11 Jan 2011
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United Kingdom
I'm running two new rads and my system is 10mm microbore (thought it was 8mm upstairs but they all look the same size to me now.)

I don't know if I have a manifold. There's a rad in the house that I think wasn't there when it was built so I lifted the floorboards on the upstairs landing expecting to see evidence of a board being lifted but there wasn't.

I'm assuming that if I lift a floorboard up near a rad, if I have a manifold I'll see nothing but 10mm but if I don't have a manifold I'll see the 22mm flow/return with the 10mm teed off? If so how far away is the rad likely to be from the 22mm flow/return?

If it's on a manifold where am I likely to find it? There's a spot on the floor in the bathroom that gets warm but it would seem strange not to have it located centrally.

Whichever system it is, I assume I'm best sticking with 10mm for the new rads to avoid starving the existing system of heat?

Also, if it turns out not to have a manifold, as the new rads are a few metres away from the nearest existing rad due to being in what was the garage, would I be best off extending the flow and return before teeing of in 10mm?


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It could be placed anywhere, ideally they would site it centrally if the house design could accept it, ensures the 10mm feeds are as close to the same length as possible to aid in balancing. Sometime there is no reason to it though and it can be down to chasing around the house with inspection holes.

You want to minimise any feed pipe lengths to avoid balancing issues.

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