Old programmer,rads turn on when hotwater is

[wrecked_24_7]

Iv recently moved into a house and the programmer doesnt seem to have a swicth for hotwater/ and central heating seperately, when i turn it on, the rads in the house heat up but i do get hot water. Also there is no cylinder thermostat and the immersion heater doesnt have a fuse in it. HOw easy is it to hook a cylinder thermostat on it and what fuse do i need for the immersion heater. Also what can i do about the rads heating up when i want hot water??? Thankyou

 

[Puddle]

Well you immersion heater will have its own fuse in the consumer unit

Do you have a room thermostat maybe that will turn heating off,hot water may have a thermostatic control near cylinder
If no room thermostat,maybe need to turn radiator valves on and off by hand
To hook up a cylinder thermostat,sounds as though you may have to up date all system controls,hard to say without knowing more,is it easy to do,thats all relevant.... many members here would say yes

 

[wrecked_24_7]

iv had a new consumer unit put in so i know it has a trip at the consumer unit, but in the airing cupboard where the immersion heater wire goes into , its a spur, but has no fuse in it, so am i right in assuming taht would be it, but even if i did get that going, in would run constant as theres no cylinder thermostat hooked upto it, and yes the programmer is very old

 

[Dannypipe]

iv had a new consumer unit put in so i know it has a trip at the consumer unit, but in the airing cupboard where the immersion heater wire goes into , its a spur, but has no fuse in it, so am i right in assuming taht would be it, but even if i did get that going, in would run constant as theres no cylinder thermostat hooked upto it, and yes the programmer is very old

The stat that you find on many cylinders (and the one you are refering too) controls the temp of the water heated via the boiler (also known as the boiler interlock - well part of it).

An immersion heater has it's own stat, which is wired in under the cap. It is a rod stat, which slides into the immersion heater.

Finally on the electrics - The immersion heater should be run as a single radial circuit. This is because 3KW running for extended periods takes a large amount of the capacity of the ring main. For this reason it is a regulation that it has it's own radial curcuit.

The immersion heater cable should terminate in a switched spur, with a diode to show that it is on. I only install 13amp fused switch spurs for extra protection. From there you should have 2.5mm (though 1.5mm does conform to standards on a 3KW Immersion Heater, best to go bigger though) - heat resistant flex. This then connects the Immersion heater to the switch. Switch being the important word!

Hope this clears it up. Dan

 

[WHPES]

Is your primary circuit to the cylinder not on a gravity flow with the programmer only operating a pump for the heating? This is how a lot of systems used to be done.

You would need to modify the pipework and convert to S or Y plan with fully pumped system and controllers if you want to update it (can't simply shove a cylinder stat on)

The fuse for the immersion (or MCB if it is an up-to-date unit) will be on the consumer unit.

 

[wrecked_24_7]

Is your primary circuit to the cylinder not on a gravity flow with the programmer only operating a pump for the heating? This is how a lot of systems used to be done.

You would need to modify the pipework and convert to S or Y plan with fully pumped system and controllers if you want to update it (can't simply shove a cylinder stat on)

The fuse for the immersion (or MCB if it is an up-to-date unit) will be on the consumer unit.

It is only a pump for the central heating from what I can see

 

[WHPES]

In that case the hot water will come on when the boiler is on and is governed by the boiler temp.

To improve efficiency, consider upgrading the system to fully pumped and controlled S plan system.

Is the heating circuit a single pipe system?

 

[Mbear]

There's a chance that it's a primatic cylinder(if there's only a pump), best getting someone in to repair the possible fault or simply update the controls.

 

[WHPES]

You can tell whether it's a Primatic cylinder or not by checking whether you have two tanks in the loft (small and large) or just one large on (Primatic).

If you have a pump only for the heating, with these old systems it is common for the rads to heat up a little with the hot water off as some hot water will flow past the pump impeller and round the rads due to gravity (this is why the system is inefficient). A modern system has motorised valves which completely shut off the heating when not required. CHeck that the pump is not actually running. If not, there is nothing wrong with the pump. Shut off the individual radiator valves for the summer to stop the rads heating up.

 

[wrecked_24_7]

In that case the hot water will come on when the boiler is on and is governed by the boiler temp.

To improve efficiency, consider upgrading the system to fully pumped and controlled S plan system.

Is the heating circuit a single pipe system?

No flow and return

There's a chance that it's a primatic cylinder(if there's only a pump), best getting someone in to repair the possible fault or simply update the controls.

The cylinder is new, it must only be a few years old looking at it

 

[WHPES]

You can still buy Primatic cylinders (though why anyone would want to is beyond me!)