Heating needs to be on to heat hot water

[davebwithane]

Hi
We have to put the heating and hot water on in order to heat the hot water. It's oil fired. Is this an electrical problem or a plumbing problem ?
Thanks
Dave

 

[londonboy]

Do you have a hot water tank with valves beside it? Possibly one or two?

 

[davebwithane]

thanks for the reply.

we have a cylinder upstairs with a pipe going in at the bottom left and coming out a foot higher, both are warm to the touch. There is a cold pipe coming in on the other side and then a hot pipe going out the top. I think it's called an indirect cylinder.

 

[seco services]

I think it's called an indirect cylinder.

yes indirect.

have you 1 of these next to cylinder ?

or 2 of these ?

 

[davebwithane]

no, but we've got a honeywell box attached to the cylinder.

 

[davebwithane]

here's a photo of it
View media item 19627

 

[davebwithane]

I've just been reading up about indirect cylinder vented systems and am I correct in saying that this is the way the system works ie. the heating has to be on to heat the water as that is the way it seems to be setup ? It looks like the water heating is a by product of the radiators being on. Is that right ?

 

[davebwithane]

Hello

"I've just been reading up about indirect cylinder vented systems and am I correct in saying that this is the way the system works ie. the heating has to be on to heat the water as that is the way it seems to be setup ? It looks like the water heating is a by product of the radiators being on. Is that right ?"

Could anyone tell me if the above description is correct and that is the way the system is supposed to work please ? Seems strange to me that in the summer time my radiators come on just because I need some hot water.
Thanks
Dave

 

[lifesagasman]

while you're waiting for the plumbing types to get out of bed (10.30 is a bit early) have a more thorough search for the above valves on your system. they are usually near to the cylinder, but not always.. the more info you have the easier the diagnosis. it goes without saying that to have heating on to get hot water is not good

 

[StephenW]

I doubt it's the way it's supposed to work. Your photo shows a cylinder thermostat which should switch the boiler off when the water in the tank is up to temperature.
Do you have separate switches for hot water and CH? If you just switch the HW on, does the CH pump run? Is the boiler to cylinder gravity fed or pumped? Do all radiators come on or just upstairs?
If you don't switch the CH on, does the water still heat up OK as well as the radiators?
Might help the experts if you specify what boiler you have.

 

[davebwithane]

Thanks for the replies.

The valves do not exist unless they are under the floor boards somewhere.

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• davebwithane
• 24 Feb 2010
• 1

"Do you have separate switches for hot water and CH? "
There are separate switches for CH and HW on the timer

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• davebwithane
• 24 Feb 2010
• 1

If you just switch the HW on, does the CH pump run?
no the pump does not run

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• davebwithane
• 24 Feb 2010
• 1

Is the boiler to cylinder gravity fed or pumped?
pumped

Do all radiators come on or just upstairs?
All of them

If you don't switch the CH on, does the water still heat up OK as well as the radiators?
No, water does not heat up unless heating is on as well

Might help the experts if you specify what boiler you have.
It's an oil boiler PerryMatic Jetstreme MK III

Also, there is a switch set to the off position on the wall next to the cylinder, no idea what it is for. There is no immersion heater.

Thanks for helping.

 

[Ronald0]

What happens to the pipework either side of the pump?

One side is the hot water flow from the boiler. The other side should go to a tee; one side of this to the hot water cylinder and the other side of the tee to the rads. Try to find the tee; is there a motorised valve located on it?

... but your pump may be on the return.

 

[davebwithane]

I found the tee, but there is no motorised valve, just a normal tee, from there one pipe goes up to the cylinder the other goes down to the rads ..

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• davebwithane
• 24 Feb 2010
• 1

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• davebwithane
• 24 Feb 2010
• 1

 

[lifesagasman]

can you backtrack a little to establish some basics?
with the CH switched off and HW programmed to on, what happens if you run all the hot water out of the tank? does the boiler fire up?
if 'no', is there a stat on the boiler? if you turh that up, does the boiler fire up? if 'no', leave it turned high and go to the tank stat. if you turn that up does the boiler fire up? if 'no', what does the switch next to the tank actually do? if you switch it on does the boiler fire up?
be a little patient on each step as there may be short delays before things happen.
unless the hot water has been run out you can't get a clear picture so now might be a good time to run a bath

 

[davebwithane]

I'll give that a whirl and get back to you later. Thanks.