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windybags · Joined: 11 Mar 2008 Posts: 4 Location: north coast

Hi,

I've got an open vent system heated by a Gerkros Gem oil fired burner which is 14 years old.
Circulating pump is a Wilo Gold RS50. Operating on setting 2.
Motorized valve is a 2 port Myson.

The problem -

If both the CH and HW switches on the control panel are on, the water in the hot tap is only lukewarm but the radiators heat ok. You can hold your hands under the running tap without getting scalded no matter how long the burner has been on.

If only the HW switch is on the water is heating ok.

Last year the same problem occurred and the original pump was replaced with the above Wilo pump.

Since the pump was replaced I have noticed a loud sound coming from some of the radiators, mostly upstairs. It sounds like rushing water.
Everything operated fine until a few weeks ago when the same problem with the hot water began.

Any assistance would be appreciated.

straker1966 · Joined: 06 Jan 2008 Posts: 164 Location: cambridge

have you been up into the loft and seen if the heating tank in there is full?

windybags · Joined: 11 Mar 2008 Posts: 4 Location: north coast

yep, checked expansion tank and its 3/4 full although there is rust coloured gung like substance around the edge.

seemed to have used a lot more heating oil since getting pump replaced.

straker1966 · Joined: 06 Jan 2008 Posts: 164 Location: cambridge

when matey changed the pump, how long did it take him?
my point being if he did it in 20 mins then he didnt drain the system and just isolated the pump at its own valves...
if he was there an hour plus then he might have had to drain the system and now theres air in the system, cold feed could be blocked etc this would explain the rushing water. have you tried venting the upstairs rads with the boiler off? wappen?

windybags · Joined: 11 Mar 2008 Posts: 4 Location: north coast

Thanks for the swift replies.

Believed it took him about 20 mins to change the pump.
He had to return a couple of days later as water was pouring out of the gate valve joints either side of the pump. They couldn't be tightened to stop the leaks and were replaced.
The heating and water worked a treat for several months then the hot water became lukewarm.

thescruff · Moderator Joined: 03 May 2003 Posts: 4659 Location: Bath

Air in the primary circuit

windybags · Joined: 11 Mar 2008 Posts: 4 Location: north coast

What's the best way to bleed the system to get the air out?