Heating problems

mad m

Recently got an extension, went with zoned heating. I noticed the other morning when I had all the zones were on (Rads downstairs,upstairs,hot water) that some of the rads downstairs went cold or luke warm on top and stone cold down bottom. Now as soon as I turn off hot water zone the rads downstairs heat up fine....

Why won't the all work at same time?

ART6

mad m wrote: »

Recently got an extension, went with zoned heating. I noticed the other morning when I had all the zones were on (Rads downstairs,upstairs,hot water) that some of the rads downstairs went cold or luke warm on top and stone cold down bottom. Now as soon as I turn off hot water zone the rads downstairs heat up fine....

Why won't the all work at same time?

Two reasons seem likely to me: 1) your boiler can't supply the heat load of all of the rads plus hot water. Check that by letting the hot tank get up to temperature and don't run any hot water for a while. If the rads then all heat up, you possibly don't have sufficient capacity for everything. More likely 2) your system need balancing. You could start by closing the outlet valve on every radiator and then opening it (say) one turn. Also look at the supply to the hot tank. If it has an inlet or outlet valve to the coil, try closing that and then opening it a couple of turns. When you've done all of that then check the rads individually and open the outlet valves on those that are still cool a quarter of a turn at a time until they are all giving you the temperatures you require.

That sounds like a long job, but it isn't really. An hour or two should do it.

copper12

dont mind him it will take you all day:D
but he's right

mad m

Just noticed the lockshield valves are all open fully....Will do as you say ART6, thanks.

JamesM

Also check that the circulating pump is on the fastest speed. Although, if you have a header tank in the attic, this can cause pitching. If you have a sealed system - have the pump on the fastest speed.
Jim.