot water from oil-based system

[mike.m]

Hi ,

       Looking for some advice after our ancient  fioul boiler finally gave up . We opened  a chambre d'hote last summer and got by with an extra in-line chauff-eau electric which produced a combined 400 litres of overnight hot water . This year we will be adding bedrooms and need to supply two bathrooms and two shower rooms so a fixed supply is no longer adequate .

                                                         Having consulted professionals who offered differing opinions I read the excellent thread on plumbing in this section which has persuaded me that the best solution would be to install a 200 litre bi-fuel (oil/electric) ballon alongside the replacement oil-boiler . This would allow cheap overnight edf to source the supply  in low demand and then be switched across to a boiler source if  additional guests arrive .

An extra background consideration is that we hope to move to solar power in the future and if the ballon could be compatible with this type of installation it would be useful to factor that in at this stage .

It may be that I have missed some obvious issue/problem or that someone has faced the same decision and come up with a better solution . So , any comments from members with experience or advice  in this area would be most welcome . I will be re-consulting my chauffagiste(s) shortly and  would like as much information as possible before taking this decision .

 

                                 Many thanks

 

[Poolguy]

It seems to me that you are moving from the darkness (fioul) back into the darkness (oil/electric) only to hope that one day to enter into the light (solar).

For goodness sake whats wrong with going directly into the light with a solar system and save yourself all the running cost after that; It is certainly no more expensive and possibly cheaper to install solar than the system you are contemplating. Its also FREE arter that to operate unlike the system you are contemplating.

Is solar reliable....... well I for one would be willing to bet that the sun will still be there tomorrow and .... perhaps the next day. Unlike oil... which is going up in price so fast that it will be unaffordable tomorrow.

To answer your question about tanks, we prefer to use a Ballon which is specifically designed for solar with the right size of serpentine(s) inside. Its not really sensible to buy one only to have to change it later.

If you want more info on the latest revolution in Solar Evacuated Tube Solar collectors look at:

http://www.poolguy.fr/solarsolaire/index.htm

I hope that this has been some help to your decision making....??

Andrew

 

[Gluestick]

Bi-Fuel tank is the optimal solution.

When you switch to solar then it is totally possible to arrange (e.g.) motorised valves to predicate which heat source heats the water.

Cheap night rate electricity for heating water is far cheaper than oil at its current price!

Heating your water when the central heating is on isn't free. It simply means you are burning more oil.

Why not evaluate a larger ballon with the capacity to provide all the hot water you require?

Or even two ballons?

A lively discussion about solar here:

http://www.completefrance.com/cs/forums/1/1157274/ShowPost.aspx#1157274

 

[Poolguy]

Hi again Gluestick

That was a good thread you raised... not sure that we have entirely finished that discussion. You were pronouncing the virtues of Pellet Burners, with which I concur  - by an large. However the capital investment for that system is very high, much higher than solar, and there is still a cost of operation and you need a pellet supplier within 80klms to be cost effective. Hence I continue to champion the cause of the humble tube on the Roof, especially since clients of ours have been reporting over 90°C from their panels through these mild February days. It make more and more and more sence again to see the sun for what it is - an endless free energy source. Once your plugged in, then there's nothing more to do, nothing more to spend, no maintenance to speak of, just heat...... lots of it, to do what you wnat with.

So notwithstanding the machinations of exemplar plumbing solutions, I have to say that from the point of view of logical analysis therefore, I cannot see the reason why the Systeme Solaire is not 'top of the heap' in the domestic and in fact commercial hot water generation Systems. Or am I missing something.......?

To contemplate a new fossil fuel system in this day an age has to amount to a new form of madness.....surely?

 

Andrew

 

[Gluestick]

Morning, Andrew.

Solar:

I think that from a houseowner's perspective, one of the core objections is probably aesthetic!

When you have people posting threads about cleaning roof tiles...............

I am not being derogatory here. If one has the space, then site the solar collectors on the ground: better, install a servo motor system to provide constant optimisation by aligning the arrays as the sun moves around the heavens!

Insofar as hot water heating is concerned, then solar is rapidly becoming pretty ubiquitous in Southern Spain and the Greek Isles.

Manufacturers need to do much more to de-mystify the technology, I feel.

There has to be a sort of  latitude-related cut-off point in France, after which, as one progresses North, solar-powered heating becomes non-viable.

As it would be for me, in Nord Pas de Calais.

Also, the old commercial reality of Price:Volume is critical: as evacuated solar collectors increase rapidly in volume and as all the ancilliaries do too, then the acquisition price will rapidly fall: making solar a much more accessible option.

Wood Pellet:

Interestingly, I was carrying out some further research this very morning!

