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Andrew Smith
Andrew Smith, Plumber
Category: Home Improvement
Satisfied Customers: 3629
Experience:  City and Guilds Qualified plumber
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I have a potterton suprima 40 he When on just hot water it

Customer Question

I have a potterton suprima 40 he
When on just hot water it locks out with either overheat water circulation or flow thermistor error.
Works fine on just central heating and on central heating then hot water added.
Submitted: 3 years ago.
Category: Home Improvement
Expert:  Andrew Smith replied 3 years ago.

Andrew Smith :

There could be a restriction in your cylinder, or if you have 2 motorised valves the hot water one may not be opening?

Andrew Smith :

Are you able to put it on hot water only and see where the heat goes, follow it around the 3 port valve and see if it goes to the cylinder?

JACUSTOMER-05y8rkpl- :

Hot water is going into the tank but boiler locked out water circulation.

Andrew Smith :

Is the water coming out cold from the other side of the coil?

Andrew Smith :

Are you able to turn the pump speed up?

JACUSTOMER-05y8rkpl- :

The water going to the tank is hot pump is on speed 2

Andrew Smith :

Can you turn it up to 3 and see if the boiler stays on longer and does not need resetting?

JACUSTOMER-05y8rkpl- :

Will try now

JACUSTOMER-05y8rkpl- :

Pump is on3 just started boiler going.

JACUSTOMER-05y8rkpl- :

Still locks out with water circulation error

Andrew Smith : There must be a restriction somewhere
Andrew Smith : can you turn down the boiler stat half way and tell me how it does?
JACUSTOMER-05y8rkpl- :

Have turned the thermostat down to half way and still locks out with water circulation error

JACUSTOMER-05y8rkpl- :

Awaiting your answer

Andrew Smith : You may have a blockage in the coil of your cylinder
Andrew Smith : perhaps you have a valve on the cylinder return pipework to balance the hot water and heating?
Andrew Smith : but it causes too much of a restriction when on hot water only?
JACUSTOMER-05y8rkpl- :

There is no blockage.

JACUSTOMER-05y8rkpl- :

All valves are clear.

Expert:  Andrew Smith replied 3 years ago.
Can you confirm how you know there is no blockage, are you getting circulation through the coil in the cylinder?
Customer: replied 3 years ago.

Yes getting circulation.

Expert:  Andrew Smith replied 3 years ago.
How long does it take the cylinder to heat, it just may be working poorly.
Can you try heating from cold and seeing how long the return pipe from the cylinder stays cold?

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