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FAQ - Oil Heating, Hot water production and plumbing “funnies” in France


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I am a bit concerned about the 1% expansion of plastic pipe when carrying hot water.  We have some very long central heating pipe runs which will be through the floor screed.  Suggestions please on how this can be done. What happens with the expansion of underfloor heating pipes?

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Long straight runs must be avoided - for the reasons and illustration given. It is far worse with 22mm PEX/PER - the 15mm and 10mm pipe is less prone. There are various means of controlling the length growth, usually be allowing bends and/or adding expansion loops. Or use copper.

Underfloor pipe is small bore and run at only 38 degrees or so. So the problem is largely insignificant. As long as the guidance provided by the suppliers is adhered to, there should be no problems.

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  • 4 weeks later...

Hi Kevin, I read your information on oil heating and found it makes excellent reading. I have recently bought a house in dept 30. It has a new oil heating system, using a Lamborghini boiler. I have fitted a wireless room stat, a frost stat as non of these were fitted with the system.

After reading your information I am concerned that the burner is not operating correctly. The boiler fires up and then after a while it swtiches off for a few minutes and then fires back on again. I am not sure if this is because the internal boiler water  temperature has reached its correct temperature or ??????. Is this normal or should the boiler run continuously. I am fairly competent with most mechanical things bu have never experienced an oil boiler. If there is a problem, is it one I can rectify/adjust. You also mention injectors, is this the brass nozzle that vapourises the oil.

You have probably guessed that I am keen to learn the workings of an oil boiler

Would be grateful for any advice

Kind regards

 

Chris

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The boiler will run for a period until the water temperature reaches the temperature set on the Aquastat on the control panel. The normal temperature setting would be 60-65C on this. The Aquastat has a hysterisis of about 6-8 C, so once the water temperature drops by this amount, the burner will restart. This is repeated until the power is cut by either a programmer and/or the room stat or frost stat. The problem with short-cycling (where the burner cuts in and out very frequently) is due to the burner being set to provide too much power. By default, burners are set to maximum from the factory. This means you probably have a 32 kW boiler for a 20 Kw demand. To rectify this involves changing the injector (the brass nozzle) for a smaller one in accord with the table in the burner manual. You probably only need about 20-22kw (I'm guessing) so you are looking for an injector of 0.50 gph maximum, with a fuel pressure of 12 bar. You could also try an injector of 0.40 gph set to 14 bar.

It is possible to reduce the fuel pressure you currently have, but below about 10-11 bar, the injector will chatter and the flame will be instable - injectors have a shut-off function to avoid drips from residual pressure.

To effect the pressure adjustment will require the use of a pressure gauge (which is screwed into the bleed screw temporarily). I suspect that you could change the injector yourself and ask a local chauffagiste to set the pressure pour boire. The air settings will also require adjustment once the injector and pressure are done. The resultant power reduction will enhance both the economy of the system and improve the longevity of the burner. And it will run somewhat quieter...

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Hi again, hope you dont mind me asking another question. I have manged to download a pdf file with the instructions for the Lamborghini boiler. It appears the boiler has an output of around 34kw, it is a combi bolier but we only use it to heat the radiators. the water is provided by electric on heures creuse.

If I purchased new injector for 0.50gph (does this stand for gallons per hour?), is it possible for me to self fit. I am confident of being able to physically fit the part into the burner unit, but if it then needs to be adjusted it will be beyond my expertise.

I am off to france on Boxing day and now you have kindly given me information I would like to use that in making the boiler more efficient

 

Thanks again

 

Chris

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Yes, they are fairly simple to fit. It's just screwed in - you need to be careful with the electrode wires and settings and the secondary air setting. These are detailed in the burner manual.

Before you do change the injector, find someone to set the pressure afterwards, and adjust the air for you.

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Chris, where did you get the PDF manual for the Lamborghini boiler from please?! I'm currently staying with relatives in France who have a Lambo (Fire 1 C/FR) which after a few hours of disuse, refuses to fire up - it's showing a red light at the top left which is clearly a 'fan failure' light - we don't have a manual, and I've figured we can restart the boiler by taking the bottom front cover off and pressing what appears to be a priming pump/switch. However, this is ponly a temporary fix. My assumption is that this is possibly associated with fuel temp - the outsoide temp being around -3 at the moment.   Any thoughts, or a hint as to where I could find a manul, would be gratefully received!!!

[quote user="chrisbooth"]

Hi again, hope you dont mind me asking another question. I have manged to download a pdf file with the instructions for the Lamborghini boiler. It appears the boiler has an output of around 34kw, it is a combi bolier but we only use it to heat the radiators. the water is provided by electric on heures creuse.

If I purchased new injector for 0.50gph (does this stand for gallons per hour?), is it possible for me to self fit. I am confident of being able to physically fit the part into the burner unit, but if it then needs to be adjusted it will be beyond my expertise.

