Vertical panel radiator problem

[Simon L]

We have 3 new vertical single panel radiators 7ft ish tall( they look like MYSON DECOR V10 rads) - two upstairs and one downstairs in an extension that the previous owners added onto a property we have just moved into. These rads take ages to heat up, when all the other traditional rads are hot (including 2 small trad rads also in extension) these are still luke warm/cold. The lockshields have all been fully opened to try help this problem but with no avail. It seems the pipework is getting warm/hot but the flow of this water around the rads is just so slow.

1.Could it be because the rads are so tall? (gravity problem), or pump not coping with these? Any ideas?

The heating system is via 2 pipe indirect with oil boiler, pump 15/50 ups grundfos, 3 way valve (I think Honeywell Y plan) with water tanks in roof.

2.I have been told that the bearings on the pump may be beggining to go and that the pipework of hot water feed from pump to radiators is only 15 mm and should be 22mm. Do you know if 15mm is standard and sufficient, for 3 bed house, 9 rads?

Simon

[Andy Hall]

You can't really determine fow in terms of the number of radiators. You have to look at individual capacities. Broadly, though, in a typical house environment, 15mm tube will carry enough water to heat

6kW of radiator. You can do a simple sanity check on that from the manufacturer data sheet for the radiator size.

You could try increasing the pump setting but also reduce the lockshield settings on the radiators that are getting warm. Take a look at the FAQ and section on balancing. The object is to get more water flowing in the larger radiators that are not warming up

[Christian McArdle]

You need to do a full balancing before you go any further. You'll need an IR non-contact thermometer and the FAQ off Ed Sirrett's sig.

Turning up the valves on the new rads is not enough if the existing rads also have theirs wide open, as those ones might hog the flow.

Christian.

[Simon L]

Thanks for the info - will check rad kw stats (i take it you mean 6kw total for all rads?)

The pump setting is already at max. The rads close to cylinder have their lockshields closed down more. This was done recently and did help but not suffiently enough to get the big vertical rads hot quickly. The pump has suspect bearings so I have been told - would you say a Grundfos 15/50 UPS (not sure what the figues mean) a direct replacement, sufficient power/type for my CH - 22mm return, 15mm feed,

9 rads, 3 of them 2m vertical type?

Once again, thank you for your comments.

Simon