Wood-burner wet system

[Boz]

Hi, I am in the process of fitting a mini top boiler to my wood-stove. I will have a 28 mm full-bore circuit to the heat-sink radiator so the heat can be dispersed by the means of gravity. The second rad will be fed by 15 mm pipework. I will use a Honeywell zone valve (usually open) and a pump on the return side of the system, leaving the flow pipe uninterrupted to the vent. I will also use a Honeywell pipe stat to energize the pump and valve at 50 C. I am led to believe this is a safe system in the event of a electrical failure.

My concern about this system is: what happens if the pump failed to operate when energized and the zone valve is closed off ?
Is the system connected in such a way that this cannot happen ?

Boz

 

[AWheating]

on a standard solid fuel system the zone valve operates on your primary gravity side to the hot water cylinder to control the hot water temp and when this shuts the heat can circulate around your heat leak radiator/s. If the hot water gets too hot the temp relief valve fitted to the cylinder will open and discharge to a safe location.

post your full system design in the solid fuel section, sounds like it needs a rethink. Do you have a hetas engineer installing the system?

welcome to the forum.

 

[Dotty]

Moving to correct sub forum.

 

[Reg Man]

You really need to use a HETAS registered engineer for this type of work. They will be able to design and install it in the correct way.

 

[Dotty]

:iagree:

Not something you can throw in and hope for the best!

 

[Boz]

Hi, this is the boiler that I was planning to use...​

It heats water far faster than the type of boiler that runs vertically up the inside of a stove and replaces the back lining panel. This is because this particular style of boiler takes direct heat from the flames as well as keeping the heat in the full body of the stove.​

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It is NOT suitable for a stove with a firebox body smaller than the following models (which you can find in our shop) : Trilby, Buckingham, Coachman 8kw, Elite 8kw, Maid, Butler. It will NOT FIT : ACORN 6kw (or any 6kw stove), ASPECT, CROFTER as the fire boxes on these models are too shallow internally to fit the boiler and allow the stove and chimney to draw.​

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We recommend you only fit this to a new stove. In stoves which have been in use for some time, the metal will be cured and hardened which gives a greater risk of cracking the cast iron when you cut the holes in the body. It can be done, but AT YOUR OWN RISK.​

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The outlet pipes on the boiler are only 1/2" BSP thread. You will need to up this to 25mm on a pumped system to supply radiators. It can be gravitationally fed to a hot water tank - but we do NOT advise this with radiators. Supply to radiators MUST be pumped and a Honeywell L641 pipe thermostat needs to be fitted within 1 metre of the stove on the hot out and set to 55deg C. A motorised valve should be fitted round your pump. This should be in closed position when power is present and open if power fails to allow water to bypass the pump. At least one of the rads should be fitted with locksheild valves. If gravitational fitting to a hot water tank, make sure the hot pipe goes straight up and that it is at least 28mm diameter. Copper piping should be used for at least the first 3 metres​

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The small boiler is likely to supply MORE to the wet side of the system than stated when fitted into larger stoves. If the boiler is much smaller than the width of the original baffle plate, you will need to custom modify your baffle to fit WITH the boiler so excess heat is not lost up the chimney. It's very important with rads to fit a header tank and be aware that it may be neccessary to fit extra rads if too much hot water is being produced.​

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[SimonG]

What part of the country?