I am off to france on Boxing day and now you have kindly given me information I would like to use that in making the boiler more efficient

 

Thanks again

 

Chris

[/quote]
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The red button is the burner lockout - the burner has failed to ignite the fuel. I suspect there is a fuel supply issue, probably a partially blocked filter. The viscosity of the oil will exagerate this problem. Or the electrodes are dirty or poorly set. I can give you the settings for these if you wish. It is not difficult to remove the burner and clean the electrodes and the gun assembly - I would clean the swirl plate too.

It is also possible that the oil pressure has been set marginally. I would suggest a chauffagiste measures both the pump aspiration and the delivery pressure to ascertain the problem. When the boiler does run, does it cough/hunt?

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Hi - thanks for the fast response!   Boiler fired up OK this morning, but it's not so cold this morning. When it runs, it runs cleanly, but does have a tendency to shut off / restart fairly regularly - but I assume this is normal

The installation is reasonably new - less than 18 months - and this is the first seriously cold weather it has encountered. Boilerhouse and tank are in an uninsulated outhouse, and I suspect fuel temperature is the issues - though I've never worked with oil-fired systems before. We're attempting to lag all feed pipes as best we can, and I'm wondering whether a standard UK 2 burner (wick) greenhouse heater would be helpful. Had a quick look (around Cahors) yesterday but couldn't find one/ (I have a standard Parasene one at home which runs 8 days on 5 litres of fuel).

Access to a PDF manual would be very useful here - since the owners don't have this in their posession. Settings would be appreciated.

Thanks very much for the help!!! The faster I get these people on broadband the better!!

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I would not recomend you put any type of oil heater in your outhouse with a oil tank.I do not think your problem is temperature of the oil.to the burner.If it really is i recomend you go to a heating suppliers and buy a Electrical Self Regulating Heating Trace Line, you tape or lay it the full lengh of the oil line.Or any other outside pipes that need extra frost protection .Happy New year.{hopefully not in orbit.}
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  • 4 weeks later...

I think our plumbing evolved rather than being designed. Our supply goes first of all goes through a pressure reducer from what to what I dont know. All the pipework is in 12mm.

When the sink tap is opened the shower stops. Clearly the solution could be wind up the pressure, but I'm not sure by how much.

What do you recon the maximum pressure should be. Also, is it usual to have such a narrow bore for all the pipework? my memory of chemical engineering has long since gone.

Cheers

Cookie

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Hi Cookie

The problem probably stems from the narrow gauge pipe rather than the pressure; it just can't deliver the quantity of water that's being demanded if it is 12mm throughout and the taps are stemming from a common feed, regardless of pressure.

Phil

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  • 4 weeks later...
  • 1 month later...
Just wanted to say thank you for the excellent rundown on the French plumbing world!  You've confirmed for us everything we've found so far.  Have to say your observations on commissioning of oil boilers by French plumbers is borne out by friends' experience.  I'm also told by the other half of 'we' that whoever did the plumbing in the pix is a 'good plumber' - huge praise from a UK building contractor!!  At least French plumbing seems to be getting there, but it's still got a long way to go.[:)]
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  • 4 weeks later...

Thanks for a very interesting article.

I have a question concerning radiator connection. Can you please tell me why the French use top flow, bottom outlet on radiators? I have some old cast iron radiators and recently purchased some very good looking chrome radiator valves from the UK expecting the plumber to fit them bottom/bottom. He was clearly bemused by these valves and tried to fit them on the top inlet at a particularly impressive 45degree to vertical angle. End result - it looked awful and so we reverted back to 'French' plastic valves. I am just about to start on a gym project and want to have another go with the same chrome valves. Do you think I would have much chance convincing a French plumber that bottom/bottom fitting is OK?

thanks for your help.

Nick

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  • 3 months later...

A lot of good stuff here - thanks for the time and effort!

I have a property which has a defunct oil central heating system. By this I mean there is an oil tank buried under the drive, the central heating boiler unit is disconnected (and rusted up) in the cellar and all the radiators have been disconnected and removed.

I have no intention of renovating this system as I will be using mainly wood open fires, wood burners and maybe some storage heaters for bedrooms.

My question concerns the oil tank under the drive. I believe the tank to be nearly full as it was filled up shortly before some previous occupants died. This was about 30 years ago. The last occupants just 'pretended it wasnt there' and up until now I have been doing the same but that is mainly because I havent spent much time at the property. Now that I will be on site more the priority has been upped!

In short is it dangerous to leave the fuel there buried underground? I obviously need to find out the size of the tank as I have never seen it - the plans are being searched for! Talking to a neighbour he said he thought it would cost a lot to pump out and fill with sand - soemwhere in the region of 1000e but I am not sure on what this was based!

Any ideas and opinions would be appreciated.

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