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Discuss What could be stopping heating working in the Plumbing Forum | Plumbing Advice area at PlumbersForums.net

KarlAtkins

KarlAtkins

So I drained my Central heating system today just to remove 1 radiator in a room I'm decorating. When I refilled the system the central heating nor the hot water will work. I thought it was the motorised valve so I replaced that but to no avail, so the valve came with a new 3 way port so I changed that too, still no joy. No other changes have been made to the system for over a year and no problems at all. The pump runs when the system is powered up and continues to run when hot water is called for but the boiler seems to go in to stand by after a minute or so when powered up. I've even removed the valve again and set the port to the mid position by hand. Nothing send to work, in completely stumped. Any suggestion please. TIA.
 
B

Ben-gee

Esteemed
Plumber
Why on earth did you change the three port valve on a whim?

Assuming everything was working properly before you drained down, the first thing to do is bleed all of the air out of the system.
 
SimonG

SimonG

Plumber
Aye airlock. Should be no need to drain down to take a rad off for decorating.
 
OP
KarlAtkins

KarlAtkins

Why on earth did you change the three port valve on a whim?

Assuming everything was working properly before you drained down, the first thing to do is bleed all of the air out of the system.
I wouldn't call it a whim, but why, why is this such a big deal? The system has been bled prior to re energising.
 
Stu-B

Stu-B

Difficult to diagnose without being there in person, but as others here have said it’s more than likely an air lock. If you’ve bled the rads try bleeding the pump
 
OP
KarlAtkins

KarlAtkins

Aye airlock. Should be no need to drain down to take a rad off for decorating.
So how do you locate and relieve an airlock?
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Difficult to diagnose without being there in person, but as others here have said it’s more than likely an air lock. If you’ve bled the rads try bleeding the pump
How do you need a pump?
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So how do you locate and relieve an airlock?
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How do you need a pump?
Bleed
 
J

John.g

If you have a open vented system with a feed and expansion tank you could consider draining down the system again and then refill the system very slowly by tying up the ball cock to just allow a trickle of water.
 
OP
KarlAtkins

KarlAtkins

If you have a open vented system with a feed and expansion tank you could consider draining down the system again and then refill the system very slowly by tying up the ball cock to just allow a trickle of water.
I don't, it's a sealed system
 
J

John.g

OK, cant, think of much else if system and pump have been vented except maybe to check for any blockage between the E.vessel and system.
 
OP
KarlAtkins

KarlAtkins

OK, cant, think of much else if system and pump have been vented except maybe to check for any blockage between the E.vessel and system.
I haven't vented the pump, I'm not sure how to do that, can you help with how to vent the pump please
 
J

John.g

You should see a brass screw in the centre of the pump, just slacken this until air/water comes out, re tighten, if you have a gas fired boiler then you won't be able to access this if inside the boiler casing, some modern pumps don't have any bleed screw on the front and just suggest running the pump on full speed (3) for 30 minutes, others, like mine, have a mode which alters the pump speed up and down for 10 minutes to expel any air,
 

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