wood burner and unvented cylinder

[abh]

Could anyone tell me, please, what extra controls would be needed to install a wood burning stove with flow and return to an unvented cylinder.
I realise that the normal situation is for a gravity system, but I wondered whether it was possible, and had anyone done it? How would you 'turn off' the wood burner and 'dump' the heat so the cylinder didn't receive too much heat.

The customer wants hot water supplied by an existing wood burner, and a solar panel.

thanks in advance

 

[gas4you]

As far as I'm aware you are not allowed to fit a wood burner or solid fuel appliance to an un-vented cylinder.

Anyway, unvented's are for fully pumped use only.

 

[Biggles..]

Yep you can, use a baker system link up but this normally incorporates a boiler as well as the 2nd heat source.
Im sure they do one for exactly what your describing, multifuel and solar but would have to check on the website.

 

[abh]

Thanks for that, lcgs.

From the website, I assume you are talking about their neutraliser, and it does indeed show a link up for an unvented system.

As for the secondary heat source, I can't see a reason why it can't be incorporated with solar, as long as there is a mechanism for ensuring that the cylinder water temp reaches 60 degrees, periodically. Or have I missed something?

 

[Biggles..]

i am indeed, speak with them they'll send you the specifics.

 

[Balenza]

abh wrote

and it does indeed show a link up for an unvented system

Can you give a link for that ?.

 

[Biggles..]

Its not as simle as that however because the wood burner and the gas/oil will be feed from the same feed tank and joined at the neutraliser. in theory you could run the solar and woodburner off glycol but as solar systems are presurised you may encounter difficulties.

Speak with them they do varying solutions, our recent one was multifuel and small electrice in to the neutraliser then solar seperate both feeding a twin coil cylinder.

Dunsley neutraliser through Bilbeck.

 

[Balenza]

Icgs wrote

Yep you can

What about this statement ?


It is a requirement of building regulations that any such heat source connected to an Unvented cylinder (such as Tribune) be under full thermostatic control and are able to turn themselves COMPLETELY off

As a result you cannot connect an Aga or a solid fuel stove to a Tribune.

 

[Biggles..]

Through the controls and the fact that the neutraliser ensures no flow to the cylinder from the multifuel when their is no demand, works much the same as a low loss header.

 

[abh]

That's what my initial concern was, Balenza. However, on their website

www.dunsleyheat.co.uk

they definitely show a neutraliser linked with an unvented cylinder. Whether that means it's OK to use that with a wood burner, I guess I'll find out when I talk to them.
Is it not enough that the 2-port valve closes and the heat from the stove is 'dumped' through a heating circuit - a radiator that can't be closed?

 

[Biggles..]

In addition to the pipestat, heat leak and anti boil stat we have fitted a temp and pressure relief valve to the circs of the multifuel.

Our install diagrams were supplied by a heating specifier and we're just the installers.

 

[Biggles..]

How do you turn solar completely off, if not purely by controls,pumps and valves or does that mean they cant be fitted to twin coil unventeds also?

 

[simond]

Your client will have a very dirty stove if he uses it with a water jacket.

You can fit pumps and thermostats but the effect is still marked. Tar deposits everywhere.

 

[Biggles..]

In addition to the pipestat, heat leak and anti boil stat we have fitted a temp and pressure relief valve to the circs of the multifuel.

Our install diagrams were supplied by a heating specifier and we're just the installers.

It appears our specifier/designer may have made an error and intended the cylinder to be a thermal store/heatbank. He's looking into his drawings for us.

 

[Onetap]

What about this statement ?


It is a requirement of building regulations that any such heat source connected to an Unvented cylinder (such as Tribune) be under full thermostatic control and are able to turn themselves COMPLETELY off

As a result you cannot connect an Aga or a solid fuel stove to a Tribune.

You can, you just need a bit of competence.

Solid fuel stove installation as normal, with open vent, heat dump radiator(s), gravity circulation to vented HWS storage cylinder, if one is fitted.

On the flow, you have a largish diameter pipe, a low-loss header, which has two closely spaced tees. From this there is a pumped secondary flow and return to/from the unvented cylinder.

The secondary pump can be turned off by the unvented cylinder's thermostat, in compliance with the building regulations. Because the tees are closely-spaced, when the secondary pump is off, there is a negligible pressure difference across them, whether the wood burner is on or off, and so there is no circulation to the unvented cylinder. That's what the low-loss header does, negligible pressure loss along it.

The Dunsley neutralizer is just a high-priced, low-loss header. A thermal store would achieve the same effect. Either one could replace the "large diameter pipe/low loss header" mentioned above without altering the system's principle of operation, i.e., no flow to the unvented cylinder, unless its secondary pump is on and its 2-port zone valve is open.

You can't use the unvented cylinder as a heat dump though, it gets switched off (by the thermostat closing the two-port NC zone valve, which you must use) when the thermostat setpoint is reached.