I need some help with a twin coil cylinder

[dickyboy]

We have fitted a new specially made twin coil cylinder (rm solar) and sealed system boiler. There is also a coal fired bbu (believed to be a Dunsley Firefly) which is linked to the second coil. We have converted the new sealed system boiler to an "S" plan with an auto bypass from a "Y" plan. No other pipework changed.

Everything has gone perfectly until the fill up...
We opened the filling loop and as normal it started to fill but we noticed once the water reached the level of the cylinder (upstairs) that water was coming out of the pipework on the solid fuel side. All we can find is the primary 28mm pipes from the coal fired bbu and the primary's from the gas boiler. We have taken up flooring all over the house but cannot see how or where the two systems connect.

The bbu and old boiler were being fed from one F + E tank. We have checked the coils on the cyl and they are correct and if we blow down the bbu vent pipe we get air out of the bleed screws on the rads. Ground fllor is a solid floor. We think there is a second set of pipes from the bbu but have never seen this set up before. Can anyone help!!!

The owner of this house has only just bought it and has no idea about operation or history of the property.

 

[mylesy]

sounds like you need more investigating, and maybe re-piping. on old gravity bbu to the cylinder was sometimes anti-gravity valves (like one way valves) on the flow to assist in the convection. be sure to take them off if there on? sometimes its good to draw out the house on paper and put in the pipework on paper, just so your sure. also it can help you find out where the rest of the system you cant see. the bbu is an un-controlled heat source, be sure it has high temp fittings. in fact id fit the solar pump assembly as it will have the expansion vessell, and programmer to turn off the pump when things are too hot etc. everything apart from the panels as instead of panels your using bbu. i would fit the two expansion vessell set up where the first on expands into the second one for protection of heat damage to the expansion vessell. you will need an s-plan plus set up with three 2 port valves, one on the CH, DHW from boiler, DHW from bbu.

 

[northstar]

i would have thought they have fixed it by now

 

[SafeGasInstall]

they better have

 

[mylesy]

oh yeah lol how did i end up going on here then hahaha