Seems the capital cost of a decent fully automatic boiler would be circa £3,500. And potentially quite a bit more.

More interestingly, I note that one supplier (UK) wants circa £333/pallet of 975Kg + £60 delivery: whereas another wants £166/tonne!

As oil has hit a $100++ price on the spot market again yesterday, there is food for thought, here!

I have yet to check the French prices. I have also been informed only recently, that there is a bio-mass wood fuel processor in the next but one village to us in France, so more investigation locally come Easter!

For those lucky individuals permanently living in France there are significant capital advantages to having a professionally installed wood pellet burner.

One area of problem herein, is that using a wood burner for CH means one also needs a pretty good sized heat store to optimise the fuel, as wood (even pellet or chips) doesn't respond as quickly as an oil-fired system and doesn't enjoy anywhere near the same latent heat as oil. You have to run the boiler almost full out then shut off. They don't like "Ticking Over". SO, you super-heat the water and then store: and take off heat as required.

Many people considering installations (like myself) have I'm sure done the sums and realised that the high capital costs involved in a wood burner, don't demonstrate a payback (in terms of reduced costs of fuel) over their expected lifespan, since most of us herein are not young!

Sadly.

I still await some decent running costs from my chum who installed a full geothermal heating system on a barn conversion in Wales (Ground Boreholes): not the warmest place in Britain! (His electricity consumption stats were badly affected by contractors still doing heavy work around the place over last Winter, so it was impossible to calculate actual running costs with any accuracy).

I will chase him up!

More anon.

 

[WJT]

This was one of my questions amongst a few others regarding solar. As I have mentioned a few times here, we are looking at alternatives. I did send Andrew a PM with a few questions, one being the possibility of it being placed on the ground versus the roof but didn't get a response. Gluestick kindly answered this question for me by saying that it is possible.

I agree about the aesthetics, we would not want it on the roof of an old stone house. To be honest, I don't think I would want them on the roof of a modern house either.

When I return to France in two weeks I will try to contact a supplier to see how feasible it is in our situation. Andrew, I assume that because you did not respond to a few of the posts in a previous thread and then a PM, it is not possible with your system. Or perhaps you are waiting to see how the system works in your own personal situation. In any case, I have a feeling solar will not work in our situation for hot water and heating with iron rads but would like to have a definitive answer before deciding to replace our oil fuelled boiler. 

I will let the forum know what I learn in our circumstances if anything. [8-)]

[Gluestick]

I think I mentioned in the other thread, WJT, some friends in Redhill who bought a house with a rather lovely large pool which was heated by a solar array sited beneath the pool at ground level.

Their place was very much undulating, however and the array couldn't not be seen from the house.

The collectors were 1970s and of black butyl rubber: worked OK Spring through Summer.

Mordern evacuated tubes would obviously be far more effective.

Depending on the distance between the collectors and the tank, you might need some pump assistance, as Thermo-Syphon works best when the hot water can rise naturally.

BTW: cast iron rads are very effective at heat exchange, when not badly internally corroded with deposits: and can usually be cleaned, pressure tested and re-finished. No reason not to be able to use these. Makes no difference whatsoever if the heat source is solar, oil, wood, coal, or electricity!

The critical thing is a really good thermal (heat) store.

 

 

[Poolguy]

[quote user="WJT"]

This was one of my questions amongst a few others regarding solar. As I have mentioned a few times here, we are looking at alternatives. I did send Andrew a PM with a few questions, one being the possibility of it being placed on the ground versus the roof but didn't get a response. Gluestick kindly answered this question for me by saying that it is possible.

I agree about the aesthetics, we would not want it on the roof of an old stone house. To be honest, I don't think I would want them on the roof of a modern house either.

When I return to France in two weeks I will try to contact a supplier to see how feasible it is in our situation. Andrew, I assume that because you did not respond to a few of the posts in a previous thread and then a PM, it is not possible with your system. Or perhaps you are waiting to see how the system works in your own personal situation. In any case, I have a feeling solar will not work in our situation for hot water and heating with iron rads but would like to have a definitive answer before deciding to replace our oil fuelled boiler. 

I will let the forum know what I learn in our circumstances if anything. [8-)]

[/quote]

 

WJT

So sorry not to have replied to your questions, I can only beg forgiveness and pleed that I am swamped with over 200 devis to produce and followups, commissioning of work orders and so forth. In the next life (this one will end shortly I think) the Octopus man sounds like a good option.

To answer your question is easy as 1,2,3....

1. You can put the Array on the roof, on the wall, or on the ground..... whereever you want, so long as you are not too far away from the heat storage say max 40m;

2. Orientation is not so critical as the old flat plate collectors as the evacuated tubes are collecting refracted radiation, as well as direct sunlight and converting into heat, so any where from SE to SW will work but S- SSW is the optimum. Also they are tubular, so the surface which is exposed to radiation is the same if the sun is rising, at its height, or on its way down.

