Refilling microbore system
- Thread starter supersmig
- Start date
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If you mean a sealed system (with pressure gauge but no header tank), look in the FAQ topic near the top of the topic index for details on filling loops. The fact that your system is microbore is not relevant to whether it's open (conventional?) or sealed.
Thanks for your quick reply.
It was the last line (never assume anything) that led me to recheck everything.
The repair to the system was to replace the leaking hot water cylinder.
i assumed that the cylinder for replacement was an indirect one as the system is pump fed hot water. I have looked at the old cylinder again and found this to be a not so common, Primatic Cylinder.
Problem solved as to why i cant fill the system.
What i would like to know now please is;
When Ihave fitted a new expansion tank in the loft can i tee the new fill and expansion pipes into the indirect coil conections on the cylinder (This is where the central heating filled on the Primatic) or has it got to be somewhere different.
The system is very basic, you can only have hot water and central heating. The heating is mostly microbore, the rest is conventional.
Everything on the system is pump fed so the heating coil in the cylinder is virtually another radiator.
What a mess.
It was the last line (never assume anything) that led me to recheck everything.
The repair to the system was to replace the leaking hot water cylinder.
i assumed that the cylinder for replacement was an indirect one as the system is pump fed hot water. I have looked at the old cylinder again and found this to be a not so common, Primatic Cylinder.
Problem solved as to why i cant fill the system.
What i would like to know now please is;
When Ihave fitted a new expansion tank in the loft can i tee the new fill and expansion pipes into the indirect coil conections on the cylinder (This is where the central heating filled on the Primatic) or has it got to be somewhere different.
The system is very basic, you can only have hot water and central heating. The heating is mostly microbore, the rest is conventional.
Everything on the system is pump fed so the heating coil in the cylinder is virtually another radiator.
What a mess.
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Glad to hear that "never assume anything" has helped someone! 
If you are replacing the cylinder it might be worth thinking about adding controls so that you can use the system more efficiently. Have a look at the Honeywell site - you could use a Y or S Plan.
On a fully pumped system the new header tank would have its feed and vent pipe connections close together on the flow pipe with no valves of any sort between the boiler flow connection and the vent connection.
If you are replacing the cylinder it might be worth thinking about adding controls so that you can use the system more efficiently. Have a look at the Honeywell site - you could use a Y or S Plan.
On a fully pumped system the new header tank would have its feed and vent pipe connections close together on the flow pipe with no valves of any sort between the boiler flow connection and the vent connection.
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