Docthebiker

This chateau has a oil burner the size of a small car and we plain can't afford to heat the whole house or run it for the small part we inhabit. We have acres of free wood hence the wood burner.

I'm putting in a big old wood burning arga (sp?) with a back boiler to run 4 or 5 radiators on the existing but redundant oil burner system.
I'm a good plumber so connecting it is no problem but I'm wondering about the set up.
I don't have a header tank so I'd prefer to take water from the main on demand.

As the radiators are 15 feet above the boiler I'm thinking it won't need to be a pumped system since convection should work (?). I would put a pump in for better efficiency but the danger then is if the power cuts (in typically french fashion) then the burning wood in the stove keeps heating the water trapped in the boiler and BANG!.

Can anyone advise?

If anyone know a plumber (who knows what they are doing) in the Jura area willing to work with what I have for a few hundred euros, rather then try and sell me all the new kit they think I should have for thousands of euros (which I don't have).
I'm not looking for perfect or a long term set up. I just want to take the chill off of a few bedrooms without the usual huge electricity bills.

jdr

Where did the old system get the water from ?
You will def need a header tank to replenish the lost water in the system.
You will def need a pump unless you have an old fashioned 1950`s type one pipe system with auto airvents at the highest points to clear trapped air.

Ka Ora!

You can run the wood system in a closed loop that will still be filled off the mains and you will need an expansion chamber. Most builders merchants have a plumbing section to get the bits, Le Plumber may help when he sees the thread.

You can get a flush valve to connect to the aga so should it get too hot cold is let in and hot released down a drain, I believe that is a must in France. Personally I would not count on convection to move the hot around, use a pump and add a 200 or 300 ltr tank that sits between the boiler (aga) and rads this way you build up a heat reserve and maintain a more constant rad temp. Zaegel Held sell the pre rad tanks. It acks like a two loop system one pump moves hot between the boiler and tank then another moves hot between the tank and rads, They do a twin closed loop tank that allows for hot tap water to be heated as well and another that can be combined with solar panels. Better to think about these things in advance.

they look like this and work a treat.




Before I forget, If the wood has not been sitting and cut for at least a year then dont burn it, Basically you cant cut wood for this winter now. Any wood cut now may be burnt next winter depending on the next summer and the type of wood it is. Some woods need 2 years plus before they can be burnt and you have to pay attention to these things when buying it, otherwise you end up with lots of co2 wood that does not burn well and other disasters.

le plumber

Hi Doc,

The best thing to do would be to link it up to a ballon tampon (sorry I don't know the english for this at the time of writing) but its a but like the system Ka ora explained, but it would have to be bigger than 2 or 300litres because it will heat up too quickly. Most ballon tampons are a minimum of 500litres going up to 1000litres. The bigger the better and although 100litres sounds a lot its not that much in reality. The ballon tampon accumulates all the energy and stoes it until needed. I know you're not looking for a perfect set up, but if you don't use a ballon tampon, you wont be able to use TRVs and your radiators are going to be far too hot and at the end of the day its just wasted energy. You're either going to be too hot or not warm enough.

I certainly wouldn't advise the radiators to be fed via convection - it just wouldn't be reliable, unless the installation is properly done. It just isn't worth the bother.
You would need at least an open expansion vessel in your roof, (or a closed expansion vessel but it would have to be a big one!), and a pressure relief valve (3bars) as well as other stuff.
When you say that you can plumb, I hope you mean with copper pipes, because (for obvious reasons) plastic PEX pipes just wont be compatable!!

Ka Ora!

Our ballon is 500 ltrs and the boiler holds about 500 as well, It most certainly works even if the stove goes out it holds heat in the rads for 8 or so hrs. As its a closed loop system on the occasions when power vanishes when the stove hits about 95c the flush systems kicks in purging the hot with cold.

I would like to find an air trap to put in to loop as having the wood system seems to produce more vapour/air in the system. I fitted a air release valve to the top of the ballon which keeps the stove and ballon free of air but because the ballon and stove are in the basement the loop and rads sit above and thats were any remaining air or vapour ends up. So I would like to find some form of air trap to sit above the rads?

le plumber

In theory, this shouldn't happen. If its a sealed system then you may have a leak somewhere whereby air is getting in. Are you regularly topping the system up with water?? Otherwise, if there is no apparent leak then its probably the expansion vessel. If the system is new and this is happening then its more than likely that the expansion vessel is too small.

