Can anyone tell me this.

[Witzend]

We've had some new rads and a new boiler installed. We had an extension a few years ago and some new rads were added but were teed off in slightly smaller pipe than the rest of the house. Now these rads worked perfectly well with the old Baxi 70FF but since we've had the new Micron 70FF these rads have been much cooler. The valves are fully open as they're last on the pipework. The rads in the rest of the house have supposedly been balanced

 

[kevplumb]

get the GC no off the boiler data plate

 

[Witzend]

GC No 41-047-50

Why, what is this?

 

[ChrisR]

It id's your boiler but, er...?
The other rads would have been opened wide for flushing. Close all the ones nearish to the pump to lust half a turn open, or 1/4 turn open for the very close. Take it from there.

If there's an air lock, close ALL the rest to push it out. Check the pump speed too; if you have 60,000 worth of rads it'll need to be on full speed.

 

[Witzend]

The pump is on full speed. We were told that it's a bigger pump (Terrier? - sorry that's from memory)

 

[DP]

Pumps either come in 5m or 6m head. Terrier is no different. I would much prefer a Grundfos as it is a better pump. I wonder if your man meant it is bigger in size (but not power)

 

[Witzend]

Terrier TC6

 

[ChrisR]

That's a 6metre head pump. On max speed it should be able to get the heat round the system as long at the pipes sizes are large enough. Try the just-open-enough approach to balancing.

 

[kevplumb]

appologies i was having a paranoid day

 

[Witzend]

The new valves (at the opposite end of the TRV's) turn about 12 turns (we just have little spindles on the older rads)

 

[ChrisR]

so...?!

 

[Witzend]

half a turn wouldn't be much if it takes 10 turns to come on full would it?

 

[ollski]

you dont want them full you want to keep the hot water in the rad which you do by restricting the flow. start at half a turn from closed and then just adjust them until the pipes into / out of the valves are at about 20 degrees difference (temp)

 

[Witzend]

Some of our rads were set like this but only the tops were getting hot (it has been desludged)