CH and HW dependence after repairs

[matt1e]

I Don't know the Flamingo or whether it has an over-run stat, but I very much doubt it.

they did (well at least the ones I know of did) but that was many moons ago but I remember you had to wire pump to boiler on fully pump systems but could go to time clock/roomstat on gravity

I found 2 ways to start the heating:
(a) Turn on a hot water tap anywhere in the house and waste a couple of litres of hot water - this kick-starts the circulation pump.

and also the boiler I reckon (I think that the ops possible "running on" pump is confusing the issue in such that he see them in different operating states)

(b) Turn up the cylinder thermostat - to above 70 deg., nearly 80 - does the same. (But water gets too hot with all that follows in terms of comfort, economy and overheating risks).

yup does the same thing as (a) it enables the heating by putting the valve back to mid position when the cylinder stat toggles over to call which then switchs the boiler/pump on

matt

 

[nyamago]

Remember that the current problem didn't exist: when we bought the house, that same system allowed independent start/stop of HW and CH.

After the re-piping, I had to do the (a) or (b) described, i.e. cheat the valve to feed radiators by manipulating the cylinder stat.

That's because the room stat no longer does it (before it did). All this with both HW and CH in 'permanent ON' at the programmer. (God knows what this has done to my energy bills).

Because the boiler is hidden away in the garage, I was never aware if it's running or not. Except on 2 occasions (in the entire 9 years) when it completely stopped and left the house cold (one was when we left the system off for a week and went skiing; the other time - for no apparent reason) - each time I had to go and manually start it.

Now this may tell you something about how connected (or not) the boiler and pump are: when we restarted the system after that winter holiday, the pump was audibly working - but water kept running cold. Which is how I realised the boiler isn't burning. So they can run independently?

Also, because the pump was noisy - it was my indicator that the system is working. Now I've just got a brand new Grundfos (very quiet) and I can now hear the valve motor, which becomes my audible 'ON' light.

 

[D_Hailsham]

There is a switch on the wall next to the programmer, which looks just like a light switch - could that be a 'master' power switch?

.
Very likely - try it and see. But use a meter to check voltages before you start attacking things with your screwdriver and fingers. Also look for a switch/socket/fused spur near the wiring centre. Some systems need to be turned off at two places (bad practice,but it happens).

 

[nyamago]

I think I am narrowing all suspicions to the motorised 3-point valve. At least by the 'walking' method, suggested by matt1e:

When running only HW (CH off at programmer and room stat) the cylinder stat does trigger boiler and pump. However, I didn't notice any movement of the little lever on the 3-point valve: it stays wherever I leave it (I don't even know which position is HW and which - CH; it is only marked 'auto' and 'manual'. I leave it somewhere in the middle and it always stays there).

When running both HW and CH they both work. 3-point valve hums (a vibration of the powerhead is clearly felt by hand; I assume the motor inside is working).

When switching off HW and trying to start the CH by turning up the room stat - nothing happens. Boiler and pump are started only by cylinder stat (while 3-point valve remains as I had left it).

From observations so far it seems that the valve is permanently in middle (A+B) position at all times, regardless of any other controls. Its motor starts every time the boiler and pump are started - but that doesn't change the flow: both the A and the B pipe are always hot.

I am not sure if that lever should be moving or how else do I monitor valve position? (apart from touching the pipes for temperature) - but it seems that something is mechanically stuck and the moving part inside doesn't even reach any microswitch.

I will still need to test electrically this weekend. I will also try to understand why the room stat does not trigger the boiler and pump (the original complaint that started this whole thread).

Another observation: various sources (in this forum, the Honeywell site and elsewhere) suggest that a V4073A with a little bump on the casing has a removable powerhead. The latter, however, doesn't seem to have any screws or other way to remove it from the brass 'T'. Do I need to open the casing to find screws inside and remove the head?

 

[D_Hailsham]

When running only HW (CH off at programmer and room stat) the cylinder stat does trigger boiler and pump. However, I didn't notice any movement of the little lever on the 3-point valve: it stays wherever I leave it (I don't even know which position is HW and which - CH; it is only marked 'auto' and 'manual'. I leave it somewhere in the middle and it always stays there).

1. The valve does nothing when you are running HW only. It is in its "rest" position, which is the HW port open (marked B on the brass valve pipe). The heating is controlled by the HW thermostat.
2. The lever doe not indicate what the valve is doing. If the valve is in the HW open position and you move the lever from AUTO to MAN you will open the valve to mid-position against a spring. The MAN position is used when you are filling the system. In normal use the lever should be in the AUTO position. When the valve has been opened by the motor to CH position or CH+HW the lever will feel floppy.

When running both HW and CH they both work. 3-point valve hums (a vibration of the powerhead is clearly felt by hand; I assume the motor inside is working).

That means the motor is opening the valve to mid position. The lever should feel floppy when you move it. It will not indicate what position the valve is in.

When switching off HW and trying to start the CH by turning up the room stat - nothing happens. Boiler and pump are started only by cylinder stat (while 3-point valve remains as I had left it).

This says that the valve is not moving the the CH port only open (port A).
1. Have you tried (a) leaving HW ON and turning HW stat down; (b)turning HW OFF. They both indicate that HW is not needed, but work in different ways.
2. When you turn HW off, by either method, can you hear the motor working ?

If the motor works with one test but not the other, it's not a valve problem. It's wiring/cylinder thermostat/programmer problem.
If the motor fails to work with either test it's most likely a valve problem.

From observations so far it seems that the valve is permanently in middle (A+B) position at all times, regardless of any other controls. Its motor starts every time the boiler and pump are started - but that doesn't change the flow: both the A and the B pipe are always hot.

