Microbore CH query

[Tim+]

A friend is having problems with her CH/HW system in her new house.

Biggest problem at the moment is that she can't get much in the way of HW (indirectly heated tank) without the CH on as well, I had a look at the HW tank to see if water was circulating through the coil and was surprised to see that the coil has been connected with Microbore pipe. Can this be right? I would have thought that this would be just too restrictive to flow from the pump. Water was circulating incidentally.

I suspect the system is a DIY install and is probably sludged up.

Another problem that she has is that whilst there is an immersion heater, it's not connected because there is a plastic header tank above the CH tank. I appreciate the overheat hazard but MUST the tank be changed before she can get the immersion heater connected?

Tim

[spuorgelgoog]

Not too restrictive, but there's a limit to the amount of heat you can tran sfer through a mmicrobore pipe without having excessively high pump speed. With 8 mm pope that may be less than 1 kW. If it exceeds 1.5m/s which is th e maximum velocity specified in BS 5449 you will start to get noise problem s. Tables are here:

-heating-systems.pdf

Usually microbore will supply *one* radiator from a manifold, not a full bo iler output of 10+ kW

No, but the imm heater stat should be changed for one with a secondary manu al-reset overheat cutout; in many cases the stat can be changed without rem oving the heater from the cylinder or draining the cylinder - it just slide s into a closed pocket inside the heater casing.

Owain

[meow2222]

Microbore works but gives a very low flow rate and thus low power transfer. Its susceptible to blockage from CH sludge. If it delivers 1kW of heat it would take maybe 3 hours to heat a cylinder up. Its a bodge that should be workable if HW is left on 24/7.

NT

[ARW]

No, but the imm heater stat should be changed for one with a secondary manual-reset overheat cutout; in many cases the stat can be changed without removing the heater from the cylinder or draining the cylinder - it just slides into a closed pocket inside the heater casing.

ISTR that not having a stat without a secondary manual reset is now a code 2 on electrical inspections.