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Andrew Smith
Andrew Smith, Engineer
Category: UK Plumbing
Satisfied Customers: 3629
Experience:  Domestic Gas, Commercial Gas, LPG, Unvented Hot Water, Part P Electrical, Commercial Catering
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We have a greenstar 30cdi hot water is flowing but no

Customer Question

hi we have a greenstar 30cdi hot water is flowing but no central heating
JA: How long has this been going on? And how severe is the problem?
Customer: since it was repaired for a leak in the boiler in the summer. we just switched on the heating over the weekend I am thinking a valve was closed that is preventing the hot water from the central heating from flowing out of the boiler
JA: Do you plan on doing the work yourself?
Customer: i was hoping to check if it was something simple when i switch on the heating, the burner light shows for about 20 seconds then goes off
JA: Anything else we should know to help you best?
Customer: there are 4 pipes under the boiler. the furthest left with an arrow that points down and has a picture of a radiator is not hot. the pipe next to it that shows an arrow down and a tap is hot
Submitted: 9 months ago.
Category: UK Plumbing
Expert:  Andrew Smith replied 9 months ago.

Can you ensure all valves are open.

It sounds like the water is not circulating, does the pump run when the heating starts?

Customer: replied 9 months ago.
The pump seems to have a constant vibration and not different when the central heating is turned on. When I switch on the CH, the burner flame goes on and I hear a noise from the pressure cylinder (sounds like water entering). It then stops and burner flame goes off after about 30 seconds. All the pipework for below the boiler have screws which are facing perpendicular to the boiler face so assumed they are open. Are there any other valves?
Expert:  Andrew Smith replied 9 months ago.

No, but again the boiler sounds like it is boiling the water and simply turning off when it reaches temperature.

Are you able to take the center screw out of the pump to check rotation?

Customer: replied 9 months ago.
I did that yesterday with the pump and it rotated fine. Water came out however the water pressure gauge did not seem to drop.
Expert:  Andrew Smith replied 9 months ago.

it sounds like a blockage then.

Is the auto air vent open on the top of the pump? - It could be air stuck in the boiler from when it was drained?

Customer: replied 9 months ago.
Where is that located? On the pump itself?
Expert:  Andrew Smith replied 9 months ago.

On the top of the pump manifold

Customer: replied 9 months ago.
It's working now. Thank you very much.
Expert:  Andrew Smith replied 9 months ago.

Brilliant - well done

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