Scots in Treignac

Any more tips, hints or instructons about buying and storing wood.

On delivery is it better to store inside or outside

If both - are ther minimum times for each.

Ka Ora!

Better to stack and let it sit outside whilst in the drying phase, Then in the summer you hit time to burn it stack it undercover because theres nothing worse than trying to burn wood with a foot of snow on it

Buying it well find out were everyone else is buying it, I have found would sellers do like to take the pee a bit when it comes to selling to brits. Green not enough that sort of thing everywere has reputable suppliers and ones to avoid. Any wood i cut down for myself sits for three years just for peace of mind, If you burn green wood most of the heat from burning goes in to removing the moisture from the wood so it proves pointless on top of how quickely the fire will get clogged up with soot as well which becomes a danger to your health.

Wet and green wood will hiss a lot when being burnt.

Ka Ora!

Considering the quantity of water the vessel could be a little small, But I could not find any bigger ones

Docthebiker

It's all great advice but my problem comes with the size of the system I want to tap into.
It's a 3 floor oil fired biggy (this place used to house 200 kids) and what I want to do is heat just a section of consecutive 4 rads on the floor above that follow on from the 2 pipes where there used to be a rad but I now have the aga.
I can't practically get it into the hot water system as the tank is below in the boiler house.

I was hoping there might be a way to use just a part of the existing system without complexity or large expense.
I can give it a water feed, and as it abuts an external wall I can add a pressure relief valve to the outside if the pump cuts and the water gets too hot.
Also if it was boiling up with just 4 rads I thought I could bring more online to use as a heat sink.

le plumber

On it (the expansion vessel that is) there should be a label which gives you some info. It should say its total capacity in litres - give me this info & I'll tell you straight away if its suitable for wood burning CH or not. If you give me N° rads you have and the height of the highest radiateur I'll tell you what size you should have and at what the nitrogen pressure inside it should be. The nitrogen pressure in the vessel is usually 1 bar when it leaves the factory, but on installation the system has to be calculated and this pressure should be reduced or topped up with nitrogen. Its more than likely that you don't have any nitrogen lying around the house but you can use a simple bike pump. I don't use this method as the nitrogen is a dry gas and the air contains humidity and isn't considered good practice, but in your case just to tide you over it will be fine.

le plumber

Hi Doc

Its possible to heat just the radiators you want on the existing system if you put on a few stop valves. However this shouldn't in anyway affect the circulation of the radiators that you want to heat. If you want it to be simple then some times the simplest of way to do things would be to re pipe the rads you want to use and in that way you would have two circuits - one for the rooms you use the most, and the other for the rest of the house. Probably not the reply you're looking for, but without seeing the actual set up its hard to advise on whats best.

To get it into the hot water system thats below, you'd have to install a pump.

A heat sink - or as I call it a heat leak- is a possibility and in your case I would advise to over size the radiator or even use two radiators for this to be effective.

By the way are the pipes in copper or steel?

Docthebiker

Definitely steel (worst luck as my experience is in copper).
I'm guessing because of the 3 foot thick walls here the system circuits round rads on the (more open) 2nd floor with drop pipes to rads that branch off the vertical pipes on the 1st floor which continue to the ground floor rads before circulating back up.

I think I can work it out to pump the water round where I need it, but I do worry that when the power goes off (as it does) and the water gets trapped in the boiler.

You'd be welcome to come see for yourself if the beer doesn't cost too much

le plumber

If your not equiped to weld the steel pipes just use a threader and then use copper. I wouldn't bother buying a threader though. I say that because I saw one today in the LIDL leaflet that comes through the letter box for 29.99€ You can hire a professional one for that and at least you wont have any problems!!

I wouldn't worry about a power cut and the water getting trapped in the boiler etc. Next to the boiler you'll have to install a pressure release valve and when it reaches 3 bar this will open and let out the surplus water to bring the pressure down again. If you're really worried about it you could do a by pass with a few stop valves that you could open in case there was a power cut but I really don't think this is necessary at all.

I could some over if you want. You're not too far from where I am - but it wouldn't be before the end of next week though...It'll have to be a big bottle of beer though!!

Docthebiker

I thought that may be the case as I've run agas with un-plumbed back boilers before without hurting them. I figuered that if we lost power and it boiled up then venting the water/steam out would be the same as running it un-plumbed.
I daresay I'd have to top up and bleed the sytem after, but that's hardly a huge job.

I'll drop you a mail about that beer