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Oil heating in our absence


Helen
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In the summer we bought our maison secondaire in southern Normandy - 150 yrs old, stone and wooden beams etc.  It has an fioul central heating system (which we have just had fully serviced) with a large 5-year old Chauffage Francais boiler, TRVs but no programmer or general thermostat.

Our question is what the best approach is to heating the house when we leave it for extended periods over winter?  We're not just thinking about frozen pipes but also about damp (we've read that woodworm is more inclined to flourish when the house is cold and damp...).  Obviously we are also interested in efficiency and cost!  We're interested to know what others with fioul heating systems do in this situation.

At the moment we've left it running continuously with the radiator thermostats set to 1.5 - just enough to keep the chill off them and the damp at bay, but not a 'living temperature' - rather than on the frost setting.  Is this a bit over-cautious?

We have thought about getting a programmer installed but wondered if it wouldn't be more efficient to keep the house a constant low temperature rather than to heat it up and then let it cool right back down.  In any event, as it has proven quite a challenge even to get the heating serviced and some repairs done when we were visiting regularly,  I am not optimistic that our remote organisational skills are up to getting them to install a programmer in our absence.   Would a plug-in time-clock suffice? (I know the risks about power cuts but we have a friend who will check on a weekly basis or more frequently in the case of thunderstorms etc.)

Alternatively, given that we are not there to keep an eye on the water pressure in the heating system, (which seems to be an important part of French heating systems and with which we had the initial problems owing to a leak), would we do better to abandon the central heating system when we are not there and get some electric oil heaters to plug in in the main rooms? 

Any advice?

Thanks

Peter & Helen

 

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We have recently bought a house in southern Normandy and are wondering how best to leave it over winter.  We have a fioul central heating system with thermostatic radiator valves but no central programmer.  The boiler is about 5 years old and we've just had it serviced.

We'd welcome advice on any of the following questions:

Is the priority simply to avoid frozen pipes (ie set the radiators to the frost-stat setting) or should we be concerned about damp and therefore leave the radiators on a low setting all the time? (Ours is a stone house, not colombage, but I have read somewhere that woodworm is deterred by warm dry houses.)

Do others in similar position use a time clock to limit the amount of time the heating is on for each day - or do you find it more efficient to keep it on low all the time, to avoid the house chilling right down and then having to be heated up again?

Are there risks in leaving an oil system running in our absence - would we be better advised to use oil-filled electric heaters in key rooms?

All advice or views on such matters welcome!

Thanks

Helen & Peter

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We've got oil central heating, but a boiler with an externally-placed sensor that will make the CH kick in only when the outside temp drops below a predetermined level. The first year we had the house, we left the heating on using this method, and because it was a cold winter, ended up spending more on heating our empty house in France than we did on heating our house in the UK!!!! Over the past couple of years, we've either left the heating off altogether, or had it come on only when the outside temp dropped very low (about 5-6 degrees) and the only problem we've had is last winter when the weather was exceptionally wet, and we got some mildew developing here and there on the internal woodwork, and in Spring the house did smell quite musty. We're further south than you, so in theory winter's a bit warmer, but have exposed stone walls and beams. We also have neighbours who pop into the house regularly and would warn us if there were any real problems. I'd say the greatest risk of leaving the CH running is the cost, and having no idea how much oil may be used while you're not there.....you wouldn't want the tank to empty while you weren't around! Have you got anyonekeeping an eye on the house for you, who could go in and check things like this?
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Helen ...What does your insurance company  require you to do when your property is not used over winter ? .....mine requires me when I shut  up the place and drain down  the water after closing it off at the main stop tap at the meter  . I know a lot of people leave power and water on and run de humidifiers  to prevent damp . ....I tend to comply with what I am required to do by my insurers in case they refuse to pay out if  I ever had to make a claim  If  anything happened while I was in the UK having left the power and water on I suspect they would rub their hands in glee ! 
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Thanks for your reply - it's good to hear of other's experiences.  Yes, we do have someone who is going to check everything once a week and who is also going to keep an eye on the oil level for us.  I don't like the sound of the heating bills that you experienced - so maybe we are being over-cautious!

Helen

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hi ok

     you can find loads of back postings on this subject ,the mouldy smell comes free with a maison secondaire ,so  unless you are Bill Gates. get the heating system filled up with antifreeze (this should have been checked/done with your service) and then turn off everything ...water leccy etc , open hot and cold taps and  flush the loo`s ,welcome to france

    Dave

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A bog standard digital plug in timer is fine in the absence of anything else. Make sure it has memory back-up to overcome the electricity problems.

Friend or no friend, if the power is down your system won't work anyway!

That said, it would be unwise to run an oil fired system of dubious standard unattended (from what you said), without someone checking on it regularly.

It could easily flame-out due to a dirty jet. Etc.