3. Latitude wise, anywhere in France is good for Evacuated Tube Solar but clearly the further South you go the more radiation/m2 - Navitron themselves are selling truckloads of panels to Clients all over England, Scotland, and Wales, must be working there too.

From the point of view of the power output and capacity to cope with the heat loads, well we are finding that our initial calculations are under estimates of the power production from the panels in France and so the sizing of systems is going down.... and so happily so is the price for the various funstions.

Aesthetics...... well, I cannot help with that question as its hehoven to the beholder. But to me anything which makes my life easier and cost less than it does now .... looks rather beautiful to me ...  in fact, I'm somewhat smitten.

Andrew

 

[mike.m]

Hello again,

                  Thanks to both poolguy and gluestick for some very useful observations and thread suggestions .

Poolguy . I admire your zeal for the solar option but in our case it is not physically practical ; it may become so if we are able to acquire a piece of neighbouring land where we could site a system but this is not certain and at best a couple of years away ; hence we want to instal a ballon which would be adaptable .

Gluestick . Can i ask a few nitty gritty questions ? Our basic water demand may be up to 6 baths in an evening (we have japanese clients ! ) so would a 200 litre ballon be up to it if they were taking two baths at 30 minute intervals for reheating ?  Would the bi-fuel ballon be sourced from a boiler with a basic central heating function only or one with a built -in ballon for water production . Our situation is fairly unusual in that the business doesnt operate over the Nov- March  months and we therefore only need background central heating during this period since we decamp to a small electrically heated apartment . Thus the need is for a  boiler which would source back-up heating for hot water in the summer and only occasional backgound central heating in the winter . I have read on this forum that state of the art condensing boilers only operate optimally at full power , which would seem to be rare in my situatioin . So I am wondering if its preferable and economic  to instal  a relatively basic boiler alongside a more sophisticated ballon ? Possibly even a recycled boiler - many 3-5 year old models are appearing in the local classified ads  these days .( Also any idea of the cost of  a bi-fuel ballon ? )

 

                                                                        Many thanks 

 

 

[Gluestick]

mike.m:

1.    A 200L Ballon would not supply 6 baths, taking into account other hot water requirements during a normal day.

Of course, all depends on the size of the bath! Japanese people with time tend to soak (I seem to recall), so they may well want to replicate their bath house habit of one bath to wash of the grime and sweat: and another, hotter, in which to soak!

Lots of water needed!

2.    Boiler: a Bi-Fuel Ballon is totally separate from the boiler and is a mains pressure supply system which is self-contained.

All that is needed is a feed and return from the boiler to the ballon as part of the CH system.

Don't buy a second-user boiler! Brico Depot are the cheapest for new kit. The problem with older boilers is spares: and finding a plombiere able and willing to repair and service.

You might be OK with for example a Viesman, as they do tend to provide service support: personally, unless it was only three years old and free, I wouldn't risk it!

For ultimate efficiency, yes a condensing boiler does need to operate full out and avoid the start-stop process, typical of badly designed systems.

The optimum approach would be to install a Thermal Store (heat store) which is a reservoir of super-heated water, exceptionally well insulated and acts as a buffer. Latent heat is extracted from the store to heat rads and the ballon.

However, then the capital cost is much higher. So probably since you only run the business for 6 months of the year, a straightforward boiler would be the best bet.

3.    Cost of Bi-Fuel Ballon: haven't a clue for France at present!

Probably you need to seek out a Chappie, Toute Fait, or similar branch or a specialist plomberie. The last 200L Bi-Fuel I priced was circa €700.

Some info here: http://www.advanceappliances.co.uk/unvented_hot_water_systems.html

I'll see if I can find out!

 

[mike.m]

Hello Gluestick,

                          Thanks very much for the advice and link . Especially useful was the reheating time schedule which gives me a firm handle on the capacity issue . The problem is the bigger the ballon for guest use the more water we have to heat unnecesarily when out of season  (unless we have two ballons ! ) In this case there is no right answer only the best compromise . As to locating a bi-fuel ballon ( not sure about seeking out a chappie !? )but if you come across a source that looks like a good deal I'd be very grateful to hear about it .

 

                                                                            Regards

Ps Will pm you on the subject of Japanese baths ![:)]

[Gluestick]

I look forward with keen anticipation to your PM!

It's been quite a few years since I had my baptism of fire into meeting Japanese businesspeople.

Everyone standing and bowing as guys left the meeting to answer faxes and telexes from Tokyo!

Different!

[:D]