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Heating fine but no hot water

Postby peterp » Wed Apr 02, 2008 11:50 am


I'm trying to save money by not using the electric immersion heater, which is permanently on at the moment and costing me a bomb. However, when I turn it off and let the gas boiler heat the water I get no hot water. Even after leaving the gas boilber on overnight. It should take about 40 minutes.

I know I don't have a combination boiler system. I think I have an indirect water heating cylinder. There is a gas boiler in the kitchen and a cylinder in the airing cupboard upstairs, with a supply tank in the loft. It looks very much like this to me:

I have uploaded some pictures of the cylinder here:

When the gas boiler is on, the pipes towards the cylinder are hot, so there is no problem with the boiler. However, there is a 'mid position activator' before the pipe enters the cyclinder, and the pipe goes gradually cold on the other side of this device. There is no hot water coming out of the cylinder from the pipe at the bottom.

Also, there is hot water going to the radiator in the hall for some reason, even when the central heating is off. This must be coming from the gas boiler. I thought the water and heating systems were independent?

Please help!


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Postby htg engineer » Wed Apr 02, 2008 6:49 pm

No the water and heating system are connected the 3 port valve is controlled by an actuator which switches between central heating and hot water.

Check the cylinder thermostat is calling for heat, there may be an arm on the side of the actuator - move this to manual. Manual means the central heating and hot water will heat up - temporary fix.

To check the actuator remove from the 3 port valve and select hot water only then central heating only, see if the 'D' shaped aperture on the actuator turns, if it doesn't or continues to turn round then replace the actuator head.

Also check the spindle is free to move on the valve body.
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Postby RolyMo » Wed Apr 02, 2008 7:47 pm

From your pictures it looks like you have a Drayton 3 port valve.

Manually opening the valve sounds like a good plan temporarily.

Before buying a complete new actuator, it is possible with some of the actuators to just replace the motor. Check inside your actuator but I'm pretty sure you will find a 'Synchronous' motor. Remember to safely isolate the electrics first!!

Plan 'B' would be to just replace the complete actuator or you may choose to go straight for this option. The new Draytons are 'snap-on' which makes life easier.
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