Rayburn Indirect Hot Water

[doitmyself88]

Hi there im thinking of installing an indriect hot water system heated by a Raburn with about three or four rads. Ive spent hours looking at diagrams but i cant understand one thing. A pump is needed to pump the hot water around the rads so that they heat up, i get that, simple. But a pump is NOT needed to pump the hot water around the coil in the cylinder? Is this true? And if so how do both returns join? Would the pumped circuit not stop the other circuit from returning? Ive heard of injector tee's, is this what they are used for? Gravitational is a word that is used a lot in this field. But how can water flow up the pipe to the cylinder in the attic? Any information on this matter would be really helpful. Thank you if youve taken the time to read this, i hope i didnt b*****t too much!

 

[princegoose]

get someone in who knows how to install it, someone put in similar system in my house before i moved in and it doesnt work very well.

Hot water is heated up by GRAVITY circulation and once the hot water is up to temperature the thermostat brings the pump on which circulates water around the rads

 

[doitmyself88]

ok thanks for that. Weve got the system in the house already (the new system is for an outbuilding) and when we want the heating on we just switch the pump on manually, dont think we have a thermostat. I still dont understand what Gravity circulation is. How does this work? Thank you!

 

[shorticus]

as the water in your boiler is heated it becomes less dense and is forced upward by the more dense (i.e. heavier) cooler water, this then extends into your flow and return pipes. The flow pipe comes out of the top of the boiler and the return should go in at the bottom. As the cooler and heavier water in the return pipe is dragged downward by gravity, the warmer and less heavy flow water is forced upwards, to the cylinder where it dissipates its heat energy thus becoming cooler and so the cycle continues, this is gravity circulation.
The injector tee is to prevent the pump from stoppping or interfering with the gravity circulation.

 

[doitmyself88]

Right i think that makes sense, thank you. So should the pipe with the hot water enter the cylinder at the top of the coil?

 

[shorticus]

for gravity to work properly you need to connect the flow to the top of the coil and return to the bottom.
One question though, you've not mentioned the fuel that your Rayburn uses?

 

[doitmyself88]

fuel for the rayburn will be a mixture of phurnacite and logs!

 

[shorticus]

solid fuel then, i was just wondering if it was oil or gas, if it was then you would have to have done away with the gravity circuit and put a pump in (Building regs Part L1b)

you may find this useful; http://www.solidfuel.co.uk/pdfs/buidling_regs_consumer%20leaflet.pdf