pump or gravity

[j77drs]

can anyone tell me how to define if i have a pump or gravity system ?

i have a boiler in the kitchen
hot water cylinder in the bathroom ( motorised valve and what looks to be a pump on one of the pipes nr the cylinder )
cold water tank in the loft

 

[bengasman]

can anyone tell me how to define if i have a pump or gravity system ?

Fairly simple: a pumped system has a pump, gravity system doesn't. Today, you are probably looking at 99% of systems being pumped.
There are still some "mixed" systems where the cylinder works on gravity (invariably 28mm pipes) and the heating is pumped.
If you have a 3-port valve of any kind, it is always "fully" pumped.
Why do you want to know?

 

[j77drs]

im changing the timer and it has p or g option ?

i have a motorised valve that operates heating / hw so assuming pumped ??

 

[bengasman]

If the current timer worked fine, use the same setting.
If the 2 zonevalves are on a split from the pipe leading directly to the pump, it is fully pumped.

 

[j77drs]

slightly confused, the drayton instructions indicate gravity as heating cannmot be on without water ??

my wiring only has 4 wire
L
E
ch on
hw on



my old timer was a switchmaster 40 which didnt have the option to change p or g

 

[bengasman]

Are you 100% sure that the new one is a direct replacement? Is it maybe "compatible" which means it needs rewiring? If it is the latter, you need a multimeter and the knowledge how to work them, or get a pro in to do it for you?

 

[D_Hailsham]

Do you have one of these? If so what is the model no? There are two types and it's important to know which it is.

View media item 5946
Or do you have two of these?

View media item 11762
In any case the switch should be set to P.

 

[j77drs]

yes i have the first one,

i called drayton who told me that this was the digital replacement

sm400 ( old timer )
L
E
ch on - port 1
hw on - port 3

lp522
L
E
ch on - port 4
hw on - port 3

they do actually say that there should be another wire in the sm400 ( ch off ) but this isnt there so i ahve just changed as per their instructions

 

[D_Hailsham]

yes i have the first one,

That only solves half the problem

If so what is the model no? There are two types and it's important to know which it is.

I should have made it clear that there are two valves which look like the one you have but they work differently, so I need to know which you have.

 

[j77drs]

i will check tonight but i do know the following

its a honeywell
position of teh motor is in the middle

when calling for hw it goes to the right

when calling for heating it goes the other way

 

[j77drs]

further to this, i have spoken to drayton again who think i have a gravity system as i cannot have the ch on without the hw ?

 

[mickyg]

there's a common phrase...something do with mountains and molehills..
anyway...op
turn on your heating only. Now does your hot water heat up at the same time?
yes= put link on G
no= put link on P

 

[kmeeres]

yes i have the first one,

i called drayton who told me that this was the digital replacement

sm400 ( old timer )
L
E
ch on - port 1
hw on - port 3

lp522
L
E
ch on - port 4
hw on - port 3

they do actually say that there should be another wire in the sm400 ( ch off ) but this isnt there so i ahve just changed as per their instructions

This sounds like a y plan system.
A fairly common design fault with this system is that in order for it to work in heating only an extra signal is required to drive the valve into its third position.
The extra wire from the programmer is require to do this from the HW off terminal on the programmer.

However this is not required if the water has heated up when the valve should go to the heating only position.
This is only true however if the cylinder stat has been wired correctly to give the hw satisfied signal(they sometimes are not).

The cw output from the timer has to be on however for this to work even though the valve should only be open on the heating side.

 

[D_Hailsham]

its a honeywell

That means it is either the V4073A or the V4044C. Which?

The difference between the two valves is that the V4044C can open either the left port or the right port, while the V4073A has a mid-position, so both ports are open.

You say you have an LP522. This should have six terminals: N, L ,1 ,2 3 and 4. Terminal 1 is HW OFF, 2 = CH OFF, 3= HW ON, 4= CH ON.

If you have the V4044C then you just need to connect to terminals 3 and 4 (and L and N of course), as advised by Drayton.

If you have a V4073A, you should also have a wire connected to HW OFF (terminal 1).

The Switchmaster 400 does not have a HW OFF terminal, so you may have the V4044C valve. But if you have theV4073A valve, someone has cannibalised the wiring to make it "work" with your SM400. This would explain why you have to have HW on when the CH is on.

Come back with the info about your valve and you will be told how to wire it so you have CH and HW separately.

 

[j77drs]

its a V4073a

just looked at the switchmaster 400 and it does have a terminal for hw off but no wires are left spare,