Gravity Fed DHW with Pumped CH or fully pumped?

[Jonathan Taylor]

Hello,

I have a Thorn EMI boiler from the 80s and I was wondering if anyone could tell me if i have a gravity DHW and pumped CH, or fully pumped system? There is a valve on the system but i cant remember if its a 3 way or two way valve (i'm currently out of the country with work). Basically my question is, does having a valve (on a very basic system i.e. only one zone CH and DHW) mean that it is fully pumped? I'm looking to upgrade my programmer and installing a room stat, as the display on the current programmer isn't working.

The reasons why i'm questioning if a valve dictates if its fully pumped or not, is because at present we can only have the DHW or DHW + CH - and i just want to see if the older programmer was never upgraded (as when looking at the Potterton LP241 programmer, the wiring diagrams don't show any valve connections for a gravity system)

Its also worth mentioning theres no stat on the cylinder.


Any advise would be much appreciated.

 

[Sharp Point]

Take the lot out and fit a new modern system, the new boiler alone will pay for its self.

 

[Best]

You almost certainly have a fully pumped system if you have a motorised valve and separate hot water facility, but no other zones.

 

[Sharp Point]

You almost certainly have a fully pumped system if you have a motorised valve and separate hot water facility, but no other zones.

Not necessarily, it may be a 'c plan' with gravity hot water and running no cyl stat. The hot water channel on programmer just opens zone valve......if it is a zone valve?

 

[Jonathan Taylor]

Sorry just to reiterate the current programmer won't allow me to have CH only, its either DHW or DHW with CH. But what i don't understand is why this is the case if i have a zone valve? Has the previous owner never bothered to upgrade the outdated programmer?

There is a cylinder stat connected to a TRV type valve.

As for the upgrade - this would be nice, but just not affordable at the moment. We have two boilers, the Thorn EMI (Downstairs CH and DHW) and another boiler Vokera Mynute 20e for CH on the top two floors of the house. I guess we will replace both when they fail beyond repair.

 

[Best]

Sorry just to reiterate the current programmer won't allow me to have CH only, its either DHW or DHW with CH. But what i don't understand is why this is the case if i have a zone valve?

If you have a zone valve after the hot cylinder connection, then when the valve is off you will have hot water only, but when it's on the boiler will heat both water & rads. That's just a simple system design. I could be wrong though

 

[Sparkgap]

Sorry just to reiterate the current programmer won't allow me to have CH only, its either DHW or DHW with CH. But what i don't understand is why this is the case if i have a zone valve? Has the previous owner never bothered to upgrade the outdated programmer?

There is a cylinder stat connected to a TRV type valve.

As for the upgrade - this would be nice, but just not affordable at the moment. We have two boilers, the Thorn EMI (Downstairs CH and DHW) and another boiler Vokera Mynute 20e for CH on the top two floors of the house. I guess we will replace both when they fail beyond repair.

If you've got a motorised valve on it then sounds like it's fully pumped as gravity shouldn't have anything on the circuit to stop the flow otherwise your boiler starts making interesting noises!
A lot of programmers are produced to suit both gravity and fully pumped systems. There's usually a tag or cam or something inside the back of the timeswitch which can be set to release the CH side and allow you to have it on without DHW. Better still get yourself a modern new digital programmer if it's that old!