This does not tie in with what you said at the start of your post (above) about having CH OFF. Are you now saying that with CH OFF (programmer or room stat) and HW ON botA and B branches of the valve get hot and the radiators warm up? If so, the valve is probably stuck in mid position.

Quick test.
1. Turn power off to heating system (turning programmer to CH OFF and HW OFF is not sufficient
2. Move the valve lever from Auto to Man. You should feel resistance and the lever should return to the Auto position with a whirr when you let go.

If the lever is floppy (no resistance) the valve is stuck in mid position,

Another observation: various sources (in this forum, the Honeywell site and elsewhere) suggest that a V4073A with a little bump on the casing has a removable powerhead. The latter, however, doesn't seem to have any screws or other way to remove it from the brass 'T'. Do I need to open the casing to find screws inside and remove the head?[/quote]
I take it you do have the version with a little bump on the top of the silver cover. If so, remove the screws which hold the silver cover in place. This will expose the motor and inner workings (no water will come out).

 

[nyamago]

Quick test.
1. Turn power off to heating system (turning programmer to CH OFF and HW OFF is not sufficient
2. Move the valve lever from Auto to Man. You should feel resistance and the lever should return to the Auto position with a whirr when you let go.

If the lever is floppy (no resistance) the valve is stuck in mid position

The lever always stays where I leave it

There is always some resistance, but doesn't seem 'the right' resistance - i don't feel as if there is a mechanical transmission or a spring against my push. Just some friction, as if the lever is pressed towards the sides of the slot - just enough not to call it 'floppy' (as in free-hanging).

Just before the 'Manual' end of the path, there is a 4-5mm of spring-like, higher resistance, after which a little 'click' occurs ( a microswitch, I suppose). Nothing like this at the other end, though.

In the above test (power fully OFF), when I let go at the 'Manual' end, there is no whirr and no return movement whatsoever.

And, YES - I am now sure that whatever the combination of HW and CH settings, provided the boiler and pump are working - both A and B are hot. Radiators only remain cold because their thermostatic valves are set to low values. And the boiler and pump can only be started by the cylinder stat, never by the room stat.

The latter remains unexplained (to me, that is). In any case, as soon as I buy a multimeter, I will do all electric tests as well. Will also try to open (and possibly remove) the valve powerhead. Not sure if there is anything I can fix in it, but will at least try to follow and understand its workings.

 

[Homesafe]

i am currently looking at a system with a similar fault the heating doesn't come on but cylinder is hot , even if room stat turned up full nothing happens,

i' m looking at pump when they get back from hols

 

[kevplumb]

spring return valve default pos is hot water

 

[Homesafe]

spring return valve default pos is hot water

is that to me kev ??

 

[kevplumb]

spring return valve default pos is hot water

is that to me kev ??

if you wan't it dear

 

[Homesafe]

ta, luv, thort it wa mi poomp that wa knack'd tho

 

[Agile]

I Don't know the Flamingo or whether it has an over-run stat, but I very much doubt it.

Well you should do as it dates from your era!

One of the problems of helping people in situations like this is that the "standard" way to wire systems may not have been followed. Furthermore Honeywell and Drayton promote slightly different arrangements.

Tony

 

[matt1e]

[
And, YES - I am now sure that whatever the combination of HW and CH settings, provided the boiler and pump are working - both A and B are hot. Radiators only remain cold because their thermostatic valves are set to low values. And the boiler and pump can only be started by the cylinder stat, never by the room stat.

The latter remains unexplained (to me, that is).

I thought I had

this is the point (traveling from mid to heating only) where in a heathy system there is a momentary loss of supply to the boiler ie it will switch off when the cyl stat is satisfied,if the valve is at mid position (CH calling) then the valve will motor on to block the HW port then toggle the micro switch connected between white and orange to restore power to the boiler s/live

but just to clarify
in a correctly wired fully functioning y-plan system
when ever hot woter is in demand
then the boiler is switched on/off via the cylinder stat or HW switch on the programmer
if CH only is in demand then the power to fire the boiler comes from the room stat via the micro switch in the valve head

just a quick point, do you have the ability to have hot water only? (without turning down the trv's)
if so then my money is still on a knackered valve/accuator

do you have a multimeter yet?

note to agile was it not the flamingo's over run timers that were notoreous for failing and running on and on and on

Matt

 

[nyamago]

just a quick point, do you have the ability to have hot water only? (without turning down the trv's)
if so then my money is still on a knackered valve/accuator

I knew this but just checked to make sure:

CH OFF (Room stat to 'Min' and Programmer w CH 'Off')
HW ON (Cylinder stat On at 70 deg, Programmer w HW 'On')
3p Valve on 'Auto', both A and B pipes feel equally hot
Boiler and pump running

In these conditions, opening any TRV gets the radiator hot, despite CH fully 'Off'.

I hope to get a multimeter on Saturday (too busy to go to Maplin's during workdays )

Also - re. Flamingo over-run: when cylinder stat cuts demand, the pump keeps working for a little longer. I haven't clocked it, but it's not more than a couple of minutes. Not sure if this can have anything to do with the above porblem - probably not.

 

[D_Hailsham]

CH OFF (Room stat to 'Min' and Programmer w CH 'Off')
HW ON (Cylinder stat On at 70 deg, Programmer w HW 'On')
3p Valve on 'Auto', both A and B pipes feel equally hot
Boiler and pump running

The valve is sticking in mid position.

Remove the actuator (box on top) and you will see the valve spindle. This should turn easily but about a quarter turn or less.If it is hard to turn, a little WD40 may free it. If that does not work you will have to change the whole valve

re. Flamingo over-run: when cylinder stat cuts demand, the pump keeps working for a little longer. I haven't clocked it, but it's not more than a couple of minutes. Not sure if this can have anything to do with the above problem - probably not.

That's definitely pump overrun; and it's nothing to do with your problem.