Programmer needs both heating and hot water to be switched on for heating to work?

[Adam78]

Hi,

I have an old conventional boiler (Glowworm spacesaver) and its hooked up to a RWB2E Seimens programmer (see pic). My problem is I'm having to switch both the HW and central heating switch on inorder to get the central heating on. If I switch the HW off the central heating switches off too. Any idea why it needs both switches on as the programmer is suppose to be dual control? I shouldnt have to keep the hot water on simply to switch the central heating on as the water then gets too hot?

Could it be becuase its a gravity hot water system (i.e. hot water tank in the loft)?

Any advise would be helpfull.

below is the link to the RWB2E manual:

http://w3.siemens.co.uk/buildingtec...l-controls/documentation/Documents/rwb2_i.pdf

 

[AtlasGas]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Are you sure it's gravity hot water? The pump would be switched on in heating but not hot water, therefore what you are explaining would not make sense on a gravity hot water configuration.

 

[Adam78]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Are you sure it's gravity hot water? The pump would be switched on in heating but not hot water, therefore what you are explaining would not make sense on a gravity hot water configuration.

How can you identify a gravity hot water system?

 

[AtlasGas]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Quickest way would be is there four pipes out of the boiler? Possibly 2 22mm and 2 28 mm. Plus gas of course

 

[snowhead]

Re: Programmer needs both heating and hot water to be switched on for heating to work

The way you describe is correct for an older system.
Gravity hot
Pumped heating.

Switching Hot water turns on the boiler
Switching heating then turns on the pump.

The older controllers used to have a mechanical link to stop you just switching off the water.
Your's may have it on the back , but some clever person may have unlinked it thinking they can have Heating with no hot water.

 

[Adam78]

Re: Programmer needs both heating and hot water to be switched on for heating to work

The way you describe is correct for an older system.
Gravity hot
Pumped heating.

Switching Hot water turns on the boiler
Switching heating then turns on the pump.

The older controllers used to have a mechanical link to stop you just switching off the water.
Your's may have it on the back , but some clever person may have unlinked it thinking they can have Heating with no hot water.

Are you saying this sytme I have requires hot water to be on inorder for heating to work or can it have individual controls?

 

[Adam78]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Quickest way would be is there four pipes out of the boiler? Possibly 2 22mm and 2 28 mm. Plus gas of course

looks like 4 from the pic, doesnt it?

 

[albatross]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Looking at the pic I'd confidently say it is gravity.

 

[stani]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Snow head is spot on, gravity hot water which switches boiler on then select heating to turn pump on, in the beginning there was no other control, very simple. Wish everything was this simple.

 

[Adam78]

Re: Programmer needs both heating and hot water to be switched on for heating to work

Snow head is spot on, gravity hot water which switches boiler on then select heating to turn pump on, in the beginning there was no other control, very simple. Wish everything was this simple.

How can you ensure the water doesnt boil then if the heating is on for long periods?

 

[stani]

Re: Programmer needs both heating and hot water to be switched on for heating to work

It will only get as hot as the boiler stat is set.

 

[zzzjim]

Re: Programmer needs both heating and hot water to be switched on for heating to work

How can you ensure the water doesnt boil then if the heating is on for long periods?

The heat is shared , its more of a problem other way round unless cylinder has a stat !