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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Dual Central Heating System https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1382368513 Message started by DonR on Oct 21^st, 2013, 4:15pm

Title: Dual Central Heating System
Post by DonR on Oct 21^st, 2013, 4:15pm

We already have a Combi Boiler which is only 12 months old and heats the rads and water perfectly. We have a large basement room into which I am planning to put a woodburner. The wooburner I have in mind can have a back boiler as part of the spec.
My question is: can the central heating system be set up so that when I want to run it off the gas I can but if I want to run it off the woodburner is there a way of shutting down the gas boiler and switching the CH system over to hot water supplied by the woodburner's back boiler?
Hope that makes sense - just to be clear, can I heat the rads and hot water in my house via two different boilers by switching from one boiler to the other when it suits me i.e switch the gas boiler off and the woodburner boiler on or vice versa.
Thanks fellas, hope someone can tell me it can be done.
Don.

Title: Re: Dual Central Heating System
Post by thescruff on Oct 21^st, 2013, 5:42pm

it can be done with something like the dunsley neutraliser

http://www.dunsleyheat.co.uk/neutralizer.html

You do need to get an expert in though

Title: Re: Dual Central Heating System
Post by CWatters on Oct 21^st, 2013, 9:33pm

What thescruff said. Essential you use an expert.

Wood burners are essentially uncontrolled devices. If the water in the back boiler starts to get too hot there is no automatic thermostat that will turn down the flames! This means all such installations have to be designed to fail safe, including in the event of a power cut. I believe this usually means at least some part of the system has to be gravity driven and there needs to be a dump rad to get rid of excess heat (eg if the stat or a power cut turns off any pumped part of the system). I may well be wrong on the detail as I'm not an expert!

Title: Re: Dual Central Heating System
Post by woodsmith on Oct 22^nd, 2013, 7:33am

I would check to see if this is really practical before spending a lot of money fitting this system. My concern is that wood burners are generally designed to produce hot water and maybe heat a radiator in a bathroom. You would need a very big wood burner to provide enough heat for full central heating. Then, unless the room is massive, it would produce too much heat in the room and make it unbearable.

We have a medium sized wood burner ( no back boiler) in a big room with vaulted ceilings and if we run it for long it soon gets the room too hot to be comfortable.

Title: Re: Dual Central Heating System
Post by londonman on Jan 29^th, 2014, 1:48pm

Isn't there also a possible issue as to how good the woodburner would be working in what is a mains pressured system? Dunno...just guessing.