Solid fuel rayburn/ water tank question

[Maris]

Hello,
I know I've rambled on this site a couple of times but this is my first big question...
Me and the husband are thinking of having a small solid fuel rayburn installed in the house we're renovating. We already know that we want a wood pellet boiler, and where it should go. What we'd like to do is have a twin coil hot water cylinder so that the rayburn can take over producing hot water whenever its on. There seem to be a couple of problems with this plan:
1-if the water tank is not directly above the rayburn, our architect doesn't think that the connections will be approved by building control or by a plumber (the pipes would run under the floor of 1 bedroom)
2- I've had a look at some twin coil cylinders, and their specifications all note that they are unvented, and that they cannot therefore be used with a solid fuel appliance.

if anybody knows of ways around either of these issues, or just the reasons for why they are issues, I'd really appreciate their advice!

thank you

Maris

 

[biffvernon]

Have a look round this website: Newark Copper Cylinder Company
They seem to be willing to make cylinders with anything you want.

 

[Aidan]

Hello,

just the reasons for why they are issues

1-if the water tank is not directly above the rayburn, our architect doesn't think that the connections will be approved by building control or by a plumber (the pipes would run under the floor of 1 bedroom)

The heating system has to be able to cope with the heat produced by a boilerful of fuel in the worst case situation, if the power fails. It would then rely on gravity circulation (no pump) to transfer heat from the boiler to the water cylinder.

Gravity circulation relies on the differential pressure between the flow and return water streams (hot water is less dense) to drive the flow; there's very little differential pressure available, compared to a pump. Each pipe fitting and each length of pipe causes a pressure loss due to friction. It can be done, but you can end up with big pipes to minimze the pressure losses.

I'm not certain that solid fuel system HAVE to be designed as gravity circulation, but you have to be able to dissipate the heat without boiling or over-pressurizing the system.

Look at the Heatas website.

2- I've had a look at some twin coil cylinders, and their specifications all note that they are unvented, and that they cannot therefore be used with a solid fuel appliance.

You could get a vented twin-coil cylinder, or you could use a cylinder designed for unvented use with a cold water storage tank as a vented system. I think the requirements are that there should be some additional safety devices if an unvented cylinder is to be used with a solid fuel heater, but the additional safety devices aren't specified.

 

[Maris]

Thank you both very much for replying. I've added Newark to the list of people to contact next week with questions. I've also found a couple of installers in the area, who are listed on the HETAS website.
I'm relieved to hear that this isn't actually some mad and impossible situation. Its a bit like everything to do with the house so far- we know what we want but its never as straightforward as we thought.