Glow worm ultimate problem

[Paulus]

Hi

Just popped across from plumbing forum. I don't touch boilers as I am not gas safe and wouldn't know where to start anyway.

Before I get someone out to the above boiler I just wondered if you could help with a diagnosis. My radiators are getting incredibly hot even when I turn the boiler stat down to minimum but my water doesn't get as hot as it should.

If I turn the pump speed up the water temperature is much better but the rads are still red hot, too hot to touch even on minimum.

My first thought was the boiler stat.

Any guidance would be greatly appreciated.

 

[Roger Welton]

I would agree boiler stat, disconnect electrically (the stat) to prove for certain

 

[aggis]

If it's getting over hot on the rads, you probably need a new boiler stat,but if you've turned the pump up & the dhw is hotter, my 1st thoughts are the circ's sludged/blocked.
With the Ultimate you can have a fully pumped or gravity circ's to the cylinder, if the later the cold feed & expansion will be connected at the cylinder F & Return. Get a magnet, put it on the tee that connects the cold feed, [could be blocking up.] if you feel the magnet holding you'll need to flush the system with chemicals or cut out all the effected pipework.

 

[Paulus]

Many thanks to both of you. It is a fully pumped system. I flushed with chemicals before the winter but it obviously didn't work properly as you are dead right aggis, a magnet indicates sludge in pipes around the pump. I will try to flush again before resorting to replacing the pipes.

 

[Ian400]

Hi Paulus - I know this is an old post, I've just come across it. I too have an old Glow Worm Ultimate with an identical problem, Rads getting red-hot. Have changed the boiler stat with no luck. Can you tell me how you sorted it out, was it successful ?
Would appreciate your comments. Ian

 

[Paulus]

Hi Paulus - I know this is an old post, I've just come across it. I too have an old Glow Worm Ultimate with an identical problem, Rads getting red-hot. Have changed the boiler stat with no luck. Can you tell me how you sorted it out, was it successful ?
Would appreciate your comments. Ian

I emptied system again and re-filled adding Sentinel 400x. Left it in system for a couple of weeks and then flushed out and re-filled adding inhibiter. It seems to have worked but this winter will tell me for sure.

 

[RoryD]

hear a lot of this, there should be nigh on 80 degrees at a rad, i wouldnt adjust anything at the chb. as long as you have an 11 degree diff over the flow/return all is well