I would be very grateful for any suggestions to cure a problem in a
domestic CH system located in the home of a relative of mine. The
system is gravity water, pumped heating. Boiler is Potterton Netaheat Mk2.
It has in the loft, an open vented copper cylinder with an integral ballcock
cold feed tank at the top. The flow and return pipes for the internal coil are
28mm, directly from and to the boiler located downstairs. There are no
venting plugs for these pipes upstairs or downstairs. No Share/zone valves
are used. The only valve (Drayton thermal) is in the horrizontal return pipe
near the cylinder .
About 3yrs ago, the cylinder had to be renewed because of pinhole damage
around the immersion heater flange, caused by forced removal of an open
circuit immersion heater element which had been CEMENTED in rock hard.
Prior to this, there had been no problem heating the water from the boiler .
Since the installation of the new cylinder, and for the past 3 years they have
relied upon the immersion heater to provide hot water because of no gravity
circulation through the heater coil in the cylinder. the installers had attended
twice, drained a little water out of the primaries and got it running again but f
or only a day or two. The user then gave it up and settled for the immersion
heater for their hot water and have since depended on this for 3 yrs.
The householder states that with control panel set for "Water Only", circulation
is ok and water reaches high temperature BUT set for "Water & Heating", only
the radiators get hot - no hot water!
This would seem to be an electrical problem but the flow and return from the
boiler is GRAVITY circulated, not pumped and seperate to the pumped radiator
circuit with no share valves deployed. Why would the gravity circuit fail when
the radiator circuit is running? Could there be a partial blockage between the
boiler and cylinder, reducing the flow/return and if so, how can it be cleared?
I have attended this week to renew the immersion heater which was badly
scaled, corroded and open circuit. To do this, I had to drain the cylinder to
change the immersion heater which is bottom side entry, 11 inch 3KW.
This is now OK but of course has made no difference to the lack of gravity
circulation through boiler and cylinder coil. I think that there must be debris
or air trapped in the pipes causing blockage ever since the cylinder was installed.
Would dearly love to solve this problem so that the immersion heater can be
used for backup and have the hot water primarily provided by the gas boiler.
Any suggestions would be very welcome. Thanks in advance.
domestic CH system located in the home of a relative of mine. The
system is gravity water, pumped heating. Boiler is Potterton Netaheat Mk2.
It has in the loft, an open vented copper cylinder with an integral ballcock
cold feed tank at the top. The flow and return pipes for the internal coil are
28mm, directly from and to the boiler located downstairs. There are no
venting plugs for these pipes upstairs or downstairs. No Share/zone valves
are used. The only valve (Drayton thermal) is in the horrizontal return pipe
near the cylinder .
About 3yrs ago, the cylinder had to be renewed because of pinhole damage
around the immersion heater flange, caused by forced removal of an open
circuit immersion heater element which had been CEMENTED in rock hard.
Prior to this, there had been no problem heating the water from the boiler .
Since the installation of the new cylinder, and for the past 3 years they have
relied upon the immersion heater to provide hot water because of no gravity
circulation through the heater coil in the cylinder. the installers had attended
twice, drained a little water out of the primaries and got it running again but f
or only a day or two. The user then gave it up and settled for the immersion
heater for their hot water and have since depended on this for 3 yrs.
The householder states that with control panel set for "Water Only", circulation
is ok and water reaches high temperature BUT set for "Water & Heating", only
the radiators get hot - no hot water!
This would seem to be an electrical problem but the flow and return from the
boiler is GRAVITY circulated, not pumped and seperate to the pumped radiator
circuit with no share valves deployed. Why would the gravity circuit fail when
the radiator circuit is running? Could there be a partial blockage between the
boiler and cylinder, reducing the flow/return and if so, how can it be cleared?
I have attended this week to renew the immersion heater which was badly
scaled, corroded and open circuit. To do this, I had to drain the cylinder to
change the immersion heater which is bottom side entry, 11 inch 3KW.
This is now OK but of course has made no difference to the lack of gravity
circulation through boiler and cylinder coil. I think that there must be debris
or air trapped in the pipes causing blockage ever since the cylinder was installed.
Would dearly love to solve this problem so that the immersion heater can be
used for backup and have the hot water primarily provided by the gas boiler.
Any suggestions would be very welcome. Thanks in advance.