radiators dont get hot enough

[gerinemo]

Hi All
My sisters CH was never great but since my little brother started twiddling knobs in the airing press it has taken a turn for the worst
firstly there seems to be no way of selecting hot water & heating or heating only
in the picture there is 2 pipes goint to what i assume is the coil inside the tank for hot water
there is a motorised valve probably to shut off the hot water part of the system but no aparant way of switching it

Ch Controller is a sunvic & just looks like a timeclock approx 7 years old

if i manually shut off the gate valve at the bottom of the picture the radiators heat up better (still not quite hot )
but no hot water
if i allow the hot water through the coil the radiators are noticably cooler even if left on for hours
one thing that i dont get is why is there a 1/2 in pipe joining the 2 coil pipes ( in the middle of the picture ) should the valve on this be open or closed
its a vokyera boiler and seems to be undersized for a four bed dormer bungalow
any help or advice on what this middle pipe is for would be great
Thanks

 

[lame plumber]

its a bypass and your system needs to be set up and balanced again to make it work, then slap the hands that played with it to start. the bypass allows a small flow when the valve shuts and if u have trvs and they all close, the pump has somewhere to send its output or it would burn out.

shut the middle valve on the 1/2 inch and crack it open with the pump running so u can just hear a flow. then open the coil valve and close it down enough to allow the rads to warm up and warm the hw coil, too much and itll only warm the coil and not the rads.

 

[gerinemo]

Cheers will give that a go

 

[stevetheplumber]

you could also turn the boiler stat up to full

 

[gerinemo]

Yep never even considered turning it up to full whack
Would it use more gas at full throttle or is it a false economy to run less than full as its running longer at less than full power
you guys are the experts what do most of you customers have theirs set to ?
Also theres no trv's on any of the rads the upstairs gets warmer than down stairs so would it be worth putting trv's on the upstairs to force the heat downstairs
Many thanks for your replies
John

 

[kay-jay]

Just throttle the lockshields down on the upstairs rads to force heat downstairs.

Sent from my GT-I9100 using Tapatalk 2

 

[gerinemo]

I can certainly try that also
Thanks