Could anyone please give me advice on connecting a new woodburning stove to an existing oil fired pressurised system, i have been told it can be done by using a heat leak radiator.... what is this where does it go and how does it work? I am in the building trade , and although i can solder a joint and"blunder through...i am totally lost on this ...so why change from oil because i have spent £1100 on oil since just before xmas!! Any help greatly appreciated.
trigger

thanks nicky but i already had emailed dunsley the other day with this question and they simpley said "it cant be done". Any info on the heat leak radiatorand how it works?

You could fit a twin coil cylinder and have one coil heated by woodburner and vented and one by the oil boiler as part of the sealed system.
I have just fitted a twin coil for someone but with solar and oil.
Standard cylinder coils are only tested to 3 bar but your PRV on the oil boiler will protect it.
Lots of these system boilers are now installed to give pressurised heating systems (with no tanks involved) and cylinder fed domestic water with a header tank.

Hi Trigger.
You do need some help. I've only been in the Plumbing & Heating industry for 42 years, I was taught to wipe joints on lead pipe with pot and laddle and soil fuel was king. Its like riding a bike, you never forget and what you are trying to do is achievable. But before I can give you the answers you need I need some more information about just what you want to do.

1: What is the output of the wood burner?

2: Do you want to suppliment the whole central heating system and only let the oil boiler fire when you are out and cannot keep a fire in the wood burner, or the oil boiler to top up the wood burner in extreeme conditions?

3: Do you want the wood burner just to heat the cylinder to give you hot water?

4: When you say you have a pressurised system I take it you meant the heating system is a sealed system, no feed and expansion tank

5: Is the cylinder mains unvented as well or does it have a supply tank and just the heating side pressurised.

Once you give me the answers to the above I can tell you how to legally intergate the two heat sources.

As Dantenz rightly says a wood burner is can become an uncontrolable appliance and special measures need to be inplace, but again it can be done.

Regards Cliff ( The midnight plumber)

One suggestion would be to keep the combi boiler doing the HW so that the wood burner isn't supplimenting this. Could then connect both the boiler and wodburner into a thermal store (open vented mind you) which can be heated by either. A pipe stat on the woodburner brings on a circulating pump (P1) to heat the store, a cylinder stat on the store then brings on another pump (P2) so when upto temperature distributes the heat into the heating system. Same would happen with the boiler, when switched on it's own built in pump (P3) will circulate arond the thermal store, tank reaches temperature (P2) then circulates to heating system. Sytem will also work fine with both appliances on together.

Hi Trigger,
In responce to your information my comments are as follows:-

Heat leak radiator. Solid fuel appliances should be installed with a minimum dia of 28mm Flow & Return gravity circuit to an indirect cylinder, if their is little or no demand for hot water the cylinder can overheat and start to boil, to prevent this from happening a towel rail or radiator connected across the flow and returns acts a heat leak. Its very crude but works, the heat leak can be manually closed to improve recovery on cylinder in times of high hot water demand.

Solid fuel appliances should never be connected to fully pumped systems or with zone valves unless they are the type that fail open.

How to sort out your little project? it can be done but you have keep the sealed system that is part of the heat slave separate from the open vented system that you have to form for the wood burner. You have to use a thermal store to link both heating appliances but keeping the water thats inside them separate. You could buy an off the shelf thermal store but they are expensive, you can make your own with a pre-insulated indirect cylinder suitable to work with 10 metre head and with a high recovery coil.

The cylinder/thermal store needs to be at least 1m above the wood burner, ideally at first floor level above the appliance, Flow and Return pipework from the wood burner need to be 28mm gravity, and no more than 10M away.

The possibilities are endless, I can and do have bespoke cylinders manufactured with 3 or 4 coils in to link in solar pre-heat and hot water. You could leave the oil boiler feeding part of your hot water system say shower and kitchen sink, but have a bath/ baths feed from the store, that way you reduce your dependancy on oil. The store needs to be fitted with a thermostat that will bring on the oil boiler to top it up as and when needed.

If you send me an email to warmwater@blueyonder.co.uk I will forward you a schematic drawing for the installation.

regards Cliff. The midnight Plumber.

Just one point Cliff - Energy efficiency under part L of building regs. calls for heating and hot water systems to be fully pumped these days. Does this not apply to solid fuel appliances?