I have a coil indirect hot water tank heated by oil boiler. There are
two pumps, one for the rads and one for the hot water. recently I have
been getting very tepid water no mater how long the boiler runs. The
thermostat on teh tank is set to 60 and the boiler stat is at 70.

The top feed pipe into the heat exchanger is very hot but the bottom
return pipe is freezing. I would have thought the return would have
had some heat. I have tied upping the pump speed with no luck.

Does this sound like the exchanger is blocked with sludge or maybe an
air-lock. Any ideas what it might be or how to fix it.


Peter Hawkins

"Peter Hawkins" wrote in message
...
I have a coil indirect hot water tank heated by oil boiler. There are
two pumps, one for the rads and one for the hot water. recently I have
been getting very tepid water no mater how long the boiler runs. The
thermostat on teh tank is set to 60 and the boiler stat is at 70.

The top feed pipe into the heat exchanger is very hot but the bottom
return pipe is freezing. I would have thought the return would have
had some heat. I have tied upping the pump speed with no luck.

Does this sound like the exchanger is blocked with sludge or maybe an
air-lock. Any ideas what it might be or how to fix it.


Peter Hawkins

There is a cap on the centre of the motor, unscrew this (you will get a
small amount of water coming out) and with the boiler on make sure the pump
is turning.
If not turn boiler off and turn pump with screw driver, and turn boiler on
again, if still not turning, you will then need to check wether you have a
supply voltage to the pump, if you have you need a new pump, otherwise could
be the controller.

On Wed, 22 Dec 2004 18:03:07 -0000, "Dave Jones"
wrote:


"Peter Hawkins" wrote in message
.. .
I have a coil indirect hot water tank heated by oil boiler. There are
two pumps, one for the rads and one for the hot water. recently I have
been getting very tepid water no mater how long the boiler runs. The
thermostat on teh tank is set to 60 and the boiler stat is at 70.

The top feed pipe into the heat exchanger is very hot but the bottom
return pipe is freezing. I would have thought the return would have
had some heat. I have tied upping the pump speed with no luck.

Does this sound like the exchanger is blocked with sludge or maybe an
air-lock. Any ideas what it might be or how to fix it.


Peter Hawkins

There is a cap on the centre of the motor, unscrew this (you will get a
small amount of water coming out) and with the boiler on make sure the pump
is turning.
If not turn boiler off and turn pump with screw driver, and turn boiler on
again, if still not turning, you will then need to check wether you have a
supply voltage to the pump, if you have you need a new pump, otherwise could
be the controller.


When I put my hand on the pump it does seem to be doing something, i.e
there is a vibration. Changing the pump speed causes a noticable
change in noise pitch from the pump which suggests it is turning.

I will try the screw to check anyway.

Peter