Zone Valve - fitted correct way ?

[Vee239]

Possibly a dumbass question which reveals an almighty cock up but here goes . . any advice much appreciated.
<y parents have a Potterton 10/16 boiler with hw cylinder in the loft.
No room stat connected.
An old 2 way zone valve was stuck open as they could never get hot water only.
Other than this the system appeared to be fine.

A couple of thermostatic valves on the downstairs rads started to leak so I drained down the system and changedthem.
At the same time I replaced the old 2 way zone valve, a 20+ year old ACL672ABL1. The new one is a Honeywell V4043.
I haven't wired up the new zone valve as not sure of the connections (waiting on an electrician friend to spare me 30 mins).
As the Honeywell defaults to closed I assumed that if I left the valve on manual both HW and CH would be on all the time (acceptable for a week or so until said mate gets some time).

After I refilled the system the heating worked fine but there was no flow to the hw cylinder. I opened the flow & return to the coil to release any air which may have been trapped.

My father has since discovered that if he puts the zone valve to Auto the hw heats up. On Manual, only ch works. There is no water hammer or knocking pipes whichever position the valve is in.

The old zone valve had no markings on it showing flow direction. The new one did so I fit it with the Auto/Manual switch at the top (same as the ACL one).
Before I drain down and swap over, would a zone valve fitted the wrong way around cause only hw or ch to work when left on manual ? or is something entirely unrelated likely to be the problem.

Thanks very much

 

[EliteHeat]

This sounds like a 3-port valve to me.

 

[D_Hailsham]

An old 2 way zone valve was stuck open as they could never get hot water only.

Was this the only zone valve?
Was it in the circuit to the HW cylinder?
How many wires connected to the old ACL valve?

The new one is a Honeywell V4043.

22mm or 28mm?
Is it the B, C or H version?

 

[D_Hailsham]

This sounds like a 3-port valve to me.

I think even the greenest DIYer would be able to tell the difference between

View media item 5945 and View media item 5946

 

[Vee239]

An old 2 way zone valve was stuck open as they could never get hot water only.

Was this the only zone valve?
Was it in the circuit to the HW cylinder?
How many wires connected to the old ACL valve?

Yes, the only one.
Not sure which circuit it's on but assumed the system would always feed the hw coil and the ch circuit only when required. ie valve defaults to closed and when opened allows hw to the ch circuit..
I need to check the pictures but pretty sure 5 (inc earth).

The new one is a Honeywell V4043.

22mm or 28mm?
Is it the B, C or H version?

22mm, will come back to you on the version. It does say normally closed, but I think they all do.

I've got a picture of the pipework.
Would appreciate if anyone can identify what is what and let me know what water flows where.
I've got a limited understanding and think the following . .

A = Vent (over f/e tank)
B = Motorised Valve
C = Cold feed
D = Vent
E = to HW cylinder
F = to CH circuit

Untitled

• Vee239
• 16 Dec 2008
• 1

As ever, thanks for any advice.

 

[matt1e]

hi Vee I've edited your list

A = Flow
B = Motorised Valve to central heating
C = Cold feed
D = still flow but vent after the tee above the tee labeled C
E = to HW cylinder
F = position where you would expect a mid position valve to be

An old 2 way zone valve was stuck open as they could never get hot water only.

I don't understand this do you mean

"An old 2 way zone valve was stuck open SO they could never get hot water only"?

Anyway if the hot water and the central heating worked before you changed the valve then I think the problem lies in an airlock in the cylinder coil I know you have bled it but looking at the pipework any air still in the system on the return side will head to the cylinder (via pipe adjacent to pipe E)so bleed it again other than that problem lies with imbalance between the HW/CH circuits

 

[Vee239]

hi Vee I've edited your list

A = Flow
B = Motorised Valve to central heating
C = Cold feed
D = still flow but vent after the tee above the tee labeled C
E = to HW cylinder
F = position where you would expect a mid position valve to be

An old 2 way zone valve was stuck open as they could never get hot water only.

I don't understand this do you mean

"An old 2 way zone valve was stuck open SO they could never get hot water only"?

Anyway if the hot water and the central heating worked before you changed the valve then I think the problem lies in an airlock in the cylinder coil I know you have bled it but looking at the pipework any air still in the system on the return side will head to the cylinder (via pipe adjacent to pipe E)so bleed it again other than that problem lies with imbalance between the HW/CH circuits

Thanks for the response MAtt, especially at 3am !
I meant that I assumed the valve must have been stuck open due to the fact they could not get hw only.
Will bleed the coil again today.
Thanks for explaining the pipework, on which I have one more q. The flow on the pump is up. Is this correct ?

 

[Softus]

If 'A' is the flow from the boiler, then:-

1. The pump should be pumping down.
2. The vent and cold feed and wrongly connected.
3. You've fitted the zone valve the right way round.

The whole design is shameful, and the situation is probably that the cylinder gets flow only when the CH zone valve is shut because it's been put on the pumped circuit.

You really really need a room thermostat, and you'd be well advised to put the cold feed connection between vent and pump.

