I've a couple of questions regarding the balancing of central heating radiators which hopefully some of you might be able to answer.
We recently moved into a semi which was built in 1993. It has a conventional boiler (not a combi). As microbore has been used, I have assumed it has a manifold type distribution, with drop down feeds to the downstairs rads.
With it being colder this winter we noticed that the upstairs radiators get hotter (and more quickly) than the downstairs rads. At the weekend, I checked every radiator and each lockshield valve and on/off valve (there are no TRVs) are all fully opened. I have experimented with two of the radiators in the bedrooms by closing down the lockshield valve and gradually opening them to the required temperature drop. I found that with both of these rads, they only needed to be opened about a 1/4 of a turn before they started to get too hot, so they're opened about an 1/8th now. What surprised me though was that I also noticed that the downstairs radiators seemed to get less hot and take longer to get up to temperature. The reverse of what I'd expected!
Is it satisfactory to have some of the lockshield valves opened by such a small amount?
If I'm doing this correctly, I would like to do the same thing to more radiators. All the upstairs rads and one downstairs. Will restricting the flow in this way on half the radiators put too high an increased load on the pump?
Thanks & best regards,