Electricity for heating is a better bet; provided your wiring is up to date and safe. If you opt for Heures Creuse/Heures Pleine and wire the heaters through a pulse switch it will only come on on the cheapest rate between 12.00 midnight and 08.00AM.

Best to leave some heating rather than leave the property cold.

 

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Thanks for the comments and advice.  Our insurance document gives us the option of either keeping the house heated throughout, or shutting off the water and draining fixed water tanks, apparatus and pipes.  It's not clear whether having the heating on a froststat so it only comes on when the outside temperature is near-freezing is acceptable, nor whether leaving the heating system with water in it (even with anti-freeze) would do either.  I'll get in touch with them to clarify but as we certainly aren't Bill Gates I think it's going to have to be one or the other!

Helen

 

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One thing to watch if you run de-humidifiers is how they are controlled and what happens to the water collected.

I have been told that running a reasonably powerful de-humidifier continuously can do quite a lot of damage to a building moderately quickly (as it can really draw the water out and dry out the walls/wood far too much ->cracks, etc.).  Whenever I have run a dehumidifier in an enclosed space (building or boat) I either make sure the de-humidifier has a humidity sensor on it (thus wont "over dry everything") or put it on a timeswitch so it only runs for a couple of hours per day.

Some de-humidifiers have a built-in water collection tank.  These will probably fill quite quickly and the de-humidifier will automatically switch itself off.  Thus, leave it running and a week later it switches itself off permanently because its tank is full.  Get one where you can attach a pipe to the water outlet and put the pipe down e.g. the sink (making sure the water drips straight down the plug).

Just my thoughts and I'm no expert.

Ian
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Thanks for the replies - we're going to check with the insurance company about their requirements to see if night-time heating will suffice (not entirely clear from the policy document, despite being in English).  We need the timer / programmer anyway for when we're in the house so will get on with that. 

Helen

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Ian

Re. de-humidifiers: I was thinking of the chemical ones, we have used these for the last 6 years and so far have not had a problem.

 

We don't have CH but do leave Acova heaters and heated towel rails on "Frost" setting so that they will kick in when temps. are very low.

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Can you explain a bit more about chemical dehumidifiers?  Is it like silica gel? What's it called and where do you get it/them from?

Helen

Yes I think that is what the stuff is. They are plastic boxes ( a bit larger than a shoe box) and you can buy re-fills for them.

Usually available in Brico shops/ some supermarkets and Cancailleries etc. look for

De-humidificateurs ......................I think.

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The chemical de-humidifiers will not extract much moisture from the air.  Just look at the size of the containers (and they can max fill the containers).  If you are away from the house for any time and have a humidity "issue" the chemical ones would be pretty ineffective.

Ian
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If it is any help re moisture when a house is left over winter.....What we do is buy a big ......very big ....bag of dishwasher salt......use  buckets ...bowls ...old 10 ltr paint tubs ...anything that will hold water......... Use some old tights...or fine mesh net curtains etc   and streatch it over the container  and string tie it round to give you a "drum skin " tightness ......Pile onto the mesh lots of salt .. a good heap...  double handfuls ...... You then place the containers near where you want to ensure dryness... wardrobs....beds .  kitchen  units   etc .... Over  winter the salt will suck the moisture  out of the air through it ....so much so you may after the winter find you have water in the bottom of your buckets ......It keeps working right through the winter......10 times bigger than the window ledge things from the Super U or Brico's  which  I think its the same principal .....the salt will get very damp indeed .....it works !
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hi

I would not leave CH on over winter.  I'm told from my french neighbours how expensive oil is.  We have dealt with a similar situation for 6 years of leaving a house over the winter, except we have no CH.  I insist on switching off the water, I would not be comfortable with it left on.  The idea with salt or non electric dehumidifyers is good.  Alternatively if you want to heat you home, you could think of  putting in an electric storage heater, running off cheaper overnight electricity, leave all doors open so the heat can spread.   You could try and do a cost comparison by working out the cost of the consumption of electricity.  Any small rodents you have will appreciate a warm winter house.

Doors should be left open and some sort of draft created if you don't try one of the solutions to heat your house. 

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[quote user="Deimos"]The chemical de-humidifiers will not extract much moisture from the air.  Just look at the size of the containers (and they can max fill the containers).  If you are away from the house for any time and have a humidity "issue" the chemical ones would be pretty ineffective.

Ian
[/quote]

 

Tried and tested over 6 years or so and they work for our place.[8-|]

 

[I] A couple of years ago we had VMCs installed (which are left on all year) in the two shower rooms and these are brilliant and have made a huge difference.

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In the end we have decided to get antifreeze added, turn off the oil heating, drain the rest of the water pipes and get a few electric oil-filled radiators set on time clocks / frost-stat setting.  And to follow up on the ideas for reducing damp.

And go and visit as often as possible!!

Thanks to all for your advice.

Helen

 

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