 

[Vee239]

If 'A' is the flow from the boiler, then:-

1. The pump should be pumping down.
2. The vent and cold feed and wrongly connected.
3. You've fitted the zone valve the right way round.

The whole design is shameful, and the situation is probably that the cylinder gets flow only when the CH zone valve is shut because it's been put on the pumped circuit.

You really really need a room thermostat, and you'd be well advised to put the cold feed connection between vent and pump.

Thank you Softus.
This was installed well over 20 years ago.
I believe my father has changed the pump at some point in the past and would think he would have checked the flow direction.
However, I can now see what you mean but will try and establish what the system should be doing. Again it worked with the old zone valve.

What I'd like to understand is why CH and HW both came on with the old zone valve but don't with the new one ?

As for a room stat, I'll get one at the weekend.

 

[Tipper]

Seems to be a very old system to me and they did things different in them days!

On some old setups the pump is in the return as is the cold fill, but vent on the flow. You need to establish the intended flow direction.

Also is there a cylinder thermostat? If so then the valve may only be there to limit the HW temperature when the CH is on as the HW will overheat without it.

Once you've got to the bottom of the system you would benefit from a room thermostat and either a second zone valve or 3-way valve to best control both CH and HW.

 

[Vee239]

Seems to be a very old system to me and they did things different in them days!

Indeed it is.

On some old setups the pump is in the return as is the cold fill, but vent on the flow. You need to establish the intended flow direction.

Also is there a cylinder thermostat? If so then the valve may only be there to limit the HW temperature when the CH is on as the HW will overheat without it.

There is only a stat on the top of the cylinder, in the immersion element.
Does this mean we can exclude the valve being there to limit the HW temperature and assume its for the CH flow ?

 

[Softus]

This was installed well over 20 years ago.

I very much doubt that it was installed like that. There are signs that it's been modified, and you've already said that the cylinder was moved.

I believe my father has changed the pump at some point in the past and would think he would have checked the flow direction.

It doesn't matter what he did, and whether or not he did it correctly at the time.

However, I can now see what you mean and will swap it over.

Don't change anything until you've established what's wrong and what needs doing.

You need to establish, with utter certainty, which pipe is the flow from the boiler.

Then you need to verify that this pipe leads to the inlet port of the pump.

What I'd like to understand is why CH and HW both came on with the old zone valve but don't with the new one ?

You said that the old valve was stuck open. Was that a fact, or just supposition?

As for a room stat, I'll get one at the weekend.

It isn't as simple as getting one.

Do you know what to buy? Will it be wired or wireless? Will you know how to connect it?

 

[Vee239]

Very appreciative of the time being taken to respond here . .

This was installed well over 20 years ago.

I very much doubt that it was installed like that. There are signs that it's been modified, and you've already said that the cylinder was moved.

HW cylinder was never moved
Until I changed the zone valve both hw and ch came on whenever the hw was called for.
I'm sure its never been modified but obviously cannot be certain. What are the signs ?

You need to establish, with utter certainty, which pipe is the flow from the boiler.
Then you need to verify that this pipe leads to the inlet port of the pump.

Agreed - how can I do this ? Turn on from cold and see which pipe heats up first ? Obviously one of the 22mm ones is from the boiler.

What I'd like to understand is why CH and HW both came on with the old zone valve but don't with the new one ?

You said that the old valve was stuck open. Was that a fact, or just supposition?

Supposition on the basis that they used to be able to ask for HW only but recently the CH has been coming on too.
My assumption is the valve was stuck open - would appreciate your educated view though.

As for a room stat, I'll get one at the weekend.

It isn't as simple as getting one.
Do you know what to buy? Will it be wired or wireless? Will you know how to connect it?

No idea - will pick up a wireless one and was hoping to get my leccy mate to do it.

 

[Softus]

HW cylinder was never moved

I apologise - I must have read that on another topic. Very sorry.

You need to establish, with utter certainty, which pipe is the flow from the boiler.
Then you need to verify that this pipe leads to the inlet port of the pump.

Agreed - how can I do this ? Turn on from cold and see which pipe heats up first ? Obviously one of the 22mm ones is from the boiler.

Turning on won't necessarily reveal this, because if it's pumping the wrong way round then the 'flow' will still get hot.

Look at the back of the boiler, at the pipe coming from the top of the heat exchanger. Can you follow the route of that pipe?

The pump flow direction is marked on the side of the pump body.

You said that the old valve was stuck open. Was that a fact, or just supposition?

Supposition on the basis that they used to be able to ask for HW only but recently the CH has been coming on too.
My assumption is the valve was stuck open - would appreciate your educated view though.

If you have no controls on the system that that's a reasonable supposition.

will pick up a wireless one and was hoping to get my leccy mate to do it.

Good plan.

 

[Vee239]

Some more reading came up with this diagram . . which seems to match the pipework except for the cold feed position.

Untitled

• Vee239
• 17 Dec 2008
• 1

On the actual pipework, the direction on the pump is up, therefore it's the wrong way around ?

Untitled

• Vee239
• 16 Dec 2008
• 1

[/img]